JPH07195509A - Thermoforming apparatus and method of resin sheet - Google Patents

Abstract

PURPOSE:To obtain a molded product of high quality having no harmful irregularity in wall thickness or scratch and excellent in transparency. CONSTITUTION:A pair of the respective upper and lower clamp pieces 41 of clamps 40 for supporting both side edge parts of a resin sheet S are arranged so that an interval is provided between both clamp pieces 41 in an up-and-down direction and the upper clamp piece 41 is outwardly shifted from the lower clamp piece 41 and, when the central part of the resin sheet S is raised by a male mold 10, both side edge parts of the resin sheet S follow the central part to be smoothly detached from the clamps 40. By this constitution, the pressure bending roller 30 provided to the leading end of the restriction wall part 21 of a female mold bends the resin sheet S under pressure while tumbles without generating the friction with the resin sheet S.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sheet thermoforming apparatus and a thermoforming method for obtaining a molded product using a resin sheet as a material.

[0002]

2. Description of the Related Art A thermoplastic synthetic resin sheet such as a polycarbonate resin sheet, a vinyl chloride resin sheet, or an acrylic resin sheet is bent and molded to form a molding face plate for a vending machine and a display device as shown in FIG. When obtaining a molded product (F) that requires transparency, such as a face plate, the slit heater is used to partially heat and bend the bent portion of the sheet, or the resin sheet is heated in a hot-air oven to conform to the mold. The method of bending and bending is often used.

However, since these methods are mainly carried out manually, the burden on the operator is large, and the method using the hot air oven requires heating for a long time (about 10 minutes), resulting in high work efficiency. It was very low.

Therefore, it has been earnestly desired to obtain the above-mentioned molded product (F) by utilizing a vacuum molding apparatus or the like which is being automated.

A vacuum forming method using a vacuum forming apparatus is, for example, as shown in FIG. 7A, a male mold (1) and a female mold (2).
Both edges of the resin sheet (S) are held and fixed by clamps (3) (3) arranged on both sides of the space, and the resin sheet (S) is heated and softened to a predetermined temperature by a heater (not shown). Let Thereafter, as shown in FIG. 2B, the male mold (1) is raised, and then the female mold (2) is lowered as shown in FIG. It is sandwiched between resin sheets (S). Then, the air between the male mold (1) and the resin sheet (S) is removed by suction, and the resin sheet (S) is removed.
Is adhered to the male mold (1) to mold the sheet (S), and then cooled and released to obtain a predetermined molded product.

[0006]

In addition to the above vacuum forming method, a vacuum or pressure forming method (vacuum / pressure forming method) such as a vacuum pressure forming method for performing vacuum forming while introducing air into the female mold side. In the above, since the resin sheet (S) is brought into close contact with the male mold (1) by air pressure,
The resin sheet (S) must be sufficiently softened, and it is necessary to heat the resin sheet (S) to a high temperature. Therefore, the sheet itself or the film attached to the surface of the sheet is deteriorated by heat, and transparency or the like is impaired, so that a good molded product may not be obtained. Further, when the resin sheet (S) is brought into close contact with the mold, the surface of the mold surface may be transferred to the resin sheet (S), and also from this point, the transparency may be impaired. Moreover, in order to prevent the transfer of the mold surface as much as possible, it is necessary to use a high-precision mold in which the mold surface is mirror-finished, which increases the production cost of the mold and increases the cost. There was also the problem of coming.

Further, since both edges of the resin sheet (S) are fixed by the clamps (3) and (3), both molds (1) and (2) are formed.
When the sheet (S) is sandwiched by and the sheet (S) is pushed and bent by the limiting wall portion (2a), the resin sheet (S) is stretched and an uneven thickness occurs in the sheet thickness, which is harmful to the molded product. Uneven thickness occurs. Further, when sandwiched by both molds (1) and (2), the tip of the limiting wall portion rubs against the surface of the resin sheet (S), and scratches are formed on the surface of the sheet, which makes it impossible to obtain a high-quality molded product. I also had a problem.

