JPH10264243A - Method and device for molding of resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform a product weight for each shot, prevent a slip by pulling at the time of trimming process, and at the same time, improve the yield of products by reducing the amount of scrap. SOLUTION: When a continuous resin sheet is heated to a temperature suitable for molding in a heating zone H, the sheet is softened and hangs. In this case, a molding side rail 10 is moved to the outside in parallel by a moving means such as pneumatic cylinder devices 25, 35 (or a motor device), and a corresponding interval between rails is expanded. Since one end of a heating side rail 11 is axially connected to the molding side rail 10, and the corresponding interval is expanded into an upside-down chevron-shape from a feeding location of the continuous resin sheet to a molding zone F. Under this state, the continuous resin sheet is fed to the molding zone F, and stretched in the width direction by a specified dimension, and then, a molding is performed by a relatively moving motion of molding dies.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for molding a resin sheet in which a continuous resin sheet heated and softened in a molding zone is expanded in a width direction in parallel and then molded.

[0002]

2. Description of the Related Art When a continuous resin sheet is thermoformed,
For example, in the case of a crystalline thermoplastic resin sheet such as polypropylene, a drawdown phenomenon occurs greatly during heating. In view of this, a pair of guide rails a for guiding a clamp chain that grips both side edges of the resin sheet s shown in FIG. 7 are enlarged at the outlet side o of the molding zone F with the supply position i of the resin sheet s as a fulcrum. Then, measures have been taken to prevent the draw-down phenomenon by using a molding apparatus that stretches the heated and softened continuous resin sheet s by at most about 40 mm and then performs molding.

[0003]

According to the above-mentioned conventional molding apparatus, the molding shape for each shot becomes a trapezoidal shape having a small width on the supply side and a large width on the exit side, and the thickness is not uniform. If this is trimmed, the weight differs for each product after the punching process, and a slight slippage occurs, resulting in a defective product. In addition, since the resin sheet is enlarged in the shape of the letter "C", the scrap portion protruding from the mold m becomes large and there is a disadvantage that the product yield is poor.

[0004] It is an object of the present invention to make the product weight uniform for each shot, prevent slippage during trimming, and improve the product yield by reducing the scrap amount.

[0005]

According to one aspect of the present invention, a continuous resin sheet having a pair of clamp chains on both sides of which is intermittently transported by a fixed length is provided in a heating zone. A method of forming a resin sheet by sequentially stopping at a forming zone and heating the continuous resin sheet to a forming temperature to form the resin sheet, wherein a pair of guide rails for guiding the clamp chain are provided at a supply position of the continuous resin sheet; Moving means for splitting and providing a heating-side rail disposed at the entrance of the molding zone and a molding-side rail disposed from the entrance to the exit of the molding zone, and expanding a corresponding interval of the molding-side rail in parallel; In the above-mentioned molding zone, the heat-softened continuous resin sheet is moved by moving the molding-side rail by the moving means in the molding zone. Dimension only is extended in the width direction, then and performing molding by mold relative movement.

According to a second aspect of the present invention, there is provided a method for forming a resin sheet according to the first aspect, wherein the width of the raw material of the continuous resin sheet and the width of a forming die are reduced. The width of the raw material of the continuous resin sheet is set equal or equal to or smaller than the width of the forming die except for the amount of gripping by the clamp chain.

According to a third aspect of the present invention, a continuous resin sheet having both sides gripped by a pair of clamp chains is intermittently transported by a fixed length and sequentially stopped in a heating zone and a molding zone. In a resin sheet molding apparatus that heats the sheet to a molding temperature and performs molding, a heating-side rail in which a pair of guide rails for guiding the clamp chain are arranged at an entrance of a molding zone from a supply position of the continuous resin sheet, The molding zone is divided into molding-side rails arranged from the entrance to the exit, and the molding-side rail is connected to the heating-side rail so as to be bent and stretched, and the heated and softened continuous resin sheet is stretched in the width direction. In order to achieve this, a moving means for increasing the corresponding interval of the molding side rails in parallel is provided.

The invention described in claim 4 is the same as the claim 3.
Wherein the moving means is configured to drive and rotate a screw shaft supporting the molding side rail by a motor device to move the molding side rail in a width direction of the continuous resin sheet. It is characterized by having been done.

[0009] The invention described in claim 5 is the same as in claim 3.
Wherein the moving means is configured to move the forming-side rail in a width direction of the continuous resin sheet by a pneumatic cylinder device.

[0010]

When the continuous resin sheet is gripped on both sides by a pair of clamp chains and then manually fed into the heating zone, the automatic operation from the start of heating to molding is started. When the continuous resin sheet is heated to a suitable molding temperature in the heating zone, the sheet gradually softens and starts to sag. At this time, the forming-side rail moves in parallel outward by moving means such as a motor device (or a pneumatic cylinder device), and the corresponding distance between the rails is enlarged. In addition, since one end of the heating-side rail is axially connected to the forming-side rail, the heating-side rail is spread in a C shape from the supply position of the continuous resin sheet toward the forming zone. In this state, the continuous resin sheet is sent to the molding zone, so that it is elongated in the width direction by a predetermined dimension, and then the molding is performed by the relative movement of the molding die. The continuous resin sheet after the completion of the forming process is transferred by a predetermined length, a continuous resin sheet heated and softened in a new heating zone is sent to the forming zone, and the same forming process as described above is sequentially performed.

According to the method and apparatus for molding a resin sheet, the continuous resin sheet is expanded in parallel in the width direction, so that the product weight per shot is made uniform, and the slippage during trimming is reduced. Prevention can be achieved.
In addition, when the length for extending the continuous resin sheet is the same as the gripping allowance by the clamp chain, it is possible to make the width of the sheet and the width of the forming die equal to each other. Since it is possible to make the width of the raw material of the continuous resin sheet smaller than the width of the mold except for the gripping allowance by the chain, there is an advantage that the scrap amount is reduced and the product yield is improved. .

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic side view of a molding apparatus, FIG. 2 is a schematic perspective view of a guide rail portion, and FIG.
FIG. 4 is a sectional view taken along line AA of FIG. 1, FIG. 4 is a sectional view taken along line BB of FIG.
FIG. 6 is a cross-sectional view taken along the line CC of FIG. 1, and FIG. 6 is a schematic view for explaining a moving state of the guide rail.

The molding apparatus shown in FIG. 1 is provided with a heating zone H and a molding zone F in a machine frame 1 and has a continuous resin sheet (hereinafter, referred to as a continuous resin sheet).
S) is fed out by a fixed length and sequentially stopped in the heating zone H and the forming zone F.
, The sheet s is heated to the forming temperature by the heater panels 2 and 2 in which a number of heater elements are arranged, and is formed in the forming zone F. A pair of right and left clamp chains c for gripping both side edges of the sheet s
Is a side plate 3 provided with a guide rail 10 for guiding this,
It has a general configuration in which it is wound endlessly around sprockets 5, 6, and 7 attached to the motor 4, and is driven intermittently by a motor device (not shown).

The pair of guide rails 10 includes a heating-side rail 11 disposed at the entrance of the forming zone F from the sheet supply position i and a molding-side rail 12 disposed at the entrance to the exit o of the molding zone F. They are divided, fitted in a hinge shape, and connected by a shaft 13 so as to be bent and stretched (FIG. 2). Reference numeral 14 denotes a chain guide fixed to the inner surface of each guide rail 10 for guiding the clamp chain c, and 16 denotes a pressing guide for the sheet s.

On the side plates 3, 3 to which the outer ends of the heating-side rails 11, 11 are fixed, shaft cylinders 18, 1 having female threads formed on the inner surface.
8 are attached respectively. An adjustment shaft 19 has one end supported by a bearing 20 attached to the machine frame 1 and the other end supported on the output side of a drive motor 21. Both ends of the adjustment shaft 19 have the shaft cylinders 18, 18. Are formed with external threads 19a and 19b in different lead directions. Similarly, an adjustment shaft 22 has one end supported by a bearing (not shown) attached to the machine frame 1 and the other end supported on the output side of the drive motor 23. Form external threads 22a and 22b with different lead directions. Each molding side rail 1
A first pneumatic cylinder device 25 as a moving means is attached to each of the side plates 4 to which the outer ends 12a are fixed.

