JP4648870B2 - Mold clamping force control method and mold clamping device - Google Patents

Description

  The present invention relates to a mold clamping force control method and a mold clamping device, and more specifically to a method for controlling a mold clamping force generated by an electromagnet in the mold clamping device and the mold clamping device.

  2. Description of the Related Art Conventionally, a molding machine, for example, an injection molding machine, includes an injection device, a mold device, and a mold clamping device. By injecting resin from an injection nozzle of the injection device, filling the cavity space of the mold device, and solidifying the resin. A molded product is obtained. The mold apparatus includes a fixed mold and a movable mold, and operates the mold clamping apparatus to move the movable mold forward and backward with respect to the fixed mold, thereby closing the mold, clamping and opening the mold. It can be carried out.

  The mold clamping device includes a fixed platen to which the fixed mold is attached, a movable platen to which the movable mold is attached, an electric motor, a ball screw shaft connected to an output shaft of the motor, and the ball screw. A ball screw composed of a ball nut screwed to a shaft, a cross head connected to the ball nut, a toggle mechanism disposed between the cross head and a movable platen, and the like, by driving the motor The mold can be closed and clamped by advancing the crosshead and extending the toggle mechanism.

  However, in the mold clamping apparatus having the above-described configuration, a toggle mechanism is used to generate a mold clamping force. Therefore, a bending moment acts on the movable platen, and the mold mounting surface of the movable platen is distorted. Will occur.

  Moreover, since the mold clamping is performed by extending the toggle mechanism, it becomes difficult to control the mold clamping force.

  Therefore, there is provided a mold clamping device that includes an electric motor and an electromagnet, uses the motor torque for mold closing and mold opening operations, and uses the attraction force of the electromagnet for mold clamping operations (see, for example, Patent Document 1). ).

  In the mold clamping device, a rear platen is disposed at a predetermined interval from the fixed platen, and a movable platen is disposed so as to be movable back and forth along a tie bar provided between the fixed platen and the rear platen. An electromagnet is fixed to the rear end surface of the rear platen, and an adsorption plate is disposed behind the rear platen so as to be movable back and forth. A link mechanism is disposed between the adsorption plate and the movable platen. It can be bent and stretched by a motor.

Therefore, after closing the mold by driving the motor and extending the link mechanism, the current is supplied to the coil constituting the electromagnet to drive the electromagnet, and the magnetic force according to the magnitude of the current is applied. Clamping can be performed by generating and adsorbing the adsorption plate. In this case, an electromagnet is used to generate the mold clamping force, so that the bending moment does not act on the movable platen, and the mold mounting surface is not distorted. Can be controlled.
Japanese Patent No. 3190600

  However, in the above-described mold clamping device that uses the attractive force of the electromagnet for the mold clamping operation, it is difficult to change the mold clamping force, and the mold clamping force cannot be accurately controlled during molding.

  For example, even when a current is supplied to the coil constituting the electromagnet at the start of clamping, an eddy current is generated in the direction that cancels the magnetic field, and the current is supplied but the desired magnetic field cannot be obtained. A certain time is required to generate a desired mold clamping force. This is not a steady process in the mold clamping process and is unique to the rise characteristics when the mold clamping force is changed. Not desirable. In particular, when the molding cycle is short, it is necessary to improve the productivity of the molded product by reducing the generation time of the mold clamping force as much as possible.

  Therefore, the present invention has been made in view of the above points, and in a mold clamping device that generates a mold clamping force with an electromagnet, a mold clamping force control method capable of accurately controlling the mold clamping force, and It is an object of the present invention to provide a mold clamping device.

  According to one aspect of the present invention, there is provided a mold clamping force control method for a mold clamping device that generates a mold clamping force with an electromagnet, and a magnetic flux density generated in the electromagnet and a predetermined mold clamping force corresponding to the magnetic flux density. A mold clamping force control method is provided, wherein mold clamping force control is performed based on a table that stores the relationship between.

