JP2009154475A - Mold clamping device and injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve problems of a mold clamping device used for a conventional injection molding machine wherein molding clamping force greatly varies due to variation of dimensions or abrasion of movable components with time. <P>SOLUTION: The mold clamping device 14 is provided with a fixed side platen 28 with a fixed side mold 11 attached thereto, a movable side platen 38 with a movable side mold 12 attached thereto facing the fixed side mold 11, a pressing plate 40 facing the movable side platen 38, and a platen driving means 39 driving the movable side platen 38 in the direction facing the fixed side platen 28 via the pressing plate 40. The device 14 is further provided with a Belleville spring 45 incorporated between the movable side platen 38 and pressing plate 40 of the platen driving means 39, using the elastic power of the Belleville spring 45 as the mold clamping force. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a mold clamping device used when performing molding using a fixed side mold and a movable side mold, and an injection molding machine incorporating the same.

  The mold clamping device of the injection molding machine is roughly classified into a direct pressure type and a toggle type because of the difference in structure.

  The direct pressure type mold clamping device is a system in which a hydraulic or pneumatic cylinder is directly connected to a movable platen, and mold clamping is performed by hydraulic pressure or pneumatic pressure supplied to and discharged from this cylinder. is there. In this patent document 1, a technique is also proposed in which the tip of the tie bar is guided to a recess provided in the template, and the template and the tie bar are connected via an elastic body fitted into the tip of the tie bar. Yes. The main purpose of this is to suppress the increase in component costs associated with higher accuracy of components, and without simplifying the tie bar, the shape can be simplified to reduce component costs and improve reliability. It is intended.

  On the other hand, the toggle type mold clamping device is a system that opens and closes a mold and generates a mold clamping force via a toggle mechanism attached to a movable platen. A feature of this toggle mechanism is that the moving speed of the movable platen and the magnification rate of the force can be changed according to the ratio and position of the link arm that operates. Usually, the speed of the movable platen is high at the stage of the mold clamping operation, slows at the end of the mold clamping operation, and finally becomes zero, but the force expansion rate at this time is generally about several tens of times. Because of these characteristics, as a drive source for the toggle mechanism, a small output electric motor or the like is used in addition to the hydraulic and pneumatic cylinders.

  As described above, due to the difference in structure between the direct pressure type and the toggle type, a relatively small and space-saving molding machine may use a toggle type clamping device that requires only a small output of a drive source and can be downsized. Many. However, the toggle type mold clamping device has a demerit that the mold clamping force is likely to vary due to its structural reasons. The clamping force by the toggle type clamping device is generated as follows. That is, when the link arm of the toggle mechanism starts to open to the mold clamping position, these become substantially straight and the movable mold first comes into contact with the fixed mold. The tie bar is elastically stretched by a minute amount due to the tension of the link arm at the mold clamping position where the link arm is fully opened at 180 °, and the elastic force generated with the elastic deformation of the tie bar becomes the mold clamping force. Therefore, due to variations in mold thickness, tie bar length, and other dimensional variations in other related parts, there is also wear of moving parts that occur during long-term operation. A large variation will occur in the clamping force.

  In order to suppress variations in clamping force in such a toggle type clamping device, it is necessary to increase the precision of the dimensions of the components.

Japanese Patent Laid-Open No. 06-008295

  In order to suppress variation in clamping force in the toggle type clamping apparatus, when the dimensions of the parts are increased, the cost of the parts is inevitably increased accordingly.

  A relatively large molding machine is generally equipped with a moving mechanism that can control the amount of elastic deformation of the tie bar and adjust the clamping force in the toggle mechanism so that a stable clamping force can be obtained. Known to. However, since such a moving means has a complicated structure, its parts cost is very high, and it cannot be adapted to a small mold clamping device.

  An object of the present invention is to provide a mold clamping device that is simple in structure, hardly affected by disturbances such as variation in part dimensions and wear over time, and capable of generating a stable mold clamping force, and injection molding incorporating the mold clamping device. Is to provide a machine.

