JP2008194850A - Mold clamping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold clamping device the outer shape of which can be miniaturized. <P>SOLUTION: The mold clamping device for generating mold clamping force by an electromagnet is equipped with a movable platen which has one mold, a fixed platen fixed in a mold opening/closing direction and the other mold arranged thereto and can be advanced and retracted in the mold opening/closing direction, the first attraction member keeping one attraction surface formed of the electromagnet and fixed to the fixed platen by the connection member extended from the fixed platen and a second attraction member having the other attraction surface formed thereto by the electromagnet and transmitting the attraction force by the electromagnet to the movable platen. The connection member is fixed on the surface or the side opposite to the attraction surface of the first attraction member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mold clamping device, and more particularly to a mold clamping device that generates a mold clamping force with an electromagnet.

  2. Description of the Related Art Conventionally, in an injection molding machine, resin is injected from an injection nozzle of an injection device, filled into a cavity space between a fixed mold and a movable mold, and solidified to obtain a molded product. ing. A mold clamping device is provided for moving the movable mold relative to the fixed mold to perform mold closing, mold clamping, and mold opening.

  The mold clamping device includes a hydraulic mold clamping device that is driven by supplying oil to a hydraulic cylinder, and an electric mold clamping device that is driven by an electric motor. It is widely used because it has high controllability, does not pollute the surroundings, and has high energy efficiency. In this case, by driving the electric motor, the ball screw is rotated to generate a thrust, and the thrust is expanded by a toggle mechanism to generate a large mold clamping force.

  However, since the electric mold clamping device having the above-described configuration uses a toggle mechanism, it is difficult to change the mold clamping force due to the characteristics of the toggle mechanism, and the responsiveness and stability are improved. The mold clamping force cannot be controlled during molding. Therefore, a mold clamping device is provided in which the thrust generated by the ball screw can be directly used as a mold clamping force. In this case, since the torque of the electric motor and the mold clamping force are proportional, the mold clamping force can be controlled during molding.

  However, in the conventional mold clamping device, the load resistance of the ball screw is low and a large mold clamping force cannot be generated, and the mold clamping force fluctuates due to torque ripple generated in the electric motor. In addition, in order to generate the mold clamping force, it is necessary to constantly supply current to the motor, and the power consumption and heat generation amount of the motor increase. Therefore, it is necessary to increase the rated output of the motor by that amount. The cost of the device becomes high.

Therefore, a mold clamping device using a linear motor for the mold opening / closing operation and utilizing the attractive force of an electromagnet for the mold clamping operation can be considered (for example, Patent Document 1).
WO05 / 090052 pamphlet

  However, in the mold clamping device described in Patent Document 1, four connecting members (tie bars) for connecting the fixed platen and the rear platen are disposed so as to penetrate the rear platen and the suction plate that form the suction surface by the electromagnet. Has been. Therefore, in the rear platen and the suction plate, the portion of the guide hole formed for penetrating the tie bar cannot be used as the suction surface, which is an obstructive factor for efficiently generating the suction force. Therefore, in order to ensure an appropriate suction force, there is a problem that the rear platen and the suction plate must be enlarged.

  Moreover, there is also a problem that the entire length of the mold clamping device becomes longer due to the penetrating tie bar extending rearward.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a mold clamping device capable of reducing the size of the outer shape.

  Accordingly, in order to solve the above problems, the present invention provides a mold clamping device that generates a mold clamping force by an electromagnet, in which one mold is disposed and the fixed platen fixed in the mold opening and closing direction and the other mold The first plate fixed to the fixed platen by a connecting plate extending from the fixed platen is formed with a movable platen that can be moved back and forth in the mold opening and closing direction and one attracting surface by the electromagnet. And a second attracting member for transmitting the attracting force by the electromagnet to the movable platen, wherein the connecting member is the first attracting member of the first attracting member. It is fixed on the surface opposite to the adsorption surface.

  Further, the present invention is characterized in that the connecting member does not penetrate the first adsorption member.

  Moreover, the present invention is characterized in that the connecting member does not penetrate the second adsorption member.

  Further, the present invention is characterized in that the connecting member is fixed to the first suction member by a flange.

  In the mold clamping device as described above, the outer shape can be reduced in size.

  ADVANTAGE OF THE INVENTION According to this invention, the mold clamping apparatus which can achieve size reduction of an external shape can be provided.

  Embodiments of the present invention will be described with reference to the drawings.

  First, a mold clamping device of an injection molding machine to which the present invention is applied will be described with reference to FIGS. FIG. 1 is a side view showing a state of the mold apparatus and the mold clamping apparatus when the mold is closed in the embodiment of the present invention. FIG. 2 is a side view showing a state of the mold device and the mold clamping device when the mold is opened in the embodiment of the present invention.

