JPS6092827A - Manufacturing device of cylindrical formed item - Google Patents

Abstract

PURPOSE:To obtain the titled formed item excellent as a recording medium by a method wherein a sheet is brought into close contact with a male form with a guide ring, which is located above the clamped position of the sheet sent in a vacuum forming machine, by being pushed up with the male form. CONSTITUTION:A guide ring 17, the inside diameter of which is 100-150% of the maximum diameter of a male form 9, is arranged within the height range of 2-50mm. above the clamped position of a sheet 1. When the sheet is pushed up with the male form 9, the guide ring 17 brings the sheet into close contact with the male form, resulting in obtaining a cylindrical thermoplastic resin formed item, the wall thickness of which is 10-100mum, the coefficient of variation on wall thickness of which is 0.2 or less and the centerline average roughness of the inside surface is 0.04mum or less.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for producing a cylindrical thermoplastic resin molded product, and more specifically, a thermoplastic resin sheet is vacuum formed into a cylindrical molded product with uniform wall thickness. - Oki + 6 Wandering J, the self-preparation of the cylindrical heat exchanger with a smooth and seamless back surface coated with magnetic metal and suitable for recording media used in magnetic memory, optical memory, etc. The present invention relates to an apparatus for manufacturing a plastic resin molded product.

In recent years, in the field of magnetic recording, magnetic recording devices have become smaller and the need for metal magnetic thin film media capable of high-density recording has increased. In place of the γ-Fe2O3 coated media, metal magnetic thin film media based on Co alloy based on plating methods, vacuum evaporation, etc. have been studied, and some of them are now being put into practical use.

However, the recording media used in magnetic memories, optical memories, etc. that have been proposed so far are only tape-shaped or disk-shaped, and for example, image reproduction devices such as frame-by-frame recording of television image signals or normal recording, etc. These devices had no choice but to be used for audio recording and reproducing devices, digital recording and reproducing devices for electronic computers, flexible disks for electronic cameras, and the like.

When magnetically recording a television image signal field by field on one circumference -F of such a magnetic recording medium, the inner circumference of the magnetic recording medium has a smaller relative speed between the head and the disk than the outer circumference, so In comparison, the image quality has deteriorated, and if you try to get image quality above a certain level, there is a limit to the inner circumference that can be recorded due to the relative speed, and in order to increase the number of recorded images, you have no choice but to increase the outer diameter. I didn't get it. As a result, the diameter of the disk becomes large, and there is a drawback that the entire magnetic recording/reproducing device cannot be made compact.

The performance required for the base material of magnetic recording media used in magnetic memories and the like is as follows: (1) The thickness should be 10 to 100 μm and the thickness distribution should be small.

(2) It must be smooth and free from defects such as seams, scratches, and bumps.

(3) The slope of the cylindrical part is small.

(4) There should be no deformation in the post-process of forming the magnetic thin film.

etc. can be mentioned.

Generally, a vacuum forming method has been proposed as a method for obtaining a cylindrical thermoplastic resin molded article. For example, the diameter of a cylinder (D
) and height 'L) is 1 or less, a cylindrical molded product can be obtained by simply heating the sheet and vacuuming it from the female mold. Such molding is commonly performed for polystyrene resin sheets. However, with this molding method,
The wall thickness distribution on the cylindrical side surface is large and it is not possible to obtain a wall thickness distribution that is small. Moreover, if L/D is 1 or more, the wall thickness distribution becomes even larger, making it impossible to obtain a molded product that is of sufficient practical use. There are various methods for forming so-called deep-drawn cylindrical objects with L/D of 1 or more. For example, a molding method in which a heated sheet is first inflated by applying a slight pressure of air, then pushed up into a male mold, and then a vacuum is drawn from the female mold back and forth, and at the same time the sheet is pressed against the female mold using compressed air from the male mold. There is. With this method, it is possible to obtain a cylindrical molded product with L/D of about 2, and it is also possible to reduce the coefficient of variation of the wall thickness distribution on the side surface. However, with this method, the surface of the cylindrical molded product is so rough that it is impossible to make the Ra) less than 0.04μ, or the surface is glued at a slightly larger period due to the flow of air at full pressure on the surface. It is impossible to erase.

