US3447306A - Abrading machine - Google Patents

Description

June 3, 1969 Z. JAKIMCIUS ABRADING MACHINE Filed Sept. 16, 1966 3 gmanf k Q WWW OTTORMQY June 3, 1969 z. JAKIMCIUS 3,

ABRADING MACHINE Filed Sept. 16, 1966 EI H58 'gman'f dalg mcz'ud June 3, 1969 z; JAKIMCIUS 3,447,306

ABRADING MACHINE Filed Sept. 16, 1966 Sheet 3 of s CfiTTo RMEYJ United States Patent 3,447,306 ABRADING MACHINE Zigmant Jakimcius, Rockford, Ill., assignor to Barnes Drill Co., Rockford, 11]., a corporation of Illinois Filed Sept. 16, 1966, Ser. No. 579,991 Int. Cl. B24b 21/00; F15]: 13/02, /00

US. Cl. 51-135 9 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an abrading machine of the type in which a pneumatic actuator operable in response to signals produced by a sensing apparatus induces controlled back and forth edgewise travel of an endless abrading belt to maintain the belt generally centered on its supporting rolls while eliminating repetitive and overlying abrasive cuts on the work surface being abraded. More particularly, the invention constitutes an improvement over the abrading machine disclosed in US Patent 3,363,366, in which the sensing apparatus comprises two receivers positioned along one edge of the belt and opposite two nozzles directing air jets into the receivers. The pressure signals produced as an incident to the covering and uncovering of the receivers during travel of the belt toward each of the limits of a selected range of edgewise movement control a valve for reversing the direction of operation of the actuator, and thus the direction of travel of the belt, before the belt moves beyond such limits. To keep the receivers free of dust and grit, air is directed reversely out through the receivers to flush the latter repeatedly throughout the abrading operation.

The general object of the present invention is to reverse the direction of travel of the belt and to flush the receivers with apparatus which is considerably simpler in construction and, at the same time, is more positive and troublefree in operation than arrangements previously used for related purposes.

Another object is to use the jets from the nozzles not only for sensing the position of the belt but also for directly actuating the control valve thereby eliminating the need for a separate valve actuating system.

A related object is to position the nozzles and receivers adjacent opposite edges of the belt in a novel manner such that the valve is at all times controlled by the pressure of the jets of the sensing nozzles and without the assistance of auxiliary electrical or mechanical control components.

Still another object is to insure more efficient cleaning of the receivers by flushing the receivers while they are covered by the belt and shielded from the jets directed from the nozzles.

Other objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a schematic perspective view showing the relationship of the belt, the supporting rolls, the sensing apparatus and the pneumatic actuator in an abrading machire of one type in which the present invention may be use FIG. 2 is a schematic view and fluid circuit diagram of the machine control system illustrating the condition of the system when the belt is traveling in one direction,

parts being broken away and shown in section for purposes of clarity.

FIG. 3 is a view similar to FIG. 2 showing the condition of the system while one receiver is being flushed with air.

FIG. 4 is a view similar to FIG. 2 illustrating the condition of the system when the belt is traveling in the opposite direction.

FIG. 5 is a view similar to FIG. 2 showing the condition of the system while the other receiver is being flushed with air.

As shown in the drawings for purposes of illustration, the invention is incorporated in an abrading machine in which an endless abrasive belt 10 is supported and tensioned around three parallel rotary rolls 11, 12 and 13 arranged to guide the belt along a generally triangular path with one area of the belt contacting the surface of a workpiece (not shown) to be abraded. The workpiece normally is supported on a suitable conveyor for advancement beneath the belt, the latter being driven at high speed by rotating the roll 11 with power mechanism (not shown). To maintain the belt substantially centered .on the rolls and to avoid repetitive and overlying cuts on the surface of the workpiece, controlled edgewise travel of the belt relative to the rolls and the workpiece is induced by rocking the roll 13 back and forth between two oppositely inclined positions during the abrading operation.

