JPS6233934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a vacuum forming apparatus for thermally softened sheet material.

[Prior Art] Conventionally, in vacuum forming of a heat-softened sheet material, as shown in Fig. Generally, a plastic resin plate or sheet is placed on the mold, and the vacuum function of mold 1 is activated to mold material m into mold m1.

The heat softening treatment of the material m is usually carried out by holding the material m in a stretched state by gripping the periphery of the material m or both opposing edges with a clamp or fastener 2, and then heating one or both sides of the material m. do.

[Problem that the invention seeks to solve]

In this case, the material m stretches under its own weight as the resin softens due to heating, resulting in a slack m2. In particular, when heating the material m from the bottom surface, as the slack m2 progresses, the distance between the slack surface and the heating heater becomes smaller, resulting in stronger heating, which further increases the material m.
The degree of softening and sagging increases.

Therefore, in the conventional method described above, the material m in the sagging state is applied to the mold 1, and due to the sagging, it is difficult to maintain uniform heating of the material m, and the elongation is uneven, resulting in wrinkles in the molded product. Problems such as the molded product's wall thickness becoming extremely thin in some areas were likely to occur. In particular, when the material m is an olefin resin with a low melt viscosity, the occurrence of wrinkles, wall thickness irregularities, etc. due to the above-mentioned sagging is noticeable. Even with other resins, depending on the molded shape, the above-mentioned sagging of the material can have an adverse effect on the quality and quality of the molded product.

Therefore, some devices are designed to apply tension to the material m by constantly pulling the grip 2 of the material m outward with a coil spring or the like, thereby absorbing the softened slack m2. Since it easily causes tears, tears, and excessive elongation, there is a natural limit to the tensile force that can be applied, and sufficient slack absorption cannot be achieved.

In addition, for example, if the material is in a melted or excessively softened state, such as a foamed resin plate (sheet) that has just been foamed at a high temperature, it is impossible to place the material on the mold 1; Previously, it was impossible to perform a subsequent vacuum forming process on the material, and once the foamed resin material had been produced, it was necessary to heat and soften it again and then perform the vacuum forming process.

The present invention was proposed in view of the above, and
To solve the problems caused by the above-mentioned sagging by applying a heat-softened molding material m without sagging, and to make it possible to vacuum-form the material even in a molten or excessively softened state without any trouble.
The purpose is to enable continuous and efficient vacuum forming processing.

B. Structure of the Invention [Means for Solving Problems] The present invention comprises: a sheet material output device that continuously outputs a heat-softened sheet material to be formed; and a sheet material output side of the sheet material output device. a horizontally arranged frame or flat plate; a vacuum forming mold supported above the frame or flat plate with its molding surface facing downward, and whose downward and upward movement relative to the frame or flat plate is controlled; An upper belt portion is disposed on the upper surface of the frame or the flat plate to extend approximately horizontally, and the upper belt portion is intermittently driven to rotate in a direction in which the upper belt portion moves to a side opposite to the sheet material output device side. an endless belt made of a material with high stretchability and elasticity; a device for feeding sheet material output from the sheet material output device to the upper surface of an upper belt portion of the endless belt; A continuous vacuum forming device having a sheet material fixed length cutting device on the upper surface, which operates every time the sheet material is fed out for a predetermined length to cut the fed sheet material portion and the subsequent sheet material portion. The gist is:

[Effect]

a The heat-softened sheet material to be formed, which is continuously output from the sheet material output device, is sent out by the feeding device to the upper surface of the upper belt portion of the endless belt, which is being rotationally driven at that point, and transferred to the upper surface. Then, as the belt continues to rotate, it is transported to a position between the frame or flat plate and the vacuum forming mold in the raised position with the forming surface facing downward.

(b) The rotational drive of the endless belt is temporarily stopped when a predetermined length of sheet material is conveyed to a position between the frame or flat plate and the vacuum forming mold. Further, the sheet material cutting device to a fixed length is operated to cut the sheet material portion fed to the endless belt side to a fixed length.