There is also so-called male molding, in which a heated sheet is pushed up with a male mold, vacuum is applied from the side of the male mold, and the sheet is brought into close contact with the male mold. This method is used in combination with a female compressed air system when a so-called PSP, which is made by foaming polystyrene resin or the like to about 10 times the size and processing it into a sheet shape, is molded to obtain a plastic foam molded product. This method is
This is an effective method for forming sheets that are highly flexible but difficult to stretch, such as foam sheets, but when using this method for the purpose of the present invention, there are the following problems. .

(1) When forming by deep drawing (L/D>1), wrinkles appear on the side of the cylinder.

(2) Fold-like wrinkles appear near the opening on the side of the cylindrical molded body.

(3) Sheeting force when the male die pushes up: Since the tip of the male die rubs, the sushi gets inside the side surface of the cylindrical molded body, increasing the surface roughness.

(4) The wall thickness distribution on the side surface of the cylindrical molded body is large, and it is difficult to suppress the coefficient of variation to 0.2 or less.

The present invention is aimed at solving these drawbacks, and the present invention is made by vacuum forming a thermoplastic resin sheet with a specific male die through a guide ring, thereby forming a sheet with a recording medium.
The present invention aims to provide an apparatus that can obtain a cylindrical thermoplastic resin molded product with suitable performance.

That is, in the present invention, a thermoplastic resin sheet is sent to a vacuum forming machine with both ends flanged, and a circular flange is provided around a cylindrical male die in the vacuum forming machine to partially or completely compress the sheet. In an apparatus for manufacturing a hollow cylindrical molded product, which is provided around the male mold, and further provided with a heating means and a cooling means in the male mold, and configured to switch between them, from a position where the sheet is flanged. 2~ upwards
The inner diameter is within the range of 50 mm and is 100 to 1 of the maximum diameter of the male mold.
A cylindrical molded article characterized in that a guide ring of 50 inches is provided so that when the male mold protrudes above the sheet and rises, the guide ring brings the sheet into close contact with the male mold. This is manufacturing equipment.

The present invention will be further explained in detail below.

The present invention is formed into a cylindrical shape by preheating a thermoplastic resin sheet used as a base material for media such as magnetic memory and optical memory, clamping it around a male die, and then directly sucking it into a cylindrical male die. It is a device that manufactures things. According to the present invention, when the wall thickness is 10 to 100μ, the coefficient of variation of the wall thickness distribution (σ
A cylindrical thermoplastic resin molding for use as a magnetic recording medium substrate is obtained, which has a n-1/nu) of 0.2 or less and an inner surface centerline surface roughness Ra) of 0.04 μ or less.

The reason why the coefficient of variation of the wall thickness and wall thickness distribution of the cylindrical thermoplastic resin molding and the center line surface roughness of its inner surface must be within the above range is that if it is outside this range, the metal magnetic thin film firewood This is because even if it is coated, it cannot be used as a magnetic recording medium. To explain further, in normal magnetic recording media, the thickness of the metal magnetic thin film coated on the surface of the base material is very thin, so the condition of the surface of the thermoplastic resin molding appears as unevenness on the magnetic recording medium. If the unevenness on the medium has a centerline surface roughness (Ra) of 0.04μ or more, the noise level during magnetic recording and reproduction will increase, which is undesirable. This is because if it exceeds the above range, the contact state between the magnetic recording medium and the magnetic head will change, which is not preferable.

The thermoplastic resin used in the apparatus of the present invention is one that does not deform at a temperature of 50°C or less, and specific examples thereof include thermoplastic polyester resin, vinyl chloride resin, styrene resin, polycarbonate resin, acrylic resin, etc. Among these, thermoplastic polyester resins are particularly preferred.

In the present invention, the thermoplastic resin sheet is made of the above-mentioned thermoplastic resin, and has a wall thickness of 60 to 300 μm, preferably 50 to 200 μm, and has a smooth surface and is free from hard spots and foreign matter. Refers to high quality. In order to manufacture a cylindrical molded article using such a sheet, the preheated sheet is molded using a specific male die of a vacuum forming machine. There are two types of means for supplying a thermoplastic resin sheet to a vacuum forming machine: a batch type and a continuous type.