While the roll 13 may be mounted in various ways for such rocking, herein it is fast on a coaxial shaft (not shown) which projects beyond the opposite ends of the roll and is journalled in bearing mounts 14 each pivoted on one side at 15 to the machine frame to swing about axes parallel to and spaced inwardly from the axis of the roll 13. Pivotally connected to the bearing mounts are arms 16 projecting inwardly from the mounts and eccentrically connected at 17 to the opposite ends of a shaft 18 extending parallel to the roll and journaled on the machine frame for rotation about its longitudinal axis. In this instance, the eccentric connections 17 are shown as radial crank arms on the ends of the shaft and angularly spaced about degrees apart. A similar roll mounting is shown in more detail in United States Patent No. 3,132,451.

The shaft 18 is oscillated about its longitudinal axis by an actuator 20 connected to a crank 21 fast on and projecting inwardly from the shaft. The actuator comprises a cylinder 22 slidably receiving a piston 23 (FIG. 2) and pivotally connected to the crank arm by a yoke 24 carried on the end of a piston rod 25. Thus, reciprocation of the piston within the cylinder rocks the crank 21 and the shaft 18 about the longitudinal axis of the shaft to oscillate the eccentric crank arms 17 and alternately tilt the steering roll 13 a few degrees in opposite directions to steer the belt 10 edgewise back and forth along the roll.

Reciprocation of the piston 23 is produced by air under pressure admitted alternately into the opposite ends of the cylinder 22 from a supply line 28 through two inlet ports 29 and 30 communicating through lines 31 and 32 with the outlet ports 33 and 34 of a pressure operated four-way control valve 35. The latter comprises a spool 36 formed with two spaced heads 37 and 38 fitted in a hollow cylindrical body with the opposite end portions 41 and 42 of the spool stem projecting beyond the heads and into pressure chambers 43 and 44 formed by bores in the ends of the valve body. Thus, the end portions of the stem constitute power pistons for operating the control valve by sliding the spool back and forth within the valve body as pressure fluid is admitted alternately into the chambers 43 and 44. When fluid is admitted to the right-hand chamber 44, the spool is shifted to the left to the position shown in FIG. 2 in which the supply line 28 communicates with the line 31 and the inlet port 29 in the rod end 45 of the steering cylinder 22 to shift the piston 23 to the right. When pressure fluid is admitted into the left-hand chamber 44, the spool moves to the right (FIG. 4) to introduce air from the supply line into the head end 46 of the steering cylinder through the line 32 and the port thereby returning the piston to the left.

Herein, the control valve 35 is operated in response to pressure signals produced by a sensing device including two receivers 49 and 50 formed by the open ends of pipes or tubes 51 and 52 positioned on one side of the plane of the belt 10 to be alternately covered and uncovered by the belt during its back and forth edgewise travel. On the opposite side of the plane of the belt and alined with the respective receivers are two nozzles 53 and 54 for directing jets of air into the receivers when the latter are uncovered. Thus, the changes in pressure within the receiver pipes produced by such covering and uncovering constitute pressure signals indicating when the belt is approaching the opposite limits of the selected range of edgewise movement.

The pressurized air for both the steering cylinder 22 and the nozzles 53 and 54 is supplied by a suitable high pressure source 55 (FIG. 2) communicating with the supply line 28 through a pressure reducer 56 which maintains the pressure in the supply line at a selected value such as 35 p.s.i. In addition, the source communicates with both nozzles through a line 57 and a second pressure reducer 58 which delivers air to the nozzles at a somewhat lower pressure.

Since the receivers 49 and 50 are positioned near the belt 10 and in close proximity to the workpiece, dust and grit thrown off by the belt are carried into the receivers by the air jets from the nozzles 53 and 54 and tend to collect in the receiver pipes 51 and 52. If allowed to build up on the walls of the pipes, this dust can interfere with the detection of the belt position, the receivers customarily being openings on the order of 0.060 of an inch in diameter. To prevent such build-up, air is directed reversely through the receiver pipes 51 and 52 repeatedly during the abrading operation thereby to flush out the pipes and maintain the same in a clean condition.