  The magnetic flux density stored in the table may be obtained by experiment or magnetic field analysis. The magnetic flux density actually generated in the electromagnet may be detected, and the mold clamping force corresponding to the detected magnetic flux density may be determined from the table. A difference between the mold clamping force determined from the table and a set mold clamping force set in the mold clamping device may be calculated, and a current supplied to the electromagnet may be controlled in accordance with the difference.

  According to another aspect of the present invention, a mold clamping device that generates a clamping force by an electromagnet, a current supply unit that supplies current to the electromagnet, a control unit that controls the current supply unit, and the electromagnet Magnetic flux density detection means for detecting the magnetic flux density generated in the control unit, and the control unit has a table for storing a relationship between the magnetic flux density generated in the electromagnet and a predetermined clamping force corresponding to the magnetic flux density. The mold clamping device is provided, wherein the control unit performs mold clamping force control based on the table.

  The magnetic flux density stored in the table may be obtained by experiment or magnetic field analysis. The mold clamping force actually generated in the electromagnet and corresponding to the magnetic flux density detected by the magnetic flux density detecting means may be determined from the table provided in the control unit. The control unit may control the current supply unit based on a difference between the mold clamping force determined from the table and a set mold clamping force set in the mold clamping device.

  The magnetic flux density detection means may be a Hall element. The magnetic flux density detection means may be provided at a plurality of locations in the electromagnet. The magnetic flux density detection means may be provided at a location where symmetry is maintained with respect to the coil of the electromagnet. The magnetic flux density detection means may be provided on an outer pole and an inner pole of the electromagnet. The magnetic flux density detecting means may be provided at a symmetrical place with a substantially central portion of the electromagnet as a symmetrical center.

  ADVANTAGE OF THE INVENTION According to this invention, the mold clamping force control method and the said mold clamping apparatus which can control mold clamping force accurately can be provided in the mold clamping apparatus which generate | occur | produces mold clamping force with an electromagnet.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following, for the mold clamping device, the moving direction of the movable platen when closing the mold is the front, the moving direction of the movable platen when opening the mold is the rear, and the injection device is when performing the injection In the following description, the moving direction of the screw is assumed to be the front, and the moving direction of the screw when measuring is assumed to be the rear.

  In the following description, mold clamping refers to a state in which the movable mold is further in force from the state in which the parting surface of the movable mold is in contact with the parting surface of the fixed mold. It is pressed by a movable mold.

  FIG. 2 is a schematic configuration diagram of a mold apparatus and a mold clamping apparatus according to the embodiment of the present invention.

  In FIG. 2, 10 is a mold clamping device, Fr is a frame of an injection molding machine, Gd is laid on the frame Fr to form a rail, and supports and guides the mold clamping device 10. These are two guides as one guide member. In the figure, only one of the two guides Gd is shown.

  Reference numeral 11 denotes a fixed platen as a first fixing member that is placed on the guide Gd and fixed to the frame Fr and the guide Gd. A rear platen 13 as a second fixing member is disposed at a predetermined interval 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 of the four tie bars are shown in the figure) are installed as connecting members. The rear platen 13 is placed on the guide Gd so that it can move slightly with respect to the guide Gd as the tie bar 14 expands and contracts.

  A movable platen 12 as a first movable member is disposed along the tie bar 14 so as to be capable of moving forward and backward in the mold opening / closing direction (moving in the left-right direction in the drawing). For this purpose, a guide hole (not shown) for penetrating the tie bar 14 is formed at a position corresponding to the tie bar 14 of the movable platen 12.

  A first screw portion (not shown) is formed at a front end portion (right end portion in the figure) of the tie bar 14, and the tie bar 14 is fixed to the fixed platen 11 by screwing the first screw portion and the nut n1. Fixed to. In addition, a guide post 21 as a second guide member having a smaller outer diameter than the tie bar 14 is provided at a predetermined portion on the rear side (left side in the figure) of each tie bar 14, and the rear end face (left end face in the figure). ) Projecting rearward and integrally with the tie bar 14.

