JPH06182867A - Vacuum molding machine - Google Patents

Abstract

PURPOSE:To improve a thermal efficiency at the time of heating a plastic plate and to manufacture a safely molded form having stable quality by providing a bearer for receiving the plate to be processed by an upper support surface than a hot air diffuser. CONSTITUTION:The air is not supplied to an interior surrounded by a peripheral wall of a bearer 1 at an initial time of an operation but the air is circulated by a fan 14 while gradually heating the air between upper, lower cavities 6a, 6b and a heat supply duct 12 by a heater 13. In this case, a connection hole 7 is opened, a hot air suction port 8 of a lower end of the lower cavity 6b is closed by a switching valve 10. Since a discharging pressure from a hot air diffuser 2 of an upper end of the bearer 1 is set to a higher value than that of the hole 7, the air fed by the fan 14 is not discharged from the diffuser 2 but circulated between the cavities 6a, 6b and the duct 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum forming machine for forming a thermoplastic plastic plate in a softened state by heating.

[0002]

2. Description of the Related Art Conventionally, there has been widely known a method of heating and softening a thermoplastic plastic plate and adsorbing the softened plastic plate to a mold by using a vacuum pump or the like to form the plastic plate into a required shape.

As a concrete method known in the prior art, a method or a heater (heater) in which a plastic plate is put in a heating furnace to be softened, the softened plastic plate is taken out of the heating furnace and molded by a mold is used. There is a method of heat-molding a plastic plate with a built-in molding machine.

In the former method, since the softened plastic plate is taken out from the heating furnace and then molded by the mold,
There was a problem that the plastic plate was cooled during the transfer from the heating furnace to the mold, and the molding by the mold could not be performed sufficiently. Further, in the latter method, the heater (heater) for heating the plastic plate is located above the plastic plate and heats the plastic plate from above, so that the heat from the heater (heater) easily escapes upward, The plate could not be heated efficiently. Therefore, it is possible to position the heater (heater) below the plastic plate to efficiently heat the plastic plate, but there is a risk that ignition will occur if the softened plastic plate hangs down and comes into contact with the heater (heater). There is.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve such problems, and it is an object of the present invention to improve the thermal efficiency when heating a plastic plate and to manufacture a safe and stable molded product. It is intended.

[0006]

In order to solve this problem, the present invention is characterized in that hot air outlets are formed in the upper end at appropriate intervals in the circumferential direction and are rectangular in plan view, and the inside of the peripheral wall is formed in a hollow shape. A pedestal that receives the plastic plate to be processed on the receiving surface above the hot air outlet, a hot air supply duct that supplies hot air from a hot air source to the pedestal, and an internal space surrounded by the peripheral wall of the pedestal In (1), there is provided a mold having a means capable of moving up and down and vacuum suctioning the plastic plate to be processed, and an elevating device for mounting and elevating the mold.

[0007]

