US3000148A - Two-lap lapping machine - Google Patents

Description

Sept: 19, 1961 H. F. BOVENSlEPEN TWO-LAP LAPPING MACHINE 3 Sheets-Sheet 1 Filed Dec. 28, 1959 jm eman' v I p 1961 H. F. BOVENSIEPEN 3,000,148

TWO-LAP LAPPING MACHINE Filed Dec. 28, 1959 3 Sheets-Sheet 2 Fig. 3

.[UI QULUI. Hm 1:14AM w Sept. 19, 1961 H. F. BOVENSIEPEN 3,000,143

TWO-LAP LAPPING MACHINE Filed Dec. 28, 1959 3 Sheets-Sheet 3 Fig. 4

United States Patent 6 3,000,148 TWO-*LAP LAPPlNG MACHINE Hans Friedrich Bovensiepen, Hasselerstr. 32, Mettmann, Rhineland, Germany Filed Dec. 28, 1959, Ser. No. 862,418 14 Claims. (Cl. 51-111) The present invention relates to lapping or abrading machines in general, and more particularly to a two-disc lapping or grinding machine of the type wherein one of the discoid lapping or grinding members is swingable with the upper frame part about a vertical axis into alignment with and laterally away from the other lapping or grinding member.

In presently known machines of this general character, it was considered necessary to remove the lapping or grinding members from the machine when the abrading surfaces of such members were unevenly worn away beyond a permissible extent. The lapping or grinding members were then placed into special machines and subjected to the turning or restoring action of a rotary cutting tool or to the truing action of a diamond to restore the finish of their surfaces.

It was already proposed to avoid the time-consuming and cumbersome removal of lapping or grinding members from such machines by the provision of an adjusting or dressing tool which is mounted on a swingable arm permanently fastened to the trough of the machine frame. The adjusting or dressing tool comprises a steel cutter or a truing diamond which is swingable with the arm along the abrading surface of the upper or lower lapping or grinding member to impart a required finish to the surface. A disadvantage of such construction is in that it requires a number of costly precision-finished supporting parts for the dressing tool and also in that it occupies too much space in a lapping or grinding machine. In addition, since the maximum distance between the two lapping or grinding members is comparatively small, the dimensions of the aforementioned swinging arm for the dressing tool must be held as low as possible, which, in turn, renders it difficult to insure a rigid mounting of the dressing tool such as would prevent the formation of chatter marks on the trued or refinished surfaces.

An important object of the present invention is to provide a two-lap lapping or grinding machine which is combined with a dressing or surface-restoring tool and a novel drive for the upper part of the machine frame, and wherein the dressing tool may be used for refinishing of surfaces on both lapping or grinding members without leaving any chatter marks on the treated surfaces and without requiring removal of the lapping or grinding members from the machine.

Another important object of the invention is to provide a machine of the above outlined characteristics which embodies two seats for the dressing tool and wherein the seats are provided at such points of the machine as to require no dimensional changes in the latters construction.

A further object of the instant invention is to provide a machine of the above outlined type wherein the mounting of the dressing tool in each of its positions is such as to positively prevent rattling of the tool when the latter is in actual use.

A concomitant object of the invention is to provide a novel drive for the swingable part of the lapping or grinding machine which is adapted to bring the dressing tool into contact with each zone of the operating surfaces on the lapping or grinding members, which is of very simple construction, which occupies little space, and which may be readily installed in the lapping or grinding machines of presently known design.

With the above objects in view, the invention resides in the provision of a lapping or grinding machine which itlddjs ice comprises a stationary lower frame member for rotatably supporting a discoid lower lapping or grinding member, and an upper frame member which carries the upper lapping or grinding member and is swingable about a vertical axis to move the upper lapping or grinding member into alignment with or laterally away from the lower lap plug or grinding member. Each frame member is provided with a seat for rigidly but removably receiving the holder of a surface-restoring or dressing tool, and the upper frame member is combined with a novel drive which imparts thereto a swinging or pendulum movement in order to move the abrading surface of the upper lapping or grinding member into contact with the dressing tool when the latters holder is mounted in the seat of the lower frame member, or to move the dressing tool into contact with the exposed surface of the lower lapping or grinding member when the holder of the dressing tool is mounted in the seat of the upper frame member.

