US3339242A

US3339242A - Collapsible tools for use in the moulding, casting or pressing of hollow articles

Info

Publication number: US3339242A
Application number: US409207A
Authority: US
Inventors: Lamb Harry
Original assignee: Ketch Plastics Ltd
Current assignee: Ketch Plastics Ltd
Priority date: 1963-11-12
Filing date: 1964-11-05
Publication date: 1967-09-05
Anticipated expiration: 1984-09-05
Also published as: NL6412871A; GB1045350A; BE655157A; DK121200B; NO117326B; SE306824B; DE1479374B2; DE1479374A1

Description

3,339,242 .CASTING Sept. 5, 1967 H. LAMB COLLAPSIBLE TOOLS FOR USE IN THE MOULDING,

OR PRESSING OF HOLLOW ARTICLES 7 Sheets-Sheet 1 Filed Nqv. 5, 1964 lillll JNN Sept. 5, 1967 OR P Filed Nov. 5, 1964 COLLAPSIBLE TOOLS F RESS H. LAMB OR THE M0 USE' IN NG OF HOLLOW ART 3,3 ULDING, CASTING ICLES 7SheetS-Sheet 2 /i] Z Y Sept; 5, 1967 H. LAMB 3,339,242

COLLAPSIBLE TOOLS FOR USE IN THE MOULDING, CASTING OR PRE RTI Filed Nov. 5, 1964 Sept. 5, 1967 H. LAMB 3,339,242 GOLLAPSIBLE TOOL OR USE IN THE MOULDING, CASTING 0R PRE NG OF HOLLOW ARTICLES '7 Sheets-Sheet 4.

K. k M 5/ Sept. 5, 1967 H. LAMB FOR USE IN THE M COLLAPSIBLE TOOLS I OR PRESS'ING OF HOLLOW AR Filed Nov. 5, 1964 7 Sheets-Sheet 5 I v Q,

Ar/ 7 Q% n HQ 7 Q @W A? 1mm, U .H .H. w w Rm MN 3 M Q Sept. 5, 1967 v H. LAMB COLLAPSIBLE TOOLS FOR USE IN THE MOULDING, CASTING OR PRESSING OF HOLLOW ARTICLES 7 Sheets-Sheet 6 Filed Nov. 5, 1964 H. LAMB Sept. 5, 1967 COLLAPSIBLE TOOLS FOR USE IN THE MOULDING, CASTING OR PRESSING OF HOLLOW ARTICLES 7 Sheets-Sheet 7 Filed Nov. 5, 1964 United States Patent COLLAPSIBLE TOOLS FOR USE IN THE MOULD- Claims priority, application Great Britain, Nov. 12, 1963,

44,573/ 63 8 Claims. (Cl. 1842) This invention relates to cores for use in the moulding,

casting or pressing of hollow articles, such cores being collapsible to allow the withdrawal thereof when the interior of the formed article is of re-entrant configuration. It is an object of the invention to provide a collapsible 'core which can be simply collapsed for withdrawal without first being dismantled.

A collapsible core according to the invention comprises a tapered spigot member, havingfirst and second sets 'of inclined faces, the faces of said first set being more i steeply inclined to the axis of the spigot member than the faces of said second set and the faces of said first set being disposed respectively between adjacent faces of said second set and a plurality of segments slidably retained respectively on said inclined faces, the arrangement being such that the spigot member can be moved relative to -the segments from a working position, in which the segments combine to form a surface complementary to the internal surface of the article, to a withdrawal position in which all the segments are displaced towards the axis of e the spigot member, the segments mounted on said first set of faces being displaced by a distance greater than the segments mounted on said second set and each of the segments mounted on said second set of faces projecting at opposite lateral sides into-the spaces vacated by the ad- .jacent segments mounted on said first set of faces;

The invention also resides in an injection moulding machine incorporating a core as above defined.

7 Reference will now be made to the accompanying drawings in which:

FIGURE 1 is a diagrammatic plan view of an injection A r moulding machine;

FIGURE 2 is a sectional view showing an example of a collapsible core in accordance with the invention, the

core being shown in a working position;

FIGURE 3 is a section on line 33 in FIGURE 2; FIGURE 4 is a view similar to FIGURE 2, but showing the core in a collapsed condition;

- FIGURE 5 isa section on line 5-5 in FIGURE 4;

FIGURE 6 is a sectional view like FIGURE ing another example of the invention;

FIGURE 7 is a half section on line 7-7 in FIGURE 6 2 but showshowing the" core in a working position and FIGURE 8 is a half section similar to FIGURE 7 but showing the core collapsed.