  A second screw portion (not shown) is formed in the vicinity of the rear end surface of the rear platen 13 of each guide post 21. The fixed platen 11 and the rear platen 13 screw the second screw portion and the nut n2. Are linked by In the present embodiment, the guide post 21 is formed integrally with the tie bar 14, but the guide post 21 may be formed separately from the tie bar 14.

  A fixed mold 15 as a first mold is fixed to the fixed platen 11, and a movable mold 16 as a second mold is fixed to the movable platen 12. Accordingly, the fixed mold 15 and the movable mold 16 are brought into contact with and separated from each other, and mold closing, mold clamping, and mold opening are performed.

  As the mold clamping is performed, a plurality of cavity spaces (not shown) are formed between the fixed mold 15 and the movable mold 16, and the molding material injected from the injection nozzle 18 of the injection apparatus 17 is used as a molding material. A resin (not shown) is filled in each cavity space.

  A mold apparatus 19 is configured by the fixed mold 15 and the movable mold 16.

  A suction plate 22 as a second movable member 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 posts 21 and is guided by the guide posts 21. Is done. The suction plate 22 is formed with guide holes 23 that penetrate the guide posts 21 at locations corresponding to the guide posts 21.

  The guide hole 23 is opened at the front end surface (right end surface in the drawing), is opened at the rear end surface of the large diameter portion 24 that accommodates the ball nut n2 and the suction plate 22, and is slid with the guide post 21. A small-diameter portion 25 having a sliding surface is provided. In the present embodiment, the suction plate 22 is guided by the guide post 21, but the suction plate 22 can be guided not only by the guide post 21 but also by the guide Gd.

  By the way, in order to move the movable platen 12 forward and backward, a linear motor 28 as a first drive unit and as a mold opening / closing drive unit is disposed between the movable platen 12 and the frame Fr. The linear motor 28 includes a stator 29 as a first drive element formed on the frame Fr in parallel with the guide Gd and corresponding to the moving range of the movable platen 12, and the movable platen 12. A movable element 31 as a second driving element is provided at the lower end of the second element so as to face the stator 29 and to be formed over a predetermined range.

  The mover 31 includes a core 34 projecting 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 (not shown) and a permanent magnet (not shown) formed so as to extend on the core. The permanent magnet alternates between the magnetic poles of N pole and S pole, and the magnetic poles. It is formed by magnetizing at the same pitch as the teeth 33.

  Accordingly, when the linear motor 28 is driven by supplying a predetermined current to the coil 35, the movable element 31 moves forward and backward, and accordingly, the movable platen 12 moves forward and backward, and mold closing and mold opening can be performed. .

  In the present embodiment, the permanent magnet is disposed on the stator 29 and the coil 35 is disposed on the mover 31, but the coil is disposed on the stator and the permanent magnet is disposed on the mover. You can also. In this case, since the coil does not move as the linear motor 28 is driven, wiring for supplying power to the coil can be easily performed.

  By the way, when the movable platen 12 is moved forward (moved 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, and then the mold clamping is performed. In order to perform mold clamping, an electromagnet unit 37 as a second drive unit and as a mold clamping drive unit is disposed between the rear platen 13 and the suction plate 22.

  In order to transmit the mold clamping force generated by the electromagnet unit 37 to the movable platen 12 at the time of mold clamping, the suction plate 22 is moved back and forth in conjunction with the advance and retreat of the movable platen 12 at the time of mold closing and mold opening. A rod 39 as a clamping force transmission member that extends through the rear platen 13 and the suction plate 22 and connects the movable platen 12 and the suction plate 22 is disposed so as to freely advance and retract.

