JP6345508B2 - Movable platen, opening / closing device and molding device - Google Patents

Description

  The present invention relates to a toggle type mold clamping device of a molding apparatus such as an injection molding machine or a die casting machine.

  Toggle type mold clamping devices for injection molding machines, die casting machines, etc. are fixed die plates to which fixed dies are attached, movable tie plates to which movable dies are attached, and one end is fixed to a fixed die plate for movement. A toggle link mechanism that includes a plurality of (for example, four) tie bars that extend through the die plate to the rear plate and moves the movable die plate to generate a mold opening / closing and clamping force is provided on the rear plate. And a movable die plate.

  Conventionally, as one of molding methods in an injection molding machine, foam molding is widely performed by foaming a resin to obtain a molded product. The foam molded article is lightweight and can be added with various properties such as heat insulation and sound absorption.

  In the foam molding, a mold resin cavity is filled with a molten resin containing a foaming agent. After the surface layer of the molten resin is hardened and the skin layer is formed, it is necessary to hold the position by opening the mold (also referred to as a core back) in order to foam the resin. In foam molding, since the thickness of the molded product is determined by the opening amount when the mold is opened, its stop accuracy is a very important factor for ensuring the quality of the molded product.

  The stopping accuracy when the mold is opened at the time of foaming becomes a big problem particularly in a toggle type mold clamping device. This is because in the toggle type mold clamping device, there is a minute gap between the link connecting the links of the toggle link mechanism, and this gap reduces the stopping accuracy.

  Conventionally, in the toggle type mold clamping device, various devices have been devised in order to increase the accuracy of mold stop for opening when foaming. For example, in Patent Documents 1 and 2, the positional relationship between the movable platen and the cross head when the mold is opened is stored in advance as positional relationship data, and the position of the movable platen when opening the die is determined from this position data. A method has been proposed in which the position of the corresponding crosshead is calculated and the crosshead is stopped at this position.

  Patent Document 3 proposes a mold clamping device in which a special cavity enlargement mechanism is provided around the mold between the fixed platen and the movable platen, and the mold is accurately opened by this cavity enlargement mechanism. Has been.

JP 2008-143061 A JP-A-2005-254607 JP 2006-334793 A

  However, as in the prior arts of Patent Documents 1 and 2, in order to store the positional relationship between the movable platen and the crosshead as positional relationship data, it is necessary to perform a teaching process for that purpose after replacing the die. There is a problem that it takes a considerable time from the replacement to the start of continuous molding.

  On the other hand, if a cavity enlargement mechanism is separately installed around the mold as in the prior art of Patent Document 3, a force is applied to the fixed platen and the movable platen, which may cause damage to the fixed platen and the movable platen. . In addition, since the cavity enlargement mechanism is attached around the mold, there is a problem that workability in mold exchange or the like is deteriorated.

  The present invention has been made in view of the above-described problems of the prior art. By using a braking mechanism having a simple configuration, the movable platen is caused by a minute gap in the link pin portion or friction of a sliding portion of the movable platen. It is an object of the present invention to provide a movable platen, an opening / closing device, and a molding device that can surely eliminate the influence on the stopping accuracy of the machine.

In order to achieve the above object, the movable platen of the present invention is a movable platen, and the movable platen moves when the movable plate reaches a predetermined opening amount. It has a braking device which stops.

  The opening / closing device of the present invention includes a fixed plate, the movable plate described above, and an opening / closing mechanism for moving the movable plate to open / close the mold.

  Moreover, the shaping | molding apparatus of this invention is equipped with the opening / closing apparatus as described above, It is characterized by the above-mentioned.

It is a side view which shows the outline | summary of the injection molding machine to which the mold clamping apparatus of this invention is applied. It is a side view of the mold clamping apparatus of the injection molding machine by one Embodiment of this invention. It is a perspective view which shows the principal part of the mold clamping apparatus of the injection molding machine by one Embodiment of this invention. It is a front view which shows operation | movement of the brake device installed in the movement die plate. It is a front view which shows arrangement | positioning of the brake device in a movement die plate. It is a front view which shows the other example of arrangement | positioning of the brake device in a movement die plate. It is process explanatory drawing of foam molding.

