KR20020065339A - Mold-clamping apparatus and method of controlling operation of the apparatus - Google Patents

Abstract

In a hybrid-type mold-clamping device, an electric motor-type drive mechanism and a hydraulic cylinder device-type mechanism are used in combination to serve as a power source. Known devices are novel in manufacturing and simple in mechanism and excellent in energy efficiency, allowing for quick mold opening and closing operations and high-pressure mold-clamping operations. The pressure-generating cylinder device is driven by ball-screw mechanisms 18 and 48. The pressure-generating piston 34 of the pressure-generating cylinder device is integrally operated with the mechanical ram such that the movable platen 14 fixed to the mechanical ram 12 moves in the mold open and closed positions. In addition, the pressure-generating piston 34 has a fluid pressure generated in the pressure-generating cylinder 40 formed between the mechanical ram 12 and the pressure-generating piston 34. And relative to the mechanical ram 12 for delivery to The fluid pressure generated in the mold-clamping chamber 76 is applied to the mechanical ram 12 such that the mechanical ram 12 generates and moves the mold-clamping force.

Description

MOLD-CLAMPING APPARATUS AND METHOD OF CONTROLLING OPERATION OF THE APPARATUS

For example, a device for clamping a mold used in an injection molding machine, wherein the movable platen moves away from and toward the platen to open and close a mold partitioned between the movable platen and the stationary platen. And a direct-pressure type mold with a hydraulic cylinder-piston mechanism that generates driving force applied directly to the movable platen to press the movable platen onto the stationary platen to clamp the mold between the movable platen and the stationary platen. A toggle-type clamping device is known, which is equipped with a clamping device and a linking mechanism in which driving force is applied to the movable platen by the linking mechanism. Another type of mold-clamping device is also known, which includes a ball screw and an electric motor. In such a ball-screw type clamping device, the rotational driving force of the electric motor is converted into the repeating driving force by the ball-screw, thereby performing the mold opening and closing and the clamping action by using the driving force of this repetition.

In the act of opening and closing the mold, such a mold-clamping device is required to move the movable platen at a relatively high speed so as to reduce the cycle time of the injection molding machine forming operation. On the other hand, in the mold-clamping action, the mold-clamping device is required to apply a relatively large driving force to the movable platen such that the movable platen is pressed toward the stationary platen with a sufficiently large mold-clamping force, thereby achieving the injection molding. High accuracy is guaranteed. However, the mold-clamping apparatus using the conventional ball-screw has had difficulty satisfying these two needs.

The present inventor has presented in JP-U-3-3389 (Japanese Utility Model Application Publication No. 3-3389) a mold-clamping device equipped with a hydraulic cylinder-piston mechanism as well as an electric motor and a ball-screw. This mold-clamping device further comprises an air container to collect the pressurized fluid, and the movable platen is moved by using a ball-screw to open and close the mold and by using the ball-screw to open and close the mold. It is installed to use the pressurized fluid accumulated in the air container during closing and to press against the fixing plate therebetween to clamp the mold by means of a hydraulic cylinder-piston mechanism. Such a mold-clamping device can satisfy two of the above needs. That is, the presented mold-clamping device allows the opening and closing operation of the mold at a relatively high speed by using a combination of electric motors and a small ball-screw, and the relatively large mold-clamping force easily by using a hydraulic cylinder-piston mechanism. To ensure its creation.

However, the presented mold-clamping device uses pressurized fluid which is collected in the air container in advance and then applied to the cylinder chamber of the cylinder-piston mechanism by means of a suitable switch valve. This requires switching operation of the switch valve under a given hydraulic pressure generated by the pressurized fluid, and requires a relatively large driving force and a relatively large switch valve to drive the large switch valve, thus consuming the switching operation of the switch valve. Causes time to become. In addition, the presented mold-clamping device has a problem of pressure loss of pressurized fluid while collecting in an air container. Thus, the presented mold-clamping device lacks the necessary properties.

It is therefore an object of the present invention to ensure the reciprocating motion of the movable platen at a relatively high speed, and to easily produce a relatively large mold-clamping force using a hydraulic device, the desired driving force easily by the electric motor and the ball-screw. And an improved mold-clamping device that easily produces Another object of the present invention is to provide a suitable method for controlling the operation of such a mold-clamping device.

The present invention generally relates to a mold clamping of an injection molding machine comprising a drive device having a ball-screw driven by an electric motor, with the movable platen reciprocating away from and towards the platen, thereby closing and opening the mold. Relates to a device. More specifically, the present invention relates to a mold-clamping device with a novel structure, in which a hydraulic cylinder-piston mechanism is used to obtain an effective method for controlling the operation of the mold-clamping device and to obtain increased mold-clamping force.

1 is a partial view in longitudinal section of a mold-clamping apparatus shown in accordance with one preferred embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a hydraulic device used in the mold-clamping device of FIG. 1. FIG.

3 is a flow chart showing a control program as the engagement position of the mold-clamping ram and the mold opening and closing cylinders are adjusted.

4 is a schematic diagram illustrating an embodiment of a particular operation of the mold-clamping device to adjust the engagement position of the mold-clamping ram and the mold opening and closing cylinders, in accordance with the method of the present invention.

5 is a graph illustrating a method of controlling mold-clamping pressure in accordance with the present invention.

6 is a graph illustrating a method of controlling the output torque of a servomotor according to the present invention based on the execution of the mold-clamping mold-clamping pressure-reducing operation of FIG.

7 is a time chart of the mold-clamping pressure-reducing operation of FIG. 6.

8 is a time chart of another embodiment of a mold-clamping pressure-reducing operation of the mold-clamping apparatus of FIG. 1 controlled based on the rotational speed of an electric servomer in accordance with the present invention.

9 is a partial cross-sectional plan view of the mold-clamping apparatus shown in accordance with a second preferred embodiment of the present invention.

10 is an enlarged fragmentary view of the mold-clamping device of FIG. 9.

The above object can be achieved according to the following manner of the present invention. The invention may be practiced in any possible combination of this manner of the invention. The present invention is not intended to be limited to the technical features described below and the following manners of the invention, but is understood by those of ordinary skill in the art in view of the disclosure of the specification and drawings or based on the spirit of the invention disclosed in the specification and drawings. Will be understood.

The first method of the present invention provides a mold-clamping device of an injection-molding machine for clamping a mold, wherein the mold-clamping device: (a) is fixedly fixed to the base of the injection-molding machine so as to face each other therebetween. Losing fixed platen and aft platen; (b) a movable platen placed between the stationary platen and the trailing platen such that the stationary and trailing platens operate between the stationary platen and the trailing platen in opposite directions; (c) a drive mechanism disposed between the rear platen and the movable platen and having an electric motor operable to move the movable platen away from and toward the platen; (d) a first ball-screw shaft supported by one of the movable platen and the rear platen, a first screw-coupled with the first ball-screw shaft and supported by the other of the movable platen and the rear platen A ball-nut, and a mold-driven electric motor adapted to rotate the first ball-screw shaft and nut relative to each other to produce a relative longitudinal motion of the first ball-screw shaft and nut, the first ball-screw A mold opening and closing mechanism adapted to open and close the mold based on the relative longitudinal motion of the shaft and nut; (e) a pressure-generating cylinder device positioned and operable on the side of the rear platen to produce hydraulic pressure based on the relative longitudinal motion of the first ball-screw shaft and nut; (f) a mold-clamping cylinder device having a mold-clamping ram connectable to the movable platen, which is placed on the side of the rear platen and applied to the generated hydraulic pressure in the pressure-generating cylinder device; And (g) the mold is closed and operable to engage the movable platen and the mold-clamping ram, such that the mold produced by the mold-clamping cylinder device based on the relative longitudinal motion of the first ball-screw shaft and the nut- And a coupling device for applying the clamping force to the movable platen.

In the mold-clamping apparatus shown in accordance with the first method of the present invention, the mold opening and closing operation is such that a ball-screw type mold opening and closing mechanism reciprocates the movable platen between the mold opening position and the mold-closing position. To be used for the purpose of doing so. That is, the first ball-screw shaft and the first ball-nut are rotated relative to each other by a mold-driven electric motor to produce relative longitudinal motion. The movable platen is intended to be directly moved by the longitudinal movement of the ball-screw shaft and nut away from the stationary platen and in the direction towards the stationary platen to open and close the mold. Moreover, the mold-clamping operation and the hydraulic pressure-reducing operation can be carried out using a pressure-generating and mold-clamping cylinder device, as well as a mold opening and closing mechanism. That is, the first ball-screw shaft and the ball-nut of the mold opening and closing mechanism are first ball-screw shaft based on a hydraulic-generating cylinder device which is operated by the mold-driven electric motor to rotate against each other to generate hydraulic pressure. And longitudinal motion of the nut. The hydraulic pressure generated in such a hydraulic-generating cylinder device is applied to the mold-clamping cylinder device to operate the mold-clamping cylinder device to produce an increased hydraulic pressure. This increased hydraulic pressure is applied to the movable platen to pressurize the stationary platen with the increased hydraulic pressure to which the movable platen is applied, clamping the mold between the movable platen and the stationary platen.

Thus, in the illustrated mold-clamping device, only the electric motor is used as the power source. The power of the electric motor is applied directly to the movable platen by a ball-screw device consisting of a ball-screw shaft and a nut, so that the mold is opened and opened. This results in a direct power transfer system for closed operation. The power of the electric motor is also transmitted to the movable platen by a hydraulic system comprising a hydraulic-generating and mold-clamping cylinder device to form a hydraulic power transmission system for mold-clamping operation. In particular, the mold-clamping force applied to the movable platen in the mold-clamping operation is not directly obtained by the driving force generated by the ball-screw device, but is obtained by converting the driving force generated by the ball-screw device into liquid pressure. Lose.

Thus, the mold-clamping device of the inventive method does not require a large-size or powerful ball-screw device even in the case where a relatively large mold-clamping force is required. Thus, the mold-clamping device can satisfy the need for rapid mold opening and closing operation by a ball-screw device and to ensure a sufficiently large mold-clamping force by a small ball-screw device.

In the mold-clamping operation, the mold-clamping device is operated so that the hydraulic-generating cylinder device is operated by a ball-screw device to generate the liquid pressure. The liquid pressure generated in the pressure-generating cylinder device is quickly applied to the mold-clamping cylinder device to produce an increased liquid pressure applied to the movable platen with the mold-clamping force. Since the mold-clamping force is applied directly to the movable platen and is produced by the manufactured hydraulic system, without being stored in a suitable air container, the mold-clamping device according to the first aspect of the present invention is a mold-clamping force. The pressure loss of the working fluid can be minimized compared to the mold-clamping device which is easy to control and which uses an air container.

When the mold-clamping device changes the operation of the device from the mold opening and closing operation to the mold-clamping operation, and vice versa, the hydraulic circuit can be changed between the hydraulic-generating cylinder device and the mold-clamping cylinder device. Can be. In this case, the hydraulic circuit can be changed under the relatively low hydraulic pressure applied thereto to allow easy and quick change of the hydraulic circuit. Thus, the mold-clamping apparatus shown according to the first scheme of the present invention ensures smooth movement from the mold opening and closing operation to the mold-clamping operation and vice versa.

Furthermore, for example, the mold-clamping device shown according to the first method of the present invention is easy to detect the liquid pressure in the pressure-generating cylinder device and the mold-clamping cylinder device with a pressure sensor having a suitable mold-clamping force. It has the advantage that it can be correctly approved.

The second form of the invention further comprises a pressurization device adapted to pressurize the pressure-generating piston towards the fully retracted position to increase the volume of the pressure-generating chamber of the pressure-generating cylinder device. -Clamping device. The provision of a pressurization device allows easy determination of the initial positioning of the pressure-generating piston, which easily and accurately controls the operation of the pressure-generating cylinder device. In this respect, the pressing device can be arranged to have the necessary pressing force that resists the driving force of the ball-screw type mold opening and closing mechanism applied to the pressing device during the mold-closing operation. In this arrangement, the pressurizing device prevents the transmission of the driving force or power of the mold-driven electric motor to the pressure-generating cylinder device during the mold-closing operation in order to suppress the operation of the pressure-generating cylinder device, and the pressing force of the pressurizing device. The driving force of the larger mold opening and closing mechanism can act on the basis of its pressing force to allow operation of the pressure-generating cylinder device after completion of the mold-closing operation applied to the pressure-generating piston.