To explain further, the batch method is a method in which a sheet cut to a certain size is placed in a cylinder, preheated, and then fed to a vacuum forming machine, while the continuous method is a method in which a roll of thermoplastic resin material is fed into a preheating zone. This is a method of passing the material through and supplying it to the vacuum forming machine.

The present invention will be explained below with reference to the drawings. The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory diagram of the device, and FIG.
The figure is an explanatory diagram of the male mold, FIG. 6 is an explanatory diagram showing the state when the male mold pushes up the sheet, and FIG. 4 is an explanatory diagram of the piping of the heating and cooling means of the male mold.

As shown in FIG. 1, the apparatus of the present invention has K (A), (B
).

It consists of each zone (C). First, zone (A
), the thermoplastic resin sheet 1 is fixed to the clamp 2. Next, the heater 3, which has been preheated in zone (B), moves to zone (A), heats it to the temperature required to form the sheet 1, and then retreats to zone (B). At the same time, the cylinder 2 moves to the forming zone (C) while holding the sheet therebetween. Note that the sheet fixing and heating method of the present invention is not limited to the above-mentioned method, and may be performed by other known methods. For example, the width of a rolled sheet is held in a clamp and moved intermittently, heated to a predetermined temperature through a heating zone, transferred to a forming zone, and sequentially formed. Continuous molding as done. As soon as the movement of the sheet to zone (C) is completed, air cylinders 6 and 7 are activated, and the knock plate 4 is activated.
At the same time, the pre-cylinder plate 5 rises and the cylinder -
The molds are individually secured around the male mold shown in FIG. When molding is performed using multiple male molds, the state of the sheet for each male mold is l'LI? i' becomes the same, and the difference in molding conditions between various types of molds can be reduced.

Another meaning of the above operation is that the sheet is fixed in a circular manner around each male mold, so that when the male mold pushes up in the next step, the sheet is stretched uniformly, resulting in a better result. It becomes possible to minimize the thickness distribution of the cylindrical molded product in the circumferential direction. Further, as shown in FIG. 3, if a disc-shaped guide ring 17 is provided on the upper part of the knock plate 4, when the male die 9 is raised, the sheet 1 will be easily brought into close contact with the male die. Immediately after the above process or within a few seconds, the lower table 8 is raised by hydraulic pressure and the male die 9 is lifted up from the sheet 1, and at the same time or after a few seconds,
Piping 1 from the vacuum hole 15 provided at the bottom of the male mold 9
The sheet is vacuum-suctioned by a vacuum pump connected to 0 and molded into a male shape.

Furthermore, the guide ring, which is a feature of the present invention, will be explained.

If the guide/glue 17 is not provided, the sheet sucked into the lower part of the male die is likely to wrinkle when vacuum is applied, and the wall thickness distribution on the side surface of the cylindrical molded body becomes large.

The material of the guide ring is not particularly limited, but
The part that comes into contact with the heated sheet when the male mold is pushed up needs to be made of a material that has heat insulation properties and is compatible with the heated sheet. For example, ceramic materials such as boron nitride and titanium nitride 1, and plastic materials such as fluororesin are particularly excellent.

In addition, the guide ring is made of metal material, and its surface, especially the part that comes into contact with the heated sheet, is coated with fluororesin.
A cloth such as flannel may be pasted on the surface. If only metal is used as the material for the guide ring, the heat of the sheet will be rapidly absorbed when it comes into contact with the sheet, causing the sheet to solidify locally and not being stretched uniformly, causing the molded body's thickness to deteriorate. Thickness distribution becomes poor. Furthermore, plastic materials such as Bakelite plates and acrylic plates cannot be stretched uniformly due to their poor adhesion to the sheet.

Next, as for the arrangement of this guide ring, it is preferable to provide it at a position in the range of 2W to 50m11L above the position where the seat is flanged, and its inner diameter is about 100 to 150% of the maximum diameter of the male cylinder. Appropriate. If the inner diameter of the guide ring exceeds 150 inches, the effect of squeezing the sheet will hardly be recognized.

In the present invention, when vacuum forming a sheet, it is necessary to heat the male die to the temperature required for forming. Because the sheet hardens too quickly when suctioned,
This is because if the mirror surface of the male mold is not sufficiently transferred, the molded product is likely to wrinkle, making it impossible to obtain the cylindrical molded product that is the object of the present invention. The heating temperature is a temperature at which the thermoplastic resin sheet is plasticized and molded easily, and although it varies depending on the type of sheet, it is generally 50 to 150°C, preferably 80 to 120°C.