Even if the sheet material transferred to the upper belt part of the endless belt and conveyed between the frame or flat plate and the vacuum molding die is sufficiently heated and softened and is likely to stretch or sag, The belt is stretched horizontally and stably held in a generally flat state on the upper belt portion of an endless belt made of a highly elastic material.

c The vacuum forming mold, which is supported with its forming surface facing downward, is lowered with respect to the sheet material that is held flat and temporarily stopped at a position below the vacuum forming mold, and the vacuum forming mold is lowered, and the molding surface of the vacuum forming mold is moved downwardly. The sheet material held flat is applied, and the vacuum function of the mold brings the sheet material into direct suction contact with the downward forming surface of the mold to vacuum form it.

That is, the sheet material to be molded is always applied to the mold in a substantially flat state, and therefore problems such as wrinkles and irregular wall thickness of the molded product due to sagging of the sheet material, as in the conventional method described above, do not occur.

d. The vacuum forming mold is then moved upward, the molded product is removed from the mold, and the rotation of the endless belt and the feeding of the sheet material by the sheet material feeding device to the belt are restarted.

By repeating the operations a to d above as one cycle, the sheet material that is continuously output from the sheet material output device is continuously and efficiently vacuum formed.

[Example] First Example (Figs. 1 to 3) In Fig. 1, 7 is a continuous sheet material softening device as a device that continuously outputs the sheet material m to be formed in a thermally softened state. It mainly consists of a continuous conveyor 7a and a heater 7b.

Reference numeral 4 denotes a frame body disposed substantially horizontally on the sheet material output side of the device 7. The frame body 4 has a shape and size that approximately corresponds to the outer peripheral shape and size of the lower surface side of the vacuum forming mold 1, which will be described later, and is fixedly installed on the floor or a stand via pedestal legs. ing.

Reference numeral 1 denotes a vacuum molding die that is supported above the frame 4 with its molding surface facing downward, and is controlled to move downward and upward with respect to the frame 4. Mold 1 in this example is a convex type. The vertical movement mechanism of this type is omitted from the figure.

Reference numeral 3 denotes a direction in which an upper belt portion (ascending belt portion) on the upper surface of the frame is extended approximately horizontally, and the upper belt portion moves toward the side opposite to the sheet material output device 7 side. This is an endless belt made of a highly elastic material that is rotated and controlled intermittently by a. Reference numeral 6 indicates a driving roller for suspending the endless belt.

The above-mentioned endless belt 3 may correspond to the amount of plunge of the mold 1 into the upper belt portion when the mold 1 is moved downward relative to the upper belt portion, or may follow the shape of the molding surface of the mold 1 used. Use a material with good elasticity; for example, rubber sheets such as silicone rubber, fluororubber, butyl rubber, and EPT rubber can be used well. The thickness of the sheet is generally about 0.2 to 3 mm, preferably about 0.3 to 1 mm. The sheet may be airtight or breathable.

When the sheet material m to be formed is placed on its upper belt portion, the endless belt 3 is stretched to a state where an appropriate tension is applied to sufficiently support the weight of the sheet material m and hold the material m substantially flat. It has been done.

8, 9, and 10 are disposed between the device 7 and the endless belt 3 as devices for feeding the sheet material m output from the device 7 to the upper surface of the upper belt portion of the endless belt 3. There are three pairs of sheet material feeding rollers: first, second, and third. The first roller pair 8 is a constantly rotating roller pair, and the second
Roller pair 9 is an intermittent rotating roller pair, third roller pair 1
0 is a pair of constantly rotating or intermittent rotating rollers.

Reference numeral 11 denotes a sheet material cutting device (cutter) to a fixed length, which is disposed between the second roller pair 9 and the third roller pair 10.

(1) The softened sheet material m continuously outputted from the device 7 passes through the first, second, and third roller pairs 8, 9, and 10 that are in rotational driving state, and then moves in the direction a. It is sent out to the upper surface of the upper belt part of the endless belt 3 which is in a rotationally driven state,
As the belt 3 rotates, the mold 1 is conveyed between the frame 4 and the mold 1 standing by in the raised position.

(2) When a predetermined length of the sheet material is sent out to the belt 3 side, the cutting device 11 is activated to cut the sheet material portion sent to the belt 3 side and the subsequent sheet material portion.

