GB2094219A

GB2094219A - Die closure unit of an injection moulding machine

Info

Publication number: GB2094219A
Application number: GB8200082A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-01-12
Filing date: 1982-01-04
Publication date: 1982-09-15
Also published as: GB2094219B; NL8200010A; CA1175621A; FR2497721A1; IT8219053A0; AT382110B; JPS57142338A; ATA3082A; CH655274A5; FR2497721B1; IT1149432B

Abstract

A coupling means (20), which is disposed within the moulding die (25), connects the ejector plate (27) to the piston rod (21) of the ejector means. The coupling is releasable by means of a member which is guided perpendicular to the coupling axis in a bore (48) formed in the mounting plate (25b). The mounting plate (25b) is guided on guide elements of the die carrier for a replacement movement parallel to the bore (48). With such a construction, it is possible to replace the hydraulically tightly-clampable moulding die (25) with fewer operational steps and with a smaller potential opening width for the die closure unit. <IMAGE>

Description

SPECIFICATION Die closure unit of an injection moulding machine The present invention relates to the die closure unit of a plastics injection moulding machine including a device for ejecting the finished moulding, which device includes a hydraulic piston-and-cylinder unit (hydraulic cylinder), mounted on the movable die carrier, and a coupling means which is mounted on the ejector plate of the injection moulding die and by means of which the piston rod of the hydraulic cylinder is connectable to the ejector plate, whereby at least one coupling element, guided radially relative to the piston rod, is engageable behind a coupling head of the piston rod by the loading of a spring, which coupling element is displaceable from its coupling position by means of an unlocking element in opposition to the action of the spring.

In a known device of this type (AT PS 320 192), the coupling between the piston rod and the ejector plate is automatically released by the rearward movement of the piston rod as soon as the ejector plate has reached its basic rearward position. In such a case, the coupling elements which are jointly guided by the piston rod run on inclined faces of a sleeve which surrounds the coupling head. This operating principle necessitates a large axial dimension for the coupling means which protrudes beyond the mounting plate in the coupling direction.

It is also known to provide a die closure unit with a mounting device for alternate mounting or releasing of the injection moulding die on the die carriers (German PS 2 724 020). When the injection moulding die is changed the clamping pins of the mounting device, acting as the components of the moulding die halves, are necessarily inserted with the moulding die into the clamping space of the die closure unit. The moulding die halves are then placed, in a centering manner, against the clamping faces of the die carriers in a movement which is parallel to the closure movement of the injection moulding die. A change of moulding dies of this type presupposes that the maximum opening width of the die carriers is greater, by the length of the clamping pins, than is required for the maximum installation depth of the injection moulding die.

On the basis of the prior art mentioned, the invention seeks to develop a die closure unit of the above-mentioned type such that the injection moulding die may be replaced substantially more quickly and with fewer operational steps.

According to the invention, this object is achieved in that the unlocking element of the coupling means disposed within the mounting plate of the injection moulding die is actuable by means of a member which is displaceably mounted in a bore which is formed in the mounting plate and extends perpendicularto the coupling axis, and in that the lateral edges of the mounting plate abut against guide elements of the die carrier for a substitution or replacement movement of the injection moulding die parallel to the clamping face of the die carrier.

This solution substantially contains a full integration of the coupling means in favour of a replacement movement of the injection moulding die which runs transversely to the coupling axis. This concept presupposes that the unlocking element is actuable in the injection moulding die via a bore which extends transversely to the coupling axis.

in this solution for achieving the object, the die carriers are set at a reciprocal distance which is slightly greater, e.g. approximately 1 mm greater, than the dimension for the depth of the injection moulding for the replacement operation of the injection moulding die. The injection moulding die is then inserted between the die carriers as far as a stop in a movement which extends exclusively perpendicular to the coupling axis. In such a case, the injection moulding die is guided on the guide elements of the die carriers and on their clamping faces. The coupling rod of the ejector device is then inserted into the coupling means, incorporated into the injection moulding die, for automatic coupling.If it is necessary to change the moulding die again, the unlocking element of the coupling means is first actuated via the bore formed in the injection moulding die wholly independent of an axial movement of the piston rod of the ejector device. The uncoupled coupling rod is then extracted from the injection moulding die. The die carriers are then set at a reciprocal distance which is only slightly greater than the dimension for the depth of the injection moulding die. Then, by being guided on the guide elements of the die carriers and by being guided on the clamping faces of these die carriers, the injection moulding die is in turn removed from the clamping space in a direction of movement which is perpendicular to the coupling axis.