  The mold clamping device 10 is constituted by 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 as a first driving member disposed on the rear platen 13 side, and an attracting portion 51 as a second driving member disposed on the suction plate 22 side.

  The attracting portion is formed at a predetermined portion of the front end surface of the attracting plate 22, in the present embodiment, the portion surrounding the rod 39 in the attracting plate 22 and facing the electromagnet 49. Further, in the present embodiment, a predetermined portion of the rear end surface of the rear platen 13, slightly above and below the rod 39, extends in the horizontal direction, and two grooves 45 are formed in parallel to each other. A core 46 having a rectangular shape between 45 and a yoke 47 is formed in other portions. A coil 48 is wound around the core 46.

  The core 46 and the yoke 47 of the rear platen 13 and the suction plate 22 are formed by laminating thin plates made of a ferromagnetic material, and constitute an electromagnetic laminated steel plate. In the present embodiment, an electromagnet 49 is provided separately from the rear platen 13 and an adsorbing portion 51 is provided separately from the adsorption plate 22. The electromagnet is adsorbed as a part of the adsorption plate 22 as a part of the rear platen 13. A part can also be formed.

  In the drawing in which thin plates are laminated, a current flows from the back side to the front side of the coil 48 wound on the upper side, and a current flows from the front side to the back side of the coil 48 wound on the lower side. ing.

  Therefore, in the electromagnet unit 37, when an electric current is supplied to the coil 48 provided in the groove 45, the electromagnet 49 is driven to attract the attracting portion 51 and generate the mold clamping force.

  The rod 39 is connected to the suction plate 22 at the rear end (left end in the drawing) and connected to the movable platen 12 at the front end. Accordingly, the rod 39 is advanced as the movable platen 12 advances when the mold is closed, and advances the suction plate 22, and when the mold is opened, the movable platen 12 moves backward (moves leftward in the figure). Then, the suction plate 22 is moved backward.

  Therefore, a hole 41 for passing the rod 39 and a hole 42 for penetrating the rod 39 are formed in the central portion of the rear platen 13, and an opening at the front end of the hole 41. A bearing member Br1 such as a bush for slidably supporting the rod 39 is disposed. Further, a screw 43 is formed at the rear end portion of the rod 39, and the screw 43 and a nut 44 rotatably supported with respect to the suction plate 22 are screwed together.

  In the present embodiment, the Hall element 9 is further provided as a magnetic flux density detecting means on the surface of the rear platen 13 facing the suction plate 22. The Hall element 9 is a magnetoelectric conversion element using the Hall effect, and detects the magnetic flux density generated in the electromagnet.

  The Hall element 9 is connected to the control unit 4, and the coil 48 is connected to the driver 5 serving as a current supply unit. The control unit 4 and the driver 5 are connected, and the control unit 4 controls the operation of the driver 5 based on the detection signal sent from the Hall element 9 to control the current supplied to the coil 48, and as a result The mold clamping force is controlled. This mold clamping force control will be described in detail below.

  FIG. 2 is a view of the rear platen 13 shown in FIG. More specifically, FIG. 2A shows a side cross section of the rear platen 13 shown in FIG. 1 and the suction plate 22 provided behind the rear platen 13, and FIG. 2B shows the side view of FIG. 2 shows the rear end surface of the rear platen 13 when viewed from the direction of arrow A. In FIG. 2A, for convenience of explanation, the Hall element 9 (see FIG. 1) is not shown.

  With reference to FIGS. 1 and 2, as described above, the suction plate 22 is moved forward in the substantially central portion of the rear platen 13 made of a conductor such as iron as the movable platen 12 moves forward and backward. A hole 41 for penetrating the rod 39 is formed. Two grooves 45 extending in the horizontal direction are formed above and below the hole 41 in parallel to each other, a core 46 having a rectangular shape is formed between the grooves 45, and a yoke 47 is formed in the other part. ing. A coil 48 is provided in the groove 45, and the coil 48 is wound around the core 46.

