JPH0661835B2 - Vacuum, pressure and pressure control equipment for press molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pressure control device for controlling a stretch amount and force in a two-dimensional direction of a synthetic resin sheet when heating the synthetic resin sheet for vacuum, compressed air and press forming. Regarding

[Conventional technology]

Vacuum, pressure forming and press forming are performed by a heating step of heating and softening the synthetic resin sheet, and a forming step of bringing the synthetic resin sheet into close contact with a die by vacuum or pressure forming or pressing.

By the way, a molded product having a deep mold or a complicated shape may be obtained. In such a case, if a heated / softened sheet is suddenly formed, the part that was not stretched much may become thicker, or the part that is stretched more may become thinner, resulting in uneven product thickness. There were many

Therefore, conventionally, one side with a synthetic resin sheet as a boundary is made airtight, and after the heating step of heating and softening the synthetic resin sheet, the pressure of the airtight chamber is adjusted to inflate or dent the softened sheet. The method of forming the softened synthetic resin sheet into a shape close to the shape of the product by increasing the amount of stretching by adding a free blowing process such as

[Problems to be Solved by the Invention]

However, according to the conventional method, only one side is made airtight with the synthetic resin sheet as a boundary, and the combination of atmospheric pressure and pressurized air and atmospheric pressure and negative pressure air is used. Therefore, the sheet is molded, that is, the synthetic resin sheet is heated and softened. The elongation (wall thickness) was adjusted only by the degree of softening of the resin and the difference in air pressure. Therefore, in the conventional type, volume expansion occurs indefinitely when a certain temperature and a certain air pressure difference are exceeded, and it is extremely difficult to control the stretch amount and force of the sheet, and the die has a deep shape or a complicated shape. There was a limit to obtaining a product with a uniform thickness. Further, in the conventional molding, since the amount of stretch of the sheet cannot be controlled, the stretch could not be sufficiently performed, so that the material is limited to the thermoplastic resin, and the thermosetting resin and FRP, FRTP and a plurality of different resins are used. It was not possible to form a composite material such as a multi-layered sheet to which is added.

The present invention has been devised in view of the above points, and performs flow blowing while controlling the stretch amount and force of a synthetic resin sheet in a two-dimensional direction to form a mold having a deep mold or a complicated shape. It is an object of the present invention to provide a vacuum, compressed air, and pressure control device for press molding that can mold a product to a uniform wall thickness and expand the molding application range.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the present invention, upper and lower chambers partitioned by a synthetic resin sheet clamped at the approximate center of an airtight box, and a pipe with a valp of compressed gas of the same pressure in the upper and lower chambers. A pressure source that is pressure-fed through, a heating device that can be moved directly above and below the synthetic resin sheet, and a vacuum having a molding die that can be moved upward or downward in one or both of the upper and lower chambers, In a pressurized air and press molding apparatus, a primary chamber communicating with the upper chamber, a secondary chamber communicating with the lower chamber, a balance cylinder having a piston defining the secondary chamber, and a piston rod of the balance cylinder. It is characterized by comprising a connected servo motor and pressure control means for controlling the pressure of the upper and lower chambers by performing position control or speed control of the piston using the servo motor.

[Action]

In the above structure, compressed gas having the same pressure is pressure-fed to the upper and lower chambers to pressurize the synthetic resin sheet and heat the synthetic resin sheet by the heating device. Thereafter, the pressure control means controls the piston of the balance cylinder to control the pressures of the primary chamber and the secondary chamber, whereby the pressures of the upper and lower chambers are controlled. Using the pressure difference between the upper and lower chambers, the synthetic resin sheet 2
It is possible to perform free-blowing while controlling the stretching amount in the dimensional direction, and perform molding in which the thickness of the synthetic resin sheet is uniform.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. The drawings are cross-sectional explanatory views of the vacuum, compressed air and press molding apparatus of the present invention. FIG. 1 is an explanatory view showing a state before heating a synthetic resin sheet, and FIG. 2 is an explanatory view showing a state during heating. 3 is an explanatory view showing a state in which the balance cylinder is moved by numerically controlled external force, the lower chamber of the airtight box is made higher in pressure than the upper chamber, and the synthetic resin sheet is inflated to the upper chamber side. FIG. 4 is a female mold. , The plug is lowered, the balance cylinder is moved in the direction opposite to that shown in FIG. 3, the heating sheet is inverted inside the female mold cavity, and the inside of the female mold cavity is evacuated to bring the heating sheet into close contact with the cavity. It is explanatory drawing which shows the state which was opened.

