JP2020196180A - Method for controlling mold clamping device and mold clamping device - Google Patents

Abstract

To provide a method for controlling a mold clamping device and a mold clamping device capable of coping with problems in which a reactive force generated in a mold changes when the mold is clamped caused by thermal expansion of the mold during continuous molding, and a moving amount for mold opening of a movable platen and the like changes during release of mold clamping pressure, to prevent a trouble that occurs in the mold during continuous molding, and a trouble that occurs in the mold clamping device during disengagement between a half nut and an engaging part.SOLUTION: In a method for controlling a mold clamping device 13 provided with: a mold opening/closing mechanism 21 for mold-opening/closing a movable mold 19 with respect to a stationary mold 17; and a mold clamping mechanism 22 for mold clamping the movable mold 19 and the stationary mold 17, a mold-opening movement position p2 of a movable platen 20 or a stationary mold 19 in releasing mold clamping by the mold clamping mechanism 22 is detected to compensate a position t2 for mold-closing control.SELECTED DRAWING: Figure 4

Description

The present invention is a control method and mold clamping of a mold clamping device provided with a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold. It is about the device.

As a problem during continuous molding of the mold clamping device of an injection molding machine, as the molding cycle is repeated from the start of molding, each member such as a fixed plate, a movable plate, a tie bar, and a bed rises and thermally expands around the molding die. There is a problem that it occurs. Continuing molding while leaving such thermal expansion of the molding die unattended has an adverse effect on the quality of the injection molding machine including the molding die and the molded product molded by the injection molding machine. Those described in Patent Document 1 and Patent Document 2 are known to deal with the problem of thermal expansion.

The one described in Patent Document 1 corrects the mold thickness dimension based on the position of the movable mold detected by the mold position detecting means after confirming the completion of mold clamping. Further, the one described in Patent Document 2 uses a half nut as a mold clamping device, and has a free running distance until the mold clamping surface of the half nut and the mold clamping surface of the engaging portion come into contact with each other. Based on this, the half nut or engaging portion, which is a member on the mold clamping side, is moved to the engaging start position. Then, the free running distance (measured value) is obtained for each molding cycle, and the position of the ram (half nut) when the half nut is engaged is continuously corrected to cope with the thermal expansion of the mold.

JP-A-7-148740 (Claim 1, 0037, 0046) JP 2011-110700 (Claim 1, 0032, 0033)

However, the devices of Patent Document 1 and Patent Document 2 do not consider any change in the reaction force generated inside the mold when the thermally expanded molding mold is compacted. That is, in the thermally expanded molding die, the reaction force generated inside the mold does not increase in proportion to the increase in the mold thickness due to the thermal expansion due to the difference in the mold structure. For example, the reaction force accumulated inside the molding die at the time of mold clamping differs depending on the material of the molding die, the coupling relationship of each member of the die, and whether or not the die is a spring die. If the reaction force generated inside the molding die at the time of mold clamping is left unattended, problems such as galling of each member of the molding die may occur.

Further, when the mold is released by the mold clamping mechanism, there is a problem that the movable platen, the half nut on the mold clamping cylinder side, and the engaging portion provided on the tie bar or the ram are moved by the reaction force of the molding die. If the movement of the movable platen, tie bar, etc. is not corrected, the surface of the half nut and the surface of the engaging portion will come into contact with each other with a certain force or more when engaging and disengaging the half nut to the engaging portion, resulting in galling. May cause problems such as the occurrence of.

Therefore, in view of the above problems, in the present invention, the reaction force generated inside the mold when the mold is compacted due to the thermal expansion of the molding mold during continuous molding changes, and the mold is movable when the mold is pressed and pressed. It is possible to deal with the problem that the amount of mold opening movement of the plate etc. changes, and to prevent problems that occur in the molding die in continuous molding and problems that occur in the mold clamping device when the half nut and the engaging part are engaged and disengaged. It is an object of the present invention to provide a method of controlling a mold clamping device and a mold clamping device. Alternatively, it is an object of the present invention to provide a method for controlling a mold clamping device and a mold clamping device capable of continuously molding a good molded product even when the molding die expands during continuous molding.

The method for controlling the mold clamping device according to claim 1 of the present invention includes a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold. The control method of the mold clamping device provided with the above is characterized in that the mold opening movement position of the movable platen or the movable mold at the time of mold clamping release by the mold clamping mechanism is detected and the position for mold closing control is corrected. ..

The method for controlling the mold clamping device according to claim 2 of the present invention includes a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold. In the control method of the mold clamping device provided with, the feature is that the mold opening movement position of the movable platen or the movable mold at the time of mold release is detected by the mold clamping mechanism, and the position used for half nut engagement is corrected. To do.