A replacement operation of this type is not only easier, it can also be carried out by less technical staff and with fewer operational steps than is possible with known systems. In addition, there is a saving in the dimensions for the hydraulic drive means for the die carriers because an opening width which corresponds to the maximum installation depth of the injection moulding die is only in fact required for the die closure unit.

The small installation depth of the coupling means which is required for the incorporation of the coupling means results from the features claimed in claims 2 - 12.

In many cases, it is advantageous to free, at least for a short time, the interior space within the box-like die carrier (13) for the additional incorporation of special units - the coupling rod of the ejector means spanning the interior space. For this purpose, a piston rod portion, serving as a coupling rod, is provided with identical coupling heads on both ends and is connectable, by means of its coupling head remote from the injection moulding die, to a further coupling means which is mounted on another piston rod portion of the ejector mearis and is identical to the coupling means mounted on the ejector plate.

The method of attaching such a special unit, e.g. in the form of a device for un-screwing threaded cores from the moulding, is described, for example, in German PS 2 806 060.

The invention will be described further, by way of example, with reference to the accompanying draw ings in which: Figure 1 is a side elevation of a die closure unit partly in section; Figures 2 and 3 are side and front elevations of the injection moulding die of the die closure unit including a coupling means and device for ejecting the moulding; Figure 4 is an enlarged sectional view through the coupling means taken along the line IV-IV in Figure 3; Figures Sand 5a illustrate the diametrical coupling elements of the coupling means in co-operation with an unlocking element (eccentric) both in and out of the coupling position; Figures Sand 7 are sectional views through the coupling means, taken along the line VII-VII of Figure 9, both in and out of the coupling position;; Figure 8 is an exploded view partly in section of the coupling means (sectional view through disc 20aa taken along the line VIII-VIII in Figure 7); Figure 9 shows a portion of the piston rod (18, 21) in the region of the second coupling means disposed within the box-like die carrier; Figure 10 is a view corresponding to Figures 6 and 7, but on an enlarged scale, of an alternative arrangement of the coupling means; Figure 11 is an enlarged, partially sectional view through a portion of the injection moulding die, taken along the line Xl-Xl of Figure 3 and including the driving device for the unlocking element; and Figure 12 is a part section through an alternative embodiment of the arrangement of Figure 11.

Figure 1 shows the right-hand part of the die closure unit without the piston-and-cylinder unit for the drive of movable die carrier 13 and without the mounting plate which carries this piston-andcylinder unit and which is supported on machine base 10. A mounting plate and stationary die carrier 12 are mounted on slide rails 11 of the machine base 10. The piston rod 16 of the piston-and-cylinder unit, mounted on the back of the mounting plate, extends through this mounting plate and abuts against the pressure absorbing plate 13b of the displaceable die carrier 13 via a pressure transmitting plate 15. The end of the piston rod 16 which strikes against the pressure transmitting plate 15 has a bore 19 formed therein which forms the cylinder spaces for the piston-and-cylinder unit (hydraulic cylinder) of the device for ejecting the moulding.

A piston rod 18,21 of this hydraulic cylinder is connected to an ejector plate 27 of injection moulding die 25 via a coupling means 20. The box-like die carrier 13 is displaceably mounted on tie-rods 14 which are accommodated, at one end, by the mounting plate and, at the other end, by the stationary die carrier 12. The pressure absorbing plate 13b of the die carrier 13 is connected to the clamping plate 13a of this die carrier 13 via supporting ribs 13c.The injection moulding die 25 comprises a mounting plate 25b on the coupling side, a mounting plate 46 on the moulding side, a contour plate 25 which is adjacent to the separating plane a-a, a contour support plate 40, two spacers 25a which are disposed symmetrically to the coupling axis h-h and define a free space 26 for the ejector plate 27 guided on guide pins 41, and ejector cover plate 28 for anchoring the ejector pins 42, and a shaping plate 44 on the moulding side. The moulding is denoted by the reference numeral 43.

In the embodiment shown in the drawings, the piston rod 18,21 of the device for ejecting the moulding connects the piston of the hydraulic cylinder of this device to the ejector plate 27 and comprises two piston rod portions 18 and 21.

The piston rod 21 on the moulding die side has identical coupling heads 21b on both ends. With its coupling head 21b remote from the injection moulding die 25, the piston rod is connectable to a further coupling means mounted on the other piston rod portion 18.This coupling means is identical to the coupling means 20 mounted on the ejector plate 27.