On the other hand, also in the method of performing bending molding without removing and introducing air by using a vacuum / compressed air forming apparatus, so-called ridge forming method, the above-mentioned vacuum / compressed air forming apparatus is used. Similarly, when the sheet is bent by the female limiting wall portion, the sheet stretches and the leading edge of the limiting wall portion rubs against the sheet, which causes uneven thickness in the sheet thickness and scratches on the sheet surface. It was not preventable.

The present invention solves the above-mentioned problems of the prior art, makes it possible to obtain a high-quality molded product which is free from harmful uneven thickness and scratches and is excellent in transparency, and further improves work efficiency and reduces cost. Another object of the present invention is to provide a thermoforming apparatus and thermoforming method for a resin sheet that can be expected.

[0010]

In order to achieve the above object, the first invention of the present application is such that a resin sheet is sandwiched between a male mold and a female mold from above and below, and the resin sheet is pushed and bent by a limiting wall portion of the female mold. A resin sheet thermoforming apparatus, wherein the resin sheet bending portion of the limiting wall portion is provided with a bending roller that rolls on the sheet without rubbing against the resin sheet,
Clamps on one side and the other side, each having a pair of rod-shaped clamp pieces parallel to the bending roller, are arranged on both sides between the molds, and each pair of clamp pieces is vertically spaced. And the upper clamp piece is spaced from the lower clamp piece in the outward direction, and the opposite side edges of the resin sheet allow the detachment movement between the pair of clamp pieces. The gist is that it is configured to be inserted and supported in each state.

In the first aspect of the present invention, the vertical interval between the pair of clamp pieces of the clamp is set to be substantially equal to the thickness of the resin sheet, and the horizontal interval is 2 mm to the resin sheet thickness. It is preferable to adopt a configuration in which the dimension is set to include 3 mm.

In order to achieve the above object, the second invention of the present application is such that a resin sheet is sandwiched between a male mold and a female mold from above and below, and the resin sheet is pressed and bent by the limiting wall portion of the female mold. A method is provided in which a bending roller is provided on the bending portion of the resin sheet of the limiting wall portion and rolls on the sheet without rubbing against the resin sheet, and is arranged on both sides of both molds. One side and the other side of the clamp,
Each of the pair of clamp pieces has a pair of rod-shaped clamp pieces parallel to the bending roller, each pair of clamp pieces is vertically spaced, and the upper clamp piece is outward from the lower clamp piece. Prepare one side and the other side clamps which are arranged at intervals, and insert and support the opposite side edges of the resin sheet between the pair of clamp pieces while allowing the detachment movement. ,
The gist of the invention is to soften the resin sheet to a predetermined temperature and sandwich the resin sheet between the molds.

In the second invention, the thickness is 1 mm.
It is preferable to use a resin sheet of ˜8 mm.

Further, the heating softening temperature of the resin sheet is set to 11
It is better to set it to 0 ° C to 180 ° C.

[0015]

According to the present invention, the pair of clamp pieces of one side and the other side of the clamp for supporting both side edges of the resin sheet are vertically spaced from each other, and the upper side clamp pieces are lower side. Since the clamp pieces are spaced from each other in the outward direction, the space between the pair of clamp pieces is opened toward the sheet detaching direction, and the central portion of the resin sheet is pushed in by the male mold. At this time, the both side edges of the resin sheet follow the central part,
It will be removed from the clamp smoothly without resistance. Further, since a bending roller is provided on the bending portion of the resin sheet on the limiting wall portion of the female die to push and bend the resin sheet, the bending roller rolls without rubbing against the resin sheet. While pressing and bending the sheet, it is possible to prevent scratches from being formed on the surface of the sheet.

Since the resin sheet is not brought into close contact with the mold unlike the vacuum / compressed air molding method, it is not necessary to soften the resin sheet at an unnecessarily high temperature, and the film itself or the film attached to the surface of the sheet. Does not deteriorate due to heat, and the surface of the mold surface is not transferred to the resin sheet.