The control method of the mold clamping device according to claim 3 of the present invention is the position used for engaging the half nut in claim 2 when the half nut is engaged with the engaging portion of the tie bar or the ram. It is characterized in that it is a stop position of a tie bar or a ram.

The mold clamping device according to claim 4 of the present invention includes a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping the movable mold and the fixed mold. In the mold clamping device, a mold clamping mechanism that performs mold clamping and mold clamping release, a sensor that detects the mold opening movement position of the movable platen or the movable mold at the time of mold clamping release, and a movable platen or a movable platen at the time of mold clamping release. It is characterized by being provided with a control device that corrects a position for mold closing control from a mold opening moving position of a movable mold.

The control method of the mold clamping device of the present invention includes a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping the movable mold and the fixed mold. In the control method of the device, the mold opening movement position of the movable platen or the movable mold at the time of mold release is detected by the mold clamping mechanism, and the position for mold closing control is corrected, so that the mold or the like is thermally expanded during molding. Can be dealt with.

It is a front view which shows the mold open state of the mold clamping device of this embodiment which partially represented by the cross section. It is a front view which shows the mold closed state of the mold clamping device of this embodiment which partially represented by the cross section. It is a figure which shows the relationship between the engaging tooth of a half nut and the engaging groove of a tie bar at the time of controlling the mold clamping device of this embodiment. It is a flowchart about the tie bar target position correction at the time of automatic molding of the mold clamping device of this embodiment. It is a figure which shows the change of the mold opening movement amount of the movable plate | die by the reaction force of the mold at the time of the die clamping pressure release at the time of the continuous molding start of the mold clamping device of this embodiment, and when the continuous molding is continued for a certain period of time. It is a top view of the mold clamping device of another embodiment which partially represented by the cross section. It is a front view of the mold clamping device of still another embodiment which partially represented by the cross section.

The injection molding machine 11 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2 in which the cover and the safety door are omitted. The hybrid injection molding machine 11 that uses both a hydraulic mechanism and an electric drive mechanism includes an injection device 12 on one side (right side in FIG. 1) and a mold clamping device 13 on the other side (left side in FIG. 1). There is.

The injection device 12 will be described first. A known electric injection device is used as the injection device 12, and a screw forward / backward mechanism and a screw rotation mechanism (not shown) are driven by an electric motor such as a servomotor. The injection device 12 is provided with a nozzle 15 on the tip end side of a heating cylinder 14 provided with a heater (not shown). A material supply device 16 is provided on a housing plate (not shown) near the rear portion of the heating cylinder 14. Further, a screw (not shown) is arranged in the inner hole of the heating cylinder 14. The screw can be rotated by the screw rotation mechanism and can be moved forward and backward by the screw forward / backward movement mechanism. The injection device 12 may use a hydraulic mechanism.

Next, the mold clamping device 13 will be described. The mold clamping device 13 moves the movable plate 20 to which the movable mold 19 is attached to the fixed plate 18 to which the fixed mold 17 is attached by the mold opening / closing mechanism 21, and molds the mold. Molding is performed by the mechanism 22. Many, but not all, molding machines in which the mold opening / closing mechanism 21 and the mold clamping mechanism 22 are independently provided, such as the injection molding machine 11, are relatively large.

A fixed plate 18 is fixedly erected on the bed 23. A fixed mold 17, which is one of the molding dies, is attached to the mold mounting surface 24 of the fixed plate 18. Further, a recess 26 through which the heating cylinder 14 of the injection device 12 and the nozzle 15 are inserted is formed in the central portion of the fixing plate 18 on the back surface 25, which is the surface opposite to the mold mounting surface 24. The nozzle 15 of the injection device 12 can come into contact with the fixed mold 17 via the recess 26 and a locate ring (not shown). In the present embodiment, the molding dies 17 and 19 are molded by the mold clamping cylinder 27 of the mold clamping mechanism 22 using a pressure medium (hydraulic oil). The mold clamping cylinder 27 is provided near each of the four corners of the fixing plate 18. A tie bar 28 is fixed to the other side of the piston 27a of the mold clamping cylinder 27. The rod of the mold clamping cylinder 27 constitutes the tie bar 28. In the present embodiment, the mold clamping cylinder 27 is a single-acting type having only an oil chamber 27b to which hydraulic oil is supplied at the time of mold clamping, but hydraulic oil is supplied to perform strong mold release (release). It may be a recovery type that also has an oil chamber. Two adjusting cylinders 47 of the tie bar position adjusting mechanism for adjusting the positions of the piston 27a and the tie bar 28 are attached around the piston 27a of the mold clamping cylinder 27 on the back surface 25 of the fixing plate 18. A rod 48 is also fixed to the end surface of the piston 47. The tip of the rod 47a of the adjusting cylinder 47 and the tip of the rod 48 are attached to the same plate 49, respectively. The tie bar position adjusting mechanism may be an electric mechanism.