After forming is completed, the vacuum suction is continued and either immediately or after being held at this temperature for up to several minutes.
Cooling water is passed through the male mold to cool it, and if the vacuum suction is stopped while the male mold is still at a high temperature during the mold release process, the molded product will deform. After molding, it is necessary to maintain the temperature of the male mold for up to several minutes and perform heat treatment.

Only by providing means for rapidly heating and cooling the male mold as described above can a cylindrical molded product meeting the purpose of the present invention be obtained in an industrially possible cycle.

Various methods can be considered as means for this rapid heating and cooling, but the most efficient method is to rapidly switch between steam or hot water and cold water and circulate them within the male mold.

The male type heating and cooling means of the present invention will be specifically explained with reference to FIG. Although FIG. 4 shows the case where there is only one male mold, molding can be carried out in the same way when using a large number of male molds. Pulp 1 when heating male mold 9
8.19 is closed, the pulp 20 is opened and steam or hot water is supplied to the manifold 22, where it is divided into male molds and supplied. Temperature is controlled by steam pressure in the case of steam, and by a temperature controller in the case of hot water. The opening degree of the pulp 21 on the drainage side can be appropriately controlled.

During cooling, the pulp 20 is closed and the pulp 19 is opened to supply cooling water to the manifold 22, which communicates with the male mold.

The pulp 21 is completely opened, and the cooling water collected in the male mold holder 23 is discharged to the outside of the system.

During reheating, the pulp 18 is opened while the pulps 19 and 20 are closed, blowing air into the manifold 22,
The remaining water is discharged out of the system through the manifold 23 and the pulp 21, the pulp 18 is closed and the pulp 20 is opened to allow steam or hot water to pass through.

The male type has a joint 24, which is connected to a double pipe having an inner pipe 25 and an outer pipe 26, and a manifold 2.
2 will be supplied. The heat medium passes through the joint 24, passes through the inner pipe 25, enters the male mold, and enters the joint 24 from the wide outer pipe 26.
will be returned to.

The pulps 18, 19, and 20 are preferably of an electromagnetic opening/closing type that is operated by a timer.

The male mold used in the present invention will be explained in more detail with reference to FIGS. 2 and 3.

The tip head 11 of the male mold 9 is made of the same metal material as the male mold body or a heat insulating material. As the heat insulating material, for example, a synthetic resin material that can withstand relatively high temperatures, such as Bakelite or nylon, is used. Further, when the male head 11 is made of a metal material, it is preferable to use one whose corners are partially curved to a radius of 1R or more and further polished to a mirror surface. This is to make the part of the corner that comes into contact with the heated sheet as smooth as possible when the male mold pushes up the sheet, and to prevent scratches when the sheet slides.

The side surface 12 of the male mold body is sloped between 30 minutes and 2 degrees for release from the mold after molding. This slope is 6
If it is less than 0 minutes, it will be extremely difficult to release the mold, and if it is more than 2 degrees,
It cannot be used as a cylindrical substrate for magnetic memory media.

On the other hand, the surface roughness (Ra) of the side surface portion 12 is finished to a super mirror surface of 0.04μ or less, and the inside of the side surface of the cylindrical molded product is finished with the desired surface precision by transferring this super mirror surface. molded into something.

Further, the surface of the side surface portion 12 is preferably subjected to a hardening treatment or a surface coating such that it has a Pickus hardness of 1000 or more. This is to prevent scratches from occurring when the molded product is released from the male mold. The side surface of the male mold is required to have an extension 13 having the same slope from the side surface 12 corresponding to the portion of the cylindrical molded article on which the magnetic film is formed. The reason for this is to ensure that the thickness distribution of the side surface portion 12 used as a recording medium is completely within the above range. Although the length of the extended portion 13 varies depending on the diameter of the molded body, it is usually within the range of 10 to 70. The lower part 14 of the side part has an angle of 0 to 6 from the horizontal plane.
It is also possible to form a curved surface with an appropriate radius within the range of 0 degrees as required. The male mold 9 is provided with a plurality of vacuum holes 15 inside, so that the heated sheet can be sucked. Their number and location are arbitrary, but
It cannot be provided on the side surface portion 12.

