JP2000127239A - Method and device for forming plastic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the drawdown of a sheet at the time of heating the sheet by bringing a heater into contact with both faces of the plastic sheet, heating the plastic sheet and forming the plastic sheet thus heated. SOLUTION: Fixed members 22 and 22' are provided on the upper and lower sections of a sheet heating section 5, and respective air cylinders 12 and 12' are set on the fixing members 22 and 22'. An upper lifting and lowering member 20 is fixed on the end of a lifting and lowering rod 19 of one air cylinder 12, while another lifting and lowering member 20' is fixed on the end of a lifting and lowering rod 19' of the other air cylinder 12'. A fixed heater 10 is fixed on the lower face of the upper lifting and lowering member 20, while another fixed heater 10' is fixed on the upper face of the lower lifting and lowering member 20, and cartridge heaters 11 and 11' are set removably on the lifting and lowering members 20 and 20' on the upstream side of respective fixed heaters 10 and 10', and a plastic sheet 2 is heated by the fixed heaters 10 and 10' and the cartridge heaters 11 and 11' and then formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for forming a plastic sheet, and more particularly to a method and an apparatus for heating the plastic sheet.

[0002]

2. Description of the Related Art Conventional plastic sheet (hereinafter simply referred to as "sheet") molding methods include an indirect heating method by heat transfer and a direct heating method by heat conduction.

The direct heating method has advantages such as no drawdown of the sheet, no uneven heating of the sheet, and good energy efficiency. However, since the heating means is provided to face the molding die, plug molding cannot be performed at the time of molding, and deep products cannot be molded.

[0004] In addition, the current direct heating method is as follows.
Because of the single-sided heating method, there is a limit to the thickness of the sheet that can be heated, and the molding method by indirect heating of the sheet is mainly used except for some uses.

[0005]

However, the above-mentioned conventional indirect heating method of the sheet involves drawdown due to softening of the sheet during heating depending on the material of the sheet to be heated, poor energy efficiency, and uniform heating of the sheet. Are difficult.

The present invention has been made to solve the above problems, and provides a method and an apparatus for forming a plastic sheet capable of forming a thick sheet quickly and accurately by bringing a heating device into direct contact with both sides of the sheet. The purpose is to do.

[0007]

In order to achieve the above object, the present invention provides: [1] In a method for forming a plastic sheet, a heating device installed above and below a heating section of the plastic sheet moves up and down, and The plastic sheet is heated by bringing the heating device into contact with both surfaces of the plastic sheet, and the heated plastic sheet is formed.

[2] In the method for molding a plastic sheet according to the above [1], the heating length of the plastic sheet is adjusted by adjusting the number of cartridge heaters.

[3] In the method for molding a plastic sheet according to the above [1], the end portion of the plastic sheet is clamped by a clamper in a molding section, so that the plastic sheet can be held and expanded during molding. .

[4] In the method for forming a plastic sheet according to the above [1], a sheet feeder is used on a supply side of the plastic sheet to a heater and on a discharge side of a forming section, so that fixed-size feeding and sheet stretching feeding are enabled. Things.

[5] In the method for forming a plastic sheet according to the above [2], a heating metal sheet is provided on a heating surface side of a heating device which is in direct contact with the plastic sheet, the heated metal sheet is subjected to a surface treatment, and heated. The plastic sheet material is used to avoid the adhesion between the surface of the plastic sheet and the heated metal sheet.

[6] In the method for forming a plastic sheet according to the above [5], the surface treatment of the heated metal sheet may include
After the heated metal sheet surface is mirror-finished, Teflon coating is applied to the heated metal sheet surface.

[7] In the method for forming a plastic sheet according to the above [2], a heating metal sheet is provided on a heating surface side of a heating device which is in direct contact with the plastic sheet, and the heating metal sheet is used when the plastic sheet is in contact with the plastic sheet. A large number of small-diameter holes are made in the heating metal sheet so that no air remains between the plastic sheet and the heating metal sheet, and the air is released to the atmosphere or evacuated from these holes.

[8] In the plastic sheet forming apparatus, a heating device installed above and below a heating section of the plastic sheet, and a heating device lowered so that the heating device can contact both surfaces of the plastic sheet. (1) a driving device, a cartridge heater capable of changing the number and arrangement thereof so that the heating length of the plastic sheet can be adjusted, and a heating metal sheet which directly contacts the plastic sheet on the surface of the heating device. , A second driving device that allows the heated metal sheet to be relaxed.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall assembly diagram of a sheet forming machine showing an embodiment of the present invention, FIG. 2 is a configuration diagram of a sheet heating section of the sheet forming machine, and FIG. 3 is a cross-sectional view of the sheet heating section in FIG. 4 is a cross-sectional view of the sheet heating unit in FIG. 1 as viewed in the direction of arrow B. FIG. 5 is an explanatory view of adjusting the sheet heating length of the sheet heating unit. FIG. 6 is an enlarged cross-sectional view of FIG. FIG. 7 is a configuration diagram of the horizontal stretching device, and FIG. 7 is a plan view of a portion A of the horizontal stretching device of the forming unit in FIG.