As shown in FIG. 4, the first pneumatic cylinder device 2
5 is provided with a casing 25a in which flanges 27 and 28 are hermetically fitted to both ends of a tube 26 and these are integrally fixed with bolts 29, and a piston portion 31 is provided in the tube 26.
By providing a cylindrical piston body 30 in which the body 32 is loosely fitted to the flanges 27 and 28, and compressed air is supplied from one of the air ports 27a and 28a provided in the flanges 27 and 28, respectively, 25a is configured to move in the axial direction by a predetermined stroke, in this example, 20 mm. A female screw 30a is formed on the inner peripheral surface of the piston body 30, and a male screw 22a (or 22b) of the adjusting shaft 22 is screwed to the female screw 30a. Reference numeral 33 denotes a stopper plate attached to a side surface of the flange 28 to prevent rotation of the piston body 30.

Reference numeral 35 shown in FIGS.
2 is a second pneumatic cylinder device as a moving means attached to each of a. In the second pneumatic cylinder device 35, flanges 37 and 38 are airtightly fitted to both ends of a tube 36, and these are integrally fixed with bolts 39.
The piston part 41 is housed inside and the body part 42 is flanged 37,
38, a cylindrical piston body 40 which is loosely fitted is provided, and a middle cylinder 43 having a female screw 43a formed on an inner peripheral surface thereof is mounted on bearings 44, 45 fixed to the inner end surface of the piston body 40. Air ports 37a, 38a respectively provided at
By supplying compressed air from either of the above, the piston body 40 is configured to move in the axial direction by a predetermined stroke, in this example, 20 mm. 46 is a sprocket attached to the flange 43b of the middle cylinder 43,
The sprocket 46 and the male screw 22a of the adjusting shaft 22
The endless chain 52 is bridged between the sprocket 47 fixed to the side end and the intermediate sprockets 48 to 51.

On the outer surface of the inner end 12b of each molding side rail 12, a screw shaft 55 projects in the horizontal direction.
Female screw 4 of the middle cylinder 43 of the second pneumatic cylinder device 35
3a is screwed. Thus, the corresponding interval of the guide rail 10 can be adjusted by driving the drive motors 21 and 23 to adjust the adjustment shaft 1.
Sheet s formed by rotating each of 9 and 22
Can be adjusted in accordance with the width dimension.

The expansion control of the sheet s in the width direction in the forming zone F shown in FIG. 6 is performed by controlling the air port 27a of the first pneumatic cylinder device 25 and the second pneumatic cylinder device 35.
Compressed air is supplied to the air ports 37a of the
This is performed by expanding the corresponding intervals of the molding-side rails 12 in parallel. The same molding-side rail 12 is enlarged by instantaneously controlling the rotation of only the drive motor 23 (motor device) without providing the first pneumatic cylinder device 25 and the second pneumatic cylinder device 35 as moving means. A configuration for performing the operation is also possible.

Next, the method of molding the resin sheet and the operation of the molding apparatus will be briefly described. When the sheet s is heated to the appropriate forming temperature in the heating zone H and gradually softens and the sagging phenomenon starts to appear, the air port 27a of the first pneumatic cylinder device 25 and the second pneumatic cylinder device 35
The compressed air is supplied to each of the air ports 37a, so that the molding-side rails 12 move in parallel outward, respectively, and the corresponding intervals between the rails 12, 12 are enlarged. at the same time,
Since the heating-side rails 11 and 11 are connected to the forming-side rail 12 by the shaft 13, respectively, the heating-side rails 11 are spread in a C-shape from the supply position i of the sheet s toward the forming zone F as shown in an exaggerated manner in FIG. . In this state, the sheet s is fed to the molding zone F, so that the sheet s is expanded in the width direction by a predetermined dimension (40 mm in this example). Then, mold M
A known forming process is performed by the relative movement operation, and the sheet s after the forming process is transported by a fixed length.
Subsequently, the sheet s newly heated and softened in the heating zone H is sent to the forming zone F, and the same forming process as described above is continuously performed.