  The mold clamping device 10 shown in FIGS. 1 and 2 is supported on a guide Gd including two rails provided on a frame Fr of an injection molding machine. The stationary platen 11 is placed on the guide Gd and is fixed to the frame Fr and the guide Gd. A rear platen 13 is disposed at a predetermined distance from the fixed platen 11 and facing the fixed platen 11. Between the fixed platen 11 and the rear platen 13, four tie bars 14 (only two are shown in the figure) are installed as connecting members. The movable platen 12 is disposed so as to be movable back and forth in the mold opening / closing direction along the tie bar 14 while being opposed to the fixed platen 11 (movable in the left-right direction in the drawing). For this purpose, a guide hole (not shown) through which the tie bar 14 passes is formed in the movable platen 12.

  In this specification, the mold opening / closing direction, that is, the moving direction of the movable platen 12 is referred to as a horizontal direction, and the direction perpendicular to the moving direction of the movable platen 12 is referred to as a vertical direction.

  The tie bar 14 is inserted through a guide hole 21 formed in the fixed platen 11. A first screw portion (not shown) is formed at the front end portion (right end portion in the figure) of the tie bar 14, and the tie bar 14 is screwed with a nut n1 as a first tie bar fixing portion on the first screw portion. The platen 11 is fixed by tightening together.

  The rear end portion (left end portion in the figure) of each tie bar 14 is formed with a second screw portion 62 having an outer diameter smaller than that of the tie bar 14. The thread portion 62 is engaged with a thread portion formed on the inner diameter side of the flange 61 as a second tie bar fixing portion disposed at a position corresponding to each tie bar 14 on the front end surface of the rear platen 13. The flange 61 has, for example, a cylindrical shape whose outer diameter is larger than that of the tie bar 14, and is fixed to the front end surface of the rear platen 13 by a plurality of bolts 63. Therefore, each tie bar 14 is fixed to the rear platen 13 by engaging with each flange 61 without penetrating the rear platen 13. Therefore, the rear platen 13 is not formed with a guide hole for allowing the tie bar 14 to pass therethrough, and the portion corresponding to the tie bar 14 on the rear end surface of the rear platen 13 (the surface facing the front end surface of the suction plate 22 described later) is It becomes a flat surface. Further, the end portion of the rear platen 13 has a solid structure without a hollow portion, so that the tie bar 14 does not interfere with the magnetic circuit formed in the rear platen 13. Thereby, a sufficient magnetic circuit can be secured. Furthermore, since it is not necessary to make the rear platen 13 into a complicated shape, the manufacturing cost can be reduced.

  A fixed mold 15 is fixed to the fixed platen 11, and a movable mold 16 is fixed to the movable platen 12. A mold apparatus 19 is configured by the fixed mold 15 and the movable mold 16. As the movable platen 12 advances and retreats, the movable mold 16 is moved with respect to the fixed mold 15 to perform mold closing, mold clamping, and mold opening. When the mold clamping is performed, a cavity space is formed between the fixed mold 15 and the movable mold 16, and resin as a molding material injected from the injection nozzle 18 of the injection device 17 is filled into the cavity space. The

  An attracting plate 22 as a magnetic body disposed in parallel with the movable platen 12 is disposed behind the rear platen 13 so as to be able to advance and retract along the guide Gd, and is guided by the guide Gd. As described above, the tie bar 14 does not penetrate the rear platen 13. Therefore, the tie bar 14 or a member extending from the tie bar 14 does not extend through the suction plate 22. Therefore, a guide hole for penetrating the member is not formed in the suction plate 22, and the front end surface of the suction plate 22 (a surface facing the rear end surface of the rear platen 13) is a flat surface.

  In order to move the movable platen 12 back and forth, a linear motor 28 is disposed between the suction plate 22 connected to the movable platen 12 and the frame Fr as a mold opening / closing drive unit. The linear motor 28 is fixed on the frame Fr to the slide base Sb on which the lower end of the suction plate 22 is fixed, and the stator 29 arranged in parallel with the guide Gd and corresponding to the moving range of the suction plate 22. And a movable element 31 which is opposed to the stator 29 and formed over a predetermined range. As shown in FIG. 2, the slide base Sb is supported on the guide Gd on both sides thereof, and supports the movable element 31 so as to be movable along the stator 29. The slide base Sb covers the upper surface of the mover 31 and extends in the extending direction of the guide Gd. Therefore, a space 81 through which the guide base Gb and the slide base Sb pass is formed at the lower end of the rear platen 13. Here, the rear platen 13 is fixed to the frame Fr by legs (not shown) so as to straddle the slide base Sb.

