Resin supply device, die lip opening and closing device

Abstract

To provide a die lip open / close device that can suppress wear and tear of a drive unit of a pusher.SOLUTION: A die lip open / close device of the present invention includes: an open / close structure that opens and closes a die lip of a T-die in response to a linear movement of a pusher; and a drive unit that drives the pusher to move in a straight line. The pusher has a plurality of sub-pushers arranged along a longitudinal direction of the die lip, and the drive unit is provided for each sub-pusher.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a die lip opening and closing device. [Background technology]

[0002] Patent Document 1 discloses a die lip opening and closing device configured to open and close the die lip of a T-die by linearly moving a pusher. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-116846 Summary of the Invention [Problem to be solved by the invention]

[0004] The pusher in Patent Document 1 has an elongated shape that extends along the longitudinal direction of the die lip. Resin pressure from the resin inside the T-die is applied to the pusher, but this resin pressure may not be applied uniformly along the longitudinal direction of the die lip, which may cause the pusher to tilt. If the force applied to the pusher is transmitted to the drive unit while the pusher is tilted, the drive unit may become susceptible to wear and breakage.

[0005] The present invention has been made in view of the above circumstances, and provides a die lip opening and closing device that can suppress wear and damage to the drive part of the pusher. [Means for solving the problem]

[0006] According to the present invention, there is provided a die lip opening and closing device comprising: an opening and closing structure that opens and closes the die lip of a T-die in accordance with the linear movement of a pusher; and a drive unit that drives the pusher to move linearly, wherein the pusher comprises a plurality of sub-pushers arranged along the longitudinal direction of the die lip; and a drive unit is provided for each of the sub-pushers.

[0007] The die lip opening and closing device of the present invention is characterized in that the pusher is composed of multiple sub-pushers, each of which is provided with a drive unit. Because the sub-pusher has a shorter longitudinal length than the pusher, it is less likely to tilt due to the resin pressure from the resin inside the T-die, thereby reducing wear and damage to the drive unit. Furthermore, if a single pusher is provided with multiple drive units instead of dividing it, the pusher is more likely to tilt due to misalignment in the operation timing of the drive units. However, by configuring the pusher with multiple sub-pushers, the pusher's tilt due to misalignment in operation timing is also reduced.

[0008] Various embodiments of the present invention will be described below as examples, and the embodiments shown below can be combined with each other. Preferably, in the die lip opening and closing device described above, the drive unit is configured by a direct acting cylinder. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a molding apparatus 10 equipped with a die lip opening and closing device 50 according to a first embodiment of the present invention. [Figure 2] 2A is a bottom view of the main part of the die lip opening and closing device 50 of FIG. 1, and FIG. 2B is a side view of the die lip opening and closing device 50, with a cross section taken along line BB in FIG. 2A being shown for a part of the configuration. [Figure 3] FIG. 2C is an enlarged view of area A in FIG. 2B. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an independent invention.

[0011] 1. First embodiment 1 and 2, a molding apparatus 10 according to a first embodiment of the present invention includes a resin supplying device 12 and a mold unit 14. The resin supplying device 12 is provided with an extruder 18 including a hopper 16 and a hydraulic motor 20. A screw (not shown) connected to the hydraulic motor 20 is provided inside the extruder 18, and the resin introduced from the hopper 16 is melted and kneaded.

[0012] The extruder 18 is connected to an accumulator 24 equipped with a plunger 26. The accumulator 24 is connected to a T-die 28 via a valve 27. The T-die 28 is provided with a die bolt 46 that adjusts the gap amount S (see FIG. 3) of a slit in a die lip 28a of the T-die 28. The die lip 28a of the T-die 28 is opened and closed by a die lip opening and closing device 50, the details of which will be described later.

[0013] The resin melted and kneaded in the extruder 18 is filled into the accumulator 24. The resin filled into the accumulator 24 is charged at high pressure into a T-die 28 by actuation of a plunger 26. While the molten resin is being filled into the T-die 28, the die lip 28a of the T-die 28 is closed. When the accumulator 24 and the T-die 28 are sufficiently filled with the amount of molten resin required for molding, the die lip 28a is opened by a die lip opening / closing device 50, and the molten resin sheet P is extruded through the slit in the die lip 28a.

[0014] The thermoplastic resin used to make the molten resin sheet P can be selected as appropriate. Examples include polyolefins such as polypropylene and polyethylene, acrylic derivatives such as polyamide, polystyrene, and polyvinyl chloride, or a mixture of two or more of these with a foaming agent added. For example, the molten resin sheet P may be made of a material containing expanded polystyrene or expanded polypropylene. The foaming agent may be a physical foaming agent, a chemical foaming agent, or a mixture thereof. Examples of physical foaming agents that can be used include inorganic physical foaming agents such as air, carbon dioxide gas, nitrogen gas, and water, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane, and dichloroethane, as well as supercritical fluids of these agents.