In accordance with the present invention, the receivers 49 and 50 and the alined nozzles 53 and 54 are advantageously positioned adjacent opposite edges of the belt 10 and communicate directly with the valve pressure chambers 43 and 44 to cause shifting of the valve spool 36 in response to the uncovering of each receiver and thereby reverse the direction of operation of the pneumatic actuator 20 and the direction of edgewise travel of the belt each time the latter reaches the extreme limits of the selected range of travel. Moreover, both receivers are covered to leave the spool in the shifted position when the belt is traveling between the limits and while air for flushing the receivers is being directed reversely through the receivers. Accordingly, reversal of the direction of belt travel is achieved with apparatus considerably simpler in construction and yet more positive and trouble-free in operation than arrangements previously used and, at the same time, more efiicient cleaning of the receivers is insured since the receivers are covered by the belt and shielded from the jets of the nozzles when air is flowing reversely out through the receivers.

In this instance, the receiver 49 and its alined nozzle 53 are spaced inwardly from the left edge 61 of the belt 10, and the receiver 50 and the nozzle 54 are similarly spaced inwardly from the right edge 62 of the belt when the latter is substantially centered on the rolls 11 to 13 as shown in FIG. 3. The spacing of the nozzles and receivers from the edges of the belt may be varied, however, in accordance with the range of edgewise travel desired so long as the distance between the receivers is maintained less than the width of the belt so that both receivers will be covered simultaneously in at least one position of the belt.

The ends of the receiver pipes 51 and 52 opposite the receivers 49 and 50 are connected to the ends of the 4- body of the control valve 35 and communicate directly with the pressure chambers 43 44, respectively. As a result, air directed into the receiver pipes from the nozzles 53 and 54 when the receivers are uncovered is admitted into the pressure chambers to shift the spool 36 back and forth between its two positions.

Herein, the receiver pipes 51 and 52 are flushed by directing the exhaust air from the steering cylinder 22 reversely through the pipes each time the piston 23 changes directions to reverse the tilt of the steering roll 13. To conduct the exhaust air from the steering cylinder 22 to the receiver pipes 51 and 52 for flushing the latter, the control valve 35 is formed with two exhaust ports 65 and 66 alternately receiving exhaust air through the valve in accordance with the position of the spool 36. An exhaust line 67 communicating with the receiver pipe 51 at a point between the receiver 49 and the pressure chamber 43 leads to the exhaust port 65, While a similar line 68 establishes communication between the exhaust port 66 and the receiver pipe 52. For preventing the pressurized air directed out of the nozzles 53 and 54 from flowing through the receivers into the exhaust ports 65 and 66, one-way valves in the form of spring-loaded check valves 70 are disposed in each of the exhaust lines 67 and 68. In addition, a selectively adjustable flow restrictor 71 in each exhaust line controls the rate of flow of exhaust air from the cylinder 22 thereby controlling the rate of movement of the piston 23. Since the pneumatic system is identical for each receiver, the flow restrictors can be adjusted to throttle the flow equally from each end of the cylinder so as to insure that the piston moves at approximately the same rate in both directions.

Operation Let it be assumed that the parts are positioned as shown in FIG. 2 with the piston 23 moving toward the head end 46 of the steering cylinder 22 and the steering roll 13 being tilted in a direction to steer the belt 10 in the direction of the arrow 74 in FIGS. 1 and 2. The receiver 49 is covered and the receiver 50 is uncovered by the belt, and the latter is moving to the right toward the receiver 50. With the belt thus positioned, the pressure in the valve pressure chamber 43 is substantially atmospheric, and the valve spool 36 has been moved to the left by the air jet from the nozzle 54 flowing through the receiver pipe 52 and into the pressure chamber 44. The flow of air from the nozzle 54 to the pressure chamber 44 is indicated by the arrow 75 in FIG. 2. High pressure air for moving the piston to the right is introduced into the rod end 45 of the steering cylinder 22 from the supply line 28 through the control valve 35 and the inlet line 31.

As the belt 10 continues to move to the right, it reaches an intermediate position (FIG. 3) covering both receivers 49 and 50 and shielding the receiver 50 from the air jet of the nozzle 54. Since the receiver 49 also is covered, the valve spool 36 remains positioned to the left. Accordingly, the piston 23 continues to move to the right with the air from the head end 46 of the cylinder 22 being exhausted into the exhaust line 68 and out through the receiver pipe 52 (as indicated by the arrow 76 in FIG. 3) to flush the latter while the receiver 50 is shielded and no air is being directed into the receiver from the nozzle 54.