As shown in FIGURES 1 to 5 the invention'can be employed in the manufacture of transparent street lamp covers 10 on an automatic injection moulding machine. The covers are of bowl-shaped form and are provided on their interior surfaces with a plurality of raised ribs 11 (see FIGURE 4). In order to form a bowl of this nature it is necessary, if the bowl is to be formed as a one-piece "moulding, to provide a core on one of the dies, which core is shaped to form the interior surface of the bowl. The raised ribs, however, prevent the use of a solid core as it would be impossible to remove the finished bowl from the core without damage to the ribs. Some form of collapsible core is therefore required and as it is to be used in an automatic process it is essential that the core should be removable from the moulding without first dismantling the core.

' on the fixed platen, however, with the Accordingly the core comprises a plurality of segments which are to be mounted on one platen of the moulding machine in such a manner that some of the segments can be displaced inwardly by a comparatively large distance so that the remaining segments can overlap these segments as they are moved inwardly by a smaller distance.

In the actual core there are eight segments four of which subtend relatively small arcs at the axis of the core. These four segments 12 are each of substantially trapezoidal cross-sectional configuration. The other four segments 13 are chamfered at their edges 13a to mate with the sides of the trapezoidal segments when the segments occupy a working position.

The eight

segments

12, 13 are slidably supported on a tapered spigot 14 which has eight faces and the two types of

segments

12, 13 alternate around the spigot. The trapezoidal segments 12 are slidable on faces 14a which are groove 14c in the associated face.

The spigot member 14 is hollow and extending through its interior is a bar 16 on one end of which a nose por tion 17 for the core is mounted.

In use the spigot member 14 is secured to a plate 18 on the movable platen 19 of an injection moulding machine. The above mentioned bar 16 is secured to the ejector plate 20 of the machine and also mounted on this plate are eight projecting pins 21 engageable respectively with the eight

core segments

12, 13.

The

platens

19, 22 are closed in the normal way and the synthetic resin material is injected by the injector 23. When the platens separate the sprue breaks in the usual way and the moulding 10 is carried away on the core. When the ejector stop 24a engages the ejector bar 24 movement of the ejector plate 20 is arrested whilst the movable platen 19 continues 'to move. Thus the nose portion 17 of the core and the

segments

12, 13 are prevented from making further axial movement whilst the spigot 14 continues to move. As a result of the relative axial movement between the'segments and the spigot all of the segments are displaced toward the axis of the spigot.

Thus the trapezoidal segments 12 are displaced rapidly towards the axis of the spigot 14 to provide spaces in the periphery of the core into which the edges ofthe other segments 13 project as they are displaced slowly towards the axis of the spigot. The position (shown in FIGURES 4 and 5) is thus finally reached where the ribs on the segments are clear of the ribs on the moulding so that the latter can easily be removed. It is to be noted that contact between

segments

12, 13 is broken as soon as their movement is arrested.

The example shown in FIGURES 6 to 8 two similar cores are employed to mould a sleeve 25 which hasan internal flange intermediate its ends and an' inturned flange at each end. In this case the operation of the core on the movable platen is exactly as described above. A similar spigot and segment arrangement is also mounted spigot secured to the 'fixed platen.

As shown the core on the movable platen 19 again includes a hollow spigot 26 attached to a plate 18 secured to platen 19. Keyed to this spigot 26 (in this case'by T- shaped keys 27) are the eight

segments

29, 30, corresponding to the

segments

12, 13 respectively.

The ejector plate 20 again has a bar 31, carrying the nose portions 32 of the die, secured to it. Also secured to it are ejector pins 33 engaging a ring 34 against which the

segments

29, 30 abut. The ring 34 is spring-loaded by means of springs 35 acting on a part 36 secured to the movable platen 19. Part 36 actually forms a part of the moulding surface.

Also secured to the movable platen 19 are a pair of transverse

horizontal guide rails

37, 37a which guide a pair of vertically split external die parts 38. The two die parts 38 are also engaged on bars 39 fixed to a stationary part of the machine and diverging in horizontal planes away from the fixed platen 22.