[0015] The mold unit 14, located below the T-die 28, includes opposing molds 32A and 32B. A cavity 116 is formed in the mold 32A. Opposing rollers 30A and 30B are provided below the T-die 28 between the molds 32A and 32B and the T-die 28. After being extruded by the resin supply device 12, the molten resin sheet P is sent downward by the rollers 30A and 30B, passes between the rollers 30A and 30B, and is then placed between the molds 32A and 32B. The rollers 30A and 30B are not necessary. This prevents a decrease in the expansion ratio due to pinching between the rollers 30A and 30B. According to the present invention, the thickness of the molten resin sheet P can be adjusted by adjusting the opening of the die lip 28a, thereby eliminating the need for rollers 30A and 30B. Furthermore, by continuously changing the opening of die lip 28a while extruding molten resin sheet P, it is possible to continuously change the thickness of molten resin sheet P without using rollers 30A and 30B. By gradually increasing the opening of the die lip while extruding, it is possible to suppress drawdown and form a molten resin sheet P that is long in the vertical direction without using rollers 30A and 30B.

[0016] A mold frame 33A is provided around the periphery of cavity 116 of mold 32A. A mold frame 33B is provided in mold 32B facing mold frame 33A. Mold frames 33A and 33B are formed in a substantially annular shape and are formed to be movable toward each other. Mold frames 33A and 33B come into contact with molten resin sheet P to sandwich it therebetween, and form a spatial region surrounded by mold 32A (cavity 116), mold frame 33A, and molten resin sheet P into an airtight space. Depending on molding needs, the space surrounded by mold 32B, mold frame 33B, and molten resin sheet P may also be formed into an airtight space. When molds 32A and 32B are closed and clamped, the air inside the airtight space formed by molten resin sheet P and cavity 116 is reduced in pressure by a vacuum pump (not shown), and molten resin sheet P is shaped into the shape of cavity 116. At this time, pressurized fluid may be pumped into the space surrounded by mold 32B, mold frame 33B, and molten resin sheet P. The molds (molds 32A, 32B) are not limited to those described above, and a pair of molds may be used in which, when the molds are closed, a pair of cavity surfaces are spaced apart by a predetermined distance greater than the thickness of the molten resin sheet P. In this case, with the molten resin sheet P sandwiched and sealed between the pair of cavities, the molten resin sheet P is sucked through tiny suction holes provided on both cavity surfaces. This pulls the molten resin sheet P in the thickness direction, improving the expansion ratio. As a result, a foam-molded product with a high expansion ratio can be obtained.

[0017] Next, the die lip opening and closing device 50 will be described in detail with reference to Fig. 2. Upper and lower plates 71 and 72 of a frame 70 of the die lip opening and closing device 50 are fixed to the T-die 28 via a bracket 73. Note that the upper and lower plates 71 and 72 of the frame 70 shown in Fig. 3 are omitted in Fig. 2.

[0018] A drive unit 51 is fixed to a plate 74 of the frame 70 on the opposite side of the T-die 28. The drive unit 51 operates under the control of a controller (not shown). In this embodiment, the drive unit 51 is a direct-acting cylinder and includes a cylinder 51a and a piston rod 51b. The piston rod 51b has a variable protrusion amount from the cylinder 51a. The power source of the drive unit 51 is not limited and may be hydraulic or electric.

[0019] A pusher 1 is provided on the T-die 28 side of the drive unit 51. The pusher 1 is configured to be driven by the drive unit 51 to move linearly. The die lip 28a of the T-die 28 opens and closes in response to the linear movement of the pusher 1.

[0020] The pusher 1 includes a plurality of sub-pushers 6 arranged along the longitudinal direction of the die lip 28a (the vertical direction in FIG. 2A). The sub-pushers 6 are movable independently of one another. Each sub-pusher 6 includes a bracket 61, a pusher base 62, and a pusher bar 63.

[0021] The pusher base 62 is connected to the piston rod 51b via a bracket 61. A plurality of generally cylindrical pusher bars 63 are provided on the T-die 28 side of the pusher base 62. In this embodiment, two pusher bars 63 are provided for each sub-pusher 6 along the longitudinal direction of the pusher base 62. Since there are two sub-pusher 6, a total of four pusher bars 63 are provided. Each pusher bar 63 is guided linearly by a bushing 73a provided on a bracket 73. A pusher head 63a curved in side view is formed at the tip of each pusher bar 63. In Patent Document 1, all pusher bars 63 are provided with a common pusher head 63a, but in this embodiment, each pusher bar 63 is provided with an individual pusher head 63a. This prevents the pusher base 62 from tilting due to resin pressure.