  A suction plate 22 is provided behind the rear platen 13. Under this structure, when a current is supplied to the coil 48, a magnetic flux is generated in the direction indicated by the solid line in FIG. In the drawing, current flows from the back side of the paper surface to the front side of the coil 48 wound on the upper side, and current flows from the front side to the back side of the paper surface of the coil 48 wound on the lower side.

However, since there is a distribution in the magnetic flux density, the magnetic flux at the location where the rear end surface of the rear platen 13 is located does not necessarily match the magnetic flux at other locations. For example, in FIG. 2B, 24 locations (P _{11 to} P ₅₅ ) are illustrated as locations for measuring the magnetic flux, but the magnetic flux values at each location do not necessarily match. For example, all magnetic circuits are not uniform due to magnetic leakage at the end of the rear platen 13, influence of tilting of the rear platen 13, positional displacement with the suction plate 22, attachment conditions, and the like.

  Therefore, as shown in FIG. 3, the value of the magnetic flux at each location varies with respect to a predetermined mold clamping force F '. Here, FIG. 3 is a graph showing the relationship between the magnetic flux density B and the clamping force F at each location on the rear end surface of the rear platen 13. FIG. 3 shows the relationship between the magnetic flux density B and the mold clamping force F at any three locations on the rear platen 13, but this is merely an example, and all the 24 locations described above are shown on the graph. There can be a maximum of 24 types of curves showing the relationship between the magnetic flux density B and the clamping force F.

The mold clamping force F and the magnetic flux density _Bn at each location on the rear end surface of the rear platen 13 have the following relationship. That is,
F = Σ (S · B _n ² / 2μ)
Here, S represents the magnetic pole area, and μ represents the vacuum permeability.

Therefore, in this embodiment, magnetic field analysis using numerical simulations such as experiments or a finite element method is performed in advance, and magnetic fluxes at 24 locations (P _{11 to} P ₅₅ ) on the rear end surface of the rear platen 13 are obtained and obtained. The mold clamping force is calculated from the magnetic flux value (magnetic flux density), and the relationship between the magnetic flux density (magnetic flux density distribution) at each location and the mold clamping force corresponding to the magnetic flux density (magnetic flux density distribution) is determined by the control unit 4 ( (See FIG. 1). Specifically, the table shown in FIG. 4 is stored in the control unit 4. Here, FIG. 4 is a table showing the relationship between the magnetic flux density and the clamping force at each location on the rear end surface of the rear platen 13.

Referring to FIG. 4, each row of B _{11 to} B ₅₅ in the table uses an experiment or numerical simulation by a finite element method or the like in advance at each position (P _{11 to} P ₅₅ ) on the rear end surface of the rear platen 13. The magnetic flux density obtained by performing the magnetic field analysis is shown, and in the column F, the mold clamping force calculated based on the magnetic flux density at each location is shown corresponding to the magnetic flux density. Therefore, by detecting the magnetic flux density at an arbitrary position on the rear end surface of the rear platen 13 by the Hall element 9 (see FIG. 1), the clamping force acting at that time is determined based on the table shown in FIG. Can do.

  The table provided in the control unit 4 may be a simplified version of the table shown in FIG. 4, for example, the table shown in FIG. Here, FIG. 5 is a table showing the relationship between the magnetic flux density and the clamping force at one place on the rear end surface of the rear platen 13.

Table shown in FIG. 5, from the table shown in FIG. 4, the rear platen one portion of the rear end face of the 13, for example, those extracted and the magnetic flux density at P _33, the value of the clamping force corresponding thereto. When it is determined in advance at which position of the rear end surface of the rear platen 13 the Hall element 9 is to be detected and the magnetic flux density is detected, the magnetic flux density at the corresponding position is detected, and the action is based on the table shown in FIG. The mold clamping force can be determined.