  When the length of the stator 29 of the linear motor 28 is Lp, the length of the movable element 31 is Lm, and the stroke of the suction plate 22 (movable platen 12) is Lst, the length Lm is the maximum by the linear motor 28. It is set according to the driving force. The length Lp is set so as to satisfy the relationship Lp> Lm + Lst.

  The mover 31 includes a core 34 protruding toward the stator 29 and having a plurality of magnetic pole teeth 33 formed at a predetermined pitch, and a coil 35 wound around each magnetic pole tooth 33. The magnetic pole teeth 33 are formed in parallel to each other in a direction perpendicular to the moving direction of the movable platen 12. The stator 29 includes a core and a permanent magnet (not shown) formed to extend on the core. The permanent magnet is formed by magnetizing the N and S magnetic poles alternately and at the same pitch as the magnetic pole teeth 33.

  Therefore, when a predetermined current is supplied to the coil 35 and the linear motor 28 is driven, the mover 31 is moved forward and backward. Along with this, the slide base Sb, the suction plate 22 fixed to the slide base Sb, and the movable platen 12 connected to the suction plate 22 by the rod 39 are moved forward and backward to perform mold closing and mold opening.

  In addition, although the permanent magnet is provided in the stator 29 and the coil 35 is provided in the mover 31, the coil may be provided in the stator and the permanent magnet may be provided in the mover. In this case, since the coil does not move when the linear motor 28 is driven, wiring for supplying power to the coil can be easily performed.

  When the movable platen 12 moves forward (moves in the right direction in the figure) and the movable mold 16 comes into contact with the fixed mold 15, the mold closing is completed. An electromagnet unit 37 as a mold-clamping drive unit is disposed between the rear platen 13 and the suction plate 22 so that mold clamping can be performed following mold closing. A rod 39 that connects the movable platen 12 and the suction plate 22 extends through the rear platen 13 and the suction plate 22. The rod 39 advances and retracts the movable platen 12 in conjunction with the advance and retreat of the suction plate 22 when the mold is closed and opened, and transmits the mold clamping force generated by the electromagnet unit 37 to the movable platen 12 when the mold is clamped. The mold clamping device 10 is configured by the frame Fr, the fixed platen 11, the movable platen 12, the rear platen 13, the suction plate 22, the linear motor 28, the electromagnet unit 37, the rod 39, and the like.

  The electromagnet unit 37 includes an electromagnet 49 disposed on the rear platen 13 side, and an attracting portion 51 disposed on the attracting plate 22 side. Two grooves 45 as a coil arrangement portion having a rectangular cross-sectional shape extending in the horizontal direction are formed in parallel to each other at a predetermined portion of the rear end surface of the rear platen 13, that is, slightly above and below the rod 39. Yes. A core 46 having a rectangular cross-sectional shape is formed between the grooves 45, and a yoke 47 is formed in a portion other than the core 46 of the rear platen. A coil 48 is wound around the core 46.

  Further, as a predetermined portion of the front end surface of the suction plate 22, a suction portion 51 is provided in a portion surrounding the rod 39 in the suction plate 22 and facing the electromagnet 49. The core 46 and the yoke 47 of the rear platen 13 and the suction plate 22 are made of electromagnetic laminated steel plates formed by laminating thin plates made of ferromagnetic materials. In addition, an electromagnet 49 is provided separately from the rear platen 13 and an adsorbing portion 51 is provided separately from the adsorption plate 22, but an electromagnet is formed as a part of the rear platen 13 and adsorbed as a part of the adsorption plate 22. A part can also be formed. Further, the electromagnetic laminated steel plate is not necessarily used, and the core 46 and the yoke 47 may be formed using an iron core made of the same member. In this way, the distance between the gaps can be set with higher accuracy.

  Therefore, in the electromagnet unit 37, when a current is supplied to the coil 48 in the groove 45, the electromagnet 49 is excited and the attracting part 51 is attracted to generate a mold clamping force.

  Here, since the surface of the rear platen 13 facing the suction plate 22 is a flat surface, a larger mold clamping force can be generated even with the same amount of current.

  The rod 39 is connected to the suction plate 22 at the rear end portion (left end portion in the figure), and is connected to the movable platen 12 at the front end portion. The rod 39 moves forward when the suction plate 22 moves forward when the mold is closed, whereby the movable platen 12 moves forward. Further, the rod 39 moves backward when the suction plate 22 moves backward (moves leftward in the figure) when the mold is opened, and thereby the movable platen 12 moves backward.