With this configuration, since the plastic plate to be processed is heated by the hot air from below, the heat efficiency is improved as compared with the case of heating from above, and the heat of the heater is not directly applied to the plastic plate to be processed, but as hot air. Since it is applied, it is possible to manufacture a safe and stable molded product.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 3, 1 is a pedestal having hot air blowing ports 2 formed at appropriate intervals in the circumferential direction at the upper end to receive the outer peripheral lower surface of a plastic plate 3 to be processed, which has a rectangular shape in plan view and a hollow inner peripheral wall. The hot air supplied from the hot air supply port 4 formed at one location on the upper end of the outer wall reaches the entire inner wall of the cavity.
A peripheral wall having a hollow inside is partitioned at an intermediate portion in the vertical direction. Reference numeral 5 is a partition plate for partitioning the inner cavity of the peripheral wall, 6a and 6b are upper and lower cavity portions partitioned by the partition plate 5, and 7 is a communication hole formed in the partition plate 5 at an intermediate portion of each side of the pedestal 1. , 8 are hot air suction ports formed directly below the communication hole 7 at the lower end of the lower cavity 6b. By the way, the hot air supply port 4 has an upper cavity 6
A hot air discharge port 9 is formed on the outer wall of a and the outer wall of the lower cavity 6b. 10 is the lower cavity 6b
Moving up and down inside the communication hole 7 and hot air suction port 8
Is an open / close valve that selectively opens and closes the lower cavity 6b.
It is moved up and down by a cylinder device 11 provided on the lower side. Specifically, the hot air suction port 8 is open when the communication hole 7 is closed, and the communication hole 7 is open when the hot air suction port 8 is closed. This operation is synchronized with the communication hole 7 and the hot air suction port 8 on each side. Reference numeral 12 denotes a hot air supply duct, one end of which is connected to the hot air supply port 4 outside the pedestal 1 and the other end of which is connected to the hot air discharge port 9. Inside the hot air supply duct 12, a heater 13 and air are blown. A fan 14 is provided. Reference numeral 15 denotes a guide which is directed at the upper end of the pedestal 1 against the hot air blown out from the hot air outlet 2 and is guided obliquely inward, and a horizontal receiving surface 16 is formed on the upper side of the guide 15 to form the plastic to be processed. It is configured to receive the plate 3 in a horizontal state. Reference numeral 17 denotes a support frame sandwiched between the outer peripheral upper surface of the plastic plate 3 to be processed placed on the receiving surface 16 and the receiving surface 16.
The support frame 17 is opened and closed by a handle (not shown), and the state in which the support frame 17 is closed and the plastic plate 3 to be processed is sandwiched is held by a lock means (not shown). Reference numeral 18 is a cover wall surrounding the peripheral wall of the pedestal 1, and the upper end of the cover wall 18 is the receiving surface.
16 and the lower end projects below the pedestal 1.
Reference numeral 19 denotes a molding mold that is located inside the pedestal 1 and enters from the lower end of the pedestal 1. The mold 19 is received by a pantograph-type lifting device 20. Further, the mold 19 is provided with means for vacuum-sucking the plastic plate 3 to be processed at the time of molding. Reference numeral 21 is a base for supporting the lower end of the pantograph type lifting device 20, and is provided so as to close the opening at the lower end of the cover wall 18.

The operation of the vacuum forming machine having the above structure will be described step by step. First, in the initial stage of operation, air is not blown into the inside surrounded by the peripheral wall of the pedestal 1, and the upper and lower cavities 6 are
A heater 13 is provided for supplying air between a and 6b and the hot air supply duct 12.
The air is circulated by the blower fan 14 while being gradually heated by. At this time, the communication hole 7 is opened, the hot air inlet 8 at the lower end of the lower cavity 6b is closed by the opening / closing valve 10, and the hot air outlet 2 at the upper end of the pedestal 1 is opened.
Since the discharge pressure from the blower fan 14 is set to be higher than that of the communication hole 7, the air blown by the blower fan 14 does not come out from the hot air blowout port 2 but between the cavities 6a and 6b and the hot air supply duct 12. Circulate. In this way, when the temperature of the air flowing between the cavities 6a, 6b and the hot air supply duct 12 reaches a predetermined value, the thermoplastic work plastic plate 3 is placed on the receiving surface 16 of the pedestal 1. Set. In this state, the hot air suction port 8 is opened and the communication hole 7 is closed by the opening / closing valve 10. As a result, the hot air that has entered the upper hollow portion 6a from the hot air supply port 4 is discharged from the hot air blowing port 2, hits the guide 15 and is guided obliquely inward, and heats the plastic plate 3 to be processed. At the same time, the temperature in the internal space surrounded by the peripheral wall of the pedestal 1 also rises, which accelerates the heating of the plastic plate 3 to be processed. At this time, the base 21 may cover the cover wall 18
Is closed at its lower end, and the hot air discharged from the hot air outlet 2 and hitting the plastic plate 3 to be processed covers the wall 18
Without escaping from the lower end of the hot air suction port 8, the hot air is introduced into the hot air supply duct 12, heated again by the heater 13, and then discharged from the hot air blowing port 2. When the plastic plate 3 to be processed is heated and softened to a state required for molding by the mold 19, the hot air suction port 8 is closed by the opening / closing valve 10 and the communication hole 7 is opened, and the upper and lower cavities 6a, 6b
Air is circulated between the hot air supply duct 12 and the hot air supply duct 12 to stop the discharge of hot air from the hot air outlet 2. In this state, when the pantograph-type lifting device 20 is lifted to lift the mold 19, the heated air in the internal space surrounded by the peripheral wall of the pedestal 1 is pushed up, and the pushed air causes the plastic to be processed. The part of the plate 3 excluding the outer periphery bulges while being extended upward with a uniform thickness (see FIG. 3 (a)), and the mold 19 further rises to contact the plastic plate 3 to be processed (see FIG. 3 (B)). . In this state, the plastic plate 3 to be processed is sucked by the vacuum suction means of the mold 19 to form the plastic plate 3 to be processed (see FIG. 3C). It should be noted that since the heated air exists below the plastic plate 3 to be processed during the molding by the mold 19, and the mold 19 itself is also in a heated state, the plastic plate 3 to be processed is kept in a softened state. While being surely molded. The plastic plate 3 to be processed thus formed is naturally cooled, waits for hardening, and is separated from the mold 19. At this time,
The vacuum suction from the mold 19 is stopped, and conversely, the plastic plate 3 to be processed and the mold 19 are separated by lowering the mold 19 while blowing air from the mold 19. After this separation is performed, the sandwiching of the processed plastic plate 3 by the support frame 17 is released, and the processed plastic plate 3 is taken out.