(3) At the same time as this cutting, the rotational drive of the second roller pair 9 is temporarily stopped. When the third roller pair 10 is an intermittent rotating roller pair, the rear end of the cut sheet material m on the belt 3 side is the third roller pair 10.
The rotation is temporarily stopped when it finishes passing 0. Subsequent sheet material portions are sequentially outputted from the device 7 side until the second roller pair 9 is driven to rotate again, but the outputted material portions are not transferred to the first roller pair 8 and the second roller pair during that time. It becomes a slack part between the roller pair 9 and stands by for the next feeding.

(4) The endless belt 3 temporarily stops rotating when the rear end of the cut sheet material m passes through the third pair of rollers 10 and the entire sheet material is conveyed to a predetermined position below the mold 1. will be stopped. Even if the conveyed sheet material m is sufficiently heated and softened and is likely to elongate or sag, it remains stretched almost horizontally and is completely spread over the upper belt portion of the endless belt made of a material with high elasticity. It is stably held in a substantially flat form.

(5) Next, the mold 1 is moved downward. The mold 1 uses its downward convex surface to push the sheet material m and the upper belt part supporting it downward into the frame 4 against the elasticity of the belt part, and finally pushes it into the frame 4. As shown in the second figure, the lower peripheral surface of the mold 1 is received by the upper surface of the frame 4 via the peripheral part of the material m and the upper belt part, and the mold 1 is lowered until the periphery of the material m is in a sealed state.

(6) Next, the vacuum mechanism (not shown) of mold 1 is activated. As a result, material m is vacuum formed m1. In this case, when the belt 3 is airtight (non-air permeable), the belt portion is apparently vacuum-formed together with the material m in close contact with the outer surface of the material m (dashed line 3' in FIG. 2). Further, when the belt 3 is breathable, air intervenes between the belt portion and the material m during vacuum forming, so that only the material m is formed into the material m1. In either case, material m is vacuum formed. Further, by carving an arbitrary uneven pattern such as a grain pattern on the molding surface of the mold 1, the uneven pattern is beautifully transferred to the surface of the molded product.

That is, since the sheet material m to be formed is supported by the upper belt portion of the endless belt 3 in a substantially horizontally stretched state and applied to the mold 1 in a substantially flat state, the molded product may have wrinkles and wall thickness due to sagging of the sheet material. Does not cause problems such as irregularities.

Cooling of the material m1 vacuum-formed on the surface of the mold 1 may be done by piping a cooling pipe inside the mold 1 to cool the mold 1 as in the conventional method, but as shown in the example in Fig. 2, the material m1 can be cooled by A water jet or cooling air blowing device 5 is provided below the belt portion to spray the material m immediately after vacuum forming.
Water or cooling air is blown onto the surface of the belt portion 3' which is apparently vacuum-formed and in close contact with the outer surface of the molded article m1, and the molded product m1 is indirectly cooled through the belt portion 3'. Alternatively, holes 31 of appropriate sizes are made in each part of the belt 3 as shown in the third figure,
Immediately after vacuum forming the material m, the device 5 is activated to directly cool the molded product m1 through the hole 31, which is effective because the molded product can be cooled efficiently and quickly.

When the above-mentioned holes 31 are provided in the belt 3, the edges of the holes 31 are made thick beaded edges 32 as shown in the figure, for example, so that the holes 31 do not become a starting point for causing tears in the sheet when the belt 3 is stretched. Take appropriate reinforcement measures. In this case, the front side of the molded product is the side in contact with the mold 1, so the hole 3 of the belt
Even if 1 is transferred as a mark on the surface of the molded product or the bottom surface of the molded product gets wet with cooling water, it will not affect the quality of the product because it is on the back surface of the molded product.

(7) Next, a type 1 upward movement is made. Molded product m1
is removed from the molding surface and sent to the next process such as a trimming process. The upper belt portion of the endless belt 3 returns to its original flat stretched state due to its own elasticity as the mold 1 and molded product m1 rise.

(8) When the mold 1 is raised, the second roller pair 9,
Third roller pair 10 (when temporarily stopped), re-rotation of endless belt 3 (re-rotation)
is carried out, and feeding of the sheet material to the upper belt portion of the endless belt 3 is restarted.