  According to a first aspect of the present invention, there is provided a fixed platen to which a fixed mold is attached, a movable platen to which a movable mold facing the fixed mold is attached, and a pressure plate facing the movable platen. And a platen driving means having a mold clamping device. The platen driving means is for driving the movable platen along the direction facing the fixed platen via the pressure plate. The mold clamping device further includes an elastic member incorporated between the movable side platen and the pressure plate of the platen driving means.

  The second aspect of the present invention is an injection device that plasticizes a resin material and injects the resin material into a cavity formed between the fixed side mold and the movable side mold by a predetermined amount. An injection molding machine comprising the mold clamping device according to the first aspect.

  In the present invention, since the elastic member is incorporated between the pressure plate of the platen driving means and the movable side platen, the movable side platen is moved along the direction facing the fixed side platen by the platen driving means via the elastic member. Driven. Therefore, when the mold is clamped, the platen driving means is operated to move the movable platen forward to the fixed platen so that the movable mold attached to the movable platen is fixed to the fixed platen. Abut. Since the pressure plate continues to advance to the mold clamping position, the elastic member built in between the pressure plate and the movable platen starts to elastically deform until the pressure plate finishes moving to the mold clamping position. Elastic deformation will continue. As a result, the elastic deformation force of the elastic member acts on the contact surface between the fixed mold and the movable mold as a clamping force.

  According to the mold clamping device of the present invention, since the elastic member is incorporated between the movable side platen and the pressure plate of the platen driving means, the elastic member is used as the mold clamping force that has been dependent on the elastic deformation amount of the tie bar until now. It became possible to utilize the elastic deformation force. The elastic coefficient of the elastic member is very small compared to that of the tie bar, so even if variations in the dimensions of various movable parts in the platen drive means that affect the clamping force or wear over time, Changes in clamping force can be minimized. As a result, a long-term stable mold clamping force can be obtained. In addition, since an elastic member is interposed between the movable platen and the pressure plate, an elastic member having an elastic coefficient that can absorb variations in clamping force can be used.

  According to the injection molding machine of the present invention, since the mold clamping device according to the present invention is provided, the structure is simple, hardly affected by disturbances such as variations in part dimensions and wear over time, and a stable mold clamping force is generated. It is possible to provide an injection molding machine having a mold clamping device.

  An embodiment in which an injection molding machine according to the present invention is applied to a vertical injection molding machine will be described in detail with reference to FIGS. 1 and 2 showing a schematic structure thereof. Note that the present invention is not limited to such an embodiment, and can be applied to other arbitrary techniques belonging to the spirit of the present invention as necessary.

  The schematic structure of the vertical injection molding machine in this embodiment is shown in FIG. 1 in the mold open state, and the mold clamping state is shown in FIG. That is, the injection molding machine 10 includes an injection device 13 that plasticizes a resin material and injects the resin material into a cavity (not shown) formed between the fixed mold 11 and the movable mold 12, and a mold clamping device. 14 and.

  The injection device 13 in the present embodiment includes a material supply unit 16 that supplies a pellet-shaped resin material into the injection cylinder 15, and plasticizes the resin material in the injection cylinder 15 and injects the resin material into the cavity by a predetermined amount. And a resin injection part 17 to be provided.

  The material supply unit 16 in the present embodiment has a hopper 18 for storing a resin material, a feeder pin 19 for sending the resin material from the hopper 18 into the injection cylinder 15, and a reciprocating drive for the feeder pin 19. The pin drive motor 20 is provided. The feeder pin 19 is slidably fitted to the material supply passage 22 of the material supply block 21 provided integrally with the upper end portion of the injection cylinder 15, and the material supply passage 22 communicates with the injection cylinder 15. is doing. A screw shaft 23 integral with the pin drive motor 20 is screwed to the feeder pin 19, and the feeder pin 19 reciprocates in the left-right direction in the figure by forward and reverse rotation of the screw shaft 23. By the reciprocating motion of the feeder pin 19, the resin material can be intermittently fed from the hopper 18 into the injection cylinder 15 through the material supply passage 22.