Further, the present invention can be carried out and the work can be automated by utilizing a conventionally known vacuum / compressed air forming apparatus or the like.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing an essential part of a thermoforming apparatus for resin sheets which is an embodiment of the present invention, and FIG. 2 is a side view. As shown in both figures, a male mold (10) and a female mold (20) are arranged at the upper and lower positions so as to be opposed to each other so that they can come into contact with and separate from each other.

Both side limiting wall portions (21) (2) of the female mold (20)
Bending rollers (30) and (30) are provided at the tip of 1). That is, as shown in FIG. 4, roller mounting brackets (31) are rotatably attached by shaft members (32) to the front and rear ends of the front end portions of the limiting walls (21) (21), and the brackets are attached to the brackets. Both ends of the rotating shaft of the bending roller (30) are rotatably attached to (31). Furthermore, each bracket (31)
The circular arc holes (33) are formed along the circular arc centering on the shaft member (32), and the position adjusting screws (34) inserted into the circular arc holes (33) are respectively formed on the limiting wall portions. It is screwed to (21). When the position adjusting screw (34) is loosened, the bracket (31) is configured so as to be able to swing around the shaft member (32) together with the bending roller (30), and the position adjusting screw ( By tightening 34), the bracket (31), that is, the bending roller (30) can be fixed at an arbitrary swing position. Thereby, the separation distance between the bending roller (30) and the molding surface (11) of the male mold (10) can be freely adjusted.

On the other hand, as shown in FIGS. 1 and 2, a pair of rod-shaped clamps are arranged in parallel with the bending rollers (30) and (30) on both sides between the molds (10) and (20). One side and the other side of the clamps (40) (40) each having a piece (41) (41) are arranged. As shown in FIG. 5 (a), the pair of clamp pieces (41) (41) of the clamp (40) are vertically spaced from each other, and the upper clamp piece (41) is the lower clamp piece. It is arranged at intervals from (41) in the outward direction. In this embodiment, the vertical interval (H) between the pair of clamp pieces (41) (41) is set to be approximately equal to the thickness of the resin sheet (S) to be molded, and the horizontal interval (L). Is set to a size obtained by adding 2 mm to 3 mm to the thickness of the resin sheet (S).

The vertical interval (H) and the horizontal interval (L) are not particularly limited in the present invention, but if they deviate greatly from these ranges, the resin sheet (S) will be described later. When the sheet is inserted into the clamp (40), good insertion force may not be obtained, or the sheet (S) may not be smoothly removed from the clamp (40), which is not preferable. However, if it deviates from the above specified range to some extent (1 mm to 2 mm), thermoforming can be performed better than in the prior art, although some problems will occur.

As shown in FIG. 2 (b), in this thermoforming apparatus, the resin sheet (S) to be formed is molded with the male mold (10) and the female mold (20) vertically retracted. Panel heaters (50) and (50) that can freely enter are provided between the male mold (10) and between the resin sheet (S) and the female mold (20).

Next, using this apparatus, a resin sheet (S)
A case where a molded product such as a molded face plate for a vending machine or a molded face plate for a display device is obtained by thermoforming is described. As the resin sheet (S) to be thermoformed, various thermoplastic synthetic resin sheets such as a polycarbonate resin sheet, a vinyl chloride resin sheet and an acrylic resin sheet can be used. Among them, a sheet made of a polycarbonate resin is preferable. It can be used preferably. Further, as the resin sheet (S), one having a thickness of 1 mm to 8 mm can be preferably used, and it is more preferable to use one having a thickness of 2 mm to 8 mm.

First, as shown in FIG. 2 (a), the male die (10) arranged on the lower side is slightly raised, and the tip surface of the molding surface (11) of the male die (10) is moved upward. While using it as a work table, one side edge of the resin sheet (S) is used as a pair of clamp pieces (41) (41) of the clamp (40) on one side.
The other side edge portion is inserted between and supported by the pair of clamp pieces (41) (41) of the clamp (40) on the other side.