A plurality of engaging grooves 28a forming an engaging portion are formed in the circumferential direction from the middle to the tip of the tie bar 28 in the axial direction. The engaging groove 28a is a groove for engaging the engaging teeth 32a of the half nut 32 described later. Although the details of the engaging portion groove 28a are omitted in FIGS. 1 and 2, as shown in FIG. 3, the engaging groove 28a of the tie bar 28 of the present embodiment is formed on the engaging tooth 32a of the half nut 32 at the time of mold clamping. It has an abutting surface 28b that is abutted and perpendicular to the axis of the tie bar 28, and an inclined surface 28c on the opposite side.

Each tie bar 28 is slidably inserted into an inner hole of a cylindrical bush 31 near the four corners of the movable platen 20. A movable mold 19 which is the other mold of the molding mold is attached to the mold mounting surface 29 of the movable plate 20. Half nuts 32 are provided around the mounting position of the bush 31 on the back surface 30, which is the surface opposite to the mold mounting surface 29 of the movable plate 20.

The half nut 32 is a member that engages with the engaging groove 28a of the tie bar 28 and transmits the mold clamping force to the movable platen 20 and the movable mold 19. The half nut 32 can be moved back and forth with respect to the engaging groove 28a of the tie bar 28 by a drive mechanism (not shown). The half nut 32 is formed with a plurality of engaging teeth 32a that are engaged with the engaging grooves 28a of the tie bar 28. The engaging teeth 32a are provided with a contact surface 32b that is in contact with the contact surface 28b of the tie bar 28 at the time of mold clamping and is perpendicular to the upper surface of the bed 23. Further, the engaging teeth 32a are provided with an inclined surface 32c on the opposite side of the contact surface 32b. The relationship between the half nut 32 and the engaging portion of the tie bar 28 is not limited to the above. For example, the two surfaces on both sides of the engaging teeth 32a of the half nut 32 and the two surfaces on both sides of the engaging groove 28a of the engaging portion may have their respective surfaces perpendicular to the bed 23 or the like. Further, the side of the engaging portion of the tie bar 28 may be the engaging tooth and the side of the half nut 32 may be the engaging groove, and in either case, the number of engaging teeth and engaging grooves is not limited.

The movable board 20 is provided with legs 35 on the bed side (ground plane side). On the other hand, at least two guide rails 34 (or guide plates) are provided on the upper surface of the bed 23 so as to face one side and the other side in FIGS. 1 and 2. The movable platen 20 is guided by the guide rail 34 via the legs 35 and can move in the mold opening / closing direction. Further, an ejector mechanism (not shown) is provided on the back surface 30 of the movable board 20.

In the present embodiment, the end side of the tie bar 28 is inserted into the tie bar holder 36 erected on the upper surface of the bed 23 on the other side of the movable board 20. Regarding the relationship between the tie bar holder 36 and the tie bar 28, the circumferential surface of the tie bar 28 is slidably inserted into the tie bar holder 36. The tie bar holder 36 is a member that does not receive the mold clamping force, and is a thin plate as compared with the fixing plate 18 and the like. Further, since the tie bar holder 36 itself is not an essential member, it may not be arranged.

Next, the mold opening / closing mechanism 21 of the mold clamping device 13 will be described. In the present invention, the mold opening / closing mechanism 21 uses an electric mechanism using an electric motor and a screw feed mechanism. Both of the mold opening / closing mechanisms 21 are arranged on the lower side surface on the operation side and the lower side surface on the opposite side of the movable board 20. Explaining the operation-side mold opening / closing mechanism 21 shown in FIG. 1, both ends of the ball screw 38 are held in a double-holding state by bearings 39 and 40 attached to brackets on the bed 23, respectively. A servomotor 44 is fixed to the tie bar holder 36 or a bracket (not shown) on the bed, and a drive pulley (not shown) fixed to the drive shaft of the servomotor 44 and a driven pulley 41 fixed to the ball screw 38 are belted. Is connected by. Further, as described above, the ball screw nut 33 is fixed to the bracket of the movable platen 20, and the ball screw 38 is inserted through the ball screw nut 33. As is well known, the servomotor 44 includes a rotary encoder 45, and can detect a rotation angle (rotation amount or movement amount). That is, the rotary encoder 45, which is a sensor, can detect the positions of the movable platen 20 and the movable mold 19 in the mold opening / closing direction.

