JPH0550970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a powder slush molding device for molding a plastic skin by charging plastic powder into a heating mold.

(Prior art) In powder slush molding, plastic powder such as vinyl chloride resin is put into a preheated mold, the plastic powder is melted and adhered to the mold surface, and then heating is continued to melt the adhered powder. After completing the process and forming a uniform molten film, the film is cooled to form a plastic film in the shape of a mold surface. In addition, the mold used for powder slush molding has a structure with the opening of the bag expanded, because the skin to be molded is in the shape of a bag, and for supplying raw materials into the mold, removing the skin, etc. Moreover, since the mold is often rotated during raw material supply, heating, etc., the mold support is connected to the bag-like opening. Since the raw material put into the mold must be melted and molded to have a uniform thickness, most of the mold support part also needs to be heated to a predetermined temperature.

Therefore, a powder slush molding apparatus requires a device for heating a mold including a mold support portion, and conventionally, heating devices of the following type have been used.

The method was to put the mold in a heating furnace
-38258), a method in which a heating medium is circulated through a pipe embedded in a mold (Japanese Patent Publication No. 59-215811), and a method in which a mold is immersed in heated particles (Japanese Patent Publication No. 1983-139410).

However, in this case, a device to blow combustion gas onto the mold in a heating furnace or a device to heat the mold with an open flame is required, and in this case, a device to heat a heat medium such as oil and a device to heat the heat medium are required. In this case, a device for heating the particles and a device for blowing the heated particles up and colliding with the mold to improve heat transfer are required, both of which require powder slush molding equipment. There was a problem that became large or complicated. Further, it is preferable to uniformly heat the mold even while the mold is rotating, but this cannot be said to be easy in the above-mentioned case.

(Problems to be Solved by the Invention) Therefore, it is an object of the present invention to provide a powder slush molding apparatus which has a simple and small structure and can uniformly heat the mold even while the mold is rotating.

(Means for Solving the Problems) The gist of the present invention is to provide a heating device in which a ceramic heater, which is arranged to surround a mold including a mold support portion at a predetermined distance, can be opened and closed by at least one spindle; The powder slush molding apparatus is characterized in that the mold and the mold are relatively movable, and both are held by one rotatable support shaft.

(Function) When the plastic powder is supplied and the mold is rotated, the mold is heated by ceramic heaters placed around the mold at a predetermined distance. Therefore, since the ceramic heater is arranged to substantially match the shape of the mold, the mold can be heated uniformly. Also, since it is possible to radiantly heat the mold from a close distance,
The mold can be heated in a short time. Moreover, since the mold and heating device are fixed to one shaft,
Even when the mold is rotated, the positional relationship between the mold and the ceramic heater can be kept constant, and mold heating can always be uniformly performed. As a result, the plastic powder can be melted to a uniform thickness, and a plastic skin with a constant thickness can be obtained.

In addition, the heating device and the mold are relatively movable,
Since the ceramic heater can be opened and closed, it is possible to expand the ceramic heater and separate it from the mold after heating the mold, thereby completely blocking the influence of residual heat from the ceramic heater that remains even after the power is turned off, and allowing the mold to remain open. Can be cooled quickly. Furthermore,
Since the mold is exposed by expanding and moving the ceramic heater, the mold can be rapidly cooled by directly applying cold air, cold water, etc. to the mold. As a result, the demolding time of the plastic skin is shortened, making it possible to shorten the overall molding time.

(Example) The present invention will be explained below based on Examples.

FIG. 1 is a front view of a powder slush forming apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a heating device.

Reference numeral 10 denotes a support shaft which is rotated by the drive of a motor 12, and the end thereof has an arm shape 14.

Reference numeral 16 denotes a slush mold having a shape similar to the opening of a bag expanded, and is rotatably attached to the lower part of the arm 14 of the support shaft by a mold support 18. Note that hereinafter, the term mold 16 is also used to include the mold support portion 18. Further, 20 is a motor that rotates the mold 16.

22 is a raw material supply bucket containing plastic powder inside, and a lifting device 2 such as a cylinder.
4, it can be moved up and down, and furthermore, it can be moved in the horizontal direction. Then, when it rises and meets the opening edge of the mold 16, the raw material supply bucket 22 and the mold 1
6 are engaged and fixed, and can be rotated together by the drive of the motor 20. Note that during the rotation, the raw material supply bucket 22 is maintained in a state separated from the lifting device 24. Further, the lifting device 24 is lowered and further moved in the horizontal direction so as not to interfere with the rotation of the mold.

26 is a heating device for the mold, and a lifting device 28 such as a cylinder is placed above the arm 14 of the support shaft so that it can be moved up and down (more precisely, it can be moved relative to the mold 16).
It is attached so that it rotates together with the mold 16 when the support shaft 10 rotates. The heating device 26 is
A plurality of ceramic heaters 3 surrounding the mold 16
0 is fixed to a support body 36 through a shock absorber 32 made of rubber or the like with a fixing member 34 such as a bolt, and the support body 36 is connected to the support body 36 by a support shaft 38 so as to be openable and closable. The support shaft 38 consists of opening/closing parts such as hinges, the number and position of which are determined by the number of ceramic heaters depending on the shape of the mold 16.