By repeating the operations (1) to (8) above as one cycle, the sheet material that is continuously output from the device 7 is continuously and efficiently vacuum formed.

Second Embodiment (Fig. 4) In this example, a high-temperature foam sheet m that has been subjected to a foaming furnace treatment in a foaming furnace 12 and is continuously sent out is sequentially used in a cyclical manner using a plurality of vacuum forming molds, one after another. This is an example of efficient vacuum forming.

That is, 12 is a heating and foaming furnace for the foamable resin material m;
Reference numeral 3 denotes a heat-retaining furnace connected thereto, and within the heat-retaining furnace 13, first to third roller pairs 8 to 10 and a cutter device 11 similar to the example shown in FIG. 1 are arranged. Endless belt devices 3 and 6 including frames 4 are arranged in series with the material outlet 14 of the heat-retaining furnace 13, as in the example shown in FIG. However, in this example, since a concave mold is used as the vacuum forming mold 1, the frame body 4 may be simply a flat plate.

In this example, four molds 1 are used, and a drive device (not shown) sequentially circulates and moves the molding station A → cooling station B → molded product release station C → molding station A. are placed in heating furnace 1 at molding station A in order.
The material m sent out from the outlet of No. 3 is placed on the endless belt 3, which rotates and then stops temporarily, to vacuum form the material m, and then mold the molded product m1.
The molded product is held as it is and moved to the cooling station B, and the molded product is not cooled by the cooling water injection device 5.
Next, the molded product m1 is moved to station C to be released from the mold, and then returned to molding station A and lowered onto the sheet 3 on which material m is placed, and the cycle is repeated.

As a result, even if the material processing speed in the foaming furnace 12 is high, the material coming out of the foaming furnace can be vacuum-formed continuously and rapidly.

C. Effects of the Invention As described above, according to the apparatus of the present invention, (1) Since the sheet material m to be formed can always be applied to the mold 1 in a substantially flat state, it is possible to apply the sheet material m to the mold 1 in a substantially flat state, so that it is possible to apply the sheet material m to the mold 1 in a substantially flat state. Does not cause problems such as wrinkles or irregular wall thickness of the molded product.

(2) Regardless of whether it is soft or hard, even materials that have been heated to high temperatures and have been melted or excessively softened can be vacuum formed.

(3) Since the mold 1 faces downward, the cooling medium can sufficiently act directly on only the molded product m1 without wetting the mold 1, compared to the case where molded product m1 is indirectly cooled by cooling mold 1, for example The molded product can be released from the mold quickly.

(4) Vacuum forming process is performed continuously.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the device of the first embodiment, Fig. 2 is a state diagram when the mold is lowered, Fig. 3 is an enlarged sectional view of a part of an example in which holes are provided on the endless belt surface, and Fig. 4 is A schematic configuration diagram of the second embodiment device, and FIG. 5 is a diagram showing a conventional example. 1 is a vacuum forming mold, 3 is an endless belt, and 4 is a frame or a flat plate.

Claims (1)

[Scope of Claims] 1. Sheet material output devices 7 and 12 that continuously output sheet material m to be formed in a thermally softened state, and a frame body disposed approximately horizontally on the sheet material output side of the sheet material output device. 4 or a flat plate; a vacuum forming mold 1 supported above the frame or the flat plate with its molding surface facing downward, and whose downward and upward movements are controlled relative to the frame or the flat plate; and the frame or the flat plate. A telescoping device in which an upper belt portion is disposed on the upper surface side so as to extend approximately horizontally, and the upper belt portion is intermittently rotationally controlled in a direction in which the upper belt portion moves toward the side opposite to the sheet material output device side. An endless belt 3 made of a highly elastic material; devices 8, 9, and 10 for feeding sheet material output from the sheet material output device to the upper surface of the upper belt portion of the endless belt; and an upper belt portion of the endless belt. A sheet material standard length cutting device 1 that operates every time a predetermined length of sheet material is fed out on the upper surface and cuts the fed sheet material portion and the subsequent sheet material portion.
1. A continuous vacuum forming apparatus comprising: