JP2006167788A

JP2006167788A - Press forming apparatus

Info

Publication number: JP2006167788A
Application number: JP2004367021A
Authority: JP
Inventors: Koji Mitsuyoshi; 宏治三吉
Original assignee: Komatsu Ltd; Komatsu Sanki Kk; コマツ産機株式会社; 株式会社小松製作所
Priority date: 2004-12-20
Filing date: 2004-12-20
Publication date: 2006-06-29
Also published as: CN1799808A; TW200626336A; CN1799808B; TWI322076B; KR20060070438A

Abstract

<P>PROBLEM TO BE SOLVED: To perform thermal transfer press forming at high speed with high accuracy by using a motor driven servo press. <P>SOLUTION: The press forming apparatus 1 is equipped with a stamper for press forming, a temperature control plate for heating and cooling the stamper, servo motors 11, 11 for moving the stamper and a controller 17 for driving the servo motors 11. The controller 17 moves the stamper by position control up to the position just before the stamper is touched with the surface of a thermoplastic working object by the servo motors 11, and thereafter, when the stamper is heated by the temperature control panel up to the temperature at which the working object can be plastically deformed, the servo motors 11 are driven by press force control to press the stamper to the working object 2, thereby conducting press forming. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an apparatus for press-molding a thermoplastic workpiece, and more particularly to a press-forming apparatus using a servo motor.

For example, as in Patent Documents 1 and 2, an apparatus that performs thermal transfer press molding of a fine pattern using a thermoplastic resin as a material is known. This press molding apparatus is used, for example, for manufacturing a light guide plate made of a thermoplastic resin used in a liquid crystal display panel. In these press molding apparatuses, a hydraulic press is generally used.
JP 2003-1705 A JP 2004-102106 A

However, if a hydraulic press is used to mold the stamper with a fine pattern against the surface of the thermoplastic resin plate and transfer the pattern onto the surface of the thermoplastic resin plate, the moving speed of the slide with the stamper attached is slow. It is difficult to increase production speed. Further, fine molding such as transfer molding of a fine pattern is often performed in a clean room, and use of a hydraulic press using oil is not preferable.

On the other hand, when an electric servo press using a servo motor is used, the above problems are solved, but the following problems are newly generated. That is, when slide control is performed using high-precision position control, the transferred pattern has 5 to 25 μm in unevenness, but the thermoplastic resin (for example, acrylic, polymethyl methacrylate, polycarbonate, etc.) ) Since the plate thickness variation is about 50 μm, the pattern transfer is incomplete due to the material thickness variation.

In thermal transfer press molding, a stamper heated above the softening temperature of a thermoplastic resin is pressed against the surface of the thermoplastic resin to transfer the pattern, and then the stamper is kept pressed against the surface of the thermoplastic resin. It is necessary to cool the stamper until the temperature becomes equal to or lower than the softening temperature of the thermoplastic resin, and to freeze the shape of the pattern transferred to the surface of the thermoplastic resin. However, when the stamper is cooled, if the slide is held at a predetermined position by position control, the die attached with the stamper changes in size due to thermal shrinkage as it cools, and the pressing pressure of the stamper on the thermoplastic resin plate May decrease and transfer defects (untransferred or wrinkle patterns) may occur.

On the other hand, when the stamper is pressed so as not to cause the transfer failure as described above, the surface of the thermoplastic resin plate is firmly attached to the stamper. If the thermoplastic resin plate molded with the stamper is forcibly released in this state, there arises a problem that the stamper is peeled off from the slide side or the transferred pattern shape is deformed.

Therefore, an object of the present invention is to provide a technique for performing thermal transfer press molding at high speed and with high accuracy using an electric servo press.

Another object of the present invention is to provide a technique for easily releasing the workpiece from the stamper without destroying the pattern transferred to the workpiece surface after the thermal transfer press molding.

A press molding apparatus according to an embodiment of the present invention includes a stamper for press-molding a thermoplastic workpiece, a temperature adjusting unit for heating and cooling the stamper, and the stamper for the workpiece. And a controller for driving the electric motor, and a press molding apparatus including a motor that generates power for pressing and approaching and moving relatively. The controller causes the stamper to approach the position immediately before contacting the surface of the workpiece by position control, and then the stamper is heated to a temperature at which the workpiece can be thermally deformed by the temperature adjustment unit. If it is, the electric motor is driven by pressure control to press the stamper against the object to be pressed.

In a preferred embodiment, when a predetermined time elapses with the stamper being pressed against the workpiece at the heat-deformable temperature, the temperature adjusting unit is controlled by the stamper while the controller continues to perform the pressure control. You may make it cool.

In a preferred embodiment, after the workpiece formed by the press molding is released from the stamper, the controller drives the electric motor so as to separate the stamper from the workpiece by position control. You may do it.

In a preferred embodiment, the controller drives the electric motor so as to press the stamper against the workpiece with a first pressurizing force capable of being press-molded at the heat-deformable temperature in the pressurizing control. Then, the electric motor can be driven so as to press the stamper with a second pressing force smaller than the first pressing force while cooling the stamper with the temperature adjusting unit.

In a preferred embodiment, the apparatus further includes a blower for blowing an air blow to a contact surface between the workpiece and the stamper. In the pressurization control, the controller drives the servo motor so as to press the stamper against the workpiece with the second pressurizing force for a predetermined time, and then the pressurization force on the workpiece is The blower may be controlled to be zero, and when the pressure is zero, the blower may blow out an air blow to a contact surface between the workpiece and the stamper.

In a preferred embodiment, when the stamper is in a position immediately before contacting the surface of the workpiece, a vacuum chamber is formed in which the stamper and the workpiece are housed. Furthermore, the press molding apparatus includes a pressure sensor that detects a pressure in the vacuum chamber. The controller may drive the servo motor to press the stamper against the workpiece when the pressure in the vacuum chamber detected by the pressure sensor becomes a predetermined value or less.

Hereinafter, a press molding apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a press forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the press molding apparatus 1 includes a press unit 30 that presses the workpiece 2 and a configuration for controlling the press unit 30. The configuration for controlling the press unit 30 includes servo motors 11 and 11 that are electric motors for moving the slide 21 up and down, and a power conversion mechanism (pulley) that converts rotation of the servo motors 11 and 11 into linear motion of the slide 21. 12, 12, timing belts 13 and 13, ball screws 14 and 14), and a controller 17 for driving the servo motors 11 and 11. The controller 17 outputs a control signal for driving the servo motors 11 and 11 by position control based on the outputs of the slide position detecting means 23 and 23, and based on the outputs of the pressure detection means 24 and 24, A control signal for driving the servo motors 11 and 11 is output by pressure control. Details of the control signal output by the controller 17 will be described later. When the servo amplifiers 16 and 16 receive a control signal from the controller 17, the current output to the servo motors 11 and 11 is controlled based on the control signal and the outputs of the encoders 15 and 15. That is, the servo motor 11 operates in accordance with an instruction from the controller 17, and a stamper (described later) attached to the slide 21 approaches and separates from the workpiece 2. Further, the stamper is pressed against the workpiece 2 according to an instruction from the controller 17, and the workpiece 2 is press-molded.

FIG. 2 is a cross-sectional view illustrating a detailed configuration of the press unit 30. The press unit 30 includes an upper case 31 coupled to the slide 21 and a lower case 32 coupled to the bolster 22. As the slide 21 moves up and down, the upper case 31 moves up and down. And the vacuum packing 39, 39, 39, 39 is attached to the part which the upper case 31 and the lower case 32 contact, respectively. When the upper packing 31 is lowered and the vacuum packings 39 and 39 attached to the upper case 31 come into contact with the vacuum packings 39 and 39 attached to the lower case 32, the inside of the upper case 31 and the lower case 32 A sealed space (vacuum chamber) is formed.

The upper case 31 includes blowers 41 and 41 that generate an air blow, and nozzles 42 and 42 that blow out the air blow. This air blow is blown near the contact surface between the stamper 35 and the workpiece 2 in order to release the workpiece 2 from the stamper 35 after press molding. The timing of blowing the air blow will be described later.

The lower case 32 is provided with a vacuum suction port 37. When air is sucked by the pump 40, the inside of the vacuum chamber can be evacuated or decompressed. The lower case 32 is attached with a pressure sensor 36 for detecting the pressure in the vacuum chamber.

Inside each of the upper case 31 and the lower case 32, heat insulating plates 33, 33, plate-like temperature control containers (hereinafter referred to as temperature control plates) 34, 34, and a predetermined uneven pattern are formed from the outside to the inside. The stampers 35 and 35 for transferring the material to the workpiece 2 are stacked in this order. The temperature control plates 34, 34 are provided with temperature sensors 38, 38 for detecting the temperature of the temperature control plate.