In the following part of this description, the generally discoid or annular members whose surfaces may be treated by the dressing tool will be referred to as lapping members or laps and the machine as a lapping machine. However, it should be understood that the invention may be embodied in a two-disc grinding machine in which event the dressing tool, i.e. a diamond, is utilized for refinishing the abrading surfaces on the upper and lower grinding disc.

It is preferred to provide the seat in the upper frame member coaxially with the upper lap, i.e. in the latters hub. The seat in the lower frame member is preferably provided in the customary trough for the lower lap at a point close to the latters periphery. The improved drive for imparting swinging or pendulum movements to the upper frame member is preferably installed at a point adjacent to the vertical bearings in which the upper frame member is swingably mounted on the lower frame memher. The provision of the drive at such a point requires no increases in the dimensions of the machine and also insures ready access to all parts for inspection or repair of the drive, if necessary.

The pendulum movements of the upper frame member under the action of my improved drive are comparatively slow. In order to insure a uniform and fully controlled movement which is free of rattling, i.e. a movement which cannot cause the formation of chatter marks on the treated lap surfaces, the movable components of the upper frame member are subjected to a residual or initial stress so as to prevent any other but strictly pivotal movements of the upper frame member about a vertical axis. Such residual stress may be generated and its magnitude varied by a throttle valve which forms part of the hydraulic actuating and control system for the pendulum drive. The latter comprises a gear segment mounted on the lower frame member and a series of gears which are alternately rotated in opposing directions by a system of toothed racks and pistons. When the gears are moved into mesh with the segment, the upper frame member is caused to perform pendulum movements with respect to the lower frame member.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of a specific embodiment when read in connection with the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic side elevational view of the two-lap lapping machine embodying my invention with certain parts of the frame and both lapping members shown in vertical section;

FIG. 2 is a top plan view of the lapping machine with the upper lapping member pivoted laterally and out of vertical alignment with the lower lapping member;

FIG. 3 is a front elevational view of the lapping machine in the position of FIG. 2, certain parts of the frame and both lapping members being shown in vertical section substantially as seen from the line III-III of FIG. 1 in the direction of arrows;

FIG. 4 is a greatly enlarged schematic partly elevational and partly sectional view of the drive for reciprocating the upper part of the machine frame and the upper lapping member;

FIG. is a fragmentary detail sectional view of a gear arrangement forming part of the drive, the section of FIG. 5 being taken along the 1ine.V-V of FIG. 4, as seen in the direction of arrows;

FIG. 6 illustrates the hydraulic control and actuating system including the pumping device utilized for imparting motion to the drive of FIG. 4; and

FIG. 7 illustrates in different position a slide valve which forms part of the hydraulic control system shown in FIG. 6.

Referring now in greater detail to the drawings, and first to FIGS. 1 to 3, there is shown a two-lap lapping machine L which comprises a frame consisting of a lower frame member or base 1 and an upper frame member 9. The base 1 is formed with a trough 2 which is provided with a lateral extension 3. The trough 2 surrounds a discoid lower lapping member or lap 4 which is rotatably mounted on a vertical shaft and is driven by a suitable motor through a system of non-represented pulleys and endless belts or the like. The means for rotating the lower lap 4 is installed in the base 1 and is accessible through the doors 5 and 6 shown in FIG. 1. The base 1 also comprises or is rigidly connected with a vertical center column or support 7 for the bearing sleeve 8 of the upper frame member 9. The latter is swingable about the vertical axis of the sleeve 8 between a first position (FIG. 1) in which its head 12 is located above the trough 2 and lower lapping member 4, and a second position (FIGS. 2 and 3) in which the head 12 is located above the lateral extension 3. The lower end of the sleeve 8 is rotatably mounted in a needle bearing 10.