Continuing to the right, the belt edge 61 reaches an extreme position uncovering the receiver 49 and exposing the same to the jet of air from the nozzle 53 .(FIG. 4). As a result, the pressure in the receiver pipe 51 and the left valve pressure chamber 43 increases under the influence of the air flowing in the direction of the arrow 77 and shifts the valve spool 36 to the right. With the spool in this position, communication is established between the supply line 28 and the head end 46 of the steering cylinder 22 to begin moving the piston 23 back to the left to reverse the tilt of the steering roll 13. The belt 10 thus also begins to move back to the left as indicated by the arrow 78 in FIG. 4.

As the belt moves to the left, it again reaches an intermediate position (FIG. 5) covering both receivers 49 and 50. The valve spool 36, however, remains positioned to the right so that the piston 23 continues its leftward movement. Consequently, exhaust air from the rod end 45 of the steering cylinder 22 is forced into the exhaust line 67 and out through the receiver pipe 51, the direction of flow being indicated by the arrow 79. As in the case of the receiver pipe 52, the pipe 51 is flushed with the exhaust air While the belt 10 is covering the receiver 49 to deflect the air jet from the nozzle 53 away from the receiver.

Continued movement of the belt 10 to the left uncovers the receiver 50 to allow the air jet from the nozzle 54 to enter the pressure chamber 44 thereby returning the valve spool 36 back to the left position shown in FIG. 2. Accordingly, high-pressure air again will'be admitted to the rod end 45 of the steering cylinder 22 to start the belt through another cycle of edgewise travel.

From the foregoing, it will be apparent that the novel arrangement of the receivers 49 and 50 relative to the belt 10 and the valve chambers 43 and 44 enables extremely simple and positive control of the direction of travel of the belt and also of the flow of the exhaust air, the only moving part in the control system being the valve spool 36. Moreover, exhaust air flows reversely through the receivers during periods when the nozzles 53 and 54 are shielded thus providing very effective cleaning and enabling uniform control of the rate of movement of the piston 23 in both directions by means of the flow restrictors 71.

I claim as my invention:

1. In an abrading machine, the combination of, an endless abrading belt, means supporting said belt for movement along a continuous path, said supporting means including a tiltable steering roll for inducing back and forth edgewise travel of said belt upon back and forth tilting of said roll between two oppositely inclined positions, a double-acting pneumatic actuator including a cylinder and a piston mounted for reciprocation in said cylinder, said actuator being connected to said steering roll to tilt the latter between said positions in response to the admission of pressure fluid into opposite ends of said cylinder, a device for sensing edgewise movement of said belt to the two extremes of a preselected range of lateral travel comprising first and second receivers spaced apart laterally of said belt alongside the plane thereof and opening toward said plane, first and second nozzles respectively alined with said receivers to direct jets of air across said plane and into the receivers thereby causing pressure rises in the receivers, said receivers and the alined nozzles being supported adjacent opposite edges of said belt for lateral travel of the belt between the receivers and the nozzles and from a first extreme position covering said first receiver and uncovering said second receiver, an intermediate position covering both of said receivers, a second extreme position uncovering said first receiver and covering said second receiver, and back, a valve operable in response to a pressure rise in said first receiver when the latter is uncovered during travel of said belt toward said second extreme position to operate said actuator in one direction to tilt said roll to a position inducing travel of said belt back toward said first extreme position, said valve being operable in response to a pressure rise in said second receiver when the latter is uncovered during travel of said belt toward said first extreme position to operate said actuator in the opposite direction to tilt said roll to a position inducing travel of said belt back toward said second extreme position, and means receiving exhaust air from said cylinder in both directions of operation of said actuator and directing the exhaust air out through said first receiver when said belt is traveling through said intermediate position toward said first extreme position,

and out through said second receiver when said belt is traveling through said intermediate position toward said second extreme position thereby to clean out each of said receivers once during each cycle of operation of said actuator and while the receivers are covered by the belt.

2. An abrading machine as defined in claim 1 further including selectively adjustable means maintaining the rate of flow of exhaust air through each receiver approximately equal whereby said piston moves at about the same rate in each direction of reciprocation.