In the third method of the present invention having a mold-clamping device according to the first or second method of the present invention, the pressure-generating cylinder device is adapted to prevent movement of the pressure-generating piston relative to the pressure-generating cylinder. And a lock operable to fixedly connect the pressure-generating piston to the pressure-generating cylinder of the pressure-generating cylinder device. In this manner of the mold-clamping device, the pressure-generating piston of the pressure-generating cylinder device can be kept fixed at a predetermined initial position by a locking device which is easy to control the mold opening and closing positions of the movable-platen. have. Since the movement of the pressure-generating cylinder device can be fixedly suppressed by the locking device during the mold-closing operation, the mold-closing operation opens the mold without the adverse effect of the unexpected operation of the pressure-generating piston during the rapid mold-closing operation. And by a closing mechanism. It will be appreciated that the locking device is releasable in the mold-clamping operation so that the mold-clamping device can move smoothly in its mode of operation from the mold-closing operation to the mold-clamping operation.

According to any one of the first to third methods of the present invention, the fourth method of the present invention, which includes a mold-clamping device, includes a pressure-generating chamber of a pressure-generating cylinder device and a mold-clamping of a mold-clamping cylinder device. And a hydraulic system having a hydraulic circuit for fluid transport between the chambers and a switch valve for selectively connecting and disconnecting the pressure-generating chamber from and towards the mold-clamping chamber. In this manner of the invention, the mold-closing operation or the mold-clamping of the mold-clamping device is controlled by controlling the switching operation of the switch valve to allow and suppress fluid transfer between the pressure-generating and the mold-clamping chambers. Can be. For example, the switch valve is closed so that the pressure-generating cylinder device is closed to inhibit fluid transfer between the pressure-generating and mold-clamping chambers in a failed mold-closing operation to stabilize the mold-closing operation.

In a fifth aspect of the invention comprising a mold-clamping device according to any one of the first to fourth aspects of the invention, the pressure-generating piston is a hollow cylindrical member and the pressure-generating chamber is a hollow pressure-generating piston. Partially partitioned by the outer circumferential surface of the first ball-screw shaft is positioned extending through the bore of the hollow pressure-generating piston, and the first ball-nut is secured to the hollow pressure-generating piston. In this way, the pressure-generating piston uses a hollow space in the bore of the hollow cylindrical pressure-generating piston that leads to a reduction in the size of the mold-clamping device, thereby allowing the effective arrangement of the first ball-screw shaft and the nut. It is a cylindrical member.

In a sixth aspect of the present invention comprising a mold-clamping device according to any one of the first to fifth methods of the present invention, the mold-clamping cylinder device has a central axis of the mold-clamping cylinder device of the movable platen. Placed in alignment with the central axis, and the mold-clamping ram comprises a hollow cylindrical member, the mold-clamping device comprising: a mechanical ram fixed to the movable platen and extending through the bore of the hollow mold-clamping ram, The coupling device is operable to engage the mechanical ram to hold the hollow mold-clamping ram. In this way, the mold-clamping force generated by the mold-clamping cylinder device can be applied to the central portion of the movable platen, which is undesirable even when only one mold-clamping cylinder device is used. Effectively prevent bad posture. Thus, the mold-clamping device in this manner ensures a stable posture of the movable platen during the mold-clamping operation.

In a seventh aspect of the present invention having a mold-clamping device according to the sixth aspect of the present invention, the coupling device includes a plurality of couplings formed on the outer circumferential surface of the mechanical ram so as to be spaced apart from each other at regular intervals in the axial direction of the mechanical ram. The first engageable protrusion and the engaging member are not actuated in the axial direction of the mechanical ram, and the mechanical ram to engage and disengage the second engageable protrusion from the first engageable protrusion and with the first engageable protrusion. And a joining member having a plurality of second joinable protrusions operative away from and towards the outer circumferential surface of the support and supported by the mold-clamping ram. In this manner of the present invention, the engagement position of the second engageable protrusion relative to the first engageable protrusion can be selectively changed in the axial direction of the mechanical ram, that is, in the direction of the reciprocating motion of the movable platen. This means that the mold-clamping device uses various types of molds with different thicknesses. For example, the first engageable protrusion may extend in the circumferential direction of the mechanical ram.

The eighth aspect of the present invention further comprises a positioning electric motor having a mold-clamping device according to the seventh aspect of the present invention and adapted to move the engaging member with respect to the mechanical ram in the axial direction of the mechanical ram. The second engageable protrusion of the member is suitably positioned to engage the first engageable protrusion of the mechanical ram. This alignment facilitates positioning of the first and second engageable projections relative to each other in the axial direction of the mechanical ram in the direction in which the movable platen is reciprocated. Preferably, the positioning electric motor can be a servomotor, wherein the first engageable protrusion and the second engageable protrusion are positioned relative to each other with high accuracy.

In the ninth method of the present invention having the mold-clamping device according to the seventh to eighth methods of the present invention, the hollow mold-clamping ram of the mold-clamping cylinder device is a mold between the rear platen and the movable platen. -During application of the clamping force an operable stroke made greater than the sum of the increase in the axial distance between the rear platen and the movable platen and the pitch of the first engageable projection. In this way, the required stroke length of the mold-clamping ram is between the rear platen and the movable platen caused by the case of the mold-clamping force which facilitates positioning of the first and second engageable projections relative to each other. It is obtained by considering the amount of increase in the axial distance of.

In a tenth aspect of the present invention having a mold-clamping device according to any one of the sixth to ninth aspects of the present invention, the mechanical ram comprises a hollow cylindrical member, and the mold-clamping device comprises a movable platen. The ejector fixed to the tongue, a second ball-screw shaft positioned in the bore of the hollow mechanical ram and fixed to the ejector, a screw-coupled with the second ball-screw shaft and the other mechanical ram and A ball-screw type electrically-operated ejector device having a second ball-nut secured to the ejector; And an ejecting electric motor adapted to rotate the second ball-screw shaft and the nut relative to each other to generate the relative longitudinal motion of the second ball-screw shaft and the nut to drive the ejector. In this way, the ejector device is supplied with electricity. Moreover, the ejector device can be installed in the bore of the mechanical ram with improved space usage resulting in a compact, electrically operated ejector device. Furthermore, the second ball-screw shaft and nut adapted to apply the driving force to the ejector may be placed such that the center axis of the second ball-screw shaft is aligned with the center axis of the movable platen. This arrangement is effective in preventing the undesired tilting of the ejector due to, for example, unstable driving force on the ejector, which causes the ejector to operate and to stabilize during ejection operation.

In an eleventh aspect of the present invention having a mold-clamping device according to the tenth aspect of the present invention, the ejecting electric motor is placed fixedly in the bore of the hollow mechanical ram, and the hollow mechanical ram is placed in the axial direction. It has an air flow passage extending through it. In this way, the internal space of the bore of the mechanical ram is effectively used so that the ejecting electric motor is placed in the bore of the mechanical ram. In this case, the electric motor can extend along the axial direction of the mechanical ram, causing an increase in the power of the ejecting electric motor without increasing the size of the mold-clamping device. In addition, the air passages allow ventilation of the internal space of the bore of the mechanical ram according to the axial reciprocating motion of the mechanical ram, effectively eliminating the problem of heat generated by the ejector electric motor.

In the twelfth aspect of the present invention, wherein the pressure-generating cylinder apparatus includes a mold-clamping apparatus according to any one of the first to eleventh aspects of the present invention, the pressure-generating cylinder apparatus includes a plurality of pressure-positions about the central axis of the movable platen. Produce cylinder device. In this way, the use of a plurality of pressure-generating cylinder devices is effective in miniaturization of each pressure-generating cylinder device, leading to an overall size reduction of the mold-clamping device.

In a thirteenth aspect of the present invention having a mold-clamping device according to the twelfth aspect of the present invention, each of the plurality of pressure-generating cylinder devices comprises: a pressure-generating piston in the form of a hollow cylinder; A pressure-generating chamber partially defined by the outer circumferential surface of the hollow pressure-generating piston; A first ball-screw shaft positioned to extend through the bore of the hollow pressure-generating piston; A first ball-nut fixed to the hollow pressure-generating piston; And a mold drive electric motor which is fixedly supported by the movable platen and adapted to rotate the first ball-screw shaft and the nut relative to each other. In this way, the mold-driven electric motor is supported by the movable platen so that the overall length of the mold-clamping device is effectively reduced. Furthermore, the plurality of first ball-screw shafts and nuts are placed about the central axis of the movable platen, so as to ensure the driving force in a stable case to the movable platen by means of the plurality of first ball-screw shafts, Resulting in improved stability of mold opening and closing operations.

In a fourteenth aspect of the invention comprising a mold-clamping device according to any one of the sixth to ninth aspects of the invention, the mechanical ram comprises a hollow mechanical ram and the first ball-screw shaft is hollow It extends through the bore of the mechanical ram. In this way, the first ball-screw shaft can be arranged into the bore of the mechanical ram with high space utilization. In addition, the first ball-screw shaft may be arranged such that the axis of the first ball-screw shaft is aligned with the central axis of the movable platen. Thus, the driving force generated by the one mold opening and closing mechanism is fixedly applied to the movable platen by the first ball-screw shaft.

In a fifteenth aspect of the present invention having a mold-clamping device according to the fourteenth aspect of the present invention, the first ball-screw shaft is axially supported by the base of the injection-molding machine with the fixing platen being fixedly supported. While not being moved and the first ball-nut is secured to the pressure-generating piston, the pressure-generating piston slides in the bore of the mechanical ram to form a pressure-generating cylinder arrangement. In this way, improved space usage effectively places in the bore of the mechanical ram so that the first ball-nut effectively reduces the axial length of the mold-clamping device.

In a sixteenth aspect of the invention, provided with a mold-clamping apparatus in accordance with the first aspect of the invention, the apparatus is: (α) supported by the base of the injection molding machine so as to be rotatable about one axis and not move in the axial direction. A first ball-screw shaft of the mold opening and closing mechanism; (β) a mold-driven electric motor adapted to rotate the first ball-screw shaft in the forward and backward directions; (γ) Hollow, fixed to the opposing end in one axial direction on the movable platen and placed radially outward on the first ball-screw shaft, axially movable relative to the base of the injection-molding machine and not rotating about the axis Mechanical ram; (δ) a sliding reciprocating motion in the axial direction of the mechanical ram is possible and placed radially inside the mechanical ram so as not to rotate about the axis of the mechanical ram, and reduced by movement toward the opposite end in one axial direction of the mechanical ram; A pressure-generating piston interacting with the mechanical ram to define a pressure-generating chamber between the volumes and interacting with the pressure-generating chamber to form a pressure-generating cylinder arrangement; (ε) a pressurization device adapted to pressurize the pressure-generating piston of the pressure-generating cylinder device against the mechanical ram such that the pressure-generating piston is pressed toward one axis end of the pressure-generating cylinder away from the movable platen; (ζ) a mold which is screwed with the first ball-screw shaft and fixed in the pressure-generating position of the pressure-generating cylinder device to rotate relative to each other with the first ball-screw shaft to reciprocate the pressure-generating piston. First ball-screw nuts of the opening and closing mechanisms; (η) a mold-clamping cylinder placed radially outward of the mechanical ram and fixedly supported by the base of the injection-molding machine; (θ) a mold-clamping which lies radially inside the mold-clamping cylinder and radially outside of the mechanical ram to slide in the axial direction of the mold-clamping cylinder and interacts with the mold-clamping cylinder to partition between the mold-clamping chambers. Mold-clamping rams of the cylinder device; (ι) a positioning electric motor adapted to move the mold-clamping ram relative to the mold-clamping ram in order to position the mold-clamping ram relative to the mold-clamping cylinder in the axial direction of the mold-clamping cylinder; (κ) Equipped with a hydraulic circuit for fluid transport between the pressure-generating chamber of the pressure-generating cylinder device and the mold-clamping chamber of the mold-clamping cylinder device, and applying hydraulic pressure to the mold-clamping ram with hydraulic driving force; Hydraulic pressure generated in the pressure-generating chamber by the relative longitudinal movement of the first ball-screw shaft and the nut in accordance with the rotation of the first ball-screw shaft delivered to the mold-clamping chamber to create hydraulic pressure in the mold-clamping ram. Hydraulic system to allow; (λ) The mold-clamping ram is placed between the mold-clamping ram of the mold-clamping cylinder device and the mechanical ram, and applies the hydraulic drive force applied to the mechanical ram with the mold-clamping force to the mold-clamping ram of the mold-clamping cylinder device. And a coupling device operable to couple the mechanical rams with each other. As in the fourteenth and fifteenth embodiments of the present invention, this method uses an elastic ball-screw type with simple structure by using one mold opening and closing mechanism, one pressure-generating cylinder device and one mold-clamping cylinder device. It is effective to achieve the mold clamping mechanism.