In FIG. 1, 1 is an airtight box, 2 and 2'are clamps,
3, 3'is a heater. The both ends of the synthetic resin sheet 10 are fixed to clamps, and the airtight box 1 is partitioned into an upper chamber 11 and a lower chamber 12 at an intermediate position of the airtight box 1. Also,
A heater storage case 25 is disposed on the side of the synthetic resin sheet 10, and heaters 3 and 3'movable near the upper and lower sides of the synthetic resin sheet 10 for heating and softening the synthetic resin sheet 10.
Is stored.

A pipe 26 connected to the pressurized air source 4 via a control valve 6 is connected to the lower chamber 12. Also, the upper chamber 1
A pipe 15 is connected to the pipe 1 via a pipe 16 branched from the pipe 26, a control valve 5, and a pipe 27. Further, the lower chamber 12 is connected to the secondary chamber 14 defined by the piston 8 of the balance cylinder 7 via pipes 26, 16 and 16 '.

Further, the upper chamber 11 is a piston 8 of the balance cylinder 7.
To the primary chamber 13 similarly defined by
Connected through. The piston rods 9 and 9'of the balance cylinder 7 have the same diameter and are extended outside both ends of the cylinder 7.

A feed screw 23 is threaded on the extending portion on the piston rod 9'side, and a gear 28 with a nut screwed onto the feed screw 23 is rotated by a servomotor 29 via a gear 30 to form a piston rod 9 '. Is designed to reciprocate left and right.

The rotation amount of the servo motor 29 is output to the servo control unit 32 by a pre-programmed amount from the NC control unit 31, and is transmitted from the servo control unit 32 to the servo motor 29.

When the piston rod 9'reciprocates due to the rotation of the servo motor 29 and the position of the piston 8 of the balance cylinder 7 changes, the detection unit 33 attached to the other piston rod 9 detects the moving position and the moving speed. Feedback to the servo control unit 32.

On the other hand, in the lower chamber 12, a female die 19 of the forming die is provided so as to be vertically movable by a die moving device 17. Reference numeral 22 denotes a passage for discharging the air inside the cavity when the synthetic resin sheet 10 is pushed into the female mold 19 by the plug 20 described later, and penetrates the center of the mold moving device 17 and is connected to a vacuum source (not shown). It continues to line 21. Further, a plug 20 is provided in the upper chamber 11 so as to be vertically movable by a mold moving device 18.

Next, the operation will be described.

As shown in FIG. 1, the synthetic resin sheet 10 is clamped 2,
It is fixed to 2 ', the control valves 5 and 6 are set to the open position, and pressurized air is sent from the pressurized air source to the upper chamber 11 and the lower chamber 12. Next, the control valves 5 and 6 are set to the closed position, and as shown in FIG.
The heaters 3 and 3 ′ are moved from above the heater storage case 25 to directly above and below the synthetic resin sheet 10 to heat them. Of course, in this state, the piston 8 of the balance cylinder 7 is in the neutral stop state. When the seat 10 reaches an appropriate temperature, the heater 3,
3'is returned to the heater storage case 25.

Next, as shown in FIG. 3, the piston rod 9'of the balance cylinder 7 is moved by the servomotor 29 by a moving amount programmed in advance according to the degree of heating and softening of the material of the sheet.
Is rotated to move the piston 8 in the direction of the arrow. When the piston 8 is moved in the direction of the arrow, the secondary chamber 14 inside the cylinder 7 is pressurized, the lower chamber 12 of the airtight box 1 is also pressurized, and the softened sheet 10 moves upward as shown in FIG. Swell.

At this time, the air pressure in the upper chamber 11 in the airtight box 1 also rises,
Since it is connected to the primary chamber 13 in the cylinder 7 through the pipes 15 and 15 ', the movement of the piston 8 causes the primary chamber 13 to move.
Finally, the upper chamber 11 of the airtight box and the primary chamber 13 of the cylinder 7 and the lower chamber 12 of the airtight box and the secondary chamber of the cylinder 7 have the same pressure. That is, by controlling the movement of the piston rod 9 ', free blowing is performed and the amount and force of stretching the seats 10, 10' in the two-dimensional direction are NC.
It can be numerically controlled by the device.

