JP2009285842A - Method for operating mold clamping device of toggle type injection molding machine and mold clamping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for operating the mold clamping device of a toggle type injection molding machine which prevents a movable platen from staggering and slanting. <P>SOLUTION: A pair of tapered spacers (42 and 43) is set between the inner surface of a tie-bar nut pocket (26) and a tie-bar nut (25). When implementing at least a mold opening process, a mold closing process, and a mold clamping process, the spacer (42) is driven by a piston cylinder unit (45), and clearances (S1, S1, etc.) in the axial direction of a tie-bar are eliminated substantially. When adjusting mold clamping force, the spacer (42) is made to take shelter to secure the clearances (S1, S1, etc.). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixed platen to which a fixed side mold is attached, a movable platen to which a movable side die is attached, a mold clamping housing, and a plurality of plates that penetrate the movable platen and connect the fixed platen and the mold clamping housing. A tie bar and a toggle mechanism provided between the movable platen and the mold clamping housing. The tie bar is provided with a tie bar nut, and a predetermined portion of the tie bar nut is provided in the mold clamping housing. The present invention relates to a method of operating a mold clamping device of a toggle type injection molding machine and a mold clamping device which are housed in a tie bar nut pocket and can be adjusted when a tie bar nut is driven.

  The mold clamping device of the toggle type injection molding machine includes a fixed platen to which a fixed side mold is attached, a movable platen to which a movable side die is attached, a mold clamping housing, a fixed platen and a mold clamping housing that penetrate the movable platen. And a toggle mechanism provided between the movable platen and the mold clamping housing. When a toggle mechanism of a mold clamping device to which a pair of molds composed of a fixed mold and a movable mold is attached is driven, the pair of molds are closed and the tie bar is elastically extended. Then, a predetermined mold clamping force is obtained by the tension of the tie bar. When a molten resin or molten metal is injected into the cavity formed in the mold and the mold is opened after cooling and solidification, a desired molded product is obtained. An appropriate mold clamping force can be obtained by driving the cross head constituting the toggle mechanism to a predetermined position. By the way, the thickness of the pair of molds that are closed is different for each mold. Therefore, the distance between the fixed platen and the movable platen when the mold is closed, that is, the mold thickness also varies depending on the mold to be attached. Therefore, in order to obtain an appropriate clamping force, the distance between the clamping housing and the stationary platen is set in advance according to the thickness of the mold so that the crosshead position becomes a predetermined position when clamping. It needs to be adjusted. This adjustment is called mold clamping force adjustment or mold thickness adjustment.

  Male screws are formed at both ends of the tie bar connecting the fixed platen and the mold clamping housing. One end of the tie bar is inserted into a through hole provided in the fixed platen, and a tie bar fixing member, that is, a fixing nut is screwed together. Thus, one end of the tie bar is fixed to the fixed platen. The other end passes through a through-hole formed in the mold clamping housing, and a tie bar nut is screwed and attached to the mold clamping housing. The mold clamping force adjustment is performed by changing the length of the tie bar divided by the fixing member and the tie bar nut, that is, the effective length of the tie bar. Specifically, the mold clamping force is rotated by driving the tie bar nut. The tie bars are composed of a plurality of, for example, four, and are provided at the four corners of the mold clamping housing having a substantially square plane or side shape. The driven gears are fixed to the tie bar nuts screwed to the respective tie bars, and the four driven gears are one relatively large diameter center gear provided at the center of the mold clamping housing. Is engaged. Accordingly, when the center gear is driven to rotate, the four tie bar nuts rotate by the same rotation angle, and the mold clamping force is adjusted while maintaining the parallelism of the mold clamping housing with respect to the fixed platen.

Japanese Patent Laid-Open No. 2000-15777

  Conventionally, various methods have been proposed for adjusting the mold clamping force. For example, Patent Document 1 proposes a mold clamping force adjusting method in which a predetermined mold clamping force can be easily obtained in a toggle type injection molding machine. . According to the mold clamping force adjusting method described in Patent Document 1, the distance between the fixed platen and the movable platen is set larger than the thickness of the pair of molds, and the crosshead of the toggle mechanism is used to obtain a predetermined mold clamping force. When the tie bar nut is rotated until the pair of dies touch each other while the crosshead position is maintained, a predetermined clamping force can be obtained.