  The resin injection part 17 in this embodiment includes a previous injection cylinder 15, a plunger 24 slidably fitted to the injection cylinder 15, and plunger drive means 25 for reciprocatingly driving the plunger 24. It has. A nozzle 27 is formed at the tip of the injection cylinder 15 whose outer periphery is surrounded by a heater 26, and is integrally connected to the stationary platen 28. A plurality of guide shafts 29 project from the stationary platen 28, and an end plate 30 is integrally connected to the distal ends thereof. A slider 31 is disposed between the end plate 30 and the stationary platen 28, and the slider 31 is slidably held along the plurality of guide shafts 29 penetrating the slider 31. The previous plunger 24 protrudes from the slider 31 toward the injection cylinder 15. The plunger driving means 25 includes an injection motor 32, a ball nut 33 that is rotatably supported with respect to the end plate 30, and a ball that protrudes from the slider 31 on the side opposite to the plunger 24 and is screwed into the ball nut 33. And a screw shaft 34. A driving sprocket 35 is integrally connected to the injection motor 32, and an endless toothed belt 37 is stretched between the driving sprocket 35 and a driven sprocket 36 provided integrally with the ball nut 33. Yes.

  Accordingly, when the injection motor 32 is rotated forward and backward, the ball nut 33 is rotated forward and backward via the toothed belt 37. As a result, the slider 31 integrated with the ball screw shaft 34 reciprocates along the guide shaft 29, and the plunger 24 can reciprocate with respect to the injection cylinder 15. That is, for each injection operation, the reciprocating motion of the plunger 24 and the reciprocating motion of the previous feeder pin 19 are combined, and the nozzle 27 of the injection cylinder 15 is plasticized while the resin material supplied into the injection cylinder 15 is plasticized. Can be sequentially injected into the cavity by a predetermined amount.

  In addition, as the injection device 13 described above, any known configuration other than the present embodiment can be appropriately employed.

  On the other hand, the mold clamping device 14 in the present embodiment includes a fixed platen 28 to which the fixed mold 11 is attached, a movable platen 38 to which the movable mold 12 facing the fixed mold 11 is attached, Platen drive means 39. The platen driving means 39 has a pressure plate 40 facing the movable platen 38, and drives the movable platen 38 along the direction facing the fixed platen 28 via the pressure plate 40. is there.

  The other ends of the plurality of tie bars 41 whose one ends are integrally connected to the stationary platen 28 are integrally connected to the base plate 42. The movable side platen 38 through which the tie bar 41 passes is slidably held with respect to the tie bar 41 and can move along the tie bar 41 in a direction parallel to the facing direction of the fixed side platen 28. A plurality of guide rods 43 project from the movable platen 38 toward the base plate 42 in parallel with the tie bars 41, and the pressure plate 40 through which the guide rods 43 pass is slid along the guide rods 43. It is held freely. At the tip of the guide rod 43, a retaining stopper 44 having a flange shape for preventing the pressure plate 40 from coming off from the guide rod 43 is formed. A disc spring 45 as an elastic member of the present invention is interposed between the movable platen 38 and the pressure plate 40, and loads on the movable mold 12 and the movable platen 38 are applied via the disc spring 45. The pressure plate 40 is loaded.

  The disc spring 45 in the present embodiment is formed by forming a disc having flexibility such as metal into a truncated cone shape, but has an arbitrary contour shape such as an annular shape or a shape in which slits are formed radially. Can be adopted. Thus, when the disc spring 45 is used as the elastic member, the arrangement space can be reduced as compared with the case where a coil spring or a leaf spring is used as the elastic member, and the injection molding machine 10 can be downsized. It is advantageous.