When the mold opening / closing mechanism 21 is an electric mechanism using an electric motor and a screw feed mechanism, the arrangement and drive method of each member are not limited to the above. Further, the mold opening / closing mechanism may use a hydraulic cylinder. When the mold opening / closing mechanism uses a hydraulic cylinder, a sensor for detecting the position of the movable plate 20 with respect to the fixed plate 18 (or bed 23) is separately provided. Further, even in the case of an electric mechanism, a sensor for detecting the position of the movable plate 20 and the movable mold 19 in the mold opening / closing direction may be separately provided.

Next, the control system of the present embodiment will be briefly described with reference to FIGS. 1 and 2. Each servomotor 44 is connected to a servo amplifier 43 (only the servo amplifier 43 of one servomotor 44 is shown in the figure). .. Each servo amplifier 43 is connected to a higher-level control device 37. Further, the control device 37 is connected to a setting display device (not shown) that inputs a setting and displays the state of the injection molding machine 11 and a hydraulic mechanism 42 that controls the mold clamping cylinder 27. The hydraulic mechanism 42 includes a pump, each valve, a pressure sensor, and the like. The control device 37 is also connected to each sensor and the like, and detects the mold opening movement position p2 of the movable platen 19 or the movable mold 19 when the mold is released by the mold clamping mechanism of the present invention (or the control device 37 described above. The mold opening movement position c1 is subtracted from the mold opening movement position p2 to calculate the mold opening movement amount d2), and the tie bar target position t2, which is the position for mold closing control, is corrected.

Next, a method of operating the injection molding machine 11 will be described, particularly a method of controlling the mold clamping device including a method of correcting the position for controlling mold closing during continuous molding. These explanations are based on the flowchart of FIG. 4, a diagram showing the relationship between the engaging teeth 32a of the half nut 32 and the engaging groove 28a of the tie bar 28 during control of FIG. 3, and the reaction force of the mold of FIG. This will be described with reference to the figure showing the change in the mold opening movement amount of the movable plate 20 according to the above. As described in the columns of "Background Technology" and "Problems to be Solved by the Invention", in the mold clamping device 13 of the injection molding machine 11, the molding dies 17 and 19 are mainly used as the molding cycles are repeated during continuous molding. The temperature of each member such as the fixed plate 18, the movable plate 20, the tie bar 28, and the bed 23 rises, and thermal expansion occurs. Further, due to the thermal expansion of the molding dies 17 and 19, the reaction force generated in the molding dies 17 and 19 at the time of mold clamping also changes. In the present embodiment, the following controls are performed corresponding to them.

The control method of the mold clamping device of the present embodiment is used in the mode of fully automatic molding (automatic cycle) after trial molding by manual molding. When the fully automatic molding (automatic cycle) mode is started (s1), the movable mold 19 and the movable plate 20 are moved to close the mold by the operation of the mold opening / closing mechanism 21 in the mold closing process. Then, when the mold closing is completed (s2), the cavity C is formed between the fixed mold 17 and the movable mold 19. Further, a signal indicating the mold closing completion state is sent to the control device 37.

In the next half nut locking step, a driving means (not shown) of the half nut 32 is driven, and the engaging teeth 32a of the half nut 32 are advanced toward the engaging groove 28a of the tie bar 28. At this time, if the engaging teeth 32a of the half nut 32 are not engaged with the engaging grooves 28a of the tie bar 28 with gaps on both sides, the engaging teeth 32a or the engaging grooves 28a may be damaged or engaged. Charging may occur on the contact surface 32b of the teeth 32a or the contact surface 28b of the engaging groove 28a. Therefore, at the start of continuous molding, the relative positions of the half nut 32 when engaged are adjusted so that the engaging teeth 32a of the half nut 32 are engaged without contacting the engaging groove 28a of the tie bar 28. It has been done. That is, in the present invention, the "position for mold closing control" refers to the position of the movable platen 20 when the half nut 32 is engaged (the position of the half nut 32), the position of the tie bar 28 (the position of the engaging portion), and the movable platen 20. (Position of half nut 32) and relative position of tie bar 28 (position of engaging portion) are included.

In general, the position where the mold closing is completed in the mold closing step is the position where the parting surface of the fixed mold 17 and the parting surface of the movable mold 19 are in contact with each other, and the parting surfaces are in contact with each other. The half nut 32 is engaged with the engaging portion at the position where the movable platen 20 is touched and stopped. However, when performing injection compression molding (injection press molding), when you want to speed up the molding cycle as much as possible, when using a spring mold, etc., the position where the parting surfaces in front of them are not in contact with each other is when the mold closing is completed. It may be the engaging position of the movable platen 20 or the engaging position of the half nut 32.

Then, in the half nut locking step, it is confirmed by a sensor (s3) that the half nut 32 has been advanced and the engaging teeth 32a are completely engaged with the engaging groove 28a of the engaging portion of the tie bar 28 (s3). .. This state is the state (a) in FIG. In the next mold clamping step, hydraulic oil is supplied to the oil chamber 27b of the mold clamping cylinder 27 of the mold clamping mechanism 22, and the tie bar 28 is towed in the right direction (one side direction) in FIG. As a result, as shown in FIG. 3B, the contact surface 28b of the tie bar 28 and the contact surface 32b of the half nut 32 are brought into contact with each other. Then, when the oil pressure of the hydraulic oil in the oil chamber 27b is increased to a predetermined value, the mold clamping is completed (s4).

In this mold clamping completed state, the tie bar 28 is extended, and the molding dies 17 and 19 composed of the fixed dies 17 and the movable dies 19 are in a state where the gaps between the members are eliminated and the die thickness is very slightly reduced. .. Further, the reaction force is accumulated inside the molding dies 17 and 19 by the mold clamping. The reaction force at this time differs depending on the mold thickness, material, arrangement between each member, and the difference in thermal expansion due to the difference in temperature rise of each part. Further, especially in the case of a spring mold, the reaction force becomes large due to the elastic force of the spring.

Then, when it is confirmed that the mold clamping is completed, the process proceeds to the injection process (including the pressure holding process), and the molten resin is injected from the injection device 12 into the cavity C. The injected molten resin is cooled and solidified in the next cooling step. Then, when the cooling step is completed, the mold clamping pressure release step (mold clamping release step) is performed (s5). In the mold clamping / pressing process, the mold clamping force is returned to zero by returning the hydraulic oil in the positive pressure state in the oil chamber 27b of the mold clamping cylinder 27 to the tank from a drain circuit (not shown). (Release of mold tightening) is performed.

As a result, as shown in FIG. 3 (c), at the end of mold clamping and depressurization (when the mold is released), the extension of the tie bar 28 is eliminated, the reaction force inside the tie bar is released, and the molding metal is formed. The compressed state of the molds 17 and 19 is eliminated, and at the same time, the reaction force accumulated inside the molding molds 17 and 19 is released. When the reaction force accumulated in the molding dies 17 and 19 is larger than a certain size due to the release of the reaction force at this time, the movable die 19 and the movable plate 20 are slightly moved in the mold opening direction. .. The amount d2 of the mold opening movement in the mold opening direction of the movable mold 19 and the movable plate 20 differs depending on the magnitude of the reaction force. Then, the mold opening moving positions p1 and p2 to which the movable plate 20 is moved at the end of mold clamping and pressing are detected by the rotary encoder 45 of the servomotor 44 of the mold opening / closing mechanism 21 (s6). When there are two or more mold opening / closing mechanisms 21 and the number of rotary encoders 45 corresponding to each other, the detection value of any of the rotary encoders 45 may be used, or the average value of the detection values of a plurality of rotary encoders 45 may be used. You may. At this time, a sensor separately provided detects the mold opening movement positions p1 and p2 of the movable plate 20 with respect to the fixed plate 18 and the bed 23 and the mold opening movement positions p1 and p2 of the movable mold 19 with respect to the fixed mold 17. It may be.

Next, it is determined whether or not the number of cycles of fully automatic molding (automatic cycle) is the first (first cycle) (s7). Then, in the case of the first cycle (s7 = Y), since the value of the moving position of the movable plate at the time of the previous mold clamping release is not saved, "determined by calculating the tie bar target position t2 without the amount of mold position change". (S8). That is, when the fixed mold 17 and the movable mold 19 come into contact with each other in a state where the molding dies 17 and 19 are not thermally expanded, the half nut 32 satisfactorily fills the engaging groove 28a of the engaging portion of the tie bar 28. The tie bar target position t2 is calculated and determined by adding the measurement positions of the movable platen 20 at the time of the current mold clamping with the engaged position as the basic value. Here, the "tie bar target position t2" is included in the "position for mold closing control" and is a target position when the tie bar 28 is moved for the next engagement of the half nut 32. At this stage, the thermal expansion of the molding dies 17 and 19 is actually small as shown at the start of continuous molding (A) on the left side of FIG. That is, in FIG. 5A, the mold opening movement amount d1 due to the reaction force is determined from the mold opening movement position p1 of the movable platen 20 after the mold clamping pressure is released by the control device 37 to the mold clamping position of the movable plate 20 at the time of mold clamping. It is obtained by subtracting c1, but it is often negligibly small as a value.