  According to the mold clamping force adjusting method described in Patent Document 1, since a predetermined mold clamping force can be obtained easily and accurately, it is excellent as a mold clamping force adjusting method. However, similar to other well-known mold clamping force adjustment methods, there are problems to be solved. Hereinafter, these problems will be described with reference to FIG.

  The sectional view of FIG. 5 shows a part of a fixed plate 71, a part of a mold clamping housing 72, a tie bar 73, etc. of a conventionally known toggle type injection molding machine. A through hole 75 is formed in the fixed plate 71, and a tie bar fixing member 76 having a female screw on the inner peripheral surface is fixed to the fixed plate 71. One end of the tie bar 73 passes through the through hole 75, and the female screw of the tie bar fixing member 76 is screwed into the male screw formed in the penetrating part. Thus, one end of the tie bar 73 is fixed to the fixed plate 71. A through-hole 78 is also formed in the mold clamping housing 72, but a tie bar nut insertion hole 79 whose diameter is enlarged by a predetermined length is formed in the vicinity of the outlet of the through-hole 78, and a bottom portion of the tie bar nut insertion hole 79 is formed. A tie bar nut seating surface 80 is formed. The other end portion of the tie bar 73 passes through the through-hole 78 of the mold clamping housing 72, and a tie bar nut 81 is screwed into a male screw provided near the end portion. Thus, the other end of the tie bar 73 is attached to the mold clamping housing 72. The tie bar nut 81 is provided with a small diameter portion 82 and a large diameter portion 83, and a shoulder portion 84 is formed. The tie bar nut 81 has a large diameter portion 83 inserted into the tie bar nut insertion hole 79, and a shoulder portion 84 is held by a nut cover 86 fixed to the mold clamping housing 72. That is, the large diameter portion 83 of the tie bar nut 81 is stored in a tie bar nut pocket 90 constituted by the tie bar nut insertion hole 79 and the nut cover 86, and a part of the small diameter portion 82 protrudes from the nut cover 86 to the outside. Yes. A driven gear 88 is fixed to the side portion of the small-diameter portion 82 that protrudes. Accordingly, when the center gear not shown in FIG. 5 is driven, the driven gear 88 meshing with the center gear is driven, and the tie bar nut 81 is also rotated. Since the rotation of the tie bar 73 is restricted by the tie bar fixing member 76, when the tie bar nut 81 rotates, the tie bar nut 81 moves in the axial direction. That is, the mold clamping housing 72 moves in the axial direction. As a result, the tie bar effective length 92 between the tie bar fixing member 76 and the tie bar nut 81 changes. Thereby, the mold clamping force can be adjusted.

  Such a tie bar nut pocket 90 is formed slightly larger than the large-diameter portion 83 of the tie bar nut 81 so that the tie bar nut 81 can rotate smoothly, and is provided with play. Is secured. That is, a first gap 93 is formed between the tie bar nut 81 and the tie bar nut seating surface 80, and a second gap 94 is formed between the tie bar nut 81 and the nut cover 86. The first and second gaps 93 and 94 change in the mold clamping process and the mold opening process of the mold clamping device. Specifically, in the mold clamping step, a force acts in a direction in which the fixed platen 71 and the mold clamping housing 72 are separated from each other due to the reaction of the mold clamping force, so that the tie bar nut 81 is seated on the tie bar nut seating surface 80 and is first. The gap 93 becomes substantially zero, and the second gap 94 widens. In the mold opening process, the separating force is released from the stationary platen 71 and the mold clamping housing 72, so that the tie bar nut 81 is separated from the tie bar nut seating surface 80 and a first gap 93 is generated. The toggle type mold clamping device of the injection molding machine is provided with a plurality of tie bars, but each tie bar has all the first and second gaps 93 and 94 as described above due to the effects of component tolerance and assembly accuracy. It does not change uniformly in the tie bar. If the change becomes non-uniform, the mold clamping housing 72 is wobbled or tilted, and the movable platen is also wobbled or tilted via the toggle mechanism. As a result, the following various problems occur. For example, the straightness of the movable plate deteriorates before and after the mold touches, the angle of the movable plate changes, and the parting line shifts. If it does so, a shift | offset | difference will arise also in the shape of the cavity formed with a fixed side metal mold | die and a movable side metal mold | die, and a shaping | molding defect will generate | occur | produce. In particular, in the case of a lens that requires high optical characteristics, an optical axis shift, aberration deterioration, and the like occur. Further, if the straightness of the movable platen is impaired, in the case of a die provided with a guide pin or an inlay type die, the guide pin and the inlay portion are worn. Furthermore, the so-called injection compression molding method, in which the mold is slightly opened and is injected and clamped and compressed, is known as an injection molding method with excellent transferability, but if the movable plate fluctuates during injection, the molded product Variation in weight and variation in plate thickness will occur. The above-described problems are likely to occur in a molded product that is strongly required to be uniform in weight and thickness, such as an optical disk, and is molded in a high cycle. Problems also arise in the mold opening process. That is, when the mold is opened and the molded product is taken out by a robot arm or the like, the accuracy of the stop position cannot be obtained, so that a takeout failure occurs. Furthermore, when the injection molding machine is operated for a long period of time, the tie bar nut 81 may rotate and become loose, and the mold clamping force may change.