Next, as shown in FIG. 2B, a male type (1
0) is temporarily retracted downward, and then the panel heater (50) is advanced to both upper and lower sides of the resin sheet (S), and the heater (50) heats the resin sheet (S) for about 2 minutes to soften it. Let The appropriate range of the heating temperature at this time varies depending on the type of the sheet (S) to be molded, but is 170 ° C. to 180 ° C. for a polycarbonate resin, for example.
℃, for those made of vinyl chloride resin 110 ℃ ~ 120 ℃,
For those made of acrylic resin, the temperature is preferably set to 140 ° C to 150 ° C.

After heating the resin sheet (S) to the above-mentioned predetermined temperature, as shown in FIG.
0) is evacuated, then the male mold (10) is raised and the central portion of the resin sheet (S) is pushed up by the male mold (10), and as shown in FIGS. (20)
And lower the resin sheet (S) into both molds (10) (2
0) and the limiting wall part (21) of the female mold (20)
The resin sheet (S) is pushed and bent along the molding surface (11) of the male mold (10) by the bending roller (30) at the tip. At this time, as shown in FIG. 5B, in the clamp (40), the upper clamp piece (41) is the lower clamp piece (41).
Since it is arranged at a distance from the outer side to the upper side, the space between the pair of clamp pieces (41) (41) is opened obliquely upward, in other words, the resin sheet (S) is opened toward the exit direction,
Both side edge portions of the resin sheet (S) follow the center portion, smoothly move in the removing direction without resistance, and are removed as shown in FIG. 5 (c). Further, the roller (30) attached to the limiting wall portion (21) pushes and bends the sheet (S) while rolling without sliding on the resin sheet (S).

After the resin sheet (S) is molded in this way, it is cooled and released to obtain a predetermined molded product.

According to this embodiment, when the resin sheet (S) is sandwiched between the molds (10) and (20) and is pushed and bent, both side edges of the resin sheet (S) follow the central portion. Since the resin sheets (S) are smoothly detached from the clamps (40) (40) without resistance, the resin sheet (S) is not stretched, and uneven thickness of the sheet can be prevented. Further, the roller (30) attached to the limiting wall (21)
However, the sheet (S) is pushed and bent while rolling on the sheet without rubbing against the resin sheet (S).
No scratches are formed on the surface of the sheet. Therefore, it is possible to obtain a high-quality molded product having a uniform thickness and no scratches.

Further, since the resin sheet (S) is not brought into close contact with the molding surface by air pressure, the resin sheet (S)
It is not necessary to soften the resin at an unnecessarily high temperature, and the sheet itself or the film attached to the sheet surface is not thermally deteriorated, and a good molded article having high transparency can be obtained. For reference, in the case of using a polycarbonate resin sheet, in this example, if the sheet is heated to about 170 ° C., good thermoforming can be performed.
It is necessary to heat to 190 ° C. in the conventional ridge molding method and to less than 200 ° C. in the vacuum / pneumatic molding method.

Further, since the resin sheet (S) is not brought into close contact with the molding surface, the surface of the mold is not transferred to the resin sheet, and a molded product having higher transparency can be obtained. Moreover, since the transfer of the surface of the die surface can be prevented, it is not necessary to use an expensive die having a mirror finish, and the cost can be reduced.

Further, by utilizing the well-known vacuum / pressure air forming apparatus and the like, the thermoforming apparatus and method of the present embodiment can be easily realized and the work can be automated, thus reducing the burden on the operator. Therefore, the work efficiency can be improved.

Further, in the above embodiment, the roller (30)
Is supported by a bracket (31) which can be fixed at an arbitrary swing position, so that the molding surface (11) of the roller (30) and the male mold (10) is matched with the sheet thickness of the resin sheet to be thermoformed. ) Can be freely adjusted, and sheets of various thicknesses can be formed.

In the above embodiment, the male type (1
0) is placed on the lower side and the female die (20) is placed on the upper side, but the male die may be placed on the upper side and the female die may be placed on the lower side.