The head 12 of the swingable upper frame member 9 rotatably supports a discoid upper lapping member or lap 11. The latters non-represented shaft is vertically reciprocable in a spindle sleeve 13 extending downwardly from the head 12, i.e. the upper lap 11 is reciprocable toward and away from the upper side or lapping surface of the lower lap 4. When the upper frame member 9 is in the position of FIGS. 2 and 3, the upper lap 11 is completely surrounded by the trough extension 3.

The hub 14 of the upper lap 11 is formed with a coaxial retaining seat 15 for the holder '16 of a dressing or truing tool 17. Since the drawings show two lapping members 4, 11 in the form of grinding discs, the tool 17 is a truing diamond. The tool holder '16 is formed with a coaxial centering pin or trunnion 19 which is snugly received in the seat 15 of the hub 14. The tool holder 16 may be readily removed from the seat 15 (FIG. 1) and transferred into the position of FIG. 3, i.e. mounted in the trough 2 adjacent to the periphery of the lower lap 4. The trough is formed with a seat 18 which corresponds to the seat 15 in the hub 14 of the upper. lap 11 and is adapted to receive the centering pin 19 of the tool holder 16. The tool holder further comprises an annular flange 20 which may be removably secured to the hub 14 (FIG. 1) or to the trough 2 (FIG. 3). For example, the flange 20 may be fastened to the part 14 or 2 by a number of screws or the like. It will be noted that the tool holder is adapted to be mounted concentrically with the upper lap 11 but is eccentric to the lower lap 4 when in the position of FIG. 3. This is due to the fact that the hub of lower lap 4 normally affords no room for the formation of a seat (such as the seats 15 and 18) because the space necessary for such a seat is occopied by the drive means which rotates the lapping members. The non-represented shaft of the upper lap 11 is preferably rotated by the same drive which also rotates the lower lap 4. The laps 4, 11 may be rotated in opposing directions or in the same direction but at different speeds, depending upon the nature of desired finish and the material of the work pieces to be treated in the lapping machine.

Both positions of the tool holder 16 are indicated in FIG. 2 by the reference numerals 16, 16", respectively. When in the position 16, the tool holder is mounted in the hub 14 of the upper lap 11. Numeral 16 indicates the position of the tool holder 16 in the trough 2 adjacent to the lower lap 4. The tool holder is mounted in the position 16' or 16" only when in actual use for refinishing the lapping surfaces of members 4, 11 but is removed from the machine L when the latter is in operation to lap the surfaces of non-represented work pieces which are then placed onto the upper side of the lower lap 4 and subjected to a requisite lapping load by the upper lap 11.

It will be noted that, in either of its positions 16, 16", the tool holder 16 occupies readily available and accessible space in the lapping machine. Owing to the rigid mounting in the axis of the upper lap 11 or on the solid trough 2 of the machine base 1, the reaction force of the tool 17 is taken up without any lateral movements of the tool holder 16 with respect to its seat so that the truing of lapping surfaces on the lap 4 or 11 may be carried out without the formation of chatter marks. When in the position 16, the tool holder is swingable with the upper frame member 9 whose mounting is suificiently rigid to prevent any deflection of the tool holder under comparatively low reaction forces which develop when the tool 17 is in actual use.

At the lower end of the sleeve 8, there is provided a novel hydraulically actuated swinging or pendulum drive 21 which is adapted to reciprocate the upper frame member 9 with the tool holder 16 (in the latters position 16) when the operator desires to treat the upper side of the lower lap 4. Alternately, when the tool holder is in the position 16", the swinging movements of the upper frame member 9 caused by the drive 21 will enable an operator to treat the underside of the lap 11. The drive 21 comprises a stationary toothed segment 23 which is mounted in a horizontal plane and is rigidly fixed to the center support 7. The gear segment 23 is adapted to mesh with a system 22 of two gears including a lower gear 25 and an upper gear 28. These gears are mounted on a coaxial vertically reciprocable shaft 26 which is carried by the frame member 9 or its sleeve 8 and is constantly biased in upward direction by a helical spring 24, the latter having its upper end anchored in the upper frame member 9.