In FIG. 1, reference numeral 100 denotes a sheet forming machine.
At one end, a web feeder 1 is provided.
The sheet feeding device 3 for feeding the plastic sheet 2 (hereinafter, simply referred to as a sheet) fed from the sheet feeding unit 5 to the sheet heating unit 5 is provided.

On the downstream side of the sheet heating section 5, a forming section 7 for forming the sheet 2 is provided.
Are provided with upper and lower dies 8, 8 '. 9 is the mold 8
Reference numeral 4 denotes an output sheet feeder provided downstream of the forming section 7. The entrance and exit sheet feeding devices are devices that intermittently feed both ends of the sheet 2 by clamping them, and are conventionally generally used, and the structure thereof is omitted.

Next, the sheet heating section 5 will be described with reference to FIGS.

Reference numerals 22 and 22 'denote fixing members disposed on the upper and lower portions of the sheet heating section, respectively.
Air cylinders 12 and 12 '(first driving device) (an AC servomotor and a ball screw may be used instead of the air cylinder) are provided at 2'.

Between the upper and lower fixing members 22 and 22 ′, the elevating members 20 and 20 ′ are vertically moved along the flow direction of the sheet 2.
Is provided, and the upper elevating member 20 is provided with the air cylinder 12.
Is fixed to the tip of the lifting rod 19, and the lower lifting member 2
0 'is fixed to the tip of a lifting rod 19' of the air cylinder 12 '. 23, 23 'are the lifting members 20,
It is a guide rod for guiding 20 'to the fixing members 22, 22'.

On the lower surface of the upper elevating member 20 on the molding portion side,
The fixed heater 10 is fixed by bolts 25, and the fixed heater 10 'is fixed by bolts 25' on the upper surface of the lower elevating member 20 'on the forming portion side. On the upstream side of the fixed heaters 10 and 10 ', cartridge heaters 11 and 11' for adjusting the heating length of the sheet 2 are provided detachably to the elevating members 20 and 20 'by bolts 25 and 25'. ing. The fixed heaters 10 and 10 'and the cartridge heaters 11 and 11' are provided with sheathed heater elements 5A and 5A ', respectively, and the heater heat shield plates 15 and 15' on the side of the lifting members 20 and 20 '. Is provided.

On the molding portion side of the lifting members 20, 20 ', metal brackets 6, 6' for sheet heating (SUS: Special Use Sta) are provided via brackets 26, 26 '.
Inless Steel) is fixed at one end.
The sheet heating metal sheet 6.6 'is fixed to the fixed heater 10,
10 'and cartridge heaters 11 and 11' are disposed on the heating surface side, and the other ends thereof are SUS sheet tensioning air cylinders 14 and 14 '(second wires) via SUS sheet tensioning wires 13 and 13'. (A driving device) (an AC servomotor and a ball screw may be used instead of the air cylinder).

The sheet heating metal sheets 6, 6 '
A large number of small holes (not shown) having a diameter of 0.1 to 0.3 mm are formed on the surface of the sheet 2 so that air cannot be trapped between the sheet 2 and the metal sheets 6, 6 'during heating. I have.

SUS sheet tension air cylinder 14,
14 'is provided on the elevating members 20, 20', and the SUS sheet tensioning wires 13, 13 'are connected to the elevating members 20, 2'.
It is supported by turning sheaves 21, 21 'provided at 0'. The SUS sheet tension wires 13 and 13 ′ and the sheet heating metal sheets 6 and 6 ′ are attached to the brackets 27 and 2.
Persisted through 7 '.

At the end of the elevating member 20, 20 'on the side of the forming part,
Shutters 16 and 16 'are provided for shielding the forming section 7 and the sheet heating section 5, and shutter driving air cylinders 17 and 17' provided on the elevating members 20 and 20 '.
(An AC servomotor and a ball screw may be used instead of the air cylinder.) On the entrance side of the sheet 2 of the sheet heating unit 5, entrance-side sheet heat shielding plates 18, 18 ′ are detachably supported on the frame of the sheet heating unit so as to sandwich the sheet 2. Cooling pipes 18A, 18A,
18A 'is provided so that the shielding plates 18, 18' can be cooled.