Hereinafter, an embodiment of a mold clamping device of an injection molding machine according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an outline of the configuration of an injection molding machine (molding apparatus) 10 to which a mold clamping apparatus according to an embodiment of the present invention is applied. In FIG. 1, reference numeral 12 indicates the entire injection apparatus of the injection molding machine. Reference numeral 14 denotes a mold clamping device (mold opening / closing device, opening / closing device) of an injection molding machine.

  A screw 16 is inserted into the barrel 15 of the injection device 12 so as to be rotatable and movable in the axial direction. Resin (molding material, material) is put into the barrel 15 from the hopper 17. Around the barrel 15, a heater (not shown) for heating the resin is disposed. In the injection device 12, the screw 16 is rotated by a metering motor (not shown), and the resin is accumulated in front of the barrel 15 while the resin is melted and kneaded. The resin stored in front of the barrel 15 is filled into a cavity formed by the fixed mold 21 and the movable mold 23 from the nozzle 18 by advancing the screw 16 by an injection motor, a ball screw and a nut (not shown). The

Next, the mold clamping device 14 will be described with reference to FIG.
The mold clamping device 14 includes, for example, a fixed die plate (fixed platen) 20 fixed to the frame 11, a rear plate (pressure platen) 24 installed on the frame 11, and between the fixed die plate 20 and the rear plate 24. And a movable die plate (movable platen) 22 that is movably installed in the machine.

  A fixed die 21 is attached to the fixed die plate 20, and a moving die 23 is attached to the moving die plate 22 so as to face the fixed die 21.

  The fixed die plate 20 and the rear plate 24 are connected by a plurality of (for example, four) tie bars 36. The tie bar 36 receives a mold clamping force generated by a toggle link mechanism (opening / closing mechanism, mold opening / closing mechanism, mold clamping mechanism) 28 described below when the mold is tightened (clamping). Yes.

  In FIG. 2, reference numeral 26 denotes a crosshead. A nut portion (not shown) of a ball screw mechanism that drives the toggle link mechanism 28 is provided at the center of the cross head 26, and a ball screw 27 is screwed into the nut portion. A guide for guiding the movement of the cross head 26 in the front-rear direction is supported by the arm portion 24 a of the rear plate 24. The ball screw 27 is driven via a timing belt 29 by a servo motor (not shown).

  One end of the link 30 is connected to the cross head 26, one end of the link 31 is connected to the rear plate 24, and the links 30 and 31 and the link 32 constitute a toggle link up and down. One end of the link 32 is connected to a toggle link connecting portion 34 provided on the back surface of the movable die plate 22.

  By such a toggle link mechanism 28, the movable die plate 22 is moved for opening and closing the mold, and the mold clamping force is transmitted.

  The tie bar 36 is different from the conventional structure in which the tie bar 36 is inserted into the four corners of the moving die plate 22 through bushes to guide the moving die plate 22. In the case of this embodiment, notches (notches) 40 are formed at end portions (more specifically, four corners) of the movable die plate 22. Due to the presence of this notch 40, the tie bar 36 is disposed so as to extend between the fixed die plate 20 and the rear plate 24 without contacting (without contacting) the movable die plate 22.

  In order to guide the movable die plate 22, linear guide rails 41 are laid on both the left and right sides of the base 11 in parallel with the tie bars 36, and the linear guides 42 slidable on the linear guide rails 41 are movable die. The plate 22 is attached to both the left and right side surfaces.

  As shown in FIG. 3, in the mold clamping device of this embodiment, in order to brake the moving die plate 22 when the mold is opened when foaming resin, the following braking device ( (Braking device) 50 is provided. The brake device 50 includes, for example, a braking member having a movable brake shoe 52 and a fixed brake shoe 53, and generates a braking force by sandwiching the tie bar 36 with the braking member.