The core on the fixed platen 22 includes a hollow spigot 40 identical to spigot 26 and secured to the fixed platen. Keyed to spigot 40 are segments 41, 42 corresponding to

segments

29, 30 respectively. The segments are movable relative to the spigot by means of a ring member 43 to which a pair of headed bolts 44 are secured. These bolts 44 can co-act with catch plates 45 on the die parts 38. There is also provided a bar 46 carrying the nose 47 of the fixed die.

In use, after the injection has been completed, the movable platen 19 is withdrawn as usual. The dies separate along the line market by the arrow A in FIGURE 6. Thus initial movement of platen 19 causes ring member 43 to be displaced from platen 22 by virtue of the fact that bolts 44 are caught behind plates 45. This causes segments 41, 42 to be displaced axially and to carry with them nose portion 47. Thus, at this stage the whole of the mould is being moved axially as a unit. The segments 41, 42, are, however, being displaced inwardly and the die parts 38 are being displaced outwardly. The stage is finally reached where the catch plates 45 are so far separated that they can no longer retain the bolts 44 and the inclinations of the faces of spigot 40 and of bars 39 are such as to ensure the die parts 38 and the segments 41, 42 are now clear of the moulding.

The mould now splits and the moulding is carried away on the core of the movable platen, from which it is released as described in the first mentioned example of the invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A collapsible core comprising a tapered spigot member having first and second sets of inclined faces, the faces of said first set being more steeply inclined to the axis of the spigot member than the faces of said second set and the faces of said first set being disposed respectively between adjacent faces of said second set and a plurality of segments slidably retained respectively, on said inclined faces, the arrangement being such that the spigot member can be moved relative to the segments from a working position, in which the segments combine to form a surface complementary to the intemal surface of the article, to a withdrawal position in which all the segments are displaced towards the axis of the spigot member, the segments mounted on said first set of faces being displaced by a distance greater than the segments mounted on said second set and each of the segments mounted on said second set of faces projecting at opposite lateral sides into the spaces vacated by the adjacent segments mounted on said first set of faces.

2. A collapsible core comprising a tapered spigot having an axial passage formed therein and having first and second sets of inclined faces, the faces of said first set being more steeply inclined to the axis of the spigot member than the faces of the second set, and the faces of the first set being disposed respectively between the faces of the second set, a plurality of segments mounted respectively on said inclined faces, means retaining the segments in contact with the respective faces so that axial displacement of any segment relative to the spigot member results in displacement of the segment towards the axis of the spigot member at a rate determined by the inclination of the associated face of the spigot member, a bar extending through the axial passage in the spigot member, a nose portion on one end of the bar, the segments each abutting at one end against the nose portion to form in combination therewith a working surface of the tool, and means whereby the segments and bar are movable axially relative to the spigot member to effect inward displacement of the segments to a withdrawal position in which the segments on the faces of the second set overlap the segments on the faces of the second set.

3. In an injection moulding machine of the type having a fixed platen, a movable platen and an ejector mechanism associated with the movable platen, a collapsible core mounted on the movable platen and comprising a tapered spigot member secured relative to the movable platen and having first and second sets of inclined faces, the faces of said first set being more steeply inclined to the axis of the spigot member than the faces of said second set and the faces of said first set being disposed respectively between the faces of said second set, a plurality of segments mounted respectively on said faces and retained thereon by key means which serve to cause the segments to be displaced inwardly when moved axially along the spigot member and means operable by said ejector mechanism to displace the segments from a working position along the spigot member to a withdrawal position during movement of the movable platen away from the fixed platen, the segments forming in said working position a moulding surface complementary to the internal surface of a hollow article to be moulded in the machine and being arranged in said withdrawal position with the segments on the faces of the second set overlapping the segments on the faces of the first set.

4. In an injection moulding machine of the type having a fixed platen, a movable platen and an ejector mechanism associated with the movable platen, the combination of first and second collapsible cores mounted respectively on the fixed and movable platens and each comprising a tapered spigot member secured relative to the associated platen and having first and second sets of inclined faces, the faces of the first set being more steeply inclined to the axis of the spigot than the faces of the second set and the faces of the first set being disposed respectively between adjacent faces of the second set, a plurality of segments mounted on the inclined faces of the spigot member, means retaining the segments on the respective faces of the spigot member whereby axial movement of any segment causes it to be displaced inwardly by a distance determined by the inclination of the associated face so that the segments can be axially displaced along the spigot simultaneously from a working position, in which the segments form in combination a part of a mould surface complementary to the internal surface of a hollow article to be moulded in the machine, to a withdrawal position in which the segments on the faces of the second set overlap the segments on the faces of the first set, means operable by initial movement of the movable platen away from the fixed platen to displace the segments of the first core relative to the spigot member thereof from the working position to the withdrawal position, and means operable by the ejector mechanism to displace the segments of the second core relative to the spigot member thereof from the working position to the withdrawal position.