The clamping device for the sheet 2 of the forming section 7 will be described with reference to FIGS.

The sheet clamping device 29 is provided with a sheet stretching air cylinder 3 provided on the frame 28 of the forming section 7.
4 (a hydraulic cylinder or an AC servomotor and a ball screw may be used instead of the air cylinder) and the piston rod 33 of the air cylinder 34
Is formed of a sheet clamp portion 35 provided at the tip of the.

The sheet clamp portion 35 includes clamp plates 30 and 30 ′ provided on the sheet clamp frame 36 so as to be openable and closable, and a sheet piercing needle 31 provided on the clamp side of the sheet 2 of the clamp plates 30 and 30 ′.
And clamp plate opening / closing cylinders 32, 32 'provided on the sheet clamp frame 36 for opening and closing the clamp plates 30, 30'.

The sheet clamp device 29 is provided to face the sheet 2 therebetween. Further, in order to support the sheet clamp frame 36 on the frame 28 so as to be able to advance and retreat, a guide rod 37 is provided on the sheet clamp frame 36, and a guide member 38 for guiding the guide rod 37 is provided on the frame 28.

With the above construction, in FIG. 1, the sheet 2 fed by the raw material feeding device 1 is sent to the output side by the input side sheet feeding device 3 and the output side sheet feeding device 4.

When the sheet 2 is set in the sheet heating device 5, the sheet heating metal sheets 6 and 6 'are moved up and down from above and below to come into contact with the sheet 2 and start heating. When the heating time is over, after the sheet heating device 5 is separated from the sheet 2, the heated sheet 2 is sent to the forming section 7, and the upper and lower dies 8 and 8 'are moved to the forming position by the forming table driving device 9. , Start molding.

At this time, the entrance side sheet feeder 3
The sheet heating device 5 moves up and down simultaneously with the start of forming the sheet 2 newly sent to the sheet heating device 5 to be in a closed state,
The heating of the sheet 2 is started.

2 to 5, the sheet heating device 5
Is a shutter driving air cylinder 17 from the sheet heating metal sheets 6 and 6 'and the fixed heaters 10 and 10'.
And 17 'and sheet heat shielding plates 18 and 18' on the entrance side.

Here, the sheet heating device 5 heats the sheet 2 sent to the heating section by fixed heaters 10 and 10 'and cartridge heaters 11 and 11' for adjusting the heating length (hereinafter simply referred to as cartridge heaters). Is done. The lifting and lowering of the sheet heating device 5 is performed by the air cylinders 12 and 12 '.

The change of the sheet heating length can be adjusted by changing the number and the installation position of the fixed heaters 10 and 10 'of fixed size and the cartridge heaters 11 and 11' which are heaters for adjusting the heating length. ing. That is, SUS
By driving the air cylinders 14 and 14 ′ for tensioning the seat,
After the SUS sheet tensioning wires 13 and 13 'are loosened and the number of the cartridge heaters 11 and 11' is adjusted, the SUS sheet tensioning air cylinders 14 and 1 'are again formed.
4 'to drive the SUS sheet tensioning wires 13 and 1
3 'can be tensioned to adjust the overall sheet heating length.

For example, when it is desired to shorten the entire sheet heating length, as shown in FIG. 5A, one cartridge heater 11 'is provided. If it is desired to lengthen the entire sheet heating length considerably, as shown in FIG. 5B, four cartridge heaters 11 'are provided. Further, when it is desired to maximize the entire sheet heating length, as shown in FIG. 5C, the cartridge heater 11 'is arranged to the full length of the elevating member 20. Here, the fixed heaters 10 and 1
0 'and cartridge heaters 11 and 11' make holes in the heater block,
Use the one with A 'embedded. Although not shown, the heater is controlled by a heater temperature sensor and a controller.

To prevent the sheet heating metal sheets (SUS sheets) 6 and 6 'from being loosened, the ends of the sheet heating metal sheets 6 and 6' are connected via SUS sheet tensioning wires 13 and 13 '. And the SUS sheet tensioning air cylinders 14 and 14 'are always tensioned.

Further, the surfaces of the metal sheets 6 and 6 'for sheet heating are mirror-finished and further coated with Teflon to prevent adhesion of resin.

Further, heater heat shield plates 15 and 15 'are provided on the elevating member side of the fixed heaters 10 and 10' and the heating length adjusting cartridge heaters 11 and 11 '. On the exit side of the heating device, a shutter 16 used for molding is provided.
And 16 'are mounted and opened and closed by shutter driving air cylinders 17 and 17'.