  An object of the present invention is to provide a method of operating a mold clamping device of a toggle type injection molding machine and a mold clamping device, which have solved the above-described conventional problems or problems. Specifically, by preventing wobbling and tilting of the movable platen, there is no deviation in the parting line during mold clamping, there is no deviation in the shape of the cavity, and the mold or inlay type with guide pins. Guide pins and inlay parts are not worn even in molds, and the movable platen does not fluctuate during injection in injection compression molding, and can be stopped at the mold opening position with high accuracy even during product removal. An object of the present invention is to provide a method of operating a mold clamping device and a mold clamping device of a toggle type injection molding machine, which can obtain a stable mold clamping force without loosening a tie bar nut even when operated for a long period of time.

  In the present invention, in order to achieve the above object, a tie bar nut pocket is provided with a tapered spacer having a predetermined shape and an actuator for driving the spacer. The spacer is provided between predetermined inner surfaces of the tie bar nut and the tie bar nut pocket. At this time, it is configured such that a gap allowing the axial movement of the tie bar is secured between the spacer and the tie bar nut or between the tie bar nut and the tie bar nut pocket. When the actuator is driven, the gap is configured to be substantially zero.

  Specifically, in order to achieve the above object, the invention according to claim 1 includes a stationary platen to which a stationary mold is attached, a movable plate to which a movable mold is attached, a mold clamping housing, and the movable plate. A plurality of tie bars penetrating through and connecting the fixed plate and the mold clamping housing; and a toggle mechanism provided between the movable plate and the mold clamping housing. A nut is provided, and a predetermined portion of the tie bar nut is housed in a tie bar nut pocket provided in the mold clamping housing, and the mold clamping force can be adjusted by rotating the tie bar nut. In the mold clamping device of the toggle type injection molding machine, at least the mold opening process, the mold closing process, and the mold clamping process are performed by the tie bar nut pocket and the tie bar nut. A predetermined taper-shaped spacer is inserted into the gap in the axial direction of the tie bar provided between the tie bars so that the gap becomes substantially zero. Thus, the gap is ensured and implemented.

  According to a second aspect of the present invention, there is provided a fixed platen to which the fixed side mold is attached, a movable platen to which the movable side die is attached, a mold clamping housing, the fixed platen and the mold clamping through the movable platen. A plurality of tie bars connecting the housing, and a toggle mechanism provided between the movable platen and the mold clamping housing, the tie bar is provided with a tie bar nut, and the tie bar A predetermined part of the nut is accommodated in a tie bar nut pocket provided in the mold clamping housing, and the mold clamping force can be adjusted by rotationally driving the tie bar nut. In the mold clamping device, the tie bar nut pocket has a tapered space provided between a predetermined inner surface of the tie bar nut pocket and the tie bar nut. And an actuator for driving the spacer, and a predetermined gap in the axial direction of the tie bar between at least the spacer and the tie bar nut or between the tie bar nut and the tie bar nut pocket drives the actuator. Then, the spacer is configured to be substantially zero. According to a third aspect of the present invention, in the apparatus according to the second aspect of the present invention, the spacer has a first surface in which one surface is inclined with respect to the other surface and the plate thickness is reduced in one direction. The pair of spacers are provided in a state in which the thinner and thicker plates are overlapped with each other. According to a fourth aspect of the present invention, in the apparatus according to the second or third aspect, the actuator is constituted by a fluid type piston cylinder unit or an electromagnetic solenoid.