  Next, as shown in FIG. 4, the stationary brake shoe 53 is fixed to the vertical surface 59 among the surfaces of the movable die plate 22 forming the notch 40. The inner surface of the fixed brake shoe (first braking member, second braking member) 53 is a concave curved surface corresponding to the curvature of the tie bar 36, and for example, a brake lining 56 is mounted. The brake lining 56 is in contact with the surface of the tie bar 36, or a slight gap is formed.

  On the other hand, the movable brake shoe (second brake member, first brake member) 52 is disposed so as to face the fixed brake shoe 53 with respect to the tie bar 36. The inner side surface of the movable brake shoe 52 is also a concave curved surface corresponding to the curvature of the tie bar 36, and for example, a brake lining 57 is attached. Such a movable brake shoe 52 is swingably connected to the movable die plate 22 via a pin 61. A connecting member 55 is attached to the upper end of the movable brake shoe 52, and the piston rod 54 of the hydraulic cylinder (driving unit) 51 is connected to the connecting member 55 via a pin 62. FIG. 4A shows a state in which the piston rod 54 of the hydraulic cylinder 51 moves in the direction of the arrow and the movable brake shoe 52 is pulled toward the tie bar 36 so that the brake is effective. FIG. 4B shows a state in which the piston rod 54 extends in the arrow direction and the brake is released.

  As shown in FIG. 5, one such brake device 50 is installed at each of the four corners of the movable die plate 22 so as to be arranged with respect to each tie bar 36. In the case of a relatively small mold clamping device, the braking force required to stop the movable die plate 22 is also small, so that two brake devices 50 on the diagonal line are provided as shown in FIG. The tie bars 36 may be arranged respectively.

The mold clamping device of the injection molding machine according to the present embodiment is configured as described above. Next, the operation and effect of the brake device 50 in relation to foam molding will be described.
The mold clamping device 14 is a toggle link type mold clamping device in which the movement of the movable die plate 22 for mold closing and mold opening and mold clamping is performed by the toggle link mechanism 28. When performing normal injection molding, the brake device 50 is not used.

  In the toggle link type mold clamping device, when performing foam molding as shown in FIG. 7, first, a melt containing foaming agent in the cavity 60 formed by the fixed mold 21 and the movable mold 23 is performed. The resin is filled, and the surface layer of the molten resin is hardened to form a skin layer (FIG. 7A). Then, the resin is foamed by slightly opening the moving mold 23 by a predetermined moving amount δ (FIG. 7B). After foaming, after cooling, the moving mold 23 is retracted to open the mold, and the molded product 62 is taken out (FIG. 7C).

  In the mold clamping device 14 according to the present embodiment, when the mold is opened, the movable die plate 22 is moved in the mold opening direction and, for example, a linear encoder (detector) (not shown) provided on the linear guide rail 41 is used. The amount of movement of the movable die plate 22 is obtained by a control device (not shown).

  When the moving amount of the moving die plate 22 reaches a predetermined moving amount (opening amount, opening amount), it is installed at the end of the moving die plate 22 as shown in FIGS. The brake device 50 is activated to stop the movement of the movable die plate 22. The amount of opening of the movable die plate 22 is obtained, for example, by being input to a control device (not shown) by an operator.

  Specifically, when the movable die plate 22 reaches the movement amount at the time of opening when the mold is opened, the piston rod 54 of the hydraulic cylinder 51 is drawn in the direction of the arrow in FIG. The side brake shoe 52 is pressed against the tie bar 36. As a result, the fixed brake shoe 53 and the movable brake shoe 52 sandwich the tie bar 36, and a large braking force is generated on the moving die plate 22 to stop the movement of the moving die plate 22. Therefore, the movable die plate 22 can be stopped at a position opened by the opening amount.