3. In an abrading machine, the combination of, an endless abrading belt, means supporting said belt for movement along a continuous path, mechanism for inducing back and forth edgewise travel of said belt relative to said supporting means including a reciprocating pneumatic actuator operable when actuated to reverse the direction of edgewise travel of said belt, a device for sensing the edgewise travel of said belt comprising first and second receivers spaced apart laterally of the belt alongside the plane thereof and opening toward said plane, first and second nozzles respectively alined with said receivers to direct jets of air across said plane and into the receivers thereby causing pressure rises in the receivers, said receivers and the alined nozzles being supported adjacent opposite edges of said belt for back andforth lateral travel of the belt from a first extreme position covering said first receiver and uncovering said second receiver, through an intermediate position covering both of said receivers, and to a second extreme position uncovering said first receiver and covering said second receiver, control mechanism operable in response to the pressure rise in each receiver when the latter is uncovered by travel of said belt toward one extreme position to operate said actuator thereby reversing the direction of travel of the belt back toward the other extreme position, and means receiving exhaust air from said actuator and alternating the fiow of exhaust air between the two receivers as said belt travels through said intermediate position thereby to clean out the receivers repeatedly during the abrading operation and while the receivers are covered by said belt.

4. An abrading machine as defined in claim 3 in which said actuator comprises a cylinder and a piston mounted for reciprocation in said cylinder, and said control mechanism includes a valve for directing air under pressure alternately to opposite ends of said cylinder.

5. An abrading machine as defined in claim 4 in which said valve includes a body communicating with said receivers to receive air directed into the receivers by said nozzles, and a member mounted for back and forth movement within said body between a first position directing air under pressure to one end of said cylinder and a second position directing air under pressure to the other end of the cylinder, said member moving to one of said positions as said first receiver is uncovered by said belt, remaining in said one position when both receivers are covered by said belt, and moving to the other position as said second receiver is uncovered by said belt.

6. An abrading machine as defined in claim 5 in which said valve includes pressure chambers disposed between said body and said member and communicating with said receivers, said member being moved between said positions in response to air from said nozzles being directed into said chambers through said receivers when the latter are uncovered.

7. In an abrading machine, the combination of, an endless abrading belt, means supporting said belt for movement along a continuous path, mechanism for inducing back and forth edgewise travel of said belt relative to said supporting means including a reciprocating pneumatic actuator operable upon reversing directions to reverse the direction of edgewise travel of said belt, a device for sensing the edgewise travel of said belt comprising first and second receivers spaced apart laterally of said belt alongside the plane thereof and opening toward said plane, first and second nozzles respectively alined with said receivers to direct jets of air across said plane and into the receivers for causing pressure rises in the receivers, and receivers and the alined nozzles being supported adjacent opposite edges of said belt with the distance between said first receiver and nozzle and said second receiver and nozzle being less than the width of the belt whereby the belt alternately covers and uncovers the receivers during back and forth edgewise movement and causes said nozzles to induce .a pressure rise first in one of said receivers and then in the other of said receivers, a pneumatically responsive control valve operable when actuated between first and second conditions to reverse the direction of operation of said actuator thereby reversing the direction of edgewise travel of said belt, and means establishing communication between said receivers and said control valve for causing actuation of said control valve to said first condition in response to a pressure rise in one of said receivers and to said second condition in response to a pressure rise in the other of said receivers.

8. An abrading machine as defined in claim 7 in which said valve includes a body and a member slidable within said body, pressure chambers disposed between opposite ends of said body and said member whereby pressurized air admitted into said chambers slides said member within said body, and said last-mentioned means establishing communication between said chambers and said receivers and directing the jets of air from said nozzles to said pressure chambers when said receivers are uncovered.

9. An abrading machine as defined in claim 7 further including means for directing exhaust air from said ac tuator through said valve and out through said receivers when the latter are covered by said belt and shielded from said nozzles.

References Cited UNITED STATES PATENTS 2,114,716 4/1938 Kunzle. 2,274,268 2/1942 Hercik. 3,008,276 11/1961 Kile 51-138 3,132,451 5/1964 Kile 51138 3,363,366 1/1968 Estabrook;

ROBERT C. RIORDON, Primary Examiner.

D. G. KELLY, Assistant Examiner.

US. Cl. X.R. 91-3; 137-83

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