  The disc spring 45 preferably has a size corresponding to the end surface of the movable platen 38 and the end surface of the pressure plate 40 with which the plate spring 45 abuts so that the elastic force is uniformly transmitted as a clamping force. Here, the size corresponding to the end surface of the movable platen 38 with which the disc spring 45 abuts and the end surface of the pressure plate 40 intends the following matters. That is, the outer peripheral edge of the elastic member does not protrude from each end surface of the movable platen 38 and the pressure plate 40 at the tip of the platen driving means 39 with which the elastic member (belleville spring 45) abuts. Further, it is also a size that the elastic member can take without interfering with the guide rod 43 protruding from the movable platen 38 and the end face of the pressure plate 40. In other words, only a single elastic member is in contact with the end surfaces of the movable platen 38 and the pressure plate 40, so that two or more elastic members of the same size cannot be arranged side by side on the end surface of the movable platen 38. Intended for things. However, it is also included in the scope of the present invention that a plurality of disc springs 45 are stacked and other well-known elastic members such as coil springs and leaf springs are used instead of the disc springs 45. Even when a coil spring, a leaf spring, or the like is used, it is desirable to adopt one having an outer dimension as large as possible as in the case of the disc spring 45.

  As with the movable side platen 38, the tie bar 41 may be configured to penetrate the pressure plate 40, and the pressure plate 40 may be slidably held along the tie bar 41. In this case, it can be said that the guide rod 43 can be omitted, and the size of the elastic member, that is, the disc spring 45 can be set larger, which is more preferable.

  The platen drive means 39 in the present embodiment includes a mold clamping motor 46, a toggle mechanism 49 having two link arms 47 and 48, and a pressure plate 40. The mold clamping motor 46 is installed in a housing 50 that accommodates the base plate 42, and a ball screw shaft 51 that extends in a direction orthogonal to the longitudinal direction of the tie bar 41 is integrally connected via a joint 52. ing. The ball screw shaft 51 is rotatably accommodated in the housing 50 via a pair of bearing brackets 53. A toggle mechanism 49 is incorporated between the ball nut 54 screwed onto the ball screw shaft 51 and the pressure plate 40. One end of a follower arm 47 is rotatably connected to the pressure plate 40 via a pin 55, and an intermediate part is swingable via a pivot 56 to the other end of the follower arm 47. One end of the drive arm 48 connected to the base plate 42 is connected via a swing pin 57. The ball nut 54 is provided with a guide pin 58 that protrudes in a state perpendicular to the axis of the ball screw shaft 51 and the longitudinal direction of the tie bar 41, and this guide pin 58 is formed at the other end of the drive arm 48. The long hole 59 is slidably engaged.

  Therefore, when the ball screw shaft 51 is driven by normally rotating the mold clamping motor 46 from the mold open state shown in FIG. 1, the ball nut 54 starts to move from the proximal end portion to the distal end portion of the ball screw shaft 51. Along with this, the drive arm 48 that has fallen begins to rise so that the movable mold 12 rises toward the fixed mold 11. At this time, due to inertia, a large force is applied to the disc spring 45 in the compression direction and the plate spring 45 is bent, so that the movable die 12 and the movable platen 38 do not swing with this. It is effective to give an appropriate compressive force, that is, a preload, to. More specifically, the disc spring 45 in the no-load state has a gap between the movable platen 38 and the pressure plate 40 so that the pressure plate 40 presses against the stopper 44 of the guide rod 43 in the mold open state. Set narrower than the height of.

  Now, as the ball nut 54 moves, the movable mold 12 gradually approaches the fixed mold 11 and these parting surfaces 60 come into contact with each other, so that the driven arm 47 and the drive arm 48 are formed. The angle is close to approximately 180 °. If the mold clamping motor 46 is further rotated forward from here, the movable side mold 12 and the movable side platen 38 remain pressed against the fixed side mold 11, and no further movement of the movable side mold 12 occurs. . On the other hand, the pressure plate 40 continues to move to the movable platen 38 with the elastic deformation of the disc spring 45. As a result, the repulsive force generated by the compression of the disc spring 45 acts on the parting surface 60 between the movable mold 12 and the fixed mold 11 as a clamping force. Finally, the driven arm 47 and the drive arm 48 are in a straight line. At this time, the amount of bending of the disc spring 45 is maximized, and the maximum clamping force due to elastic deformation of the disc spring 45 is generated. In this case, it is possible to perform a design that does not cause elastic deformation of the tie bar 41. Therefore, the fixed side platen 28 and the fixed side mold 11 are not displaced by the mold clamping operation, and the injection device is applied to the fixed side platen 28. 13 can be attached with high accuracy.

  By the way, even if the rising end position of the movable mold 12 with respect to the fixed mold 11, that is, the mold clamping position is changed due to variation in the dimensions of the toggle mechanism 49 or the tie bar 41, wear or the like, this is caused by the elastic deformation of the disc spring 45. Changes will be absorbed. For this reason, it is possible to minimize the change in the clamping force. In other words, the disc spring 45 needs to further have an elastic deformation amount capable of absorbing a change in the mold clamping position of the movable mold 12 in addition to the elastic deformation amount corresponding to the mold clamping force.

  After completion of the mold clamping, the injection nozzle 27 of the injection cylinder 15 enters a cavity formed between the fixed platen 28 and the movable mold 12 through a resin passage (not shown) formed in the fixed mold 11. Molten resin is injected. Then, by reversing the mold clamping motor 46 through the cooling process, the mold opening is performed in the reverse procedure to that described above, and the molded product is taken out from the movable mold 12 to complete a series of molding processes. .

  Although the vertical injection molding machine 10 has been described in the above-described embodiment, the present invention can also be applied to various horizontal molding machines, a tie barless molding machine that does not have the tie bar 41, and the like. The present invention should be construed only from the matters described in the scope of the claims, and in the above-described embodiments, all the changes and modifications included in the concept of the present invention are possible other than the matters described. It is. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

It is sectional drawing showing schematic structure of one Embodiment of the injection molding machine by this invention, and has shown the mold open state. In the embodiment shown in FIG. 1, it is sectional drawing which shows the clamping state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Injection molding machine 11 Fixed side metal mold 12 Movable side metal mold 13 Injection device 14 Clamping device 15 Injection cylinder 16 Material supply part 17 Resin injection part 18 Hopper 19 Feeder pin 20 Pin drive motor 21 Material supply block 22 Material supply path 23 Screw shaft 24 Plunger 25 Plunger drive means 26 Heater 27 Nozzle 28 Fixed side platen 29 Guide shaft 30 End plate 31 Slider 32 Injection motor 33 Ball nut 34 Ball screw shaft 35 Drive sprocket 36 Driven sprocket 37 Toothed belt 38 Movable side platen 39 Platen driving means 40 Pressure plate 41 Tie bar 42 Base plate 43 Guide rod 44 Retaining stopper 45 Belleville spring 46 Clamping motor 47 Follow arm (link arm)
48 Drive arm (link arm)
49 Toggle mechanism 50 Housing 51 Ball screw shaft 52 Joint 53 Bearing bracket 54 Ball nut 55 Pin 56 Pivot 57 Oscillating pin 58 Guide pin 59 Long hole 60 Parting surface

Claims (6)

A stationary platen to which the stationary mold is attached;
A movable platen to which a movable mold facing the fixed mold is attached;
A mold clamping device having a pressure plate facing the movable platen, and platen driving means for driving the movable platen along the direction facing the fixed platen via the pressure plate. There,
A mold clamping device, further comprising an elastic member incorporated between the movable platen and a pressure plate of the platen driving means.   The mold clamping apparatus according to claim 1, further comprising a guide rod having one end connected to the movable platen and the pressure plate penetratingly slidably guiding the movement thereof.   The said elastic member is a disc spring, This disc spring has a magnitude | size corresponding to the end surface of the said movable side platen which this contact | abuts, and the end surface of the said pressurization plate, The Claim 1 or Claim 2 characterized by the above-mentioned. Clamping device.   4. The tie bar according to claim 1, further comprising a tie bar having one end connected to the fixed side platen and slidably penetrating the movable side platen to guide its movement. Mold clamping device.   The mold clamping device according to any one of claims 1 to 4, wherein the platen driving means has a toggle mechanism. An injection device that plasticizes the resin material and injects the resin material by a predetermined amount into a cavity formed between the fixed side mold and the movable side mold;
An injection molding machine comprising: the mold clamping device according to any one of claims 1 to 5.

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