  In a transmission system of a toggle type mold clamping device that transmits power to the movable die plate 22, the transmission is transmitted to the movable die plate 22 via mechanical elements such as a timing belt 29, a ball screw mechanism, a cross head 26, and a toggle link mechanism 28. However, in such a transmission system, for example, there is an extension of the timing belt 29, a gap between the link and the pin of the toggle link mechanism 28, and so on, so that the stop accuracy of the mold opening operation of the movable die plate 22 is lowered. It was a factor to make.

  In the toggle type mold clamping device according to the present embodiment, the brake device 50 is mounted on the movable die plate 22. Moreover, in the brake device 50 of this embodiment, the movable side brake shoe 52 and the fixed side brake shoe 53 are attached using the notch 40 of the movable die plate 22, and the tie bar 36 is sandwiched therebetween. Although it is a simple structure, it is possible to generate a braking force sufficient to stop the movable die plate 22 at an accurate position using the tie bar 36.

  For this reason, when the mold is opened, the moving die plate 22 is moved backward while detecting the position, and the moving amount when the moving die plate 22 is set (the operation of the moving die plate 22 when opening). When the amount reaches, the moving die plate 22 can be stopped at a predetermined position by braking with the brake device 50. As a result, error factors such as elongation of the timing belt, a gap between the link and the pin of the toggle link mechanism, or friction of the sliding portion can be completely eliminated.

  As described above, when foam molding is continuously performed, the mold can always be opened to an accurate position at the time of core back, so that the quality of the molded product can be made constant.

  In the present embodiment, the hydraulic cylinder is applied as the drive unit of the brake device 50, but the present invention is not limited to this. For example, an electric drive unit (more specifically, an electrically driven ball screw and nut), an air cylinder, or the like may be applied as the drive unit of the brake device 50.

  Moreover, although this invention was applied to the injection molding machine in this embodiment, this invention is not restricted to this. For example, the present invention can be applied to other molding apparatuses such as a die casting machine.

DESCRIPTION OF SYMBOLS 10 ... Injection molding machine (molding device), 12 ... Injection device, 14 ... Clamping device (opening / closing device, mold opening / closing device), 15 ... Barrel, 16 ... Screw, 17 ... Hopper, 18 ... Nozzle, 20 ... Fixed die plate (Fixed platen), 21 ... fixed mold, 22 ... moving die plate (movable platen), 23 ... moving die, 24 ... rear plate (pressure plate), 26 ... cross head, 27 ... ball screw, 28 ... toggle link Mechanism (opening / closing mechanism, mold opening / closing mechanism, mold clamping mechanism), 29... Timing belt, 30, 31, 32... Link, 34. 36 ... Tie bar, 40 ... Notch (notch), 42 ... Linear guide, 50 ... Brake device (braking device), 51 ... Hydraulic cylinder (drive unit), 52 ... Movable brake shoe (braking member, first braking) Member, second brake member), 53... Fixed brake shoe (brake member, first brake member, second brake member)

Claims (6)

A movable movable plate,
The movable platen has a braking device for stopping the movement of the movable platen when the movable plate reaches a preset opening amount . The braking device is:
The movable platen according to claim 1, further comprising a braking member that generates a braking force by sandwiching a tie bar that receives a clamping force. The movable platen is
Having a notch to prevent interference with the tie bar ,
The movable board according to claim 1, wherein the braking device is provided in the notch. The braking device is:
A braking member comprising: a first braking member fixed to a vertical surface that forms the notch portion of the movable plate; and a second braking member that can swing in opposition to the first braking member ;
The movable platen according to claim 3, further comprising: a drive unit that attracts the second braking member to sandwich the tie bar between the first braking member and the second braking member . A fixed plate,
The movable platen according to any one of claims 1 to 4,
An opening and closing mechanism for moving the movable plate to open and close the mold;
An opening / closing device comprising:   A molding apparatus comprising the opening / closing device according to claim 5.

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