  As described above, according to the present invention, the mold clamping force is adjusted by securing the axial clearance of the tie bar between the tie bar nut pocket and a predetermined portion of the tie bar nut. Similarly to the above, the tie bar nut can be smoothly rotated and the mold clamping force can be easily adjusted. According to the present invention, the mold opening process, the mold closing process, and the mold clamping process are carried out by inserting a predetermined spacer into the gap to make the gap substantially zero, so that the mold clamping housing does not fluctuate. Therefore, the movable plate does not fluctuate, and the movable plate is driven with high accuracy while maintaining straightness. The angle of the movable side mold does not change immediately before and after the touch with the fixed side mold, and the parting line does not shift, so the shape of the cavity formed in the mold does not distort. Accordingly, molding defects do not occur. Even in the case of a lens for which high accuracy is required, there is no variation in optical axis deviation or aberration. Further, even if the mold is provided with a guide pin or an inlay portion, the movable plate keeps straight running, so that the guide pin and the inlay portion are not easily worn. Furthermore, even when the injection compression molding method is performed, the movable platen does not fluctuate at the time of injection, so there is no variation in the weight or thickness of the molded product. Accordingly, uniformity in weight and plate thickness is strongly required, and even when an optical disc is molded at a high cycle, molding defects are unlikely to occur. In addition, since the movable plate can be stopped with high accuracy even when the mold is opened, defective takeout of the molded product is reduced. Furthermore, since the tie bar nut is substantially fixed in the tie bar nut pocket and cannot be rotated, the tie bar nut does not loosen even when operated for a long period of time, and the clamping force is stabilized. In addition, according to another invention, the structure is simple and can be provided at low cost simply by being composed of an actuator such as a piston cylinder unit, an electromagnetic solenoid, and a spacer, and the existing toggle injection molding. It can be easily attached to the machine.

  Embodiments of the present invention will be described below. The mold clamping apparatus of the toggle type injection molding machine according to the embodiment of the present invention is also generally configured in the same manner as the mold clamping apparatus of a conventionally known toggle type injection molding machine. That is, as shown in the front view of FIG. 1, the mold clamping device 1 of the toggle type injection molding machine according to the present embodiment includes a stationary platen 3 to which a stationary mold 2 is attached, and a movable mold. , And four tie bars 10, 10,... That connect the fixed plate 3 and the mold clamping housing 8 through the movable plate 6, and the movable plate 6. And a toggle mechanism 11 provided between the mold clamping housing 8 and the mold clamping housing 8. Through holes are made in the fixed platen 3, and tie bar fixing members 13, 13,... Made of female screws are fixed at positions corresponding to these through holes. One end of each of the tie bars 10, 10,... Penetrates through the through hole of the fixed platen 3, and the male screw formed in the penetrating portion is screwed into the female screw of the tie bar fixing members 13, 13,. Yes. Thereby, one end of the tie bars 10, 10,... Is fixed to the stationary platen 3. The other end of each of the tie bars 10, 10,... Penetrates a through hole opened in the mold clamping housing 8, as will be described in detail later. .. Although not shown in FIG. 1, a tie bar nut is screwed into a male screw provided at the other end of the tie bars 10, 10,.

  According to the present embodiment, the tie bar nut pressing devices 21, 21,... Are provided on the opposite side of the toggle mechanism 11 indicated by the arrow Y 1 of the mold clamping housing 8. As shown in FIG. 2A, the tie bar nut pressing devices 21, 21,... Are provided corresponding to the four tie bars 10, 10,. 3 (a) also shows such tie bar nut pressing devices 21, 21,..., Mold clamping housing 8, tie bars 10, 10,.