In the present invention, the piston rod of the balance cylinder is connected to the servomotor and the position of the piston is numerically controlled by the NC device. However, as shown in FIG. 5, the piston rod 9'is replaced with the servomotor 29. Alternatively, the position of the piston may be position-controlled or speed-controlled by the dock 37 and the limit switches 35 and 36 by connecting with a drive source such as the cylinder 29 '.

Next, the female die 19 is raised by the die moving device 17, and the plug 20 is lowered by the upper die moving device 18.
At the same time, the piston 8 of the balance cylinder 7 is moved in the direction opposite to the arrow in FIG. Then, the heating sheet 10 'is inverted inside the cavity of the female die 19, and the system path 21
By making the vacuum of (2), the air inside the cavity is discharged through the passage 22 and the sheet 10 'comes into close contact with the cavity and is cured.

Next, by sending pressurized air to the system path 21, the molded sheet is released from the mold, and the molding is completed.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and embodiments can be made without departing from the spirit of the invention.

〔The invention's effect〕

As described above, according to the pressure control device for vacuum, compressed air and press molding of the present invention, a secondary chamber communicating with the upper chamber of the airtight box and the secondary chamber communicating with the lower chamber of the airtight box, outside the airtight box. A balance cylinder having a piston defining a chamber is provided, the piston rod of the balance cylinder is connected to a drive source such as a servomotor, and the piston position is numerically controlled by an NC device, or position control or speed control is performed by switches. Therefore, it is possible to perform free-blowing while controlling the stretch amount (including the wall thickness) and the force (pressure) of the synthetic resin sheet in the two-dimensional direction, and perform molding with a uniform wall thickness. Also, unlike conventional molding, the optimum blow speed can be controlled even with a high blow pressure in the initial stage of stretching after heating the sheet, so large items such as thermosetting sheets and FRP can be controlled.
Composite materials such as FRTP and multi-layer sheets with different resins added can also be molded, and the applicable range of molding can be greatly expanded.

[Brief description of drawings]

The drawings (FIGS. 1 to 4) show a vacuum of one embodiment of the present invention,
FIG. 1 is a cross-sectional explanatory view of a compressed air and press molding apparatus, FIG. 1 is an explanatory view showing a state before heating of a synthetic resin sheet, FIG. 2 is an explanatory view showing a state during heating, and FIG. 3 is also an inflated state. FIG. 4 is an explanatory view showing that a female cavity is closely attached, and FIG. 5 is another embodiment in which the piston rod of the balance cylinder is connected to another cylinder and the position is controlled by a limit switch. It is an explanatory view showing a state. 1 ... Airtight box, 2, 2 '... Clamp 3, 3' ... Heater, 4 ... Pressurized air source 5, 6 ... Control valve, 7 ... Balance cylinder 8 ... Piston 9, 9 '... ... Piston rod 10 ... Synthetic resin sheet, 11 ... Upper chamber 12 ... Lower chamber, 13 ... Primary chamber 14 ... Secondary chamber, 19 ... Female 20 ... Plug, 21 ... System path 22 ... ... passage, 23 ... feed screw 29 ... servo motor, 31 ... NC control unit 32 ... servo control unit, 33 ... detection unit

Claims (1)

[Claims] 1. An upper chamber and a lower chamber which are partitioned by a synthetic resin sheet which is clamped substantially in the center of an airtight box, and a pressure source which sends a compressed gas of the same pressure to the upper and lower chambers through a pipe with a valve. , A vacuum, pressure air and press molding apparatus having a heating device movable directly above and below the synthetic resin sheet, and a molding die provided in one or both of the upper and lower chambers so as to be movable upward or downward, A primary chamber communicating with the upper chamber, a secondary chamber communicating with the lower chamber, a balance cylinder having a piston defining the secondary chamber, a servomotor connected to a piston rod of the balance cylinder, Pressure control means for controlling the position or speed of the piston by using a servo motor and controlling the pressure of the upper and lower chambers. apparatus.