In the case other than the first cycle (s7 = N), "determine by calculating the tie bar target position t2 in consideration of the amount of type position change in the previous cycle" (S9). That is, when the number of cycles of fully automatic molding (automatic cycle) is other than one, this time, the tie bar target position t1 corrected by the reaction force due to the thermal expansion of the molding dies 17 and 19 in the previous molding cycle is used as the basic value. The tie bar target position t2 is calculated and determined by adding the detection positions (mold opening movement positions) of the movable platen 20 when the mold clamping pressure is released (when the mold is released) in the molding cycle. As shown in (d) of FIG. 3 and (B) after a certain period of continuous molding on the right side of FIG. 5, when continuous molding is continued for a certain period of time and the amount of thermal expansion of the molding dies 17 and 19 increases. , The reaction force from the molding dies 17 and 19 at the time of mold clamping increases. Therefore, the value of the mold opening movement amount d2 due to the reaction force obtained by subtracting the mold clamping position c2 of the movable plate 20 at the time of mold clamping from the mold opening movement position p2 of the movable plate 20 after the mold clamping pressure is released by the control device 37. Is also getting bigger. Then, when the mold opening movement position p2 in which the movable platen 20 is moved by the reaction force of the molding dies 17 and 19 at the time of mold clamping and pressing is closer to the mold opening side than the previous time (or the mold opening of the movable platen 20 by the reaction force). When the mold opening movement amount d2 calculated from the movement position p2 is increased from the previous time), the tie bar target position t2 at the time of the next engagement of the half nut 32 is correspondingly as shown in FIG. 3 (d). , The correction amount r1 is changed from the tie bar target position t1 in the previous cycle.

In the case of (s8) and the case of (s9), the mold opening movement position p2 (position in the mold opening / closing direction of the movable platen 20) read by the rotary encoder 45, which is a sensor, is stored when the mold clamping is completed. (S10). Then, the adjusting cylinder 47, which is a tie bar position adjusting mechanism, is operated to move the tie bar 28 to the tie bar target position t2 (s11). In this state, between the contact surface 32b of the engagement tooth 32a of the half nut 32 and the contact surface 28b of the engagement groove 28a of the tie bar 28, the inclined surface 32c of the engaging tooth 32a and the inclined surface 28c of the engaging groove 28a. Appropriate gaps are formed between them. Next, the drive mechanism of the half nut 32 is operated to disengage the engaging teeth 32a of the half nut 32 from the engaging groove 28a of the tie bar 28 (s12). At this time, since a certain distance is provided between the contact surface 32b and the contact surface 28b, galling does not occur.

The tie bar 28 is moved to the tie bar target position t2 by the tie bar position adjusting mechanism from after the position detection of the movable platen 20 by the mold clamping pressure release to before the half nut 32 is engaged in the next molding cycle. For example, it may be performed at a different timing. That is, even when the contact surface 32b of the half nut 32 and the contact surface 28b of the tie bar 28 are in contact with each other when the mold is tightened and pressed, the spring mold is used and the contact surface 32b and the contact surface 28b are in contact with each other. Unless a load (pushing pressure) remains between them, galling does not occur on the contact surfaces 28b and 32b even if the half nut 32 is removed as it is. Further, when the mold clamping cylinder 27 is a recovery cylinder and a strong mold opening is performed using the mold clamping cylinder 27 at the time of mold release, the tie bar with the other inclined surface 32c (or the non-inclined contact surface) of the half nut 32. The other inclined surface 28c (or non-inclined contact surface) of 28 is abutted. In that case, the half nut 32 may be detached after the strong die is opened from the state where the inclined surfaces 28c and 32c are in contact with each other without moving the tie bar 28, and the tie bar 28 is moved to the tie bar target position t2. You may withdraw from.