  As shown in FIG. 3, through-holes 23 through which the tie bars 10 pass are opened at the four corners of the mold-clamping housing 8, and the vicinity of the outlets of the through-holes 23 is hollowed out in a predetermined shape. An insertion hole 26 is formed. The tie bar nut 25 and the tie bar nut pressing device 21 are stored or stored in the tie bar nut insertion hole 26. The bottom surface 28 of the tie bar nut insertion hole 26 is formed perpendicular to the axial direction of the tie bar 10 and is a surface on which the tie bar nut pressing device 21 is installed as will be described later. The other end portion of the tie bar 10 passes through the through hole 23, and a male screw is formed in the vicinity of the other end portion, and a tie bar nut 25 is screwed to the male screw. Thereby, the other of the tie bars 10, 10,... Is attached to the mold clamping housing 8. The tie bar nut 25 includes a small diameter portion 30 and a large diameter portion 31, and a shoulder portion 32 is formed by these. The large diameter portion 31 of the tie bar nut 25 is inserted into the tie bar nut insertion hole 26, and the shoulder portion 32 is pressed by the nut cover 35. The nut cover 35 is fixed to the mold clamping housing 8 with bolts or the like. Therefore, the large-diameter portion 31 of the tie bar nut 25 is accommodated in the tie bar nut pocket 36 constituted by the tie bar nut insertion hole 26 and the nut cover 35. A part of the tie bar nut pressing device 21 is also stored in the tie bar nut pocket 36, and the tie bar nut 25 is restricted from moving in the axial direction. A part of the small-diameter portion 30 of the tie bar nut 25 protrudes from the nut cover 35 to the driven gear 38. As shown in FIG. 2, the mold clamping housing 8 is provided with a center gear 40 having a relatively large diameter at the center, and driven gears 38, 38,. Therefore, although not shown in FIG. 2, when a predetermined drive gear is driven, the center gear 40 meshed with the drive gear is driven, and as a result, the driven gears 38, 38,. 25, 25, ... also rotate. Then, the tie bar effective length L changes and the mold clamping force can be adjusted.

  The tie bar nut pressing device 21 includes a first spacer 42, a second spacer 43, and an air type piston cylinder unit 45, and the first and second spacers 42 and 43 are accommodated in the tie bar nut pocket 36. . As shown in FIG. 2A, the first spacer 42 has a rectangular planar shape, and has a plate shape in which the upper surface 47 and the lower surface 48 are inclined at a predetermined angle 50. Therefore, the plate thickness decreases in a taper shape in the direction of the arrow Y2. The first spacer 42 has a rectangular cutout 51. The cutout 51 has a rectangular short side slightly longer than the diameter of the tie bar 10 so that the tie bar 10 can be inserted. Accordingly, the first spacer 42 is guided by the tie bar 10 and can be slid in the front-rear direction by the length of the long side of the rectangular shape of the cutout 51, and in the vertical direction with respect to FIG.

  As shown in FIG. 2C, the second spacer 43 also has a plate shape in which the planar shape is rectangular and the upper surface 53 and the lower surface 54 are inclined at a predetermined angle 56. Therefore, the plate thickness decreases in a taper shape in the arrow Y3 direction. The angle 50 of the first spacer 42 is equal to the angle 56 of the second spacer 43. Accordingly, the lower surface 48 of the first spacer 42 and the upper surface 53 of the second spacer 43 are aligned with the first and second spacers 42 and 43 in the state shown in FIGS. Then, the upper surface 47 of the first spacer 42 and the lower surface 54 of the second spacer 43 are parallel to each other, and the plate thickness is uniform as a whole. A circular insertion hole 58 through which the tie bar 10 is inserted is opened in the second spacer 43.

  Although it is described that the tie bar nut 25 is screwed onto the tie bar 10, in actuality, as shown in FIGS. After the second spacer 43 is inserted through the insertion hole 58 and then the first spacer 42 is inserted through the cutout 51, the tie bar nut 25 is screwed. Therefore, the lower surface 54 of the second spacer 43 is in contact with the bottom surface 28 of the tie bar nut pocket 36, and the tie bar nut 25 is in contact with the upper surface 47 of the first spacer 42. In practice, the tie bar nut pocket 36 is provided with play in the axial direction so that the tie bar nut 25 can rotate smoothly in the tie bar nut pocket 36. That is, in the tie bar nut pocket 36, the first gap S 1 formed between the upper surface 47 of the first spacer 42 and the tie bar nut 25, and between the shoulder portion 32 of the tie bar nut 25 and the nut cover 35. A gap in the axial direction of the tie bar, which is formed by the formed second gap S2, is provided.