In this manner of the invention, the hydraulic cylinder chamber is preferably partitioned between the outer circumferential surface of the hydraulic-generating piston and the inner circumferential surface of the mechanical ram such that the hydraulic cylinder chamber has a cylindrical configuration. For example, this arrangement allows the formation of a hydraulic chamber with good space usage and effectively provides a space for disposing the pressurization device between the mechanical ram and the pressure-generating piston.

The seventeenth manner of the present invention comprises a mold-clamping device according to the first manner of the present invention, and (i) is fixed to the rear platen and extends parallel to the central axis of the movable platen of the central axis of the movable platen. A plurality of pressure-generating pistons each having a hollow cylindrical shape that is slidably placed within the plurality of pressure-generating cylinders, and a plurality of pressure-generating pistons individually A plurality of pressure-generating cylinder devices comprising a pressure-generating chamber partially defined by an outer circumferential surface and having a volume reduced by sliding of the corresponding pressure-generating piston in a direction away from the movable platen; (ν) free from axial movement on the movable platen, disposed about the central axis of the movable platen and extending through the bore of each hollow pressure-generating piston, extending parallel to the central axis of the movable platen. A plurality of fixed first ball-screw shafts; (ξ) a plurality of mold-driven electric motors disposed on the movable platen and adapted to rotate the ball-screw shaft about their axes in the forward and backward directions; (ο) a plurality of first ball-nuts screw-coupled with the plurality of first ball-screws and secured to the plurality of pressure-generating pistons; (π) a plurality of pressurization devices adapted to pressurize the pressure-generating piston of the pressure-generating cylinder device toward the movable platen in the axial direction; (ρ) Mold-clamping cylinders fixedly fixed to the rear platen such that the center axis of the mold-clamping cylinder is aligned with the center axis of the movable platen, and the mold-clamping having a hollow cylindrical shape that slides in the mold-clamping cylinder. A mold comprising a ram, and a mold-clamping chamber having a volume partially defined by the outer circumferential surface of the mold-clamping ram and reduced by sliding motion of the mold-clamping ram in a direction away from the movable platen. Clamping cylinder device; (σ) is operated to inhibit fluid transport to the pressure-generating chamber to securely position the pressure-generating piston relative to the pressure-generating cylinder, such that the movable platen is secured with the pressure-generating cylinder to open and close the mold. And actuated to allow fluid transfer between the pressure-generating chamber and the mold-clamping chamber for sliding movement of the pressure-generating piston during movement by rotation of the first ball-screw shaft about the rear platen. A hydraulic device, wherein the hydraulic pressure generated in the pressure-generating chamber by rotation of the screw shaft is applied to the mold-clamping chamber of the mold-clamping cylinder device to apply a hydraulic driving force to the mold-clamping ram; (τ) a mechanical ram fixedly placed on the movable platen to protrude toward the rear platen along the center axis of the movable platen and extending through the bore of the mold-clamping ram of the mold-clamping cylinder device; (υ) The mold-clamping ram is placed between the mold-clamping ram of the mold-clamping cylinder device and the mechanical ram, and the mold-clamping force is applied to the mechanical ram with the mold-clamping force to apply the hydraulic driving force of the mold-clamping ram of the mold-clamping cylinder device. A coupling device operative to couple the ram and the mechanical ram together; (φ) ejector plate fixed to the movable plate, a second ball-screw shaft positioned in the bore of the hollow mechanical ram and fixed to one mechanical ram and the ejector, screw-coupled with the second ball-screw shaft and the other A second ball-nut fixed to one mechanical ram and ejector, and adapted to rotate the second ball-screw shaft and nut to each other to generate the relative longitudinal motion of the second ball-screw shaft and nut to drive the ejector And a ball-screw type electrically operated ejector device comprising an ejecting electric motor. As in the twelfth and thirteenth aspects of the present invention, in this manner, the plurality of pressure-generating cylinder devices are movable such that the mold-clamping device of this manner allows for a well balanced drive of the movable platen with high stability. It lies against the central axis of the platen.

The eighteenth manner of the present invention includes a method of controlling operation of a mold-clamping apparatus formed according to any one of the first to seventeenth aspects of the present invention, wherein the mold-clamping ram and the movable platen are mutually A plurality of first joinable protrusions formed on the mold-clamping ram and the movable platen, and a plurality of second joinables engageable with the first joinable protrusions so as to be spaced apart from each other at regular intervals in the direction of movement relative thereto. And further comprising a coupling member having a protrusion and formed on the mold-clamping ram and the other of the movable platen and moved away from and towards the first engageable member, the method comprising: (i) a fixed mold used The movable platen is fixed with the sample mold with a thickness smaller than the thickness of the tool and the movable mold half is fixed. The movable platen placed at the reference position of the movable platen and the mold-closed position obtained at the reference position of the movable platen to be moved to the mold-closed position held in contact with each other to clamp the sample mold between the ratchet and the movable platen. Determining an axial position of;

(Ii) with the movable platen in the reference position, the axial position of the mold-clamping ram relative to the mold-clamping cylinder is adjusted to ensure engagement of the first and second engageable projections. Determining a reference position of the mold-clamping ram, and an adjusted axis position of the mold-clamping ram obtained as the reference position of the mold-clamping ram; And

(Iii) on the basis of the determined reference position of the mold-clamping ram, the axial position of the mold-clamping ram against the mold-clamping cylinder in the axial direction, and the movable platen fixed with the mold used, to be maintained at the mold-closed position. And adjusting the determined reference position of the movable platen to ensure engagement of the first and second engageable projections. This arrangement allows the mold-clamping ram and movable platen to be engaged immediately after the movable platen is moved to the mold-closed position by the linear driving force of the ball-screw type mold opening and closing mechanism, regardless of the thickness of any mold. Allows the device to be quickly and securely coupled to each other by means of the device. This arrangement effectively stabilizes the injection-molding operation using the mold-clamping apparatus, and allows to effectively shorten the cycle time of the injection molding operation using the mold-clamping apparatus.

When a reference position of the mold-clamping ram and the movable platen based on the sample mold is obtained, the sample mold can be actually fixed to the movable platen and the stationary platen such that this reference position is actually measured. Optionally, the reference position can be obtained by calculation using a sample mold virtually fixed to the movable and stationary platen.

The nineteenth aspect of the present invention comprises a method of controlling operation of a mold-clamping device according to the eighteenth aspect of the present invention, wherein the first and second engageable protrusions are provided between the rear platen and the movable platen. Depending on the application of the mold-clamping force, the mold is retracted from the full entry position of the mold-clamping ram at least by an axial distance corresponding to the increased axial distance between the trailing platen and the movable platen, and the mold used when the mold used is fixed. Adjusting the axial position of the mold-clamping ram relative to the mold-clamping cylinder in the axial direction such that they engage with each other at the engagement portion closest to the mold-closed position of the clamping ram. Depending on the method of controlling the operation of the mold-clamping device, an increase in the stroke length of the mold-clamping ram according to the application of the mold-clamping force is taken into account, resulting in a high stability of the mold-clamping operation of the mold-clamping device.

The twentieth manner of the present invention comprises a method of controlling operation of the mold-clamping apparatus according to the eighteenth or nineteenth aspect of the present invention, the steps of: calculating the mold-thickness difference between the sample mold and the used mold. Making; Obtaining a mold-closed position of the mold-clamping ram when the movable platen is fixed with a used mold based on the reference position of the movable platen and the mold-thickness difference; Obtaining a distance between the obtained mold-closed position and the reference position of the mold-clamping ram of the mold-clamping cylinder device; And the axial position of the mold-clamping ram relative to the mold-clamping cylinder of the mold-clamping cylinder device required to ensure the engagement of the first and second joinable protrusions, based on the pitch and the distance obtained of the first joinable protrusion. It includes; obtaining an adjustment amount of. According to this control method of the mold-clamping device operation, the operating amount of the mold-clamping cylinder device required after completion of the mold-closing operation to ensure the first and second engageable protrusion engagement is obtained quickly and effectively.

The twenty-first aspect of the present invention has a method of control operation of a mold-clamping apparatus defined in accordance with any one of the first to seventeenth aspects of the present invention, and the mold-driven for driving the first ball-screw shaft. The electric motor comprises an electric servomotor, the steps comprising: controlling the output torque of the electric servomotor during mold-clamping operation based on a sensing signal indicative of the hydraulic pressure in the pressure-generating chamber of the pressure-generating cylinder device. Include. In this way, an electric servomotor is used as a mold-driven electric motor to ensure improved control accuracy for positioning the mold (moving platen). Thus, for example, when the mold-clamping device is operated against the detection of an entirely different member between the movable and stationary platens to protect the mold, the preferred method of the present invention is controlled by the very accurate movement of the movable platen. It is possible to do it. For example, the output torque of the electric servomotor can be controlled based on the liquid pressure in the mold-clamping chamber applied with the mold-clamping force on the movable platen, thereby controlling the mold-clamping force with high-accuracy and high-reliability. Allow.

The twenty-second aspect of the present invention has a method of control operation of a mold-clamping device defined according to any one of the first to seventeenth aspects of the present invention, and the mold-driven for driving the first ball-screw shaft. The electric motor comprises an electric servomotor, the step of which is: reducing the hydraulic pressure in the mold-clamping chamber by gradually decreasing the value of the output torque of the electric servomotor to a predetermined value so that the hydraulic pressure is reduced in the mold-clamping chamber. It includes; step. In this way, the electric servomotor is used as a mold-driven electric motor, and the output torque of the electric servomotor is effectively and steadily and easily gradually increasing the magnitude of the impact generated when the mold-clamping force is reduced in the mold-clamping force reducing operation. Controlled to reduce.

The twenty-third aspect of the present invention has a method of controlling operation of a mold-clamping device defined according to any one of the first to seventeenth aspects of the present invention, and the mold-driven for driving the first ball-screw shaft. The electric motor comprises an electric servomotor, the step of which: a predetermined period of time is required to pass through the mold-clamping chamber to reduce the pressure, and the pressure in the mold-clamping chamber is reduced by a predetermined level. Reducing the hydraulic pressure in the mold-clamping chamber by gradually or continuously changing the rotational speed of the electric servomotor in one direction to produce a decrease in the hydraulic pressure in the mold-clamping chamber until at least one condition is detected. It includes; In this manner, the rotational speed of the servomotor is controlled to effectively and stably reduce the magnitude of the impact generated when the mold-clamping force is reduced in the mold-clamping force reduction operation. In particular, since the electric servomotor is controlled based on its rotational speed, the mold-clamping force can be continuously reduced in the mold-clamping force reduction operation.

In the twenty-fourth aspect of the present invention, comprising the method of controlling operation of the mold-clamping apparatus according to any one of the twenty-first to twenty-third aspects of the present invention, the apparatus is the second, sixth and It is formed in any one of 17 ways, the step comprising: controlling the output torque of the electric servomotor taking into account the force generated in the pressure-generating piston relative to the pressing force of the applied pressurization device. In this way, the electric servomotor is controlled to take into account the pressing force of the pressing device, allowing high-precision control of the mold-clamping force while ensuring excellent positioning effect of the pressing device.

The invention will be better understood by reference to the following detailed description of the preferred embodiments of the invention when referring to the accompanying drawings.