  When the Hall elements 9 are provided at a plurality of locations on the rear end surface of the rear platen 13 and the magnetic flux density at each location is detected, the average value of each clamping force obtained from the table shown in FIG. It may be regarded as the value of the clamping force acting on the. In general, the magnetic flux density is often not uniform because of structural limitations of the apparatus. In such a case, a more accurate value of the mold clamping force can be calculated by calculating the area ratio assigned to each Hall element with respect to each magnetic flux density.

The detection signal output from the Hall element 9 that detects the magnetic flux density is sent to the control unit 4, and the control unit 4 determines the clamping force acting at that time from the table shown in FIG. 4 or FIG. When the mold clamping force is changed, such as at the start of mold clamping, it is determined whether or not the mold clamping force has reached a steady mold clamping force F ₀ that is a target mold clamping force to be obtained by the change.

When the control unit 4 determines that the mold clamping force has reached the steady mold clamping force F ₀ , the control unit 4 uses the current supplied to the coil 48 as a steady current necessary for generating the steady mold clamping force F _0. It controls the operation of the driver 5 to vary the rated current I ₀ is.

  That is, the control unit 4 obtains a difference between the mold clamping force determined based on the magnetic flux density detected by the Hall element 9 and the set mold clamping force set by the operator, and corresponds to the difference to the driver 5. To control the operation.

  Therefore, the control unit 4 can perform feedback control of the operation of the driver 5 with high accuracy. Therefore, the current supplied to the coil 48 can be controlled with high accuracy, and a desired mold clamping force can be obtained.

  Next, the mounting location of the Hall element 9 that detects the magnetic flux density will be described.

  In the present invention, there is no particular limitation on the number and location of the Hall elements 9 attached. However, as described above, there is a distribution in the magnetic flux density, and the magnetic flux at a location on the rear end surface of the rear platen 13 does not always coincide with the magnetic flux at another location, so the clamping force can be grasped more accurately. For this purpose, it is desirable to provide Hall elements 9 at a plurality of locations on the rear end surface of the rear platen 13 to detect the magnetic flux density. In particular, it is preferable to arrange at a location where symmetry with respect to the coil 48 is maintained, or at the center of each of the outer pole and the inner pole.

Referring to FIG. 2 again, in FIG. 2, the Hall element 9 is disposed at P ₃₁ and P ₃₅ where symmetry is maintained with respect to the coil 48, and P _{11 to} P ₁₅ and P _{51 to} P _55. Hall element 9 is arranged at the center of the outer pole, and Hall elements 9 of P ₂₁ , P ₂₂ , P ₂₄ , P ₂₅ , P ₄₁ , P ₄₂ , P ₄₄ , P ₄₅ are arranged at the center of the inner pole. . FIG. 2 shows an example in which P ₂₃ and P ₄₃ are arranged at the center positions of the inner periphery of the hole 41 and the coil 48. Further, they are arranged at equal intervals in the horizontal direction.

Furthermore, when the shapes of the outer and inner poles are different, one for each pole, that is, one of P _{11 to} P ₁₅ and one of P _{21 to} P ₂₅ . By providing the Hall element 9 at any one of P _{31 to} P ₃₅ , at any one of P _{41 to} P ₄₅ , and at any one of P _{51 to} P ₅₅ , accuracy is improved. Well, the magnetic flux density can be measured and the clamping force can be determined. In this _case, two points of _{P 23} and _{P 43} are so susceptible to magnetic _{saturation, P n1, P n2, P} n4, and it is desirable to select the same column of _{P n5.}

  Further, as shown in FIG. 6, the suction plate 22 may be provided to be inclined up and down with respect to the rear platen 13.

In this case, at least P ₁₃ , which is the approximate center of the position where the rear platen 13 and the suction plate 22 are farthest (location A in FIG. 6), and the position where the rear platen 13 and the suction plate 22 are closest (see FIG. 6, the Hall element 9 is provided at P ₅₃ which is substantially the center of the location C), the magnetic flux density at each location is detected, and the average value of the clamping force corresponding to the magnetic flux density is calculated. Even when tilted with respect to the rear platen 13, the mold clamping force can be obtained with high accuracy.