  For this purpose, a hole 41 for allowing the rod 39 to penetrate is provided in the center portion of the rear platen 13. In addition, a hole 42 for penetrating the rod 39 is formed in the central portion of the suction plate 22. Further, in the present embodiment, unlike the prior art, the bearing member Br1 is not disposed between the rear platen 13 and the rod 39. As a result, the rear platen 13 has a solid structure with no arrangement hole for providing the bearing member Br1, so that a sufficiently large magnetic circuit can be secured. As a result, a large clamping force can be obtained even when the amount of current applied to the coil is the same. Further, a screw 43 is formed at the rear end of the rod 39, and a nut 44 as a mold thickness adjusting mechanism that is rotatably supported with respect to the suction plate 22 is screwed into the screw 43.

  When the mold closing is completed, the suction plate 22 is close to the rear platen 13, and a gap (gap) δ is formed between the rear platen 13 and the suction plate 22. If the gap δ becomes too small or too large, the adsorbing portion 51 cannot be adsorbed sufficiently and the mold clamping force will be reduced. The optimum value (distance or dimension) of the gap δ changes as the thickness of the mold apparatus 19 changes.

  Therefore, a large-diameter gear (not shown) is formed on the outer peripheral surface of the nut 44, and a mold thickness adjusting motor (not shown) is disposed on the suction plate 22 as a drive unit for adjusting the mold thickness. A small-diameter gear attached to the output shaft of the adjustment motor is meshed with a gear formed on the outer peripheral surface of the nut 44.

  When the mold thickness adjusting motor is driven in accordance with the thickness of the mold apparatus 19 and the nut 44 as the mold thickness adjusting mechanism is rotated by a predetermined amount with respect to the screw 43, the position of the rod 39 with respect to the suction plate 22 is changed. By adjusting the position of the suction plate 22 with respect to the fixed platen 11 and the movable platen 12, the gap δ can be set to an optimum value. That is, the mold thickness is adjusted by changing the relative positions of the movable platen 12 and the suction plate 22.

  Four tie bars 14 are arranged between the fixed platen 11 and the rear platen 13. Here, if the distances between all the fixed platens 11 and the rear platen 13 do not match, the mold clamping force cannot be applied uniformly to the mold, and an offset load is applied to the mold. It will reduce the service life. Therefore, in the present embodiment, the distance between the fixed platen 11 and the rear platen 13 can be adjusted by adjusting the distance between the flange 61 and the rear platen 13 with the bolt 63. Furthermore, the distance between the flange 61 and the rear platen 13 can be adjusted by adjusting the screwing depth of the tie bar 14 into the flange 61. Thereby, the load added to a metal mold | die can be made uniform.

  A mold thickness adjusting device is configured by the mold thickness adjusting motor, the gear, the nut 44, the rod 39, and the like. In addition, a rotation transmitting portion that transmits the rotation of the mold thickness adjusting motor to the nut 44 is constituted by the gear. The nut 44 and the screw 43 constitute a movement direction conversion unit, and the rotation movement of the nut 44 is converted into a straight movement of the rod 39 in the movement direction conversion unit.

  Next, the operation of the mold clamping device 10 will be described.

  First, when the mold is closed, a current is supplied to the coil 35 in the state shown in FIG. Thereby, the linear motor 28 is driven, the movable platen 12 is advanced together with the suction plate 22, and the movable mold 16 is brought into contact with the fixed mold 15 as shown in FIG. At this time, as a result of finely adjusting the position of the suction plate 22 using a shim between the rear platen 13 and the suction plate 22, that is, between the electromagnet 49 and the suction portion 51, a target mold clamping force F is obtained. Such an optimal gap (gap) δ is formed. Note that the force required for mold closing is sufficiently smaller than the mold clamping force.

  Subsequently, an electric current is supplied to the coil 48 to attract the attracting portion 51 of the attracting plate 22, which is a magnetic material, by the attracting force of the electromagnet 49.

  Then, a current flows through the coil 48 that generates the mold clamping force. Here, it is necessary to efficiently generate the mold clamping force with the amount of current passed through the coil 48. Therefore, in the mold clamping device 10 in the present embodiment, a tie bar fixing portion is formed on the surface of the rear platen 13 on the movable platen 12 side. As a result, the rear end surface of the rear platen 13 can be flattened, and a large mold clamping force can be obtained even with the same amount of current. As a result, the suction force is transmitted as a mold clamping force to the movable platen 12 via the suction plate 22 and the rod 39, and the mold clamping is performed. Here, since the tie bar 14 is coupled to the first fixed portion formed on the fixed platen 11 side and the second fixed portion formed on the rear platen 13 side, the tie bar 14 is connected to the fixed platen 11 and the rear platen 13. Make a drawing equivalent to the clamping force.