Further, the sheet 2 is placed on the SUS sheet 6 from above and below.
When air is left between the sheet 2 and the sheet heating metal sheets 6 and 6 'when the sheet is sandwiched between the sheet 2 and the sheet heating metal sheet 6 and 6', the expansion and contraction speed of the air cylinders 12, 12 'arranged in the sheet feeding direction is changed. The SUS sheets 6, 6 'are controlled so as not to contact the entire surface of the sheet 2 at once, or a large number of small-diameter holes (for example, 0.1 to 10) are formed in the sheet heating metal sheets 6 and 6'.
(0.3 mm) 6A, 6A 'may be opened to allow air to escape from this hole (see FIG. 4).

In some cases, the fixed heaters 10 and 10 'and the heater heater 1 for adjusting the heating length can be evacuated from this hole to remove air.
1 and 11 'also have small diameter holes 10A, 10A'11A,
11A '(note that 10A and 10A' are small-diameter holes formed in the fixed heaters 10 and 10 ', but are not shown), and suction is performed through the holes.

The heat-shielding plates 18 and 18 'for the sheet heating metal sheets 6 and 6' are used for heat-shielding the portions of the sheet-side heating unnecessary portion from the sheets. Adjustment cartridge heater 1
The positions of the shielding plates 18 and 18 'are adjusted according to the increase and decrease of 1, 11'.

When the heated sheet 2 is sent to the forming section 7, the incoming sheet feeding device 3 and the outgoing sheet feeding device 4
Sends sheet 2 in tune. At this time, if the exit side sheet feeder 4 moves more than the entrance side sheet feeder 3, the sheet 2 is longitudinally stretched.

6 and 7, the sheet 2 is restrained by sheet piercing needles 31 provided on the sheet clamp plates 30 and 30 'and the upper clamp plate 30. Opening and closing of the clamp plates 30 and 30 'are performed by air cylinders 32 and 3 for opening and closing the clamp plates.
2 '.

The position adjustment of the clamp plates 30 and 30 ′ is performed by driving the piston rod 33 of the sheet stretching air cylinder 34 in accordance with the width of the sheet 2. The elimination and expansion of the drawdown of the sheet 2 is also performed by the expansion and contraction of the sheet stretching air cylinder 34. Clamp plate 30
And 30 'are adapted to the mold.

It should be noted that the present invention is not limited to the above-described embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0048]

As described above, according to the present invention, the following effects can be obtained.

(1) Since both surfaces of the sheet are heated by direct contact, even a thick sheet can be uniformly heated over the entire molding area.

Heating with a small temperature difference between the surface and the inner surface of the sheet became possible.

Since the sheet can be heated at a low temperature, the transparency after molding of the transparent sheet is better than that of the indirect heating method.

Since the sheet heating set temperature is low and the sheet is directly contact heated, energy consumption is greatly reduced.

In the conventional indirect heating, a large number of heaters are individually controlled. On the other hand, according to the present invention, the control of the heater is performed at two points, that is, the upper one point and the lower one point, and the control is easily facilitated.

The draw down of the sheet during the heating of the sheet was eliminated, and the molding was facilitated greatly. Further, even in a printing sheet which has conventionally been difficult to form, there is little deviation in the printing position, so that printing can be easily performed.

The heating set temperature can be lowered, and there is no fear of burnout of the sheet.

(2) Since the sheet heating section and the forming section are separated from each other, it is possible to perform plug forming for forming a deep molded product while directly heating.

(3) As a sheet feeding system, a two-point feeder system of an entrance side sheet supply unit and a molding exit side unit, and a molding unit side crumbling system are adopted. Seat drawdown can now be eliminated.

The sheet can be stretched in the feeding direction and the direction perpendicular to the feeding.

In the case of feeding a sheet, a conventional spike chain has a structure in which it is forced to bite, so that some waste may be generated. However, according to the method using the needle of the present invention, an excessive stab may be caused. There was no scum generation because there was no.

[Brief description of the drawings]

FIG. 1 is an overall assembly diagram of a sheet forming machine showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a sheet heating unit of the sheet forming machine according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the sheet heating unit shown in FIG.

FIG. 4 is a cross-sectional view of the sheet heating unit shown in FIG.

FIG. 5 is an explanatory diagram of adjusting a sheet heating length of a sheet heating unit according to the embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view taken along the arrow C of FIG. 1 showing an embodiment of the present invention, and is a configuration diagram of a laterally extending device of a forming section.