The drive 21 is shown in greater detail in FIG. 4. The upper end of the shaft 26 carries a third gear 27. The gear 28 is rotatable on the median portion of the shaft 26 between the gears 25 and 27 which latter are rigid with the member 26. The gears 25, 27 and 28 are of identical diameters and are formed with the same number of equally shaped teeth. The axial length of gears 27, 28 is such that their teeth remain in permanent mesh with a pair of horizontal toothed racks 29, 30, respectively, despite any vertical displacements of the shaft 26 which latter is capable of performing an axial stroke h. When the shaft 26 reaches the lower end of its stroke (in the position of FIG. 4), not only the gear 25 but the gear 28 also meshes with the gear means 23. When the shaft 26 reaches the upper endof the stroke h, the gears 25 and 28 are moved out of mesh with the segment 23, i.e. the length of stroke it exceeds the height of they segment 23. In the position of FIG. 4, the gear 25' meshes with the lower half of the segment 23. whose upper half is then in mesh with the gear 28. In the uppermost position of the shaft 26, the gear 28 meshes solely with the toothed rack 30. Racks 29 and 30 are carried by the sleeve 8 and are swingable with the upper frame member 9 about the column 7.

The upper end of the gear 27 terminates in a plunger 31 which is reciprocable in a vertical cylinder 32. The rod 33 of the plunger 31 extends through the upper end wall of the cylinder 32 and is connected with the lower end of the aforementioned resilient element 24. Thus, not only the shaft 26 with the gears 25, 27 and 28, but the plunger 31, too, is permanently biased in upward direction.

It is assumed in FIG. 4 that the plunger 31 is rotatable in its cylinder 32. However, it is equally possible and normally preferred to provide a rotary connection between the plunger 31 and the uppermost end of the gear 27 so that the plunger need not and preferably should not rotate but is merely axially reciprocable in its cylinder 32.

The longitudinal ends of the upper toothed rack 29 are connected to a pair of pistons 34, 35 which are reciprocable in cylinders 38, 39, respectively. In the same manner, the ends of the lower toothed rack 30 carry a pair of pistons 36, 37 received in cylinders 40, 41, respectively. The piston pairs 34, 35 and 36, 37 always move in unison because the segment 23 is normally in mesh with the gear 25 and the latter is rigidly connected with the gear 27 by means of the common shaft 26. Also, in the position of FIG. 4, the gears 25, 27 and 28 necessarily rotate in unison since the gear 28 meshes with the segment 23 as well as with the toothed rack 30, i.e. the gears 25 and 27 cannot rotate with respect to the third gear 28.

The actuating and control system for the cylinders 32, 3839 and 4041 comprises a slide valve 46 which is shown in FIG. 6. This valve is connected with cylinders 32, 38, 39, 4t) and 41 by means of conduits 48, 42, 43, 44 and 45 in that order. The conduit 48 has a branch line 48a which extends into a source of hydraulic fluid shown in FIG. 6 as a liquid tank T. The pumping device 47, e.g. a rotary gear pump, is installed in the line 48a and delivers fluid pressure medium into the conduit 48 and through the latter to the cylinder 32 and slide valve 46. The valve 46 is connected with a throttle or choke valve 49 by means of a conduit 50 and the latters branch line 50a. A conduit 51 connects the throttle valve 49 with the tank T; this conduit has a pair of branch lines 51a, 51b, both connected with the housing of the slide valve 46. The hydraulic control and actuating system for the drive 21 further comprises an overflow or pressure relief valve 52 which is mounted in the conduit 52a connected to the conduit 48a at the pressure side of the pumping means 47 and leading into the liquid tank T. The valves 46, 49 are provided with actuating handgrip means in the form of knobs 53, 54, respectively. The knob 53 is utilized for axially displacing the shiftable member of slide valve 46. The other knob 54 is used for rotating the valve member in the housing of throttle valve 49.