Further, calculating the adsorption plate 22, if provided inclined to the left and right with respect to the rear platen 13, the Hall element 9, provided on P ₃₁ and P _35, the mold clamping force by detecting a magnetic flux density of each You may make it do.

Further, in a place where a hole 41 provided in the approximate center of the rear platen 13 for penetrating the rod 39 is formed (place B in FIG. 6), a place symmetric with respect to the hole 41, that is, P Hall elements 9 are provided at _{31 to} P ₃₅ , the magnetic flux density at each location is detected, and the average of the clamping force corresponding to the magnetic flux density is calculated, whereby the suction plate 22 is inclined with respect to the rear platen 13. However, the clamping force can be obtained with high accuracy.

  Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes are within the scope of the gist of the present invention described in the claims. It can be changed.

It is a schematic block diagram of the metal mold apparatus and the mold clamping apparatus in embodiment of this invention. It is a figure of the rear platen shown in FIG. It is a graph which shows the relationship between the magnetic flux density in each location of the rear-end surface of a rear platen, and mold clamping force. It is a table | surface which shows the relationship between the magnetic flux density and mold clamping force in each location of the rear-end surface of a rear platen. It is a table | surface which shows the relationship between the magnetic flux density in one place of the rear-end surface of a rear platen, and mold clamping force. 4 is a side cross-sectional view of the rear platen and the suction plate when the suction plate is provided to be inclined with respect to the rear platen.

Explanation of symbols

4 Control unit 5 Driver 9 Hall element 10 Mold clamping device 49 Electromagnet B Magnetic flux density F Mold clamping force

Claims (8)

A mold clamping force control method for a mold clamping device that generates a mold clamping force with an electromagnet,
The mold clamping corresponding to the detected value is based on a detected value of the magnetic flux density at a plurality of locations of the coil holding part that holds the coil of the electromagnet and a table that stores the relationship between the clamping force corresponding to the magnetic flux density. A mold clamping force control method, wherein mold clamping force control is performed by calculating an average force. The mold clamping force control method according to claim 1 ,
Calculating the difference between the clamping force determined from the table and the set clamping force set in the clamping device;
A mold clamping force control method, wherein a current supplied to the electromagnet is controlled corresponding to the difference. A mold clamping device for generating a mold clamping force by an electromagnet,
A current supply for supplying current to the coil of the electromagnet;
A control unit for controlling the current supply unit;
A coil holding part for holding the coil; and a magnetic flux density detecting means for detecting a magnetic flux density at a plurality of locations of the coil holding part,
The control unit sets the detected value based on a detected value of the magnetic flux density at the plurality of locations detected by the magnetic flux density detecting means and a table storing a relationship between mold clamping forces corresponding to the magnetic flux density. A mold clamping device that performs mold clamping force control by calculating an average of corresponding mold clamping forces . The mold clamping device according to claim 3 , wherein
The control unit controls the current supply unit based on a difference between the mold clamping force determined from the table and a set mold clamping force set in the mold clamping device. apparatus. The mold clamping device according to claim 3 or 4 ,
The mold clamping apparatus, wherein the magnetic flux density detection means is a Hall element. The mold clamping device according to any one of claims 3 to 5 ,
The mold clamping apparatus, wherein the magnetic flux density detection means is provided at a location where symmetry is maintained with respect to the coil. The mold clamping device according to any one of claims 3 to 5 ,
The mold clamping apparatus, wherein the magnetic flux density detecting means is provided on an outer pole and an inner pole of the electromagnet. The mold clamping device according to any one of claims 3 to 5 ,
The said magnetic flux density detection means is provided in the location which becomes the said symmetry about the substantially center part of the said electromagnet as the center of symmetry.

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