Referring first to FIG. 1, there is schematically shown a mold-clamping apparatus used in an injection-molding machine shown in accordance with a first embodiment of the invention. The mold-clamping device is supported by the base 10 of the injection molding machine and is a mold open and closed cylinder 12 as a mechanical ram that extends in the horizontal direction during axial movement, and one of the mold open and closed cylinders 12. A movable platen 14 fixed to the opposite axis end. The mold opening and closing cylinder 12 reciprocates in its axial direction such that the movable platen 14 reciprocates away from and toward the platen from a stationary platen (not shown) placed opposite the movable platen. As is known in the art, the movable platen 14 is supported by a plurality of support rods (not shown) so that the movable platen 14 moves away from and toward the platen along the support rods. Consistent with the direction of movement of the movable platen 14 thereafter, the left side of FIG. 1 will be referred to as the "retraction side" while the right side of FIG. 1 will be referred to as the "entry side".

More specifically, the mold-clamping apparatus of this embodiment includes a bracket 16 placed on the base 10 and a first ball-screw shaft 18 extending in an axial direction parallel to the horizontal direction. The first ball-screw shaft 18 is supported by a bearing 19 on one axial facing end (left end shown in FIG. 1) with the bracket 16 and is not rotated axially. The screw shaft 18 is rotatable about its axis. The first ball-screw shaft 18 protrudes to one axial facing side of the bracket 16 (shown to the right in FIG. 1) at a sufficiently large axial length, and is supported of the first ball-screw shaft 18. The bottom end slightly protrudes from the bracket 16. The protruding bottom end of the first ball-screw shaft 18 is fixed with the toothed pulley 20. As a mold-driven electric motor, the first servomotor 22 is fixed to the bracket 16 and the output shaft of the first servomotor 22 is fixed to the toothed pulley 24. These toothed pulleys 20, 24 are mechanically connected to each other by toothed belts 25 wound around the outer circumferential surface of the pulleys 20, 24 such that the rotation of the first ball-screw shaft 18 is pulley 20. , 24, and by the rotation of the first servomotor 22 transmitted through the toothed belt 25.

The mold opening and closing cylinder 12 has a generally hollow cylindrical shape and is disposed radially outward on the right protrusion of the first ball-screw shaft 18 with a space provided therebetween, so that the first ball-screw shaft 18 ) Will cover the outer circumferential surface. The mold opening and closing cylinder 12, which is coaxial with the first ball-screw shaft 18, is movable relative to the first ball-screw shaft 18 in the axial direction. At the entry-to-open end of the mold opening and closing cylinder 12, the length of the mold opening and closing cylinder 12 (in this embodiment, substantially half the length of the axial length of the mold opening and closing cylinder 12) A cylindrical flange metal member 28 is inserted with a smaller axis length. The flange metal member 28 has an annular radial protrusion 30 formed at one axial opposite end to protrude in the axial outward direction. The annular radial protrusion 30 is bolted to overlap one end face of the mold opening and closing cylinder 12. The flange metal member 28 has an inner diameter that is larger than the outer diameter of the first ball-screw shaft 18, and has an outer diameter that is smaller than the inner diameter of the mold open and closed cylinders 12. Thus, the mold opening and closing cylinders 12 interact with the flange metal member 28 to partition between the annular cylinder receiving spaces 32 that are open toward the retracted-opening opening end of the mold opening and closing cylinders 12. In the meantime, the first ball-screw shaft 18 extends through the bore of the flange metal member 28. The mold open and closed cylinder 12 has an axial length slightly larger than the length of the protrusion of the first ball-screw shaft 18 from the bracket 16. Thus, the entry-to-open end 26 of the mold opening and closing cylinder 12 protrudes outward from the corresponding axis end face of the first ball-screw shaft 18 with a slight axis length. At the protruding end of the mold opening and closing cylinder 12, the movable platen 14 is fixed.

In the bore of the mold opening and closing cylinder 12, a cylindrical piston 34 is fitted. The cylindrical piston 34 has an overall cylindrical shape and is kept in closed contact with the inner circumferential surface of the mold opening and closing cylinder 12 such that the cylindrical piston 34 is in the axial direction of the mold opening and closing cylinder 12. Reciprocating operation. The inner circumferential surface of the mold opening and closing cylinder 12 is made large on the axially retracted side to form a large-diameter inner circumferential surface 36. The cylindrical piston 34 has a sliding surface 38 which slides into the large-diameter inner circumferential surface 36 of the mold opening and closing member 12 and is fluid-sealed so that the hydraulic chamber 40 has a large-diameter interior. Formed between the circumferential surface 36 and the outer circumferential surface of the cylindrical piston 34, the hydraulic chamber 40 has an annular structure as a whole and its axially opposite ends extending continuously in its axial direction (FIG. 1). It has a large diameter sliding surface 38 formed at the left end shown. This hydraulic chamber 40 has a volume which is increased and decreased by the reciprocating motion of the cylindrical piston 34 in the mold opening and closing cylinder 12. The volume of the hydraulic chamber 40 is reduced by the movement of the cylindrical piston 34 to the entered side (right side in FIG. 1), and increased by the movement of the cylindrical piston to the retracted side (left side in FIG. 1). At the sliding interface between the inner circumferential surface of the mold opening and closing cylinder 12 and the outer circumferential surface of the cylindrical piston 34, a plurality of annular sealing members 42 are placed at the axially opposite ends of the cylindrical piston 34, The sealing member 42 opposes each other in the axial direction with the hydraulic chamber 40 interposed therebetween. In this embodiment, the mold open and closed cylinders and the cylindrical piston 34 interact to form a pressure-generating cylinder arrangement.

The entry axial end of the cylindrical piston 34 is in sliding contact with the flange metal member 28 and is always radially outward so that a plurality of protrusions 47 formed on the inner circumference of the cylindrical piston 34 are formed of the flange member 28. It is continuously coupled with a plurality of grooves 44 formed on the outer circumferential surface. That is, the cylindrical piston 34 and the mold opening and closing cylinder 12 are assembled together such that the cylindrical piston 34 is axially driven relative to the mold opening and closing cylinder 12 and not radially movable.

Moreover, as the pressing device the coil spring 46 lies radially outward of the flange metal member 28 placed radially outward of the cylindrical piston 34. Coil spring 46 is applied to apply pressure to the cylindrical piston 34 such that the cylindrical piston 34 is held in its fully retracted position to increase the volume of the hydraulic chamber 40. The fully retracted position of the cylindrical piston 34 is in contact with the cylindrical piston 34 having an annular shape and having radially inner projections 50 fixed to the retracted-opening ends of the mold opening and closing cylinders 12. By contact.

In addition, the first ball-nut 48 is threaded with the first-ball-screw shaft 18 and bolted to the retracted end of the cylindrical piston 34. That is, while the first ball-nut 48 is fixed to the cylindrical piston 34 and is supported so as not to rotate about the axis, the first ball-nut 48 together with the cylindrical piston 34 opens and closes the mold. It is movable in the axial direction in the bore of the cylinder 12. Since the rotation of the first ball-screw shaft 18 translates into the longitudinal motion of the first ball-screw shaft 18 and the first ball-nut 48, the first ball-screw shaft 18 is first modified. The first ball-nut 48 and the cylindrical piston 34 fixed to the first ball-nut 48 by rotation by the one servomotor 22 are moved in the axial direction. Since the cylindrical piston 34 is forcibly placed in the fully retracted position to be positioned in the initial position by the coil spring 46, the first ball-screw shaft is axially forward driven to the first ball-nut 48. Is rotated to apply. In this state, the cylindrical piston 34 is in its initial position until a resistive force exceeding the sum of the pressing force of the coil spring 46 and the hydraulic pressure of the hydraulic chamber 40 is applied to the mold opening and closing cylinder 12. The mold opening and closing cylinder 12 is thus moved with the cylindrical piston 34 towards its fully entered position. In this state, the first ball-screw shaft 18 rotates in the reverse direction, and the driving force in the retracted direction is applied to the first ball-nut 48 so that the mold opening and closing cylinder 12 and the cylindrical The piston 34 is retracted together in the axial direction with the cylindrical piston 34, which remains in abutment contact with the radially inner projection 50.

As described above, by the reciprocating motion of the mold opening and closing cylinder 12 in the axial direction, the movable platen fixed to the mold opening and closing cylinder 12 opens and closes the mold as it reciprocates in the axial direction. In this embodiment, the first ball-screw shaft 18, the first ball-nut 48 and the first servomotor 22 interact with each other to form a mold opening and closing mechanism of the electric ball-screw type. do.

As shown in FIG. 2, the mold-clamping apparatus of the present embodiment includes a hydraulic unit 52 constituting a hydraulic circuit connected to the hydraulic chamber 40. The hydraulic unit 52 includes first and second solenoid-operated switch valves 54, 56 with the hydraulic chamber 40 selectively maintained in the closed and open states.

On the outer circumferential surface of the mold opening and closing cylinder 12, the overall cylindrical mold-clamping cylinder 58 is placed in the radial space therebetween. The mold-clamping cylinder 58 is fixedly supported by the bracket 64 protruding from the base 10 so that the mold-clamping cylinder 58 does not interfere with the movement of the mold opening and closing cylinder 12. The mold-clamping cylinder 58 has a gradually increasing diameter of the cylinder wall portion toward the entered side of the mold opening and closing cylinder 12 (ie, the side of the movable platen 14) and a large-diameter opening of the cylinder wall portion separately. It has a large-diameter sealing flange 62 and a small-diameter sealing flange 60 fixed to the ends and the small-diameter.

In the mold-clamping cylinder 58, the mold-clamping ram 66 is assembled to extend through the bore of the mold-clamping cylinder 58. The mold-clamping ram 66 has an inner diameter larger than the outer diameter of the mold opening and closing cylinder 12 such that the mold-clamping ram 66 does not interfere with the movement of the mold opening and closing cylinder 12 therebetween. The radial opening of the mold open and closed cylinder 12 is placed into a radial space suitable for the use. In addition, the mold-clamping ram 66 has a configuration similar to that of the mold-clamping cylinder 58 with slightly smaller dimensions. The mold-clamping ram 66 has a diameter of the ram wall 68 that gradually increases toward the entrance of the mold opening and closing cylinder 12, and a small-diameter cylinder which is formed integrally with the axially opposite ends of the ram wall individually. A portion 70 and a large-diameter cylindrical portion 72 are provided.

That is, the mold-clamping ram 66 slides in the mold-clamping cylinder 58 to interface the large-diameter cylinder portion 72 and the large-diameter sealing flange 62 of the mold-clamping ram 66. Between the small-diameter cylindrical portion 70 and the small-diameter sealing flange 60 of the mold-clamping ram 66 while slipped and fluid-sealed by the annular sealing member 74 interposed therebetween. The interface of is slipped and sealed by fluid-sealing by the annular sealing member 74 interposed therebetween. This device has a mold-clamping chamber 76 partitioned between the mold-clamping ram 66 and the mold-clamping cylinder 58 extending in the circumferential direction. The hydraulic pressure generated in the mold-clamping chamber 76 is applied to the mold-clamping ram 66 such that the mold-clamping ram 66 is moved toward its entered position in the axial direction of the mold opening and closing cylinders. In this embodiment, the mold-clamping cylinder 58 and the mold-clamping ram 66 interact to form a mold-clamping device.

According to this embodiment, the mold-clamping cylinder 58 is used as a second positioning electric motor suitable for controlling and manipulating the axial positions of the mold-clamping cylinder 58 and the mold-clamping ram 66 with respect to each other. It is applied to support the servomotor 78.

The end face of the large-diameter cylindrical portion 72 of the mold-clamping ram 66 is fixed with the coupling device 79 as a coupling device. The coupling device 79 is supported by a pair of semi-circle nut halves 80, 80 and nut halves 80, 80 opposed to each other in the radial direction so as to be movable in the radial direction and not axially moved, so that the mold-clamping ram And guide housings 82 and 82 that are secured to 66. The guide housings 82, 82 are individually fixed to the cylinder arrangement 84, 84 by moving the nut halves 80, 80 away from each other and toward the nut halves, such that the pair of nut halves 80, 80 open the mold. And away from the closing cylinder 12 and towards the cylinder.

Each nut halves 80, 80 extend in the circumferential direction of the nut halves 80 having a sawtooth shape in cross section, and are provided with a plurality of second joinable protrusions 86 spaced at equal intervals from each other in the axial direction. It has an inner surface (ie, a face opposite to the outer circumferential surface of the open and closed cylinder 12). On the other hand, the outer circumferential surface of the mold opening and closing cylinder 12 also extends circumferentially in a sawtooth shape in a cross-section corresponding to the shape of the first projection, and a plurality of first spaced apart equally from each other in the axial direction. Is formed of a joinable protrusion 88. The first and second protrusions 88, 86 are aligned similar to the axial direction at regular intervals.

When a pair of nut halves 80, 80 are held by respective cylinder arrangements 84, 84 in the retracted position (i.e., part away from mold opening and closing cylinder 12 in the radial direction), the mold- The clamping ram 66 is disconnected from the mold open and closed cylinder 12 and can be freely moved in the axial direction without any restraint by the mold-clamping ram 66.

The mold opening and closing cylinder 12 has a first joinable protrusion 88 formed on the outer circumferential surface of the mold opening and closing cylinder 12 formed between the inner circumferential surfaces of the nut halves 80, 80 at radial intervals therebetween. After entering to some extent opposite the second engageable protrusions 86, 86, the pair of nut halves 80, 80 engage or connect the first and second engageable protrusions 88, 86 to each other. It is moved by the respective cylinder arrangement 84, 84 towards the entered position. In this state, the mold-clamping ram 66 is integrally connected with the mold opening and closing cylinder 12 by the coupling device 79 so that the mold-clamping ram 66 is the mold opening and closing cylinder 12. It does not move in the axial direction with respect to. In this embodiment, a sensor 90, such as a limit switch, is placed in the vicinity of the nut halves 80, 80 to detect the radial direction of the nut halves 80, 80. Based on the output signal of the sensor 90, it is determined whether the nut halves 80, 80 and the mold opening and closing cylinder 12 are engaged with each other or not.

While the mold-clamping ram 66 and the mold opening and closing cylinder 12 are coupled to each other by the coupling device 79, the hydraulic pressure generated in the hydraulic chamber 40 is transmitted to the mold-clamping chamber 76. With the hydraulic pressure applied to the mold-clamping ram 66, the mold-clamping ram 66 is moved towards its entered position. The hydraulic driving force applied to the mold-clamping ram 66 is transmitted to the movable platen 14 to apply the mold-clamping force to the movable platen 14.

The hydraulic unit 52 of the present invention is arranged to integrally connect and apply the hydraulic pressure generated in the hydraulic chamber 40 to the mold opening and closing cylinder 12 by the coupling device 79, thereby forming a mold-clamping chamber ( 76) to create a hydraulic pressure. More specifically, the hydraulic chamber 40 is connected to the mold-clamping chamber 76 by a first solenoid driven switch valve 54. The switch valve 54 is individually opened and closed for connection and disconnection between the two chambers 40, 76. As the first switch valve 54 held in the normal position (open position) and the second switch valve 56 held in the operating position (close position), a closed hydraulic circuit is formed. In this state, the first ball-screw shaft 18 is rotated to apply a driving force to the cylindrical piston 34 that resists the pressing force of the coil spring 46, so that the entry movement of the cylindrical piston 34 in the axial direction is performed. Create The sliding entry motion of the cylindrical piston 34 causes compression of the coil spring 46 in the axial direction, causing an increase in the hydraulic pressure in the hydraulic chamber 40. Thus, the increased hydraulic pressure in the hydraulic chamber 40 is transferred into the mold-clamping chamber 76 through the first solenoid valve 54.

Upon operation of the hydraulic-generating cylinder device 30, the opening and closing operations of the first and second solenoid-operated switch valves 54, 56 are controlled to facilitate filling of the closed hydraulic circuit with the working hydraulic fluid. And facilitate mixing air discharge from the closed hydraulic circuit. In this regard, FIG. 2 shows a relief valve 85 placed in order to avoid an abnormal increase in hydraulic pressure caused by unrestrained servo-system and an air bleed valve 87 for bleeding mixed air.

In this embodiment, the mold-clamping ram 66 of the mold-clamping chamber 76 has a pressure-receiving surface region that is sufficiently enlarged as compared to the region of the cylindrical piston 34 of the hydraulic chamber 40. In particular, the hydraulic chamber 40 is formed between the cylindrical piston 34 with a relatively small radial space and the mold open and closed cylinder 12 between the sufficiently reduced pressure-receiving surface zones of the cylindrical piston 34. To ensure. Accordingly, the hydraulic pressure generated in the hydraulic chamber 40 is sufficiently increased in the mold-clamping chamber 76 to cause a sufficiently increased axial driving force of the mold-clamping ram 66 which is a sufficiently increased mold-clamping force.

For example, according to the following method, the present mold-clamping apparatus described and illustrated above is suitably operated to open and close the mold and to clamp the mold.

First, as shown in FIG. 1, the mold is opened in the mold opening and closing cylinder 12 which is moved to the retracted position. In this state, the first servomotor 22 is operated to rotate the first ball-screw shaft 18 to its forward position. As forward rotation of the first ball-screw shaft 18, the cylindrical piston 34 and the mold opening and closing cylinder 12 are coiled as the cylindrical piston 34 and the mold opening and closing cylinder 12 are positioned relative to each other. Using the pressing force of the spring 46, it is integrally moved toward the entered position. Thus, as the movable platen 14 is moved toward the mold-closed position, the movable platen 14 closes the stationary platen (not shown) to close the mold in between. In this mold-closed operation, the first and second solenoid operated switch valves 54, 56 are opened or closed.

After the mold is closed between the stationary and movable platen 14, the cylinder devices 84, 84 move the nut halves 80, 80 in the entered position to engage the mold opening and closing cylinder 12. It works. Substantially, the solenoid coil of the first solenoid-operated switch valve 54 is not operated to open the first switch valve 54 for fluid transport between the hydraulic chamber 40 and the mold-clamping chamber 76. Instead, the solenoid coil of the second solenoid-operated switch valve 56 is operated to hold the mold-clamping chamber 76 and the hydraulic chamber 40 in a closed hydraulic circuit. As two chambers 40 and 76 in communication with each other in a closed hydraulic circuit, the first servomotor 22 resumes its operation to rotate the first ball-screw shaft 18 in the forward direction. , Sliding the cylindrical piston 34 toward its entered position with respect to the mold opening and closing cylinder 12. The entry motion of the cylindrical piston 34 causes an increase in the hydraulic pressure in the hydraulic chamber 40 delivered to the mold-clamping chamber 76, thereby increasing the hydraulic pressure in the mold-clamping chamber 76. Increased hydraulic pressure in the mold-clamping chamber 76 is applied to the mold-clamping ram 66 such that the mold-clamping ram 66 and the mold opening and closing cylinder 12 are integrally moved toward the stationary platen, thereby operating The platen 14 presses the stationary platen in order to clamp the mold sandwiched therebetween.

While the mold is clamped as described above, injection molding is operated to mold the product within the mold. Following the injection molding, the hydraulic pressure in the mold-clamping chamber 76 reduced as follows: first, by the first switch valve 54 not being operated and by the second solenoid driven valve 56 being operated. A mold-clamping chamber 76 and a hydraulic chamber 40 in communication with each other in a closed hydraulic circuit, wherein the first servomotor 22 rotates the first ball-screw shaft 18 in its reverse direction. It is actuated to move the movable platen 14 towards its mold-closed position.

At that time, the cylinder devices 84, 84 are operated to move the nut halves 80, 80 toward the retracted position for disengagement between the nut halves 80, 80 and the mold open and closed cylinder 21. In the above closed hydraulic circuit, the first servomotor 22 resumes its operation to rotate the first ball-screw shaft 18 in the reverse direction, so that the cylindrical piston 34 and the mold opening and The closing cylinder 12 slides integrally toward the mold opening position to open the mold.

In the present mold-clamping apparatus, after the mold-closing operation and before the mold-clamping operation, it is required to engage or connect the mold opening and closing cylinders 12 and the nut halves 80 and 80. Insufficient positioning of the first and second engageable protrusions 88, 86 relative to each other is likely to cause failure of engagement between the first and second engageable protrusions 88, 86. For example, for the proper engagement of the nut halves 80, 80 and the mold opening and closing cylinder 12, a second connection to the first joinable protrusion 88 using the second servomotor 78 is possible. The operation for positioning of the engageable protrusions 86 and 88 can be appropriately controlled according to the following method.

First, for example, the absolute angle-positioning of the first servomotor 22 is determined according to the following method. ① Initially, the sample molds, which form a pair of mold halves individually in the form of metal blocks, are fixed to the stationary and movable platens. The sample mold has a thickness as the minimum reference mold thickness made smaller than the thickness of the used mold fixed to this platen in mold operation. Substantially, the mold opening and closing cylinder 12 enters either as a reduced-speed operation or as a manual operation until the mold halves are brought into contact with each other in the mold-closed position. As the mold is closed, the mold-closed position of the movable platen is sensed as a reference position of the movable platen, and the angle-positioning of the first servomotor 22 is also the neutral angle position of the first servomotor 22. Is detected and stored as (0.00 mm). ② At that time, the fully retracted position of the mold-clamping ram 66 (mechanical limit of the retracted movement) that is moved by the second servomotor 78 is the mold as the mechanical zero position of the mold-clamping ram 66. The measurement is based on the fully entered position of the clamping ram 66 (mechanical limit of the entered motion), and the measurand A (mm) is stored. The mold opening and closing cylinder 12 is held in the mold-closed position, that is, the first servomotor 22 is held in its neutral angle position, and the mold-clamping ram 66 is fully retracted thereof. In the retained position, the axial position of the nut halves 80, 80 of the second engageable protrusion 86 relative to the first engageable protrusion 88 of the mold opening and closing cylinder 12 is the first position. And the second engageable projections 88, 86 are mechanically finely adjusted to engage with each other. For example, such fine mechanical adjustments can be made by adjusting the fixing positions of the nut halves 80, 80 relative to the mold-clamping ram 66 in the axial (mold-clamping) direction, or in the axial (mold-clamping) direction. By selectively manipulating the fixed position of the mold-clamping cylinder 58 relative to the bracket 64. In this regard, for example, this fixing position of the nut halves 80, 80 and the mold clamping cylinder 58 can be changed or adjusted by means of adjustment screws or the like.

In practice, the desired angular position of the second servomotor 78 for controlling the position of the mold-clamping ram 66 is calculated such that the first and second protrusions 88, 86 are fully engaged with each other. For example, the required angular position of the second servomotor 78 is calculated as follows: First, the axial movement amount of the mold-clamping ram 66 according to the following formula (1), (2). Preferred ranges are calculated. ② At that time, the required angular position of the second servomotor 78 is the required axial position in order to ensure the complete engagement of the first and second protrusions 88, 86 according to the control sequence shown in the flowchart of FIG. X mm) to calculate the mold-clamping ram 66.

F = E + B (1)

E <D ≤ F (2)

In this regard, D (mm) is the required range of the axial displacement of the mold-clamping ram 66. The mold-clamping ram 66 is in its fully retracted position with respect to the mold opening and closing cylinder 12 and its full entry in order to effect positioning of the first and second engageable projections 88, 86. Mechanically actuated by its stroke length A (mm) partitioned between the defined positions. Second engageable protrusion 86 (first engageable protrusion 88) for the mold opening and closing cylinder 12 in order for the mold-clamping ram 66 to be set to the distance D at which the value of B is required. It is sufficient to move only by the pitch (B (mm)) of E. E (mm) is the minimum value of D determined in consideration of the amount of extension of the support rod during clamping of the mold. The application of the clamping force causes the extension of the support rod connecting the rear platen and the bracket 64 forming the stationary platen (not shown), so that the distance between the bracket 64 and the stationary platen (not shown), i.e., the first And compared with the engagement distance of the second joinable protrusions 88 and 86, resulting in an increase in the distance between the mold-clamping cylinder 58 and the movable platen 14. To produce an effective mold-clamping force , The movable platen 14 and the mold-clamp at the stroke distance of the mold-clamping ram 66 in the entered direction. Is required to add such an increase in the axial distance between the cylinder (58). F (mm) is a maximum value of the calculated D in accordance with the formula (1) is provided with more of a value smaller than the value of F A.