The temperature control plates 34, 34 are provided with flow paths through which fluid such as liquid or gas flows. The stampers 35 and 35 are heated and cooled by flowing a fluid having a predetermined temperature through the flow path. At this time, the controller 17 can determine the heating temperature and the cooling temperature of the temperature adjustment plates 34, 34 by controlling the temperature of the fluid flowing through the flow paths in the temperature adjustment plates 34, 34.

As described above, the temperature adjustment unit includes the temperature adjustment plates 34 and 34 and the temperature sensors 38 and 38. Further, preferably, a heat insulating plate 33 is further provided.

The workpiece 2 is a plate made of a thermoplastic resin, for example, a light guide plate made of acrylic or polycarbonate. Each of the stampers 35 and 35 is a thin film having a thickness of about 0.2 to 0.5 mm made of nickel having, for example, an uneven shape to be formed on the surface of the light guide plate.

Next, 1 cycle of operation | movement of the press molding apparatus 1 which concerns on this embodiment is demonstrated using FIGS. FIG. 3 is a diagram showing a temporal change in the slide position in the vertical direction in one cycle of the press molding apparatus. FIG. 4 is a time table regarding main operations of the press molding apparatus in one cycle. FIG. 5 is a diagram schematically showing the behavior of the pressing unit 30 in one cycle. 6 to 8 are flowcharts showing an operation in one cycle.

First, with the slide 21 stopped at the upper limit position (A), heating of the temperature control plates 34 and 34 is started (af). The heating temperature at this time is a temperature at which the workpiece 2 can be thermally deformed. At this time, as shown in FIG. 4, the control of the slide motion by the controller 17 or the like is performed by position control (ad) (S101, 102).

In this state, the workpiece 2 is carried into the press unit 30 (b). At this time, the workpiece 2 may be placed at a predetermined position on the lower stamper 35, or the workpiece 2 is held so as not to contact the stampers 35, 35 by a holding device for the workpiece not shown. (S103).

When the workpiece 2 is carried into the press unit 30, a workpiece detection means (not shown) confirms that the workpiece 2 is in a predetermined position (B). Then, the controller 17 outputs a control command for lowering the slide 21 at a high speed (c). That is, the servo amplifiers 16 and 16 control the current output to the servomotors 11 and 11 based on the control command from the controller 17, and control the rotation direction and speed of the servomotors 11 and 11. At this time, the controller 17 outputs a control command so that the current slide position output by the slide position detection means 23 and the slide standby position, which is the target position for position control, coincide. Here, the slide standby position is a position immediately before the upper and lower cases 31 and 32 are closed and the upper stamper 35 contacts the surface of the workpiece 2 (S104, 105).

When the slide 21 is lowered to the standby position (C), a vacuum chamber is formed inside the upper and lower cases 31 and 32, and thus vacuuming is started by the pump 40 through the vacuum suction port 37 (d to f) ( S106).

Here, the controller 17 measures the air pressure in the vacuum chamber by the output of the pressure sensor 36 and the temperature of the temperature adjustment plate 34 by the output of the temperature sensor 38. When the air pressure in the vacuum chamber reaches a predetermined air pressure required for thermal transfer molding and the temperature of the temperature adjustment plate 34 reaches a predetermined temperature required for transfer molding (S107), the controller 17 performs a slide motion. Switch to pressure control (eh). That is, the controller 17 outputs a control command for the servo motors 11 and 11 so that the pressure applied to the slide 21 obtained by the pressure detection means 24 becomes a predetermined pressure. As a result, the slide 21 is lowered and thermal transfer molding is performed on the workpiece 2 by the stamper 35 (e) (S110).

If the temperature of the temperature control plates 34 and 34 and the degree of vacuum in the vacuum chamber do not reach the predetermined values within a predetermined time from the time when the slide 21 reaches the standby position, the press molding apparatus 1 is stopped. It may be made (S108).

Here, in the case of a multi-point press molding apparatus provided with a plurality of servo motors 11 for driving the slide 21, the applied pressure of the slide 21 obtained by the applied pressure detecting means 23 is obtained as a total applied pressure applied to the entire slide. . On the other hand, the position of the slide 21 when the slide 21 is moved up and down is independently detected for each point by the slide position detecting means 23 provided in the vicinity of each point. Even when the slide is moved up and down by the pressure control so that the pressure of the slide 21 becomes the set pressure (sections e to h), the slide is moved based on the slide position information for each point. The rotation of the servo motor at each point is independently controlled so that the parallelism of the lower surface is maintained. Therefore, even when a large number of servo motors 11 are attached and molded by a single press molding apparatus as in the present embodiment, the parallelism of the molding surface of the molded product regardless of variations in the thickness of the workpiece 2. Is preserved. Furthermore, even in the case of multi-cavity molding in which a plurality of workpieces are molded at the same time, the parallelism of the molding surface of the molded product is maintained regardless of variations in the plate thickness between the workpieces.