  The cylinder 60 of the piston cylinder unit 45 is fixed to a predetermined portion of the tie bar nut insertion hole 26 so that the piston 61 can be driven perpendicularly to the axial direction of the tie bar 10. A first spacer 42 is fixedly attached to the piston rod 62 attached to the piston 61. Therefore, when the piston cylinder unit 45 is driven, the first spacer 42 is driven up and down in FIG. Then, as will be described later, the axial gap of the tie bar in the tie bar nut pocket 36, which is composed of the first and second gaps S1 and S2, can be secured or substantially zero.

  The operation of the mold clamping device of the toggle type injection molding machine according to the present embodiment will be described. A fixed-side mold 2 and a movable-side mold 5 having a predetermined thickness are attached to the fixed platen 3 and the movable platen 6, respectively. The mold clamping force adjustment is automatically performed when a predetermined operation button provided in the injection molding machine is pressed. However, in order to simplify the description, the following description will be made manually. The toggle mechanism 11 is driven to close the mold until the fixed mold 2 and the movable mold 5 are touched, and the crosshead position of the toggle mechanism 11 at that time is stored. The touch of the mold is confirmed by a torque limiter of a servo motor for opening and closing the mold. The toggle mechanism 11 is driven to open the mold. The length of the effective tie bar length L to be adjusted is calculated from the difference between the stored crosshead position and the crosshead position that generates the desired clamping force. Drives the tie bar nut pressing devices 21, 21,. That is, the pistons 61 of the piston cylinder units 45, 45,... Are driven to retract the first spacer 42 as indicated by the arrow Y5 in FIG. Then, the first and second gaps S1 and S2 are secured, and the tie bar nut 25 can be freely rotated. The mold clamping force adjustment motor is driven to drive the drive gear. Then, the driven gears 38, 38,... Are rotated through the center gear 40, and the tie bar nuts 25, 25,. When the tie bar effective length L reaches a predetermined length, the mold clamping force adjustment motor is stopped to complete the mold clamping force adjustment.

  When the adjustment of the mold clamping force is completed, the tie bar nut pressing devices 21, 21, ... are driven. That is, the piston 61 of the piston cylinder unit 45 is driven, and the first spacer 42 is inserted in the direction of the arrow Y6 as shown in FIG. As a result, the thickness of the overlap of the first spacer 42 and the second spacer 43 increases, so that the tie bar nut 25 is pressed in the direction of the arrow Y8, and the first and second gaps S1 and S2 are substantially zero. become. In this state, the following molding cycle is performed. The toggle mechanism 11 is driven to clamp the mold. There is no gap in the tie bar nut pocket 36 in the axial direction of the tie bar, and the tie bar nut 25 is substantially fixed to the tie bar nut pocket 36. Therefore, the mold clamping housing 8 does not fluctuate, and the movable platen 6 does not fluctuate. As is conventionally known, molten resin or molten metal material is injected into a cavity formed between the fixed mold 2 and the movable mold 5. After cooling and solidification, the toggle mechanism 11 is driven to open the mold. Take out the molded product. Even when the mold is opened, the mold clamping housing 8 and the movable platen 6 do not wobble.

  The tie bar nut pressing device of the toggle type injection molding machine according to the present invention can be implemented in various forms without being limited to the above embodiment. For example, although it has been described that the tie bar nut pressing device is provided so as to be in contact with the bottom surface 28 of the tie bar nut insertion hole 26, it may be provided between the tie bar nut 25 and the nut cover 35. FIG. 4 shows a tie bar nut pressing device 21 of the toggle type injection molding machine according to the second embodiment. Since those skilled in the art can easily understand, the same reference numerals are given to the components that are similar in operation and effect to the toggle injection molding machine according to the above-described embodiment, and the description thereof will not be repeated. In the toggle type injection molding machine according to the second embodiment, the tie bar nut 25 is directly seated on the bottom surface 28 of the tie bar nut insertion hole 26 when the mold is clamped. Tightening force does not work. Therefore, there is an advantage that the spacer is hardly damaged. In addition, although it has been described that two spacers including the first and second spacers 42 and 43 are used, only the first spacer 42 can be used. For example, the bottom surface 28 of the tie bar nut insertion hole 26 is formed as a slope inclined at a predetermined angle with respect to the axial direction of the tie bar. If the first spacer 42 is slid while in contact with the inclined bottom surface 28, the first and second gaps S1 and S2 can be secured or substantially zero. Further, although the piston cylinder unit of the tie bar nut pressing device has been described as an air type, it may be a hydraulic type, and may be implemented so as to be driven by an electromagnetic solenoid instead of the piston cylinder unit.