In the molding method and the molding apparatus,
When the length for extending the sheet s and the allowance for gripping by the clamp chain c are the same, it is possible to make the width of the raw material of the sheet s equal to the width of the molding die M,
Further, it is also possible to make the width dimension of the raw material of the sheet s excluding the gripping margin by the clamp chain c smaller than the width dimension of the molding die M.

According to the resin sheet molding method and the molding apparatus, the continuous resin sheet immediately before molding is expanded in the width direction in parallel, so that the product weight per shot is made uniform,
It is possible to prevent slippage during trimming.
Furthermore, the yield of products has been significantly improved due to the reduced amount of scrap.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a molding apparatus.

FIG. 2 is a schematic perspective view of a guide rail portion.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a sectional view taken along line CC of FIG. 1;

FIG. 6 is a schematic diagram illustrating a moving state of a guide rail.

FIG. 7 is a schematic diagram illustrating a moving state of a conventional guide rail.

[Explanation of symbols]

i → supply position o → exit of molding zone H → heating zone F → molding zone s → continuous resin sheet (sheet) c → clamp chain 2 → heater panel 10 → guide rail 11 → heating side rail 12 → forming side rail 13 → shaft 14 → chain guide 19, 22 → adjustment shaft 25 → first pneumatic cylinder device (moving means) 35 → second pneumatic cylinder device (moving means)

Claims (5)

[Claims] 1. A continuous resin sheet having both sides gripped by a pair of clamp chains is intermittently transported by a fixed length and is sequentially stopped in a heating zone and a forming zone, and the continuous resin sheet is heated to a forming temperature. A method for molding a resin sheet to be molded, comprising: a heating-side rail in which a pair of guide rails for guiding the clamp chain are disposed at an entrance of a molding zone from a supply position of the continuous resin sheet; and an entrance of the molding zone. From a resin sheet molding device provided with a moving means for extending the corresponding interval of the molding side rails in parallel while being provided separately from the molding side rails arranged at the outlet portion, and the heat softening in the molding zone. The continuous resin sheet is stretched in the width direction by a predetermined dimension by the movement of the forming rail by the moving means, and then formed by the relative movement of the forming die. A method for forming a resin sheet, comprising processing. 2. The width of the raw material of the continuous resin sheet is equal to the width of the forming die, or the width of the raw material of the continuous resin sheet excluding the amount of gripping by the clamp chain is smaller than the width of the forming die. The resin sheet molding method according to claim 1, wherein the resin sheet is set to be small. 3. A continuous resin sheet having both side edges gripped by a pair of clamp chains is intermittently transported by a fixed length and sequentially stopped in a heating zone and a molding zone, and the continuous resin sheet is heated to a molding temperature. In a resin sheet molding apparatus for molding, a heating-side rail in which a pair of guide rails for guiding the clamp chain are disposed at an entrance of a molding zone from a supply position of the continuous resin sheet, and an exit from an entrance of the molding zone The molding-side rail is divided into the molding-side rails arranged in the section, and the molding-side rail is axially connected to the heating-side rail so as to be bent and stretched, and the corresponding heating-softened continuous resin sheet is stretched in the width direction. An apparatus for forming a resin sheet, comprising a moving means for expanding the interval in parallel. 4. The method according to claim 1, wherein the moving unit is configured to rotate a screw shaft supporting the molding side rail by a motor device to move the molding side rail in a width direction of the continuous resin sheet. The resin sheet molding apparatus according to claim 3, wherein: 5. The resin sheet according to claim 3, wherein the moving means is configured to move the molding-side rail in a width direction of the continuous resin sheet by a pneumatic cylinder device. Molding equipment.