[0022] A drive unit 51 is provided for each sub-pusher 6, and the multiple drive units 51 operate in conjunction with each other to enable linear movement of the pusher 1, which is made up of multiple sub-pushers 6. As described above, in the die lip opening and closing device 50 of this embodiment, the pusher 1 is made up of multiple sub-pushers 6, and each sub-pusher 6 is provided with a drive unit 51. Because the longitudinal length of the sub-pusher 6 is shorter than that of the pusher, it is less likely to tilt due to resin pressure from the resin in the T-die 28, thereby suppressing wear and damage to the drive units 51. Furthermore, if multiple drive units 51 were provided on a single pusher 1 without dividing the pusher 1, the pusher 1 would be more likely to tilt due to misalignment in the operation timing of the drive units 51. However, by configuring the pusher 1 with multiple sub-pushers 6, the tilt of the pusher 1 caused by misalignment in the operation timing is also suppressed.

[0023] The pusher base 62 is also connected to a position detection sensor 100. The position detection sensor 100 is an eddy current displacement sensor, and is capable of detecting the position of the pusher 1. As the position detection sensor 100, other types of sensors such as a proximity sensor can also be used.

[0024] The T-die 28 is provided with a receiving piece 80 corresponding to the pusher bar 63. The multiple (four in this embodiment) pusher bars 63 and the receiving piece 80 are each arranged symmetrically with respect to the central plane C in the longitudinal direction of the die lip 28a. This makes it easier to apply pressure uniformly to the die lip 28a.

[0025] The receiver 80 has a storage recess 80a that accommodates the pusher head 63a. The bottom of the storage recess 80a has a shape that is approximately complementary to the tip of the pusher head 63a. More specifically, the tip of the pusher head 63a is curved, and the bottom of the storage recess 80a is similarly curved. The tip of the pusher head 63a and the bottom of the storage recess 80a are preferably curved cylindrically. The pusher head 63a is sandwiched between an upper wall 80b and a lower wall 80c within the storage recess 80a. This prevents the pusher head 63a from rattling up and down within the storage recess 80a and ensures stable support. As shown in FIG. 3, the storage recess 80a widens toward the entrance (the pusher head 63a side) (i.e., the vertical length of the storage recess 80a increases), and the upper wall 80b and the lower wall 80c do not contact the pusher head 63a near the entrance of the storage recess 80a. This makes it easier to accommodate the pusher head 63a in the accommodation recess 80a.

[0026] The receiving piece 80 is connected to a die lip piece 81 provided on the die lip 28a. The die lip piece 81 includes a flexible portion 81a formed by cutting out a large portion of a substantially rectangular parallelepiped block to form a thin wall, a receiving piece connecting portion 81b to which the receiving piece 80 is attached, and a fixed portion 81c fixed to the main body of the T-die 28. In other words, the receiving piece connecting portion 81b and the fixed portion 81c are connected by the flexible portion 81a. An opening / closing structure W that opens and closes the slit in the die lip 28a, which is indicated by the gap amount S, includes the receiving piece 80 and the die lip piece 81.

[0027] The die lip 28a and the die lip piece 81 are sandwiched between a pair of side plates 75, and the slit of the die lip 28a opens and closes while being guided by the side plates 75. This allows the slit to be opened and closed stably.

[0028] The die lip opening / closing device 50 operates as follows. When filling the accumulator 24 or the T-die 28 with molten resin, it is necessary to close the slit in the die lip 28a. In this case, each drive unit 51 moves each sub-pusher 6 forward (linearly moving it toward the T-die 28). When the pusher head 63a of the sub-pusher 6 moves forward, the pusher head 63a presses the receiver connection portion 81b via the receiver 80, causing the flexible portion 81a to bend, and the receiver connection portion 81b moves so as to rotate downward around the flexible portion 81a. This reduces the slit gap S to 0. In other words, the die lip 28a is closed.

[0029] Furthermore, when the molten resin sheet P is extruded, each driving unit 51 retracts each sub-pusher 6. When the pusher head 63a of the sub-pusher 6 retracts, the pusher head 63a releases the pressure on the receiving piece 80, and the receiving piece 80 and the receiving piece connection part 81b return to their original positions due to the restoring force of the flexible part 81a of the die lip piece 81, thereby opening the die lip 28a (slit).