Referring next to FIG. 4 (a), the above-described calculation will be described based on the specific values indicated in the following Table 1 of one embodiment of the present mold-clamping apparatus according to the embodiment.

Item Symbol Value (mm) Mechanical Limits of Axial Displacement of Ram 66 A 20.00 Pitch of the first and second engageable protrusions 88, 86 B 12.00 Minimum mold thickness C 200.00 Minimum value of the required range D of the axial displacement of the ram 66 E 6.00 Mold thickness of used mold G 234.56

F = E + B = 6.00 + 12.00 = 18.00 (mm)

H = G-C = 234.56-200.00 = 34.56 (mm)

H / B = 34.56 / 12.00 = 2 and the rest 10.56

∴ J = 10.56 (mm)

K = A-B = 20-12 = 8.00

0 <K, therefore

K = 8.00-12.00 = -4.00 (mm)

L = J + K = 10.56-4 = 6.56 (mm)

E <L, therefore

X = L = 6.56 (mm)

As shown in Fig. 4 (a), the mold-clamping ram 66 is moved from its mechanical zero position toward its fully retracted position by an amount of X = 6.56 mm so that the movable plate 14 is When placed in the mold-closed position of the mold to ensure engagement of the first engageable protrusion 88 of the mold opening and closing cylinder 12 and the second engageable protrusion 86, 86 of the nut halves 80, 80. do.

In addition, for example, the operation of the mold-clamping apparatus shown according to the present embodiment can be controlled by using the pressure sensor 92 as shown in FIG. More specifically, the output torque of the first servomotor 22 is feedback-controlled based on the hydraulic pressure of the mold-clamping chamber 76 and the hydraulic chamber 40 sensed by the pressure sensor 92 to control the operation of the device. Causes improved accuracy.

As is apparent from FIG. 5, the output torque of the first servomotor 22 corresponds to the initial output torque corresponding to the force resisting the pressing force of the coil spring 46, as well as the output pressure corresponding to the hydraulic pressure acting with the mold-clamping force. Includes torque This means that the mold-clamping force is controlled in consideration of the initial torque of the first servomotor 22.

According to the operation of the mold-clamping apparatus of this embodiment, the mold-clamping pressure is reduced after the injection-mold operation. The mold-clamping pressure-reducing operation is performed by controlling the output torque of the first servomotor 22 to mitigate or eliminate the unexpected change in hydraulic pressure in the mold-clamping chamber 76 which causes undesirable impact. . In order to effectively reduce the mold-clamping pressure in the mold-clamping chamber 76, the output torque of the first servomotor 22 can be preferably controlled as follows: the output of the first servomutter 22. The value of torque is from the value M generated in the mold-clamping operation, the value generated when the mold-clamping pressure-reducing operation is completed in a plurality of number N operating steps within a time t of a predetermined period. Gradually decreases to (T0). 6 and 7, a time chart for showing the stage of the mold-clamping operation of this embodiment and a graph showing a change in the output torque of the first servomotor 22 controlled by the four-step control operation. In the figure, the output torque of the first servomotor 22 is controlled by a four-step control operation by embodiment. In FIG. 7, a "joining device loosening process" is performed to move the nut halves 80, 80 away from the mold opening and closing cylinder 12.

Optionally, the first servomotor 22 can be controlled based on its rotational speed to reduce the mold-clamping pressure. In particular, the first servomotor 22 is rotated in the reverse direction upon detection of the start of the input signal instruction of the mold-clamping pressure-reducing operation. The rotational speed V of the first servomotor 22 is controlled for a predetermined period of time t necessary to reduce the mold-clamping pressure, thereby effectively reducing the mold-clamping pressure. It is preferable that the value V of the rotational speed of the first servomotor 22, the number of control steps and the time of period for each control step are made adjustable. Although the mold-clamping pressure-reducing operation has not yet passed the predetermined time period t required for the mold-clamping pressure-reducing operation, the measured value of the mold-clamping pressure p is the mold-clamping pressure-reducing operation. In other words, the mold-clamping pressure-reduction process may be immediately terminated when a sufficient predetermined value p is reached to complete the process.

In Fig. 8, which is a time chart showing the control step of the mold-clamping operation of this embodiment, the rotational speed of the first servomotor 22 is controlled by the four-step control operation by the embodiment.

9 and 10, there is shown a partial cross-sectional plan view of the mold-clamping apparatus shown in accordance with each second embodiment and an enlarged cross-sectional view of the main part of the mold-clamping apparatus of the second embodiment. The mold-clamping apparatus comprises fixed and trailing platens 102 and 104 which are individually fixed and supported by the base 100 of the injection-molding machine, and they are far from and opposed to each other. Like the mold-clamping device of the first embodiment, the four support rods 106 extend parallel to each other on the stationary and trailing platens 102 and 104, and the movable platen 108 is fixed to the stationary platen 102. It is supported by four support rods 106 to move along the support rods 106 between the trailing platens 104.

Between the tail and movable platens 104, 108, a drive unit is placed which is driven by an electric motor by the movable platen 108 which is moved away from and towards the stationary platen 102. In the stationary and movable platens 102 and 108, the stationary and movable mold halves of the mold (not shown) are separately attached. By the reciprocating motion of the movable platen 108, the movable platen is moved toward the stationary platen to close and clamp the mold and from the stationary platen to open the mold.

A specific illustration of the electric-motor type drive unit of this embodiment will be described.

The drive device comprises a pair of mold opening and closing mechanisms of electric ball-screw types 110 and 110. The mold opening and closing mechanisms 110, 110 are placed opposite one another in a direction perpendicular to the center axis of the tail and movable platens 104, 108. Similarly, the pressure-generating cylinder arrangements 112, 112 are placed opposite one another in the same direction. The drive device further includes a mold-clamping cylinder device 114 placed radially outward of the central axis of the rear and movable platens 104, 108. In the driving device of the present embodiment, the mold opening and closing mechanisms 110 and 110 are formed between the pressure-generating cylinder device 112 and 112 and the mold-clamping cylinder device 114 between the movable and stationary platens 108 and 102. While applied to apply a sufficiently large mold-clamping force at, it is applied to move the movable platen 108 away from and toward the platen at a relatively high speed.

In more detail, the mold opening and closing mechanisms 110 and 110 include: first servomotors 116 and 116 as mold-driven electric motors individually fixed to horizontally opposite surfaces of the movable platen 108; And first ball-screw shafts 118, 118 horizontally positioned in the direction of motion of the movable platen 108, ie, on the opposite surface of the rear platen 104 to extend parallel to the central axis of the movable platen 108. ); Each first ball-screw shaft 118, 118 is supported by its movable platen 108 at its entered-side axis end such that the first ball-screw shaft 118 is rotatable about its axis. And does not move in the axial direction. Individually, the first ball-screw shafts 118, 118 are fixed to the output shafts of the first servomotors 116, 116. Each first servomotor 116 is equipped with an encoder 120 for sensing the amount of rotation.

Each mold opening and closing mechanism 110 includes a first ball-nut 122 screw-engaged with the first ball-screw shaft 118 and located on the side of the rear platen. The first ball-nuts 122, 122 are individually supported by pressure-generating cylinder arrangements 112, 112 fixed to each surface of the rear platen 104.

Each pressure-generating cylinder device 112 includes a pressure-generating piston 126 and a cylindrical pressure-generating cylinder 124 reciprocating in the bore of the pressure-generating cylinder 124. The outer circumferential surface of the pressure-generating piston 126 and the inner circumferential surface of the pressure-generating cylinder 124 interact to partition the pressure-generating chamber 128 therebetween. The pressure-generating cylinder device 112 is directed toward the left end of the pressure-generating cylinder 124 or toward the movable platen 108 as shown in FIG. 9 to reduce the volume of the pressure-generating chamber 128. Are arranged for movement of the pressure-generating piston 126.

The pressure-generating cylinder device 112 further includes a coil spring 130 inserted between the pressure-generating cylinder 124 and the piston 126. Coil spring 130 is adapted to apply a pressing force to pressure-generating piston 126 such that pressure-generating piston 126 is forcibly placed at the right axis end of cylinder 124 as shown in FIG. 9. The volume of the chamber 128 is maximized. In order to maintain the pressure-generating piston 126 in the retracted position with high stability, the locking cylinder 132 as a locking means is placed in the pressure-generating cylinder 124. More specifically, the locking cylinder 132 includes a reciprocating stop pin 134 in the bore. The stop pin 134 is driven away from and toward the pressure-generating piston 126 through and through the through hole formed through the outer circumferential surface of the pressure-generating cylinder 124. Thus, the stop pin 134 is disengaged from and coupled to the pressure cylinder piston 126. While the stop pin 134 is engaged with the pressure-generating piston 126, the pressure-generating piston 126 is held in its retracted position with high stability. In this regard, the lock cylinder 132 can be preferably manufactured by an air cylinder.

In the pressure-generating piston 126, which is a hollow cylindrical member with a bore 136, the first ball-nut 122 is bolted. Thus, the first ball-screw shaft 118 is placed to extend and move within the bore 136 of the pressure-generating piston 126 and the bore of the pressure-generating cylinder 124.

While the locking cylinder 132 is coupled with the pressure-generating piston 126, the first servomotor 116 is operated to rotate the first ball-screw shaft 118. Rotation of the first ball-screw shaft 118 relative to the first ball-nut 122 translates into longitudinal movement of the first ball-screw shaft 118 such that the two platens 104 and 108 are in contact with each other. Driving forces are applied between the trailing and movable platens 104 and 108 in opposite directions. Thus, the movable platen 108 is moved away from and toward the platen to open and close the mold therebetween.

On the other hand, while the locking cylinder 132 is disengaged from the pressure-generating piston 126, the first servomotor 116 is connected to the first ball-screw shaft 118 for the first ball-nut 112. It is operated to rotate. In this case, the longitudinal movement of the first ball-screw shaft 118 and the nut 122 causes the sliding motion of the pressure-generating piston 126 relative to the pressing force of the coil spring 130 to produce a hydraulic pressure. To reduce the volume of the hydraulic-generating chamber 128. The hydraulic pressure generated in the pressure-generating chamber 128 is applied to the mold-clamping cylinder device 114 to apply the mold-clamping force between the movable and stationary platens 108, 102. 114).

The mold-clamping cylinder device 114 is formed integrally with the rear platen 104 and the mold-clamping cylinder 138 in which the center axis is aligned with the center axis of the movable platen 108 and the center axis of the mold-clamping cylinder. And a sliding mold-clamping ram 142 in the bore 140 of the mold-clamping cylinder 138. As in the mold-clamping apparatus of the first embodiment, the mold-clamping cylinder 138 and the mold-clamping ram 142 interact to partition between the mold-clamping chambers 144.

Like the mold-clamping device of the first embodiment, the coupling device 146 is fixed to the large diameter end face of the mold-clamping ram 142. The coupling device 146 has an inner circumferential surface formed of a plurality of first engageable protrusions 174 extending in the circumferential direction and spaced apart from each other in the axial direction at consecutive intervals, and having a pair of nut halves opposed to each other in the radial direction ( 148, 148, and a pair of cylinder arrangements 150, 150 adapted to move the nut halves 148, 148 in the radial direction. The mold-clamping ram 142 has an bore 152 extending in the axial direction and an opening in the end faces of the large and small-diameter portions 142a and 142b. The mechanical ram 154 is secured to one axial facing end at one axial end of the movable platen 108 away from the fixed platen 102 and through the bore 152 to the fixed platen 102. Extend in a direction away from

Like the mold opening and closing cylinder 12 of the first embodiment, the mechanical ram 154 is a hollow cylindrical member and the center axis of the mechanical ram 154 is aligned with a straight line passing through the center of the movable platen 108. Positioned relative to the movable platen 108. The mechanical ram 154 is formed of a plurality of second engageable annular projections 156 each having a sawtooth shape in cross sections aligned in the axial direction at regular intervals. The first engageable protrusions 147, 147 of the nut halves 148, 148 are engageable with the second engageable annular protrusion 156 of the mechanical ram 154. While the first and second engageable protrusions 147, 147, 156 are forced and integrally coupled to each other, the first servomotor 116 increases the pressure-generating piston in the pressure-generating chamber 128. It is actuated to rotate the first ball-screw shaft 118 relative to the first ball-nut 122 to produce the entry motion of 126. The hydraulic pressure generated in the pressure-generating chamber 128 is transferred to the mold-clamping chamber 144 such that the mold-clamping ram 142 is based on the increased hydraulic pressure in the mold-clamping chamber 144. Exercise towards The entry motion of the mold-clamping ram 142 is transmitted to the movable platen 108 via the mechanical ram 154 to apply a mold-clamping force between the movable and stationary platens 108, 102.