Alternately, when the hydraulic actuating means of FIG. 6 and the drive of FIG. 4 operates without a separate pumping device 47, the conduit 48 may be connected to the main fluid pump of the lapping machine. In such instances, a shutofi valve must be provided in the line 48, or the slide valve 46 must be modified to be movable into a position in which it prevents the flow of fluid from the conduit 48 into the hydraulic cylinders.

The hydraulic system operates the drive 21 as follows:

When the pump 47 is in operation, its pressure side delivers hydraulic fluid through the lines 48a, 48 into the cylinder 32. The upper side of the plunger 31 is subjected to fluid pressure and the latter performs a downward stroke to move the gears 25, 27 and 28 against the bias of spring 24 into the position of FIG. 4, i.e., the gears 25, 28 come into mesh with the stationary segment 23. The shiftable member including the knob 53 of the slide valve 46 is in the position of FIG. 6 and permits the flow of fluid pressure medium from the conduit 48 into the conduit 44 and into the lower left-hand cylinder 40. The fluid acts against the exposed side of the piston 36 and moves the latter, together with the toothed rack 30 and piston 37, in a direction to the right. The rack 30 rotates the gear 28, together with gears 25, 27, i.e. the upper rack 29 participates in the movement of the lower rack 30. The sleeve 8 is swung about the vertical axis of the column 7 to cause a corresponding movement of the upper frame member 9 with respect to the lower lap 4 and the tool holder 16 if the latter is installed in the seat 18 of trough 2. If the tool holder 16 is installed in the seat 15 of hub 14, it moves with the upper frame member 9 relative to and along the upper side of the lower lap 4. The piston 37 expels the fluid from the cylinder 41 and through the line 45 toward the slide valve 46. Since the conduit 45 then communicates with the conduit 42 (see FIG. 6), the fluid from the cylinder 41 is free to flow into the upper left-hand cylinder 38. As is shown in FIG. 4, the volume of cylinder 38 is smaller than that of the cylinder 41; therefore, the former can receive only a part of the fluid discharged from the cylinder 41, the remaining fluid flowing through the branch line 51b and through the conduit 51 back into the tank T. No fluid pressure exists in cylinders 38 and 41.

As the piston 35 moves in a direction to the right (under the action of the gear 27), it expels fluid from its cylinder 39 into the conduits 43 and 50, the fluid overcoming the resistance of the throttle valve 49 and being discharged into the conduit 51 to return into the tank T. If the throttle valve is completely closed, the pistons cannot move and the drive 21 is brought to a halt. On the other hand, if the valve 49 is in its fully open position, the fluid flowing through the lines 43, 50 and into the conduit 51 meets no resistance whatever and, consequently, the operation is completely undamped.

It is now assumed that the setting of throttle valve 49 is such as to cause this valve to absorb one-half the driving energy of the piston 36, and also that the gear 28 acts against the segment 23 with a given force P. Thus, the upper frame member 9 is subjected to a net rotating force P/2 while the segment 23 transmits the other half of the total force P to the gear 25. The force P/ 2 transmitted to the gear 25 is the reaction of the braking force which, according to the momentary position of throttle valve 49, is transmitted by the piston 35. Thus, the meshing toothed parts and the bearings of the drive 21 are subjected to an initial or residual load which prevents any play or rattling between the relatively movable components, i.e. the upper frame member 9 is moved without rattling which is an important requirement for the treatment of lapping surfaces on members 4, 11 without the formation of chatter marks. The ratio of pressure surfaces on the pistons 36, 34 equals the ratio of force P to the force P/2, i.e. in the above example the cross-sectional area of the piston 34 equals one-half of cross-sectional area of the piston 36. Even if the ratio of the cross-sectional areas of pistons 36, 34 were reduced, i.e. were the area of piston 34 increased, this would bring about only slight changes in operation of the hydraulic system. The fluid pressure in the conduit 43 would drop but the speed of fluid flow in this conduit would increase accordingly.