When controlling the pressure of the slide 21, it is always checked whether the position of the slide 21 is within the range from the predetermined lower limit position to the upper limit position. If the slide 21 is out of this range, the press molding apparatus 1 is stopped. It may be. Here, the upper limit position (top dead center) of the slide 21 is set to a height at which the material and the molded product can be easily carried in and out, and the lower limit position of the slide 21 is set to a height at which the upper and lower stampers do not touch and break. Set (S111).

While the pressure control is being performed, the controller 17 monitors the pressure based on the output of the pressure detection means 24. Then, the pressing force is increased so that the pressing force of the slide 21 becomes a predetermined transfer pressing force necessary for the thermal transfer molding (e). When the pressing force reaches the transfer pressing force (D), the controller 17 controls the pressing force so that the pressing force of the slide 21 is held at the transfer pressing force for a predetermined holding time (f). This holding time is set in order to improve the transfer accuracy. Therefore, if there is no problem in transfer accuracy, the holding time may be zero (S113, S114).

When the transfer with the transfer pressure is held for the holding time, cooling of the temperature control plate 34 is started and the vacuum chamber is opened to the atmosphere (g to j) (S115, 116). Then, the controller 17 outputs a control command so that the pressing force of the slide 21 measured by the output of the pressing force detection means 24 becomes a predetermined holding pressing force. At this time, since the holding pressure may be smaller than the transfer pressure, the slide 21 slightly rises (E) (S117). The holding pressure may be, for example, about 1/4 to 1/2 of the transfer pressure. By setting the holding pressure to be smaller than the transfer pressure, the power consumption of the servo motor can be reduced, the maximum pressurization capacity of the press molding apparatus 1 can be reduced, and the equipment cost can be reduced.

While pressurizing with the holding pressure, the controller 17 monitors the pressure in the vacuum chamber based on the output of the pressure sensor 36, and monitors the temperature of the temperature adjustment plate 34 based on the output of the temperature sensor 38. (S118-S122). Then, when the pressure in the vacuum chamber becomes atmospheric pressure and the temperature of the temperature control plate 34 becomes a temperature suitable for release, at this time, the release of the workpiece 2 formed from the stampers 35 and 35 is performed. In order to promote, the air blow which the blowers 41 and 41 generate | occur | produce is blown through the nozzles 42 and 42 in the vicinity of the contact surface of the stampers 35 and 35 and the workpiece 2 (h) (S123). By this air blow, air enters between the workpiece 2 and the stampers 35 and 35, and it becomes easy to release. In addition, since the temperature of the workpiece 2 and the stampers 35 and 35 is slightly lowered by the air blow, the workpiece 2 contracts at this moment, and air easily enters the stamper 35.

When the air blow is blown out, the controller 17 controls the slide 21 so that the pressure applied to the slide 21 becomes zero based on the output of the pressure detection means 24. As a result, the slide 21 rises, and the pressing force becomes zero, or a slight gap is created between the workpiece 2 and the stampers 35 and 35 (F) (S124 to S128).

By promoting the release using air blow, the workpiece 2 and the stamper 35 can be released at a higher temperature, and the cooling temperature of the stamper 35 can be set higher. That is, for example, when the workpiece 2 is an acrylic plate, the acrylic plate is cured and molding is completed by cooling to a temperature slightly lower than the softening temperature at which heat deformation is possible (for example, about 80 ° C.). Difficult to release. On the other hand, when it is cooled to a temperature lower than the softening temperature (for example, about 60 ° C.), it can be easily released, but it is not preferable in consideration of reheating to process the next workpiece. These problems are solved by air blow.

As described above, the cooling temperature of the stamper 35 can be set to a temperature slightly lower than the softening temperature of the workpiece by air blowing. As a result, the temperature difference between the heating temperature and the cooling temperature of the stamper 35 can be reduced, the time required for temperature rise and cooling of the temperature control plate can be shortened, and productivity can be improved. In addition, the amount of heat required for temperature increase is reduced, and the running cost for temperature control of the stamper can be reduced.