It is a front view which shows the outline of the toggle type injection molding machine which concerns on this Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically a part of toggle type injection molding machine concerning this Embodiment, The (a) is a perspective view which shows a part of principal part of a toggle type injection molding machine, The (a), (C) ) Is a perspective view showing first and second spacers constituting the tie bar nut pressing device. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows a part of toggle type injection molding machine which concerns on this Embodiment, The (a) is a tie bar nut pressing device at the time of adjustment of mold clamping force, The (a) is a tie bar of another state It is front sectional drawing which shows a pressing device, respectively. It is a front sectional view showing typically a part of toggle type injection molding machine concerning a 2nd embodiment of the present invention. It is sectional drawing which shows the state with which the fixed platen and the mold clamping housing are connected by the tie bar of the conventional toggle type injection molding machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clamping device 2 Fixed side die 3 Fixed platen 5 Fixed side die 6 Movable platen 8 Clamping housing 10 Tie bar 11 Toggle mechanism 21 Tie bar nut pressing device 25 Tie bar nut 26 Tie bar nut insertion hole 28 Bottom surface 35 Nut cover 36 Tie bar nut Pocket 38 driven gear
42 1st spacer 43 2nd spacer 45 Piston cylinder unit 47, 53 Upper surface 48, 54 Lower surface S1 1st clearance S2 2nd clearance

Claims (4)

A fixed plate to which the fixed mold is attached, a movable plate to which the movable mold is attached, a mold clamping housing, and a plurality of plates that pass through the movable plate and connect the fixed plate and the mold clamping housing. A tie bar nut, and a toggle mechanism provided between the movable platen and the mold clamping housing. The tie bar is provided with a tie bar nut, and the tie bar nut includes a predetermined portion of the mold. In a mold clamping device of a toggle type injection molding machine, which is housed in a tie bar nut pocket provided in a clamping housing and is capable of adjusting a mold clamping force when the tie bar nut is driven to rotate,
At least the mold opening process, the mold closing process, and the mold clamping process are performed by inserting a predetermined tapered spacer into the axial gap of the tie bar provided between the tie bar nut pocket and the tie bar nut. Performed with substantially zero gap,
The method of operating a mold clamping device of a toggle type injection molding machine, wherein the adjustment of the mold clamping force is performed by retracting the spacer and securing the gap. A fixed plate to which the fixed mold is attached, a movable plate to which the movable mold is attached, a mold clamping housing, and a plurality of plates that pass through the movable plate and connect the fixed plate and the mold clamping housing. A tie bar nut, and a toggle mechanism provided between the movable platen and the mold clamping housing. The tie bar is provided with a tie bar nut, and the tie bar nut includes a predetermined portion of the mold. In a mold clamping device of a toggle type injection molding machine, which is housed in a tie bar nut pocket provided in a clamping housing and is capable of adjusting a mold clamping force when the tie bar nut is driven to rotate,
The tie bar nut pocket is provided with a tapered spacer provided between a predetermined inner surface of the tie bar nut pocket and the tie bar nut, and an actuator for driving the spacer,
The predetermined gap in the axial direction of the tie bar at least between the spacer and the tie bar nut or between the tie bar nut and the tie bar nut pocket is substantially zero by the spacer when the actuator is driven. Clamping device for toggle type injection molding machine. 3. The apparatus according to claim 2, wherein each of the spacers includes first and second spacers whose one surface is inclined with respect to the other surface and whose plate thickness is reduced in one direction. A pair of spacers is a mold-clamping device for a toggle-type injection molding machine, in which a thin plate and a thick plate are provided so as to overlap each other. 4. The apparatus according to claim 2, wherein the actuator comprises a fluid type piston cylinder unit or an electromagnetic solenoid.

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