When the slide valve 46 assumes the position of FIG. 7, the pressure line 48 communicates with the line 45 so that the piston 37 urges its associated toothed rack '30 in the opposing direction. The piston 36 participates in the movement of parts 30, 37 and expels the fluid from its cylinder 40 into the conduit 44. The latter communicates with the conduit 43 whereby the fluid flows into the cylinder 39 at the right-hand side of the piston 35. Since the volume of the cylinder 40 is greater than the volume of cylinder 39, the remaining fluid is discharged into the line 51a and flows back into the tank T. The throttle valve 49 partially blocks the flow of fluid from the line 42 (conduits 50a, 50) whereby the piston 34 provides the 7 braking force necessary for the generation of a residual stress.

When the pump 47 is arrested, the fluid pressure in the conduit 48 drops to zero. The spring 24 is then free to lift the plunger 31 with the gears 25, 27 and 28 into the uppermost position and thereby moves the gears 25, 28 out of mesh with the segment 23. The fluid expelled from the cylinder 32 flows through the lines 48, 48a and through the inactive pump 47 back into the tank T. The evacuation of the cylinder 32 need not occur at a rapid rate since, when the truing of a lapping surface is completed, the upper frame member 9 normally continues its pendulum movements for a certain period of time. Suitable limit switches or the like may be provided for reciprocating the knob 53 of slide valve 46 at certain intervals so as to move the shiftable member of this valve between the positions of FIGS. 6 and 7 in a fully automatic way in order to reverse the direction in which the upper frame member 9 moves with or with respect to the tool holder 16 and the tool 17.

The distance (1, indicated in FIG. 2, equals the effective width of the lappingsurfaces on the members 4 and 11. Depending upon the extent to which these surfaces must be treated by the tool 17, the distance a may be covered once or more than once without changing the angular position of the member 4 or 11.

When the drive 21 causes the upper frame member to perform its swinging movements with respect to the lower lap 4 either with or relative to the tool holder 16, the lap Whose surface is being treated is in continuous rotary motion.

For the purpose of making ineffective the bearing clearance of the upper lap 11 during the abrading it is advantageous to bring the upper lap 11 into its highest position towards a limitation and to construct the dressing tool 16 vertically adjustable.

In this case the spindle sleeve acts in opposition to the head 12 of the upper frame member 9 as a non-yielding fastened body.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is: I

1. In a lapping machine, in combination: a base having a seat; a lower lap having an upper surface and rotatably mounted in said base; an upper frame member having a seat and connected to said base for movement about a vertical axis; an upper lap having a lower surface, rotatably mounted in said upper frame member, and movable with the latter into vertical alignment with and laterally away from the lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in said first mentioned seat and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in said last mentioned seat.

2. In a lapping machine, in combination: a base having a seat; a lower lap having an upper surface and rotatably mounted in said base; an upper frame member connected to said base for movements about a vertical axis; an upper lap having a lower surface and a hub rotatably mounted in said upper frame member and formed with a seat, said upper lap movable with the upper frame member into vertical alignment with and laterally away from the lower lap; a tool holder removably receivable breach of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in said first mentioned seat and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in said last mentioned seat, said drive comprising means for preventing rattling of said frame member and for thereby preventing the formation of chatter marks in said surfaces.

3. In a lapping machine, in combination: a base having a trough; a lower lap having an upper surface and rotatably mounted in said trough, the trough having a seat adjacent to said lower lap; an upper frame member having a seat and connected to said base for movements about a vertical axis; an upper lap having a lower surface, rotatably mounted in said upper frame member, and movable with the latter into vertical alignment with and laterally away from the lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in said first mentioned seat and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in said last mentioned seat, said drive comprising means, for preventing rattling of said frame member and for thereby preventing the formation of chatter marks in said surfaces.