When it is confirmed by the detection means (not shown) that the workpiece 2 has been released from the stampers 35, 35, the air blow is finished, and the controller 17 converts the slide motion into position control and raises the slide 21 to the upper limit of the slide at a high speed. To stop (i, G). Then, the molded workpiece 2 is unloaded from the press unit 30 (j). Here, when the removal of the workpiece 2 is confirmed, one cycle is completed (H) (S129 to S133).

According to this embodiment, since it is a press molding apparatus using an electric servo motor, it is suitable for use in a clean room, and at the same time, it is possible to improve both the production speed and the quality of the molded product.

Further, when the electric servo motor is used, the slide moving speed is fast, so that productivity is not lowered even if the slide moving distance (stroke length) is increased. And if the stroke length of a slide is lengthened, interlock | cooperation with the automation apparatus of material carrying in / out will become easy, and also productivity will improve.

The above-described embodiments of the present invention are examples for explaining the present invention, and are not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the present invention in various other modes without departing from the gist of the present invention.

For example, the promotion of mold release by air blow can also be used in a press molding apparatus using a hydraulic press.

1 is a diagram illustrating a schematic configuration of a press molding apparatus 1 according to an embodiment of the present invention. 3 is a cross-sectional view showing a detailed configuration of a press unit 30. FIG. It is a figure which shows the time change of the slide position of the up-down direction in 1 period of a press molding apparatus. It is a timetable regarding main operation | movement of the press molding apparatus in 1 period. It is a figure which shows typically the mode of operation | movement of 1 period of the press part. It is a flowchart (1) which shows operation | movement of a press molding apparatus. It is a flowchart (2) which shows operation | movement of a press molding apparatus. It is a flowchart (3) which shows operation | movement of a press molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Press molding apparatus 2 Work object 11 Servo motor 12 Pulley 13 Timing belt 14 Ball screw 15 Encoder 16 Servo amplifier 17 Controller 21 Slide 22 Bolster 23 Slide position detection means 23 Pressure detection means 24 Pressure detection means 30 Press part 31 Top Case 32 Lower case 33 Heat insulating plate 34 Temperature control plate 35 Stamper 36 Pressure sensor 37 Vacuum suction port 38 Temperature sensor 39 Vacuum packing 40 Pump 41 Blower 42 Nozzle

Claims

A stamper for press-molding a thermoplastic workpiece,
A temperature control unit for heating and cooling the stamper;
An electric motor for generating power for moving the stamper relative to and away from the workpiece and pressing the stamper;
A press molding apparatus comprising a controller for driving the electric motor,
The controller causes the stamper to approach the position immediately before contacting the surface of the workpiece by position control, and then the stamper is heated to a temperature at which the workpiece can be thermally deformed by the temperature adjustment unit. A press molding apparatus that presses the stamper against the workpiece to perform press molding by driving the electric motor under pressure control.
When a predetermined time elapses while the stamper is pressed against the workpiece at the heat-deformable temperature,
The press molding apparatus according to claim 1, wherein the temperature adjusting unit cools the stamper while the controller continues to control the pressure.
The said controller drives the said motor so that the said stamper may be separated from the said workpiece by position control after the said workpiece formed by the said press molding was released from the said stamper. Press molding equipment.
The controller drives the electric motor so as to press the stamper against the workpiece with a first pressurizing force capable of press-molding the stamper at the heat-deformable temperature in the pressurizing control, and then the temperature The press molding apparatus according to claim 1, wherein the electric motor is driven so as to press the stamper with a second pressurizing force smaller than the first pressurizing force while cooling the stamper by the adjusting unit.
A blower for blowing out air blow to the contact surface between the workpiece and the stamper;
In the pressurizing force control, the controller drives the electric motor so as to press the stamper against the workpiece with the second pressurizing force for a predetermined time, and then the pressurizing force on the workpiece becomes zero. To control and
The press molding apparatus according to claim 4, wherein when the pressure is zero, the blower blows air blow to a contact surface between the workpiece and the stamper.
When the stamper is in a position immediately before contacting the surface of the workpiece, a vacuum chamber is formed in which the stamper and the workpiece are housed.
The press molding apparatus further includes a pressure sensor for detecting the pressure in the vacuum chamber,
2. The press molding apparatus according to claim 1, wherein the controller drives the electric motor to press the stamper against the workpiece when a pressure in the vacuum chamber detected by the pressure sensor becomes a predetermined value or less.