Next, it is determined whether the number of cycles of fully automatic molding (automatic cycle) has completed the planned number of cycles (s13). Then, when the next cycle remains (s13 = N), the process proceeds to the next cycle. In the next cycle, the tie bar 28 is stopped at the tie bar target position t2 in which the reaction force due to the thermal expansion of the molding dies 17 and 19 is added. On the other hand, the stop position when the mold closing of the movable plate 20 is completed is also changed in consideration of the amount of thermal expansion of the molding dies 17 and 19, and the contact surface 32b and the contact surface 28b are optimally spaced from each other with respect to the tie bar target position t2. The inclined surface 32c and the inclined surface 32c are also stopped at a position having an optimum distance. As a result, in the present invention, the half nut 32 is engaged in response to the occurrence of thermal expansion of the molding dies 17 and 19 during continuous molding and the change in the reaction force generated from the molding dies 17 and 19 during the accompanying mold clamping. In that case, good molding can be continued without causing any trouble.

In addition to the above-described embodiment, the present invention may use a mold clamping device of another embodiment of the injection molding machine shown in FIGS. 6 and 7, or a control method of the mold clamping device. In the example of the mold clamping device 52 of the injection molding machine 51 of another embodiment shown in FIG. 6, the half nut 53 is fixed to the front portion of the piston 62 of the mold clamping cylinder 59. The portion where the half nut 53 is engaged is not the tie bar 54 but the engaging groove 58 of the engaging portion of the ram 57 fixed to the back surface 56 of the movable platen 55. The mold clamping device 52 of FIG. 6 detects the mold opening moving position p2 of the movable platen 55 or the movable mold 60 when the mold clamping pressure is released by the mold clamping cylinder 59, which is a mold clamping mechanism, or the mold opening moving position p2. The mold opening movement amount d2 is calculated from, and the position of the piston 62 of the mold clamping cylinder 59 (half nut), which is the position for mold closing control (engagement position for the half nut) by the next engagement of the half nut 61. Both the target stop position of the half nut 53 at the time of engagement) and the positions of the movable platen 55 and the ram 57 (the target stop position of the movable platen 55 at the time of half nut engagement) are corrected. In the embodiment of FIG. 6, the mold opening movement position p2 of the movable plate 55 or the movable mold 60 at the time of mold clamping and pressing is detected (or the mold opening movement amount d2 is calculated from the mold opening movement position p2). The control for correcting the position for mold closing control is only the correction of the target stop position of the half nut 53, and the stop positions of the movable platen 55 and the ram 57 are the positions of the mold closing completion that physically cannot move forward. May be good. Therefore, in the embodiment of FIG. 6, correction of the stop position at the time of mold closing of the movable platen and the ram, which is the position for mold closing control, is not indispensable.

Further, in the example of the mold clamping device 72 of the injection molding machine 71 of another embodiment shown in FIG. 7, the tie bar 74 is fixedly provided on the fixing plate 73. An engaging groove 75, which is an engaging portion, is provided on the outer periphery of the tie bar 74 near the tip. On the other hand, the half nut 76 is provided around the tie bar 74 on the back surface 79 of the board 78 on which the mold clamping cylinder 77 is provided. Further, the front surface of the ram 80 of the mold clamping cylinder 77 is fixed to the back surface of the movable platen 81. The movable board 81 is placed on the base 82 on the front side of the board 78. The position of the movable board 81 with respect to the board 78 is detected by the position detection sensor 83. Further, the board 78 on which the board 78 and the movable board 81 are placed can be moved in the mold opening / closing direction by the mold opening / closing mechanism 84.

In the mold clamping device 72 of such a mechanism, the mold opening movement position p2 of the movable platen 55 or the movable mold 86 at the time of mold clamping pressure release by the mold clamping cylinder 77, which is a mold clamping mechanism, is detected by the sensor 83. Further, the mold opening movement amount d2 is calculated from the mold opening movement position p2. Then, the forward amount (relative position of the half nut 76) of the ram 80 of the mold clamping cylinder 77, which is the position for mold closing control, is corrected by the next engagement of the half nut 76. As a result, even if there is thermal expansion of the molding die and an increase in the reaction force at the time of mold clamping of the molding die, the fixed die 85 and the movable plate 81 attached to the fixed plate 73 at the time of the next continuous molding. The position of the half nut 76 (the position of the engaging portion of the tie bar 74 relative to the engaging groove 75) when the movable mold 86 attached to the mold is brought into contact with the mold is maintained at a good position.