4. In a lapping machine, in combination: a base having a trough; a lower lap having an upper surface and rotatably mounted in said trough, the trough having a seat adjacent to said lower lap; an upper frame member connected to said base for movements about a vertical axis; an upper lap having a lower surface and a hub rotatably mounted in said upper frame member and formed with a seat, said upper lap movable with the upper frame member into vertical alignment with and laterally away from the lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising means for preventing rattling of said frame member and for thereby preventing the formation of chatter marks in said surfaces.

5. In a lapping machine, in combination: a base having a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear means mounted on said column, second gear means carried by said upper frame member and movable into mesh with the first gear means, and hydraulic means for alternately rotating the second gear means in opposing directions whereby to reciprocate the upper frame member about said column, said hydraulic means comprising throttle valve means for subjecting said gear means to a residual stress to prevent other than pivotal movements of the upper frame member about said column.

6. In a lapping machine, in combination: a :base having a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about -a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear meansmounted on said column, second gear means comprising a first and a second gear member each mounted on said upper frame member and each movable into mesh with said first gear means, and hydraulic actuating means for alternately rotating the second gear member in opposing directions whereby to reciprocate the upper frame member about said column, said actuating means comprising throttle valve means operatively connected with said first gear member for subjecting the latter and said first gear means to a residual stress to prevent other than pivotal movements of the upper frame member about said column.

7. In a lapping machine, in combination: a base having a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear means mounted on said column, second gear means including a vertical shaft mounted on said upper frame member, a first gear member mounted at the lower end of said shaft, a second gear member mounted at the upper end of said shaft, and a third gear member mounted on the shaft between said first and second gear members, said first and third gear members movable by the shaft into and out of mesh with said first gear means, a first and a second toothed rack meshing with said second and third gear member, respectively, a first and a second pair of pistons connected to the ends of said first and second rack, respectively, cylinder means for each of said pistons, and hydraulic actuating means for said pistons including a source of fluid, conduit means connecting the source with said cylinder means, pump means for circulating the fluid in said conduit means, first valve means for regulating the flow of fluid to and from said cylinder means in such a way that the fluid alternately moves said second rack in opposing directions whereby to reciprocate the upper frame member about said column, and second valve means for controlling the flow of fluid from the cylinder means of said first pair of pistons whereby to subject the first gear member and the first gear means to a residual stress for preventing other than pivotal movements of the upper frame member about said column.

8. In a lapping machine, in combination: a base having a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear means consisting of a gear segment mounted in a horizontal plane on said column, second gear means including a first gear member and a second gear member each mounted on the upper frame member, said gear members coaxial with each other and both movable in vertical direction into and out of mesh with the segment, the first gear member adapted to mesh with the lower half of the segment and the second gear member then meshing with the upper half of said segment, and hydraulic actuating means for alternate- 1y rotating the second gear member in opposing directions whereby to reciprocate the upper frame member about said column, said actuating means comprising throttle valve means operatively connected with said first gear member for subjecting the latter and said first gear means to a residual stress to prevent other than pivotal movements of the upper frame member about said column.

9. In a lapping machine, in combination: a base having a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and compfising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear means mounted on said column, second gear means carried by said upper frame member and movable into and out of mesh with the first gear means, resilient means anchored in the upper frame member and operatively connected with the second gear means for permanently urging the latter into a position out of mesh with the first gear means, and hydraulic actuating means for alternately rotating the second gear means in opposing directions whereby to reciprocate the upper frame member about said column and for moving the second gear means against the bias of said resilient means into mesh with the first gear means, said actuating means comprising throttle valve means for subjecting the first and second gear means to a residual stress to prevent other than pivotal movements of the upper frame member about said column.