The further coupling means 20 is mounted, with a flange member 18f, on the piston rod portion 18 at the front end by means of securing screw 18h. It is in a mirror-image disposition relative to the coupling means 20 on the moulding die side. The coupling buttons 21b are each offset from the remaining piston rod portion by means of a respective neck 21a. Each coupling button 21b extends into a truncated cone 21 c. When the piston rod 18,21 is inserted into the coupling means 20, the casing surface cover of this truncated cone 21c abuts against sliding faces 23a of the coupling elements 23, which sliding faces are inclined relative to the coupling axis h-h.The diametrically disposed coupling elements 23 of the coupling means are guided radially relative to the piston 18, 21 and are thereby first pushed radially outwardly by the in-going coupling head 21b in opposition to the action of springs 24. In the coupling position, the coupling elements are affected by the loading of the initially tensioned springs 24 and engage behind the coupling head 216. In such a case, these coupling elements 23 abut against the neck 21a of the coupling rod 21. The guide paths 51 for the coupling elements 23 are formed by recesses in a disc 20a of the coupling means 20, which disc is provided with opening 20g (Figures 8, 10). The disc 20a is partially surounded by a sleeve 20a'.The coil springs 24 which load the coupling elements 23, are each accommodated in a respective bore 23cformed in each coupling element 23. They abut against the sleeve 20a'. The plate-like coupling elements 23 abut, with one broad side, against the ejector plate 27 or, resepectively, against the front face of the flange member 18f. As can be seen particularly from Figures 6,7 and 10, the guide paths 51 are defined by segmental remaining regions 20e of the disc 20a which form guide faces 25 for the coupling elements 23 which are also guided on the base face 20h of the disc 20a(Figure 8).

In the case of the coupling means 20 on the moulding die side, the sleeve 20a' is centred in an annular groove formed in the ejector plate 27, as can be seen particularly from Figure 4. In the coupling position, the coupling head 21b plunges into a central recess 54 formed in the ejector plate 27. The disc 20a is mounted on the ejector plate 27 by means of securing screws 38. The coupling elements 23 are displaceable from their coupling position by means of an unlocking element in opposition to the action of the springs 24. An eccentric 33 may be used as an unlocking element (example shown in Figures 1 - 9 and the left-hand half of the coupling means in the example shown in Figures 10, 11). At the rotational axis b-b (Figure 6) which extends radially relative to the coupling axis h-h, the eccentric 33 is rotationally mounted with one bearing portion 31a in the disc 20a.As can be seen from Figure 8 (top), the eccentric is symmetrical on both sides, i.e. has two planes of symmetry c-c and d-d. The eccentric member 33c protudes between the coupling elements 23 into the guide paths 51. By rotating the eccentric 33 about 90", the eccentric 33 arrives at an unlocked position or a locked position, which positions are shown at the top of Figure 8 and correspond to a coupling position or a non-coupling position of the coupling elements 23, as shown in Figures 4 and 5 (each simultaneously), in Figures 6 and 7 and in Figure 10 (again simultaneously). The eccentric member 33b, with its working faces 33c, is parallepiped-shaped and abuts against the coupling elements 23 alternately with its narrower or wider working faces 33c.

The eccentric 33 is actuable by means of a tool which is insertable axially in the bearing portion 33a via a bore 48 formed in the mounting plate 25b (Figures 10, 11, on the left). In such a case, the tool engages with a multi-edged profile into an internal edge 33d of the bearing portion 33a. The tool 79 thereby extends through the sleeve 20a' via holes 37. As can be seen from Figures 6 and 7, two diametrically disposed eccentrics 33 are provided in the coupling means 20. In the example shown in Figures 10 and 11, the eccentric 33 is installed as an additional unlocking element because the coupling elements 23 there are controlled by a different type of means.

In the embodiment shown in Figures 10 and 11,the unlocking element is a key 56 mounted in the disc 20a. This key is guided in the segmental remaining region 20e of the disc 20a by means of a cylindrical shaft. The key is insertable by means of a driving means between the coupling elements 23 for unlocking purposes in opposition to the action of a coil spring 57, which surrounds the shaft. As can be seen from Figure 11, the driving means 76 is a hydraulic or pneumatic piston-and-cylinder unit whose piston rod, as member 58, is guided in the bore 48 formed in the mounting plate 25b. A pin 59, anchored in the disc 20a, extends through a slot 77 formed in the shaft of the key 56 (Figure 10). The portion of the shaft of the key 56 which is surrounded by the coil spring 57 protudes into the free space 55 of the mounting plate 25a (Figures 10 - 12).The cylinder of the driving means 76 is formed by a die-piece 62 which is mounted on the clamping plate 13a of the die carrier 13 by means of securing screws 63. The hydraulic or pneumatic cylinder is sealed by a cover 66 which has an inlet bore 65 formed therein for the hydraulic or pneumatic medium. After every unlocking stroke, the piston is reset into the basic position by means of a resetting spring 64 which abuts, at one end, against a shoulder of the moulded-piece 62 and, at the other end, against the piston 58a. In the embodiment shown in Figure 12, the driving means 76 comprises a coil 72, which is accommodated in a moulded-piece 70, and an armature 71 which is disposed within the coil 72 and is axially drivable by means of induction. The moulded-piece 70 is mounted on the clamping plate 13a ofthe die carrier by means of mounting screws 63.The armature 71 is connected to a pin-like member 68, which is resettable by means of spring 67, via a connecting rod 69.