5. In an injection moulding machine of the type having a fixed platen, a movable platen and an ejector mechanism associated with the movable platen, the combination claimed in claim 4 together with a pair of die parts for forming part of a moulding surface complementary to the external surface of a hollow article to be moulded in the machine, means mounting said die parts for movement in directions diverging in an axial direction away from the fixed platen, means connecting said die parts to the movable platen so that movement of the movable platen away from the fixed platen causes the die parts to be moved away from the fixed platen and therefore separated, a ring member abutted against the segments of the first core and means forming an operative connection between the die parts and said ring member when the spacing of said die parts is less than a predetermined distance.

6. In an injection moulding machine of the type having a fixed platen, a movable platen and an ejector mechanism associated with the movable platen, the combination claimed in claim 5 in which said means forming said operative connection comprises a pair of bolts projecting from the ring member, a pair of enlarged heads on the bolts respectively and two pairs of catch plates on the die parts respectively for co-acting with said enlarged heads.

7. A collapsible core as claimed in claim 6 incorporating a plate attached to the end of said bar opposite said nose portion, and means on said plate engaging said segments at one axial end to urge the latter into abutment with said nose portion, the nose portion, bar, segments and plate being movable axially as a single unit relative to the spigot member.

8. In an injection moulding machine of the type having a fixed platen, a movable platen and an ejector mechanism associated with a movable platen, a collapsible core as set forth in claim 3 and including a plate axially movable relative to said spigot member by the ejector mechanism, a bar secured to the plate and extending through an axial passage in the spigot member, a nose portion on the bar which combines with the segments when in the working position to form said moulding surface, and means on said plate engaging the segments at one axial end to hold them against the nose portion at the opposite axial end, so that movement of the plate by the ejector mechanism causes simultaneous axial movement of the nose portion and the segments relative to the spigot member.

References Cited UNITED STATES PATENTS 1,921,125 8/1933 Hughes et a1 72393 1,995,485 3/1935 Tormyn et al. 1,997,074 4/1935 Novotny 18-30 XR 2,263,037 11/ 1941 Gits. 2,654,413 10/1953 Weidel. 2,943,667 7/1960 Ewing et a1. 3,247,548 4/ 1966 Fields et a1.

FOREIGN PATENTS 240,079 8/ 1962 Australia. 905,388 4/ 1945 France.

WILLIAM J. STEPHENSON, Primary Examiner.

Claims

1. A COLLAPSIBLE CORE COMPRISING A TAPERED SPIGOT MEMBER HAVING FIRST AND SECOND SETS OF INCLINED FACES, THE FACES OF SAID FIRST SET BEING MORE STEEPLY INCLINED TO THE AXIS OF THE SPIGOT MEMBER THAN THE FACES OF SAID SECOND SET AND THE FACES OF SAID FIRST SET BEING DISPOSED RESPECTIVELY BETWEEN ADJACENT FACES OF SAID SECOND SET AND A PLURALITY OF SEGMENTS SLIDABLY RETAINED RESPECTIVELY, ON SAID INCLINED FACES, THE ARRANGEMENT BEING SUCH THAT THE SPIGOT MEMBER CAN BE MOVED RELATIVE TO THE SEGMENTS FROM A WORKING POSITION, IN WHICH THE SEGMENTS COMBINE TO FORM A SURFACE COMPLEMENTARY TO THE INTERNAL SURFACE OF THE ARTICLE, TO A WITHDRAWAL POSITION IN WHICH ALL THE SEGMENTS ARE DISPLACED TOWARDS THE AXIS OF THE SPIGOT MEMBER, THE SEGMENTS MOUNTED ON SAID FIRST SET OF FACES BEING DISPLACED BY A DISTANCE GREATER THAN THE SEGMENTS MOUNTED ON SAID SECOND SET AND EACH OF THE SEGMENTS MOUNTED ON SAID SECOND SET OF FACES PROJECING AT OPPOSITE LATERAL SIDES INTO THE SPACES VACATED BY THE ADJACENT SEGMENTS MOUNTED ON SAID FIRST SET OF FACES.