FIG. 7 is a cross-sectional drawing device A of a forming section according to an embodiment of the present invention.
It is a partial plan view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Raw material feeding device 2 Plastic sheet 3 Entry side sheet feeder 4 Exit side sheet feeder 5 Sheet heating device 5A, 5A 'Sheath heater element 6, 6' Metal sheet for sheet heating 6A, 6A ', 10A, 10A', 11A, 11A '
Small-diameter hole 7 Molding section 8, 8 'Mold 9 Molding table drive 10, 10' Fixed heater 11, 11 'Cartridge heater for heating length adjustment 12, 12' Air cylinder (first drive) 13, 13 ′ SUS sheet tensioning wire 14, 14 ′ SUS sheet tensioning air cylinder (second driving device) 15, 15 ′ Heater heat shield plate 16, 16 ′ Shutter 17, 17 ′ for shutter clamp on sheet forming side Cylinder 18, 18 'Inlet-side sheet heat shield plate 18A, 18A' Water-cooled pipe 19, 19 'Lifting rod 20, 20' Lifting member 21, 21 Roller 22, 22 'Fixing member 23, 23' Guide rod 25, 25 'Bolt 26, 26 ', 27, 27' Bracket 28 Frame 29 Seat clamp device 30, 30 'Seat Clamp plate 31 Sheet piercing needle 32, 32 'Clamp plate opening / closing air cylinder 33 Piston rod 34 Sheet stretching air cylinder 35 Sheet clamp section 36 Sheet clamp frame 37 Guide rod 38 Guide member 100 Sheet forming machine

Continued on front page F-term (reference) 3E075 BA30 CA02 DA03 DA04 DA14 DA15 DC24 DC44 GA03 4F203 AC03 AG07 AH55 AH56 AJ02 AJ11 AK09 AM32 AR06 AR12 AR20 DA06 DA14 DB02 DC13 DD01 DE06 DH06 DJ01 DJ14 DJ29 DK07 DK13 DL01 DN10 DM11 DM23 DN23 DN24 DN26 DW41 4F208 AC03 AG07 AH55 AH56 AJ02 AJ11 AK09 AM32 AR06 AR12 AR20 MA05 MA06 MB02 MC03 MC04 MH06 MH10 MJ14 MJ15 MJ22 MJ23

Claims (8)

[Claims] In a method for forming a plastic sheet, (a) a heating device installed above and below a heating section of the plastic sheet is moved up and down, and (b) the heating device is brought into contact with both surfaces of the plastic sheet so that the plastic sheet is brought into contact. Heating, and (c) molding the heated plastic sheet. 2. The method of forming a plastic sheet according to claim 1, wherein the heating length of the plastic sheet is adjusted by adjusting the number of cartridge heaters. . 3. The method of molding a plastic sheet according to claim 1, wherein the end of the plastic sheet is clamped by a clamper in the molding section, so that the plastic sheet can be held and expanded during molding. Plastic sheet molding method. 4. The method for forming a plastic sheet according to claim 1, wherein a sheet feeder is used on a supply side of the plastic sheet to a heater and on a discharge side of a forming section to enable fixed-size feeding and sheet stretching feeding. Characteristic plastic sheet molding method. 5. The method for forming a plastic sheet according to claim 2, wherein a heating metal sheet is provided on a heating surface side of a heating device that directly contacts the plastic sheet, and the heating metal sheet is subjected to a surface treatment to be heated. A method of forming a plastic sheet, characterized in that the surface of the plastic sheet and the heated metal sheet are prevented from adhering by using a sheet material. 6. The method for forming a plastic sheet according to claim 5, wherein the surface treatment of the heated metal sheet is performed by applying a Teflon (registered trademark) coating to the surface of the heated metal sheet after mirror finishing the surface of the heated metal sheet. A method for forming a plastic sheet, comprising: 7. The method for forming a plastic sheet according to claim 2, wherein a heating metal sheet is provided on a heating surface side of a heating device that directly contacts the plastic sheet, and wherein the heating metal sheet is in contact with the plastic sheet. A method of forming a plastic sheet, comprising: forming a large number of small-diameter holes in a heated metal sheet so that air does not remain between the heating metal sheet and the heating metal sheet; 8. A plastic sheet forming apparatus, comprising: (a) a heating device provided above and below a heating section of the plastic sheet; and (b) lowering the heating device, and the heating device is provided on both surfaces of the plastic sheet. (C) a cartridge heater whose quantity and arrangement can be changed so that the heating length of the plastic sheet can be adjusted, and (d) a surface of the heating device. Is a heating metal sheet which comes into direct contact with the plastic sheet, and (e) a second driving device which allows the heating metal sheet to relax.