The spring is supported on a ring of the member 68 and abuts against an annular shoulder of the ejector plate.

Gripper projections 78a of a hydraulically actuable clamping pins 78 engage behind the mounting plate 25b of the injection moulding die 25 (Figure 1). The clamping pins 78 extend through rail-like guide elements 75 which are detachably mounted on the clamping face of the die carrier 13. The half of the injection moulding die which is hydraulically clamped tightly on the die carrier by means of the clamping pins is released in that the hydraulic clamping is reduced and the clamping pins 78 are guided by spring force slightly in the direction of the moulding die 25. By being guided on the guide elements 75 and on the clamping faces of the die carriers 12, 13, the injection moulding die 25 can then be guided out of the clamping space of the die closure unit in a replacement movement extending perpendicular to the coupling axis h-h or, if the operational steps are reversed, another moulding die may be inserted.

The eccentric 33 is axially secured by means of a radial flange which is held between an annular shoulder 61 (Figure 10) and the sleeve 20a'.

Claims

1. In a plastics injection moulding machine a die closure unit including a device for ejecting the finished moulding, which device includes a hydraulic piston-and-cylinder unit (hydraulic cylinder) mounted on a movable die carrier, and a coupling means which is mounted on the ejector plate of the injection moulding die and by means of which the piston rod of the hydraulic cylinder is connectable to the ejector plate, whereby at least one coupling element, guided radially relative to the piston rod, is engageable behind a coupling head of the piston rod by the loading of a spring, which coupling element is displaceable from its coupling position by means of an unlocking element in opposition to the action of the spring, characterised in that the unlocking element of the coupling means, which is disposed within a mounting plate of the injection moulding die, is actuable by means of a member which is displaceably mounted in a bore which is formed in the mounting plate and extends perpendicular to the coupling axis, and in that lateral edges of the mounting plate abut against guide elements of the die carrier for a return movement of the injection moulding die parallel to the clamping face of the die carrier.

2. A machine accoding to claim 1, wherein the unlocking element is a key which is mounted in a disc of the coupling means and is insertable between two diametrically disposed coupling elements by means of a drive means, mounted on the die carrier, in opposition to the action of a spring.

3. A machine according to claim 2, wherein the drive means is a hydraulic or pneumatic piston-andcylinder unit whose piston rod is guided in the bore formed in the mounting plate.

4. A machine according to claim 2, wherein the drive means includes an armature which is surrounded by a coil, said armature being axially drivable by means of induction forces and being connected, via a connecting rod, to the member which is resettable by means of a spring.

5. A machine according to one of claims 2 to 4, wherein a stationary pin extends through a slot formed in key, and wherein the shaft of the key, which is surrounded by a coil spring, protudes into a free space in the injection moulding die.

6. A machine according to one of claims 1 to 5, wherein the unlocking element is an eccentric which is rotatably mounted in a disc of the coupling means and is actuable by means of a tool which is axially insertable into its bearing portion via said bore.

7. A machine according to claim 2, wherein the guide paths for the coupling elements are formed by recesses in a disc of the coupling means, which disc is provided with an opening and is partially surrounded by a sleeve against which the springs of the coupling elements abut.

8. A machine as claimed according to claim 1, wherein the plate-like coupling elements abut against the ejector plate with one broadside, and the coupling head of the coupling rod plunges, in the coupling position, into a central recess formed in the ejector plate.

9. A machine according to claim 1, wherein gripper projections of the hydraulically actuable clamping pins reach behind the mounting plate of the injection moulding die, and the clamping pins reach behind the rail-like guide elements mounted on the die carrier.

10. A machine according to claim 1, wherein a coupling rod of the piston rod has identical coupling heads on both ends and is connectable, by means of its coupling head remote from the injection moulding die, to a further coupling means which is mounted on the piston rod portion and is identical to the coupling means mounted on the ejector plate.

11. A die closure unit of an injection moulding machine sunstantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.