As shown in FIG. 9, with respect to the hydraulic unit 52 for controlling the flow of the working fluid between the pressure-generating cylinder device 112 and the mold-clamping cylinder device 114, it is used in the first embodiment. Reference numbers are used to designate corresponding elements and there will be no description of these elements.

As shown in FIG. 10, the mechanical ram 154 is also a hollow cylindrical member. Within the bore 158 of the mechanical ram 154, the ejecting ball-screw shaft 160 as a second ball-screw shaft is placed to extend therethrough. Ejecting ball-screw shaft 160 passes through bearing 164 and is supported by one ram 154 at one axial facing end (i.e. right end) such that ejecting ball-screw shaft 160 is axially oriented. It is rotatable about its axis while not moving in the direction. The ejecting screw shaft 160 further protrudes from the mechanical ram 154 to a given axis length towards the movable platen 108. The protruding end 166 acts as a ball-screw shaft. The ejecting ball-nut 168 as the second ball-nut is screw-engaged with the protruding end 166 while being secured to the ejector plate 170 coupled in the movable platen 108. As is known in the art, the ejector plate 170 is equipped with an appropriate number of ejector pins 172 adapted to withdraw the injection molded product from the mold after the mold-opening operation.

On the other hand, at the other axis end of the ejecting ball-screw shaft 160 (ie, the left end shown in FIG. 10), the output shafts of the ejecting servomotor 162 as ejecting electric motors rotate relative to each other. The connection is fixed so as not to. Moreover, the ejecting servomotor 162 is placed in the bore 158 of the mechanical ram 154 and bolted to the axial open-end of the mechanical ram 154. The bore 158 of the mechanical ram 154 includes a void 176 formed between the outer circumferential surface of the ejecting servomotor 162 and the bore 158, and the flange portion of the ejecting servomotor 162 ( While opening at the left axis end to the atmosphere through a hole 178 formed through 179, it opens at the right axis end to the atmosphere through a communicable hole 174 formed through the base portion of the bearing 164. The provision of the communication holes 174, the voids 174 and the holes 178 enhances the ventilation of the bore 158 during the reciprocating motion of the mechanical ram 154.

The ejecting servomotor 162 is operated to rotate the ejecting ball-screw shaft 160 relative to the ejecting ball-nut 168 to cause linear movement of the ejecting ball-nut 168 in the axial direction. By the linear motion momentum of the ejector pin 172 in the axial direction, the ejector plate 170 is moved away from and toward the platen to allow the ejector pin 172 to enter and retract in the axial direction. do.

Thus, the mold-clamping apparatus shown in accordance with the second embodiment can exhibit the same desired effect as the mold-clamping apparatus of the first embodiment. That is, the mold-clamping apparatus of the present invention allows mold opening and closing operation at a relatively high-speed, according to the linear movement of the mold opening and closing mechanisms 110 and 110 applied directly to the movable platen 108. . The mold-clamping device also has a mold clamping large enough to the movable platen 108 based on the increased liquid pressure generated by using a hydraulic unit comprising pressure generating cylinder devices 112, 112 and mold clamping cylinder device 114. Force can be applied.

According to the mold-clamping apparatus of the second embodiment, the first ball-screw shaft 118 is directly connected to the output shaft of the servomotor 116 at each mold opening and closing mechanism 110. Such a device has improved noise and improved accuracy of positioning control of each ball-screw shaft 118 compared with the case where the output shaft of the servomotor and the first ball-screw shaft are connected by a suitable transmission member such as a belt. Allow a reduction.

In addition, the mold-clamping device shown in accordance with the second embodiment is characterized in that one mold opening and closing mechanism 110 and one pressure-generating cylinder device 112 are mounted on one side of the rear and movable platens 104, 108. During placement, other mold opening and closing mechanisms 110 and other pressure-generating cylinder arrangements 112 are arranged such that the rear and movable platens 104 and 108 are placed on the other side. Moreover, the first servomotors 116, 116 are supported by the movable platen 108. In such a device, the axial length of the mold-clamping device of the second embodiment is made smaller than that of the mold-clamping device of the first embodiment, resulting in a reduction in the size of the mold clamping device of the second embodiment.

In the mold-clamping device of the second embodiment, the pressure-generating piston 126 of the pressure-generating cylinder device 112 is coiled while the movable piston 108 is moved away from and towards the platen plate 102. In addition to the pressing force of the spring 130, it is held in its retracted position by a stop pin 134 that engages directly with the outer circumferential surface of the pressure-generating piston 126. Such a device ensures better stability of the mold opening and closing operations.

In the second embodiment, one mold opening and closing mechanism 110 and one pressure-generating cylinder device 112 is connected to the other mold opening and closing mechanism 110 and another pressure-generating cylinder device 112. And on one opposite side of the rear and movable platens 104, 108 while lying on the other side of the movable platen 104, such that the bore 158 of the mechanical ram 154 is ball-screw type electro-actuated. It is effectively used to accumulate in the ejector apparatus. Such devices allow for efficient charging of device components and filling of ejector devices with improved space usage.

Moreover, the interior space of the bore 158 of the mechanical ram 154 is defined by the holes 178 and voids 176 formed in the other axis ends of the mechanical ram 154 and one opposite axis end of the mechanical ram 154. Opening to the atmosphere through the formed communication holes 174 to facilitate ventilation of the interior space of the mechanical ram 154, which is undesirable in the servomotor 162 placed in the combined bore 158 of the mechanical ram 154. Effectively prevents or reduces generation of heat.

As in the first embodiment, the mold-clamping device shown in accordance with the second embodiment is adapted to steer the portion of the mold-clamping cylinder 138 relative to the rear platen 104 in the axial direction of the mechanical ram 154. It may preferably comprise a second servomotor 78 as an applied positioning electric motor. This makes the engagement positions of the first and second engageable protrusions 147, 147, 156 adjustable to facilitate the determination of the reference position of the mold-clamping ram 142 with accuracy.

As the mold used fixed to the mold-clamping apparatus, the joining positions of the first and second joinable protrusions can be preferably calculated according to various kinds of methods from each other in the reference position and idea used, and any method is It can be used in the invention. Preferably, a method of obtaining the engagement position provided by the minimum stroke of the mold-clamping ram from the mechanical zero position can be used.

In the fine motion mechanism of the above ③ executed in the first embodiment, the second engageable protrusions 86, 86 of the nut halves 80, 80 are held in their retracted positions, and the mold-clamping ram 66 ) And the first engageable protrusion 88 of the mold opening and closing cylinder 12. However, the fine mechanical adjustments of the present invention are characterized in that the first and second engageable protrusions 88, 86, which are determined by the specific angular position of the first servomotor 22 with respect to the neutral angular position of the first servomotor 22. No particular limitation is imposed on such a device provided with the engagement position of 86).

While the preferred embodiments of the present invention have been described in detail above for purposes of explanation, the present invention is not intended to limit the details of the embodiments, but various other changes and modifications that may occur to those skilled in the art without departing from the spirit and scope of the invention. And that improvements can be made.

As is clear from the above description, the mold-clamping apparatus shown according to the present invention is used as a mold-clamping apparatus of an injection-molding machine. In the mold-clamping apparatus of the present invention, the driving force for driving the movable platen away from and toward the platen is effectively produced by using a simple ball screw mechanism in manufacturing. These ball-screw mechanisms are used in conjunction with hydraulic systems to allow the creation of sufficiently large mold-clamping forces with simple mechanisms and excellent energy efficiency. Thus, in the present mold-clamping device, which is used industrially as a new mold-clamping device of the hybrid type, the electric drive mechanism and the hydraulic system are efficiently combined with each other to operate as a power source.

According to the method of the invention, the operation of the mold-clamping device shown according to the invention is applicable to industrial injection molding operations. This method allows for a reduction in the amount of impact during smooth transfer and pressure-reducing operations from the mold-close operation to the mold-clamping operation.

Claims (24)