Further, the mold clamping device used in the present invention is provided with a mold opening / closing mechanism for opening and closing the movable mold with respect to the fixed mold, and a mold clamping mechanism for clamping the movable mold and the fixed mold. If it is a device, the present invention is not limited to the above. For example, a mold clamping cylinder may be provided near the four corners of the fixing plate, and a half nut may be attached to the piston of the mold clamping cylinder on the back side of the fixing plate. In that case, the tie bar is fixedly attached to the movable platen, and the tip end side of the tie bar is provided through the hole at the center of the piston of the mold clamping cylinder. Then, an engaging portion that is engaged with the half nut is provided in a portion near the tip of the tie bar. Also in the case of the above device, the mold opening movement position p2 of the movable platen or the movable mold at the time of releasing the mold clamping pressure is detected by a sensor such as a mold opening / closing mechanism, or the mold opening movement amount d2 is calculated from the mold opening movement position p2. , Correct the position of the piston for half nut engagement (half nut position) by the next half nut engagement, or the position of the piston and movable plate of the mold clamping cylinder for half nut engagement (of the tie bar). Position) Both positions are corrected. These positions correspond to the positions for mold closure control of the present invention.

Further, the mold clamping mechanism of the mold clamping device of the present invention may be operated by an electric motor. In that case, if a predetermined mold clamping force cannot be obtained only by the combination of the electric motor and the ball screw mechanism, a known force increasing means such as a toggle mechanism, a crank mechanism, and a wedge insertion mechanism may be used in combination. Further, the mold clamping device may be a vertical mold clamping device regardless of the type of the mold clamping mechanism or the mold opening / closing mechanism. Further, the half nut may not be used when shifting to the mold clamping by the mold clamping mechanism after the mold is closed by the mold opening / closing mechanism. As an example, a mold clamping device that performs mold clamping after fixing the movable plate with a friction lock mechanism after mold closing by a mold opening / closing mechanism, a mold clamping device that performs mold clamping with a mold clamping cylinder after mold closing by a mold opening / closing mechanism using a booster cylinder, and a toggle. Examples thereof include a mold clamping device that performs mold clamping with a mold clamping cylinder after mold closing by a mold opening / closing mechanism using a mechanism.

Further, in the present invention, the mold opening movement position p2 of the movable plate or the like at the end of depressurization at which the mold clamping force becomes completely zero is detected (or the mold opening movement amount d2 is calculated from the mold opening movement position p2). It is generally used for control corresponding to the thermal expansion of the mold. However, the time when the mold is released in the present invention includes a state in which the pressure is being released, and the mold of a movable plate or the like in a state where the pressure is lowered to a certain mold clamping force or a certain hydraulic oil pressure is lowered. The open movement position p2 may be detected (or the mold open movement amount d2 may be calculated from the mold open movement position p2) and used for correcting the position for mold closing control to cope with the thermal expansion of the molding die.

Although the present invention is not listed one by one, it is needless to say that the present invention is not limited to the above-described embodiment, and is also applicable to those skilled in the art modified based on the gist of the present invention. is there. The mold clamping device may be a die casting molding machine which is a kind of injection molding machine, or a mold clamping device such as a press device or a compression device which is not used in combination with the injection device.

11 Injection molding machine
12 Injection device 13 Mold tightening device 17 Fixed mold 18 Fixed plate 19 Movable mold 20 Movable plate 21 Type opening / closing mechanism 22 Mold tightening mechanism 27 Mold tightening cylinder 28 Tie bar 28a Engagement groove 28b Contact surface 32 Half nut 32a Engagement tooth 32b Contact surface 37 Control device 44 Servo motor 45 Rotary encoder (sensor)
47 Cylinder for adjustment (tie bar position adjustment mechanism)
c1, c2 Mold clamping position d1, d2 Mold opening movement amount due to reaction force p1, p2 Mold opening movement position due to reaction force t0, t1 Tieber target position (position for mold closing control)

Claims (4)

In a control method of a mold clamping device provided with a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold.
A control method for a mold clamping device, characterized in that the mold opening movement position of a movable platen or a movable mold at the time of mold clamping release by a mold clamping mechanism is detected and the position for mold closing control is corrected. In a control method of a mold clamping device provided with a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold.
A method for controlling a mold clamping device, which comprises detecting a mold opening moving position of a movable platen or a movable mold when mold clamping is released by a mold clamping mechanism, and correcting the position used for half nut engagement. 2. The position according to claim 2, wherein the position used for engaging the half nut is a stop position of the half nut or a stop position of the tie bar or the ram when the half nut is engaged with the engaging portion of the tie bar or the ram. How to control the mold clamping device. In a mold clamping device equipped with a mold opening / closing mechanism for opening and closing a movable mold with respect to a fixed mold, and a mold clamping mechanism for clamping a movable mold and a fixed mold.
A mold clamping mechanism that performs mold clamping and mold release, and
A sensor that detects the mold opening movement position of the movable platen or movable mold when the mold is released, and
A mold clamping device provided with a control device for correcting a position for mold closing control from a mold opening / moving position of a movable platen or a movable mold at the time of mold clamping release.

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