By the way, in the embodiment described above, the mold
At the time of ascending by 19, the heated air in the inner space surrounded by the peripheral wall of the pedestal 1 is pushed up, and the pushed air greatly expands the portion of the plastic plate 3 except the outer periphery to perform deep molding. However, when the molding depth is shallow, the plastic plate 3 to be processed does not expand much even if it is directly molded by the mold 19, so that the molded plastic plate 3 to be processed does not have an extremely thin portion, Therefore, it is not necessary to largely inflate the portion of the plastic plate 3 except the outer periphery. In that case, the air in the internal space surrounded by the peripheral wall of the pedestal 1 may be opened at the one corner of the cover wall 18 (not shown) when the mold 19 moves up. .

[0011]

As described above, according to the present invention, since the plastic plate to be processed is heated by the hot air from below, the thermal efficiency is improved as compared with the case of heating from above, and the heat of the heater is directly processed. Since it hits with hot air instead of hitting the plastic plate, it is possible to manufacture a safe and stable molded product.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a vacuum forming machine according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of the vacuum forming machine.

3A to 3C are explanatory views showing a forming process by the vacuum forming machine.

[Explanation of symbols]

 1 Cradle 2 Hot air outlet 3 Worked plastic plate 4 Hot air supply port 5 Partition plates 6a, 6b Cavity 7 Communication hole 8 Hot air suction port 9 Hot air discharge port 10 Open / close valve 11 Cylinder device 12 Hot air supply duct 13 Heater 14 Blower fan 15 Guide 16 Receiving surface 17 Support frame 18 Covering wall 19 Mold 20 Lifting device 21 Base

Claims (1)

[Claims] 1. A hot air outlet is formed at an appropriate interval in the circumferential direction at the upper end and has a rectangular shape in a plan view, and the inside of a peripheral wall is formed in a hollow shape, and a plastic plate to be processed is formed on a receiving surface above the hot air outlet. A cradle for receiving and a hot air supply duct for supplying hot air from a hot air source to the cradle,
A vacuum forming machine comprising: a mold that is capable of moving up and down in an internal space surrounded by the peripheral wall of the pedestal and that has means for vacuum-sucking a plastic plate to be processed; and an elevating device that mounts and lowers the mold. .