[0030] 2. Other embodiments In the above embodiment, the drive unit 51 is a linear-acting cylinder. However, as in Patent Document 1, the drive unit may be of a type having a motion conversion unit that converts the rotational motion of the drive shaft of the motor into linear motion of the pusher. In the above embodiment, an individual pusher head 63a is provided for each pusher bar 63, but a common pusher head 63a may be provided for multiple pusher bars 63 belonging to the same sub-pusher 6. For example, a first pusher head common to the two upper pusher bars 63 in FIG. 2A and a second pusher head common to the two lower pusher bars 63 may be provided. In this case, the significance of configuring the pusher 1 with multiple sub-pusher 6 is not lost, and the number of parts can be reduced. [Explanation of symbols]

[0031] 1: Pusher 6: Sub-pusher 10: Molding equipment 12:Resin supply device 14: Mold unit 16: Hopper 18: Extruder 20: Hydraulic motor 24: Accumulator 26: Plunger 27: Valve 28: T-die 28a: Die Lip 30A: Roller 30B: Laura 32A: Mold 32B: Mold 33A: Formwork 33B: Formwork 46: Diebolt 50: Die lip opening and closing device 51: Drive unit 51a: Cylinder 51b: Piston rod 61: Bracket 62: Pusher base 63: Pusher bar 63a: Pusher head 70: Frame 71: Plate 72: Plate 73: Bracket 73a: Bush 74: Plate 75: Side plate 80: Ukekoma 80a: Receiving recess 80b: Upper wall 80c: Lower wall 81: Die lip piece 81a: flexure 81b: Receptacle connection part 81c:Fixed part 100: Position detection sensor 116: Cavity P: Molten resin sheet S: Gap amount W: Opening and closing structure

Claims

1. A resin supply device comprising an extruder, an accumulator, and a T-die, The T-die includes a die lip and a die lip opening / closing device, The die lip opening / closing device has an opening / closing structure that opens and closes the die lip in response to linear movement of a pusher; a drive unit that drives the pusher to move linearly, The pusher includes a plurality of sub-pushers arranged along the longitudinal direction of the die lip, the drive unit is provided for each of the sub-pusher, The resin melted and kneaded in the extruder is filled into the accumulator, The resin filled in the accumulator is filled into the T-die, The die lip is closed while the molten resin is being filled into the T-die, After the T-die is filled with a necessary amount of molten resin for molding, the die lip is opened by the die lip opening / closing device, and a molten resin sheet is extruded through the slit of the die lip, The plurality of drive units are configured to operate in conjunction with each other to linearly move each of the plurality of sub-pushers, thereby opening and closing the entire die lip, Each of the sub-pusher is provided with a pusher bar; A pusher head is formed at the tip of the pusher bar, The opening and closing structure includes a receiving piece and a die lip piece, the die lip piece includes a flexible portion formed by cutting out a block to have a thin wall, a receiving piece connecting portion to which the receiving piece is attached, and a fixing portion fixed to the body of the T-die, the receiving piece connecting portion and the fixing portion being connected by the flexible portion, The resin supplying device is configured so that the pusher head can press the receiver piece connecting portion via the receiver piece.

2. A resin supply device according to claim 1, The receiving piece has an accommodating recess for accommodating the pusher head.

3. A resin supply device according to claim 2, The pusher head is sandwiched between an upper wall and a lower wall of the receiving piece in the accommodating recess, The accommodating recess widens toward an entrance of the accommodating recess, and the upper wall and the lower wall do not contact the pusher head near the entrance of the accommodating recess, A resin supplying device, wherein a tip of the pusher head abuts against a bottom surface of the accommodation recess.

4. The resin supply device according to any one of claims 1 to 3, A resin supplying device, wherein each of the sub-pusher is provided with a plurality of the pusher bars.

5. an opening / closing structure that opens and closes the die lip of the T-die in response to the linear movement of the pusher; a drive unit that drives the pusher to move linearly, The pusher includes a plurality of sub-pushers arranged along the longitudinal direction of the die lip, the drive unit is provided for each of the sub-pusher, Each of the sub-pusher is provided with a pusher bar; A pusher head is formed at the tip of the pusher bar, The opening and closing structure includes a receiving piece and a die lip piece, the die lip piece includes a flexible portion formed by cutting out a block to have a thin wall, a receiving piece connecting portion to which the receiving piece is attached, and a fixing portion fixed to the body of the T-die, the receiving piece connecting portion and the fixing portion being connected by the flexible portion, The die lip opening and closing device is configured so that the pusher head can press the receiver piece connecting portion via the receiver piece.

6. A die lip opening and closing device as described in claim 5, wherein the receiving piece is provided with a accommodating recess for accommodating the pusher head.

7. A die lip opening and closing device as described in claim 6, The pusher head is sandwiched between an upper wall and a lower wall of the receiving piece in the accommodating recess, The accommodating recess widens toward an entrance of the accommodating recess, and the upper wall and the lower wall do not contact the pusher head near the entrance of the accommodating recess, A die lip opening and closing device, wherein a tip of the pusher head abuts against a bottom surface of the accommodating recess.

8. A die lip opening and closing device according to any one of claims 5 to 7, A die lip opening and closing device, wherein each of the sub-pusher is provided with a plurality of the pusher bars.

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