The ceramic heater 30 has a heating element cast into it, and preferably emits far infrared light with a wavelength of 3 to 7 microns. This ceramic heater 30
is designed to surround the mold 16 at a predetermined distance (usually 2 to 10 mm) from the outer surface of the mold 16 when the support 36 is closed, and to be detachable from the mold 16 when the support 36 is opened. It's summery. Note 4
0 is an electric cord for energizing the ceramic heater 30, and 42 is a device for opening and closing the support body 36. The opening/closing device is such that the tip of the support 36 is moved up and down with a cylinder or the like.
There is one in which the shaft is rotated around a support shaft 38.

The powder slush forming apparatus thus constructed operates as follows when forming a plastic skin.

First, the heating device 26 is lowered to a predetermined position on the outer surface of the mold 16 with the ceramic heater 30 open, and the ceramic heater 30 is closed at that position. As a result, the ceramic heater 30 surrounds the mold 16 at a predetermined distance from the outer surface of the mold 16.

After heating the mold 16 to a predetermined temperature with the ceramic heater 30, the ceramic heater 30 is opened.
Raise the heating device 26 and return it to the initial position.

Next, the raw material supply bucket 22 is raised, and the mold 16 is
Align it with the edge of the opening and engage and fix it in the mold. Note that it is also possible to raise the heating device and the bucket at the same time. Then, the mold 16 and the raw material supply bucket 22 are rotated by the drive of the motor 20, so that the bucket 22 is placed on top and the mold 16 is placed on the bottom. As a result, the plastic powder in the raw material supply bucket 22 falls and is supplied into the mold 16. At this time, since the mold surface is heated by the ceramic heater to approximately the melting temperature of the plastic powder, the plastic powder close to the mold surface is welded and adhered to the mold surface.

Thereafter, the mold 16 is rotated back to the upper position, excess plastic powder is discharged into the bucket 22, and the bucket is lowered. Thereafter, the heating device 26 is lowered again to surround the mold 16 in the same manner as described above. Then, the mold 1 is heated by the ceramic heater 30.
While heating the mold 6, the support shaft 10 is rotated by the drive of the motor 12, and the mold 16 and the heating device are rotated or oscillated together, thereby melting the plastic powder adhering to the mold surface and at the same time making the thickness uniform. do.

After a predetermined period of time has elapsed in the heated state, or after a predetermined number of rotations or swings, the rotation and heating are stopped, the ceramic heater 30 is opened, and the heating device 26 is raised. Then, the exposed mold 16 is cooled by directly blowing cold air or the like to harden the plastic film melted and formed on the mold surface, and then the desired product is obtained by removing the plastic film from the mold.

Note that instead of the above process, a ceramic heater 30
While heating the mold 16, the bucket 22 is raised and engaged with the opening edge of the mold 16, and in that state, the support 1 is
0, the bucket 22 is placed above the mold 16, and after supplying the plastic powder into the mold 16, the support shaft 10 is rotated to position the bucket 22 below the mold 16, and the excess plastic powder is removed. Alternatively, the water may be discharged into a bucket 22. That is, the mold may be heated while the raw material is being supplied. In this case, the efficiency of heating the plastic powder can be further increased. After that, the ceramic heater 30 is separated from the mold 16 after forming a molten powder film in the same manner as described above, and after cooling the mold, the plastic film is removed from the mold.

(Effects of the Invention) The present invention having the above configuration has the following effects.

First, because the ceramic heater is arranged to almost match the shape of the mold, the mold is heated evenly, and the mold and heating device are fixed to a single shaft and rotate without changing their positional relationship. This has the effect of ensuring that the heating of the mold remains constant, resulting in a plastic skin with a constant thickness.

Second, since the mold can be heated by radiation from close range, the mold can be heated in a short time.

Third, the heating device and the mold are relatively movable,
Since the ceramic heater can be opened and closed, the mold can be rapidly cooled by opening the ceramic heater and separating it from the mold after heating the mold, and by directly blowing cold air onto the exposed mold. This has the effect of allowing the product to be demolded in a short time after stopping.

Fourthly, due to the second and third effects described above, there is an effect that the entire molding time can be shortened.

Fifth, there is no need to bury a heating medium circulation pipe inside the mold, which simplifies the structure of the mold and makes it easy to manufacture.Furthermore, there is no need for a heating medium circulation device, heated particle blow-up device, heating furnace, etc. Therefore, the structure of the entire molding apparatus is simplified and the size thereof is also reduced.

Sixthly, the ceramic heater is resistant to thermal shock, which has the effect of increasing the durability of the device of the present invention.

Furthermore, an arm supported by a rotatable support shaft 10 rotatably supports the mold 16 independently of the support shaft, and a ceramic heater 30 for heating the mold 16 is also provided on the arm. Since it is movable relative to the mold, it has the advantage that a series of steps can be performed simultaneously.

[Brief explanation of drawings]

FIG. 1 is a front view of a powder slush forming apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a heating device. 16... Mold, 20... Heating device, 30... Ceramic heater, 38... Support shaft.

Claims (1)

[Claims] 1. A heating device that is capable of opening and closing a ceramic heater arranged to surround a mold including a mold support part at a predetermined distance using at least one support shaft and the mold are movable relative to each other, and both are connected to one A powder slush forming device characterized by being held by a rotatable support shaft.