In addition to the vacuum hole 15, a pressurized air hole 16 is provided to apply pressurized air during mold release to facilitate mold release.

As explained above, the apparatus of the present invention sends a thermoplastic resin sheet to a vacuum forming machine with both ends clamped, and
A circular clamp is provided around the male mold to clamp the sheet in a portion around the cylindrical lambda square mold in a vacuum forming machine, and the male mold is further provided with a heating means and a cooling means. In an apparatus for manufacturing a hollow cylindrical molded product configured to provide and switch between the two, the maximum diameter of the male cylindrical mold has an inner diameter within a range of 2 to 50 mm above the position where the sheet is clamped. According to the device of the present invention, the thickness of the molded product is 10 to 100 μm, and the thickness of the molded product is 10 to 100 μm. It has the effect that a product having a small coefficient of variation of 0.2 or less and a center line roughness of the inner surface of 0.04 μ or less can be obtained in good yield.

The present invention will be further explained below with reference to Examples.

Example A polyethylene terephthalate sheet having an average wall thickness of 130 μm was cut into a predetermined size and set in the clamp 2 of a molding machine shown in FIG. After heating the sheet to a temperature that allows molding, move it to the molding zone, immediately lower the knock plate and raise the pre-clamp plate to clamp the sheet around the male mold at 100% diameter, then heat it to 100°C with steam. The male mold was pushed up, and after another 0.2 seconds, vacuum suction was applied to the male mold to perform molding. The male die used here is a cylindrical body with a minimum diameter of 35 mm at the top, a maximum diameter at the bottom of 38 nrm, and a height of 100 ni.The surface roughness of the effective length of the side surface of 80 mm is the center line average roughness Ra. ) is 0.0
A material polished to a super mirror surface of 0.05 μm was used.

Further, the guide/graph used was provided on the knock plate 4 so that when the male die pushed up the seat, it would be at the fifth position from the bottom of the cylindrical part. After molding, the temperature of the male mold was maintained at 100° C. for 1 minute while vacuum suction was applied, and then the steam was replaced with cold water to sufficiently cool the mold to obtain a cylindrical molded product of the present invention.

The average wall thickness (ma) measured at 62 locations on the side surface of this cylindrical molded proboscis with a height of 80*m is 42μ, and the coefficient of variation of the wall thickness distribution (σn-1/ma) is 0.08. It had good thickness accuracy. Height 8. The centerline average roughness (Ra) of the inner surface of the side surface of 0.0 mm was 0.01 μm, and the surface was extremely good.

Further, this cylindrical molded product was immersed in warm water at 80° C. for 30 minutes, but no dimensional change was observed.

[BRIEF DESCRIPTION OF THE DRAWINGS] Drawing id shows the apparatus for carrying out the feeding of the present invention, in which Fig. 1 is an explanatory view of the apparatus, Fig. 2 is an explanatory view of the male type, and Fig. 6 is an explanatory view of the male type. FIG. 4 is an explanatory view of the heating and cooling means of the male mold. Code 1 - Seat 2... Clamp 3... Heater 4... 7-knot plate 5... Pre-clamp plate 6. γ...Air cylinder 8
...Table 9...Male die 10...Piping 11...Male search head 12...Male die side part 13...Jffi type interface part extension part 14...Male die side part lower part Minute 15...Vacuum hole 16...Pressure air hole 17...Guide ring 18, 19, 20.21...Valve 22.23...Manihole 24...Joint led 25...Inner pipe 26. ... Outer tube patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] The thermoplastic resin sheet is sent to a vacuum forming machine with flanged ends on both sides, and a circular flange is placed around the cylindrical male die in the vacuum forming machine to compress the sheet partially or completely. In an apparatus for producing a hollow cylindrical molded product, the male mold is provided with a heating means and a cooling means, and the male mold is configured to switch between the heating means and the cooling means. An apparatus for manufacturing a cylindrical molded product, characterized in that a guide ring is provided within a range of 2 to 50 m and an inner diameter of 100 to 150 cm of the maximum diameter of the male cylindrical mold.