[0034]

As described above, according to the present invention, a pair of clamp pieces of one side and the other side of the clamp for supporting both side edges of the resin sheet are vertically spaced from each other. Moreover, since the upper clamp piece is arranged at a distance from the lower clamp piece in the outward direction, respectively, when the central part of the resin sheet is pushed in by the male mold, both side edges of the resin sheet are centered. Since the resin sheet is smoothly removed from the clamp without resistance following the portion, the resin sheet is not stretched, and uneven thickness of the sheet can be prevented. In addition, since a bending roller is provided at the tip of the female limiting wall and the resin sheet is pushed and bent by the roller, the roller pushes and bends the sheet while rolling without rubbing against the resin sheet. It is possible to prevent the formation of scratches on the surface of the sheet. Therefore, it is possible to obtain a high-quality molded product having a uniform thickness and no scratches.

Since the resin sheet is not brought into close contact with the mold unlike the vacuum / compressed air molding method, it is not necessary to soften the resin sheet at an unnecessarily high temperature, and the film itself or the film attached to the surface of the sheet. Is not deteriorated by heat, and the surface of the mold is not transferred to the resin sheet, and a good molded article having high transparency can be obtained. Further, by utilizing a conventionally known vacuum / compressed air forming device or the like, the present invention can be easily implemented, and the work can be automated, and the work efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a thermoforming apparatus for a resin sheet which is an embodiment of the present invention.

FIG. 2 is a side view showing the thermoforming apparatus of the embodiment.

FIG. 3 is a side view showing the thermoforming apparatus of the embodiment.

FIG. 4 is a side view showing the vicinity of a bending roller mounting portion in the thermoforming apparatus of the embodiment.

FIG. 5 is a side view showing a clamp in the thermoforming apparatus of the embodiment.

FIG. 6 is a perspective view showing a molded product obtained by thermoforming a resin sheet.

FIG. 7 is a side view showing a conventional vacuum forming apparatus.

[Explanation of symbols]

 10 ... Male type 20 ... Female type 30 ... Roller 40 ... Clamp 41 ... Clamping piece H ... Vertical spacing L ... Horizontal spacing S ... Resin sheet

Claims (5)

[Claims] 1. A thermoforming apparatus for a resin sheet, wherein a resin sheet is sandwiched between a male mold and a female mold from above and below, and the resin sheet is pressed and bent by a female limiting wall portion. A pushing roller that rolls on the sheet without rubbing against the resin sheet is provided in the pushing portion, and one side and the other side clamps each having a pair of rod-shaped clamp pieces parallel to the pushing roller. Are arranged on both sides of both molds, each pair of clamp pieces is vertically spaced, and the upper clamp piece is spaced outwardly from the lower clamp piece. And the opposite side edges of the resin sheet are configured to be inserted and supported between the pair of clamp pieces in a state where they are allowed to move out and out, respectively. Apparatus. 2. The vertical interval between the pair of clamp pieces of the clamp is set to a dimension substantially equal to the thickness of the resin sheet, and the horizontal interval is a dimension obtained by adding 2 mm to 3 mm to the thickness of the resin sheet. Claim 1 which is set
A thermoforming device for a resin sheet according to item 1. 3. A thermoforming method for a resin sheet, wherein a resin sheet is sandwiched between a male mold and a female mold from above and below, and the resin sheet is pushed and bent by a female limiting wall portion. A pressing roller provided on the bending portion and rolling on the sheet without rubbing against the resin sheet is prepared. It has a pair of rod-shaped clamp pieces that are parallel to the bending roller, and the pair of clamp pieces are vertically spaced from each other and the upper clamp pieces are spaced outward from the lower clamp pieces. Prepare the one side and the other side clamps arranged at, and insert and support the opposite side edges of the resin sheet between the pair of clamp pieces while allowing the detachment movement. The tree A method for thermoforming a resin sheet, characterized in that an oil sheet is softened by heating to a predetermined temperature and sandwiched between the two molds. 4. The resin sheet has a thickness of 1 mm to
The thermoforming method for a resin sheet according to claim 3, wherein a resin sheet having a thickness of 8 mm is used. 5. The heat softening temperature of the resin sheet is 110.
The thermoforming method for a resin sheet according to claim 3 or 4, wherein the temperature is set to ℃ to 180 ℃.