10. In a lapping machine, in combination: a base hav 1 1 ing a trough and a vertical center column; a lower lap having an upper surface and rotatably mounted in said trough, the latter having a seat adjacent to the lower lap; an upper frame member mounted on said column for rotation about a vertical axis and having a head; an upper lap having a lower surface and a hub formed with a seat, said upper lap rotatably mounted in said head and swingable with the upper frame member into vertical alignment with and laterally away from said lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive for reciprocating the upper frame member about said axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and, the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first gear means mounted on'said column, second gear means carried by said upper frame member and movable into and out of mesh with the first gear means, resilient means anchored in the upper frame member and operatively connected with the second gear means for permanently urging the latter into a position out of mesh with the first gear means, and hydraulic actuating means for alternately rotating the second gear means in opposing directions whereby to reciprocate the upper frame member about said column, said actuating means comprising cylinder and piston means operatively connected with said second gear means for moving the latter against the bias of said resilient means and into mesh with said first gear means, and throttle valve means for subjecting the first and second gear means to a residual stress to prevent other than pivotal movements of the upper frame member about said column.

11. In a lapping machine, "in combination: a base having a vertical upwardly opening seat; a lower lap having an upper surface and rotatably mounted in said base; an upper frame member having a vertical downwardly opening seat and connected to said base for movements about a vertical axis; an upper lap having a lower surface, rotatably mounted in said upper frame member, and movable with the latter into vertical alignment with and laterally away from the lower lap; a tool holder having a centering pin snugly but removably receivable in each of said seats; a tool carried by said holder and adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the pin of said tool holder is received in said first mentioned seat and the tool is also adapted to treat the upper surface of said lower lap when the pin of said tool holder is received in said last mentioned seat, said drive comprising means for preventing rattling of said frame member and for thereby preventing the formation of chatter marks in said surfaces.

l2.v In a lapping machine, in combination: a base having a trough; a discoid lower lap having an upper surface and rotatably mounted in said trough, the trough having a seat adjacent to said lower lap; an upper frame member connected to said base for movements about a vertical axis; a discoid upper lap having a lower surface and a hub rotatably mounted in said upper frame member and formed with a seat, said upper lap movable with the upper frame member into vertical alignment with and laterally away from the lower lap; a tool holder snugly but removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising meshing first and second gear means connected with said base and said upper frame member, respectively, and hydraulic actuating means operatively connected with and adapted to alternately rotate the second gear means in opposing directions.

13. In a lapping machine, in combination: a base having a trough; a lower lap having an upper surface and rotatably mounted in said trough, the trough having a seat adjacent to said lower lap; an upper frame member connected to said base for movements about a vertical axis; an upper lap having a lower surface and a hub rotatably mounted in said upper frame member and formed with a seat, said upper lap movable with the upper frame member into vertical alignmentwith and laterally away from the lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in the seat of said trough and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in the seat of said hub, said drive comprising first and second gear means connected with said base and said upper frame member, respectively, resilient means for constantly urging the second gear means into a position out of mesh with the first gear means, cylinder and piston means adapted to move the second gear means against the bias of said resilient means and into mesh with said first :gear means, and hydraulic actuating means for alternately rotating said second gear means in opposing directions and for simultaneously operating said cylinder and piston means.

14. In a lapping machine, in combination: a base having a seat; a lower lap having an upper surface and rotatably mounted in said base; an upper frame member having a seat and connected to said base for movements about a vertical axis; an upper lap having a lower surface, rotatably mounted in said upper frame member, and movable with the latter into vertical alignment with and laterally away from the lower lap; a tool holder removably receivable in each of said seats and comprising a tool adapted to treat the surfaces of said laps; and a drive operatively connected with said upper frame member for reciprocating the latter about said vertical axis whereby the tool is adapted to treat the lower surface of said upper lap when the tool holder is received in said first mentioned seat and the tool is also adapted to treat the upper surface of said lower lap when the tool holder is received in said last mentioned seat, said drive comprising a segmental gear rigidly carried by said base, gear means rotatably mounted on said upper frame member and movable into and out, of mesh with the segmental gear, resilient means for constantly biasing the gear means into a position out of mesh with said segmental gear, and hydraulic actuating means for alternately rotating said gear means in opposing directions and for simultaneously moving the gear means against the bias of said resilient means and into mesh with the segmental gear.

References Cited in the file of this patent UNITED STATES PATENTS

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