  Further, the value of the current supplied to the coil 48 is determined so that the mold clamping force becomes the target set value, and the current is supplied to the coil 48 to perform mold clamping. While mold clamping is performed, the resin melted in the injection device 17 is injected from the injection nozzle 18 and filled into the cavity space of the mold device 19.

  When the resin in the cavity space is solidified, the current supply to the coil 48 is stopped in the state shown in FIG. In this case, even if the current supply to the coil 48 is stopped, the magnetism remains in the attracting part 51, so that a current is supplied in the opposite direction to when the coil 48 is clamped and remains in the attracting part 51. The magnetism is removed. Subsequently, a current in the reverse direction is supplied to the coil 35. Thereby, the linear motor 28 is driven, the movable platen 12 is moved backward, and as shown in FIG. 2, the movable mold 16 is moved to the backward limit position, and the mold opening is performed.

  As described above, in the mold clamping device 10 according to the present embodiment, the rear platen 13 and the suction plate 22 are not formed with guide holes for allowing the tie bars 14 to pass therethrough. Therefore, it is possible to increase the area that can be used as the suction surface on the facing surface. Therefore, the height or width of the rear platen 13 and the suction plate 22 required to obtain the same mold clamping force can be reduced as compared with the case where the guide holes are formed.

  Further, since there is no guide hole in the tie bar 14, the magnetic circuit can be enlarged, and a larger mold clamping force can be obtained even with the same amount of current. Further, since the rear platen 13 has a solid structure without an arrangement hole for providing the bearing member Br1, a sufficiently large magnetic circuit can be secured. Thereby, even if the amount of current applied to the coil 48 is the same, a larger clamping force can be obtained.

  Further, since the tie bar 14 does not penetrate the rear platen 14 and the suction plate 22 and extend to the rear of the mold clamping device 10, the overall length of the mold clamping device 10 can be shortened.

  The portion that functions as the flange 61 may be formed integrally with the rear platen 13. FIG. 3 is a diagram illustrating an example in which the tie bar is directly engaged with the rear platen. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 3, a protrusion 131 is formed on the front end surface of the rear platen 13 so as to protrude forward at a position corresponding to each tie bar 14. The convex portion 131 has, for example, a cylindrical shape whose outer diameter is larger than that of the tie bar 14, and a screw portion is formed on the inner diameter side thereof. Accordingly, the threaded portion 62 formed at the rear end of the tie bar 14 and the threaded portion formed at the convex portion 131 of the tie bar 14 are engaged, so that the tie bar 14 does not penetrate the rear platen 13 and the rear platen 13. Fixed to.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to such specific embodiment, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

It is a side view which shows the state at the time of the mold closing of the metal mold apparatus and mold clamping apparatus in embodiment of this invention. It is a side view which shows the state at the time of the mold opening of the metal mold | die apparatus and mold clamping apparatus in embodiment of this invention. It is a figure which shows the example in which a tie bar is directly engaged with a rear platen.

Explanation of symbols

10 mold clamping device 11 fixed platen 12 movable platen 13 rear platen 14 tie bar 15 fixed die 16 movable die 17 injection device 18 injection nozzle 19 mold device 21 guide hole 22 suction plate 28 linear motor 29 stator 31 mover 33 magnetic pole teeth 34 Core 35 Coil 37 Electromagnet unit 39 Rod 41, 42 Hole 43 Screw 44 Nut 46 Core 47 Yoke 48 Coil 49 Electromagnet 51 Adsorption part 61 Flange 62 Screw part 63 Bolt 81 Space 131 Convex part Fr Frame Gd Guide Gb Guide base Sb Slide base

Claims (4)

A mold clamping device for generating a mold clamping force by an electromagnet,
A fixed platen in which one mold is disposed and fixed in the mold opening and closing direction; a movable platen in which the other mold is disposed and which can be advanced and retracted in the mold opening and closing direction;
One adsorption surface formed by the electromagnet is formed, and a first adsorption member fixed to the fixed platen by a connecting member extending from the fixed platen;
A second attracting member for forming the other attracting surface by the electromagnet and transmitting the attracting force by the electromagnet to the movable platen;
The mold clamping apparatus, wherein the connecting member is fixed on a surface of the first suction member opposite to the suction surface. The mold clamping device according to claim 1, wherein the connecting member does not penetrate the first suction member. The mold clamping device according to claim 2, wherein the connecting member does not penetrate the second adsorption member. The mold clamping device according to claim 1, wherein the connecting member is fixed to the first suction member by a flange.

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