A stationary platen and a rear platen, which are secured to the base of the injection-molding machine so as to face each other with space; A movable platen interposed between the fixed and trailing platens for moving the fixed and trailing platens between the fixed and trailing platens in a direction opposite to each other; A drive mechanism disposed between the rear platen and the movable platen and equipped with an electric motor operable to move the movable platen away from and toward the platen; A first ball-screw shaft supported by one said movable tail platen, a first ball-nut screw-coupled with said first ball-screw shaft and supported by another said movable tail platen, and said A mold-driven electric motor adapted to rotate relative to the first ball-screw shaft and the nut to produce a relative longitudinal motion of the first ball-screw shaft and the nut, wherein the first ball-screw shaft and the nut A mold opening and closing mechanism adapted to open and close the mold based on the relative longitudinal motion of the tool; A pressure-generating cylinder device placed on the side of the rear platen and operable to generate hydraulic pressure based on the relative longitudinal motion of the first ball-screw shaft and nut; A mold-clamping cylinder device placed on the side of the rear platen and applied with the generated hydraulic pressure in the pressure-generating cylinder device and equipped with a mold-clamping ram connectable to the movable platen; And As the mold is closed, the movable platen and the mold-clamping ram are operable to engage, created by the mold-clamping cylinder device based on the relative longitudinal motion of the first ball-screw shaft and nut. And a coupling device for applying the mold-clamping force to the movable platen. The mold-clamping device of an injection-molding machine for clamping a mold. 2. The pressure generating cylinder device of claim 1, further comprising a pressurizing device adapted to pressurize the pressure-generating piston toward the fully retracted position to increase the volume of the pressure-generating chamber of the pressure-generating cylinder device. Characterized by a mold-clamping device. The pressure-generating cylinder device according to claim 1, wherein the pressure-generating cylinder device is adapted to prevent the displacement of the pressure-generating piston relative to the pressure-generating cylinder. And a locking device operable to securely connect the production piston. The hydraulic circuit according to any one of claims 1 to 3, wherein the hydraulic circuit for transporting fluid between the pressure-generating chamber of the pressure-generating cylinder device and the mold-clamping chamber of the mold-clamping cylinder device. And a hydraulic system including a switch valve for selectively connecting and disconnecting the pressure-generating chamber from and towards the clamping chamber. The pressure-generating piston of claim 1, wherein the pressure-generating piston is a hollow cylindrical member, the pressure-generating chamber is partially partitioned by an outer circumferential surface of the hollow pressure-generating piston, And a first ball-screw shaft is positioned extending through the bore of the hollow pressure-generating piston and the first ball-nut is secured to the hollow pressure-generating piston. The mold clamping cylinder according to any one of claims 1 to 5, wherein the mold-clamping cylinder device is placed so that the center axis of the mold-clamping cylinder device is aligned with the center axis of the movable platen, and the mold-clamping ram And a hollow cylindrical member, said apparatus further comprising: a mechanical ram secured to said movable platen and extending through a bore of said hollow mold-clamping ram, said coupling device being coupled to said mechanical ram to A mold clamping device, characterized in that it is operable to hold a mold clamping ram. 7. The method of claim 6, wherein the plurality of first joinable protrusions formed on the outer circumferential surface of the mechanical ram so as to be spaced apart from each other at regular intervals in the axial direction of the mechanical ram, and the second joinable protrusions are coupled to the first combination. Supported by the mold-clamping ram and move away from and towards the outer circumferential surface of the mechanical ram to enable and engage and disengage therefrom from possible protrusions and prevent movement in the axial direction of the mechanical ram and A mold-clamping device, characterized in that the coupling device comprises a coupling member having a second engageable protrusion. 8. The system of claim 7, further comprising a positioning electric motor adapted to move the engagement member relative to the mechanical ram in the axial direction of the mechanical ram. Mold clamping device, characterized in that it is properly positioned for engaging with the first engageable protrusion. 9. The method of claim 7 or 8, wherein the hollow mold-clamping ram of the mold-clamping cylinder device comprises the rear platen and the movable platen during application of a mold-clamping force between the rear platen and the movable platen. And an actuating stroke length made greater than the sum of the increase in the axial distance between the teeth and the pitch of the first joinable protrusion. 10. The mechanical ram of claim 6, wherein the mechanical ram comprises a hollow cylindrical member, the mold-clamping device comprising: an ejector fixed to the movable platen, located in the bore of the hollow mechanical ram And a second ball-screw shaft secured to one said mechanical ram and said ejector, a second ball-nut screwed to said second ball-screw and secured to another said mechanical ram and said ejector An electrically-operated ejector device of the second ball-screw type; And an ejecting electric motor adapted to rotate the second ball-screw shaft and the nut relative to each other to generate relative longitudinal motion of the second ball-screw shaft and the nut to drive the ejector. Mold-clamping device. 11. The method of claim 10, wherein the ejecting electric motor is placed fixedly in the bore of the hollow mechanical ram, and wherein the hollow mechanical ram has an air flow passage extending through the bore in an axial direction. Mold-clamping device. 12. The mold-clamping device according to any one of the preceding claims, wherein the pressure-generating cylinder device comprises a plurality of pressure-generating cylinder devices positioned about a central axis of the movable platen. 13. The apparatus of claim 12, wherein each of the plurality of pressure-generating cylinder devices is: Said pressure-generating piston in the form of a hollow cylinder; The pressure-generating chamber partially defined by the outer circumferential surface of the hollow pressure-generating piston; The first ball-screw shaft positioned to extend through the hollow pressure-generating piston; The first ball-nut fixed to the hollow pressure-generating piston; And And the mold-driven electric motor fixedly supported by the movable platen and adapted to rotate the first ball-screw shaft and the nut relative to each other. 10. The mold-according to claim 6, wherein the mechanical ram is the first ball-screw shaft which comprises a hollow mechanical ram and is positioned to extend through the bore of the hollow mechanical ram. Clamping device. The pressure-generating cylinder according to claim 14, wherein the first ball-screw shaft is supported in which the fixed plate is fixedly fixed so as not to move axially by the base of the injection-molding machine, and the pressure-generating piston is Slidingly in the bore of the mechanical ram to form a device, and wherein the first ball-nut is secured to the pressure-generating piston. The method of claim 1, The first ball-screw shaft of the mold opening and closing mechanism supported by the base of the injection-molding machine so as to be rotatable about one axis and not rotate about one axis direction; The mold-driven electric motor adapted to rotate the first ball-screw shaft in the forward and backward directions; A hollow mechanical ram fixed to one axially opposite end of the movable platen and placed radially outwardly on the first ball-screw, axially driven relative to the base of the injection-molding machine and not rotated about the axis; Between the reduced volume being reciprocally slid in the axial direction of the mechanical ram and placed radially inside the mechanical ram so as not to rotate about the axis of the mechanical ram and moving towards one axial opposite end of the mechanical ram. The pressure-generating piston interacting with the mechanical ram to define a pressure-generating chamber and interacting with the pressure-generating chamber to form the pressure-generating cylinder arrangement; A pressurizing device adapted to pressurize the pressure-generating piston of the pressure-generating cylinder device against the mechanical ram such that the pressure-generating piston is pressed away from the movable platen towards one axis end of the pressure-generating cylinder; Screwed with the first ball-screw shaft and secured to the pressure-generating piston of the pressure-generating cylinder arrangement to rotate relative to each other with the first ball-screw shaft to reciprocate the pressure-generating piston. The first ball-screw nut of the mold opening and closing mechanism; The mold-clamping cylinder placed radially outward of the mechanical ram and fixedly supported by a base of an injection-molding machine; The mold interacting with the mold-clamping cylinder to be positioned radially inside the mold-clamping cylinder and radially outside of the mechanical ram to slide in the axial direction of the mold-clamping cylinder and to partition between the mold-clamping chambers. The mold-clamping ram of the clamping cylinder device; A positioning electric motor adapted to move the mold-clamping ram relative to the mold-clamping cylinder to position the mold-clamping ram relative to the mold-clamping cylinder in the axial direction of the mold-clamping cylinder; A hydraulic circuit is provided for fluid transport between the pressure-generating chamber of the pressure-generating cylinder device and the mold-clamping chamber of the mold-clamping cylinder device, and applies hydraulic pressure to the mold-clamping ram as a hydraulic driving force. The pressure-by the relative longitudinal motion of the first ball-screw shaft and the nut in accordance with the rotation of the first ball-screw shaft delivered to the mold-clamping chamber to create a hydraulic pressure in the mold-clamping chamber. A hydraulic system for accepting the hydraulic pressure generated in the production chamber; The hydraulic driving force applied between the mold-clamping ram of the mold-clamping cylinder device and the mechanical ram and applied to the mechanical ram with mold-clamping force to the mold-clamping ram of the mold-clamping cylinder device. A coupling device operative to engage the mold-clamping ram and the mechanical ram to each other; Mold-clamping device comprising a. The device of claim 1, wherein A plurality of pressure-generating cylinders, each of which is individually hollow cylindrical in shape, secured to the aft platen and laid about an extension of the center axis of the movable platen to extend parallel to the center axis of the movable platen; And the plurality of pressure-generating pistons slidably within the plurality of pressure-generating cylinders and the plurality of pressure-generating pistons partially defined by the outer circumferential surface of the hollow pressure-generating piston and in a direction away from the movable platen. A plurality of said pressure-generating cylinders having a volume reduced by the sliding motion of said pressure-generating piston of; Individually, placed about the central axis of the movable platen so as to extend parallel to the central axis and positioned through the bore of the plurality of pressure-generating pistons, so as not to move axially on the movable platen. A plurality of first ball-screw shafts fixed; A plurality of said mold-driven electric motors placed on said movable platen and adapted to individually rotate said first ball-screw shaft in forward and rearward directions; Individually, the plurality of first ball-nuts fixed to the plurality of pressure-generating pistons and screw-coupled to the plurality of first ball-screw shafts; Individually, a plurality of pressurization devices adapted to pressurize the pressure-generating piston of the pressure-generating cylinder device toward the movable platen in an axial direction; The mold-clamping cylinder, which is fixedly fixed to the rear platen so that the center axis of the mold-clamping cylinder is aligned with the center axis of the movable platen, the hollow clamp having a cylindrical shape slidable in the mold-clamping cylinder. The mold-clamping ram, and the mold- having a volume partially defined by the outer circumferential surface of the mold-clamping ram and reduced by the sliding motion of the mold-clamping ram in a direction away from the movable platen. The mold-clamping cylinder device including a clamping chamber; Operable to inhibit fluid transport to the pressure-generating chamber to securely position the pressure-generating position relative to the pressure-generating cylinder, such that the movable platen is coupled with the pressure-generating cylinder to open and close the mold. Fluid transport between the mold-clamping chamber and the pressure-generating chamber is allowed to allow sliding of the hydraulic-generating piston during movement by rotation of the first ball-screw shaft against the fixed rear platen. Actuated to allow the hydraulic pressure generated in the pressure-generating chamber by rotation of the first ball-screw shaft to be applied to the mold-clamping chamber of the mold-clamping cylinder device, thereby providing hydraulic driving force to the mold-clamping ram. Hydraulic device for applying; A mechanical ram fixedly mounted to the movable platen to protrude toward the trailing platen along the central axis of the movable platen and extending through the bore of the mold-clamping ram of the mold-clamping cylinder device; The mold being placed between the mold clamping ram and the mechanical ram of the mold-clamping cylinder device and applying the hydraulic driving force generated by the mold-clamping cylinder device to the mechanical ram with the mold-clamping force. The coupling device operable to engage the clamping ram and the mechanical ram against each other; And An ejector plate fixed to the movable plate, a second ball-screw shaft located in the bore of the hollow mechanical ram and fixed to the mechanical ram and the ejector, screwed to the second ball-screw shaft and A second ball-nut secured to the other mechanical ram and the ejector, and the second ball-screw shaft to generate relative longitudinal motion of the second ball-screw shaft and nut to drive the ejector; A ball-screw type electrically-operated ejector device comprising an ejecting electric motor adapted to rotate against each other of the nuts; Mold-clamping device comprising a. A sample mold having a thickness smaller than the fixed and used thickness and the mold obtained as a reference position of the movable platen and the reference position of the movable platen such that the fixed platen is moved to a mold-closed position Determining an axial position of the movable platen placed in the closed position; A reference position of the mold-clamping ram of the mold-clamping cylinder device in which the axial position of the mold-clamping ram relative to the mold-clamping cylinder is adjusted to ensure engagement of the first and second engageable protrusions; and Determining an adjusted axial position of the mold-clamping ram to be obtained at the reference position of the mold-clamping ram; And Based on the determined reference position of the movable platen, the axial position of the mold-clamping ram fixed to the used mold against the mold-clamping cylinder in the axial direction, and the movable platen fixed to the used mold Adjusting the determined reference position of the mold-clamping ram to ensure the engagement of the first and second engageable protrusions when held in this mold-closed position; The apparatus includes a plurality of first engageable protrusions formed in one mold-clamping ram and the movable platen such that the mold-clamping ram and the movable platen are spaced from each other at regular intervals in the direction of movement relative to each other. And a plurality of second engageable protrusions engageable with the first engageable protrusion, the other being formed on the mold-clamping ram and the movable platen and moving away from and toward the first engageable member. 18. A method for controlling mold clamping, characterized in that it controls the operation of the mold clamping device as defined in any one of claims 1 to 17, further comprising a coupling member. The method of claim 18, The first and second engageable protrusions at least by the axial distance corresponding to the increased axial distance between the rear and movable platens in accordance with the application of a mold-clamping force between the rear platen and the movable platen. -Retracting the mold-clamping cylinder in the axial direction such that it retracts from the full entry position of the clamping ram and engages with each other at the closest part to the mold-closed position of the mold-clamping ram when the used mold is fixed. And adjusting the axis position of the mold-clamping ram relative to the mold clamping device. The method of claim 18 or 19, Calculating a mold-thickness difference between the sample mold and the used mold; Obtaining a mold-closed position of the mold-clamping ram when the movable platen is fixed with the used mold based on the reference position of the movable platen and the mold-thickness difference; Obtaining a distance between the reference position of the mold-clamping ram of the mold-clamping cylinder device and the obtained mold-closed position; And Based on the distance obtained and the pitch of the first joinable protrusion, the mold-clamping ram of the mold-clamping cylinder against the mold-clamping cylinder of the mold-clamping cylinder device required to ensure engagement of the first and second joinable protrusions. Obtaining an adjustment amount of the axis position; Method for controlling the operation of the mold-clamping device comprising a. Controlling the output torque of the electric servomotor in a mold-clamping operation, based on a signal indicative of hydraulic pressure in the pressure-generating chamber of the pressure-generating cylinder device, The motor-driven electric motor for driving the first ball-screw shaft controls the operation of the mold-clamping device as defined in any one of claims 1 to 17, comprising an electric servomotor. -Clamping control method. Reducing the hydraulic pressure in the mold-clamping chamber by gradually reducing the value of the output torque of the electric servomotor to a predetermined value such that the hydraulic pressure is reduced in the mold-clamping chamber, The mold-driven electric motor for driving the first ball-screw shaft further comprises an electric servomotor, the method of controlling the operation of the mold clamping device as defined in any one of claims 1 to 17. . The mold- until the predetermined time period required for reducing the pressure in the mold-clamping chamber has passed, and at least one condition in which the pressure is reduced in the mold-clamping chamber is detected. Reducing the hydraulic pressure in the mold-clamping chamber by gradually or continuously changing the rotational speed of the electric servomotor in one direction to produce a reduction in the hydraulic pressure in the clamping chamber, wherein the mold-driven electric motor is 18. A method for controlling the operation of a mold-clamping device as defined in any of claims 1 to 17, comprising an electric servomotor for driving a first ball-screw shaft. 24. The pressure-generating piston as claimed in any of claims 21 to 23, wherein the device is defined in any of claims 2, 16 and 17 and with respect to the pressing force of the pressurization device applied. Controlling the output torque of the servomotor to take into account the forces generated in the mold-clamping device.