Molding method and production apparatus for foamed resin molded product

Abstract

To provide a production method and production apparatus for a foamed resin molded product that can stabilize the product weight of the foamed resin molded product and improve the work efficiency.SOLUTION: A method for producing a foamed resin molded product includes: automatically measuring a specific gravity of pre-expanded particles transferred from a maturation silo to a molding machine; calculating an optimum value for a die crack width d from the obtained specific gravity value and actual performance data including past product weights; filling the pre-expanded particles after adjusting the crack width based on the optimum value; measuring the weight of a foamed resin molded product removed from the die and transferred to a downstream side after molding in the die; and readjusting the crack width d from the downstream side using a remote control terminal device 80, when the measured weight value is outside a target range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for molding a foamed resin molded product and a manufacturing apparatus therefor.

Background Art

[0002] As a method for molding a foamed resin molded product from thermoplastic resin particles, after pre-foaming raw material beads containing a foaming agent such as pentane gas, aging is performed in an aging silo for a certain period of time to stabilize them, and the pre-foamed particles after aging are filled into a mold, heated to foam, and after cooling, the foamed resin molded product is taken out of the mold. This method is widely known.

[0003] As a method for filling pre-foamed particles into a mold, a method of transferring the pre-foamed particles from an aging silo to a service hopper of a molding machine and then feeding them into the mold together with compressed air is common. At this time, a slight gap is provided between the movable mold and the fixed mold, and a cracking filling method of filling while discharging the compressed air from this gap is known.

[0004] By the way, the pre-foamed particles may have a difference in foaming ratio due to variations in the quality of the raw material beads. In addition, when these pre-foamed particles with different foaming ratios are classified in the aging silo, the specific gravity of the pre-foamed particles often becomes uneven between the upper side and the lower side of the aging silo.

[0005] These cause the specific gravity of the pre-foamed particles filled into the mold to vary from molding cycle to molding cycle. When the mold is filled with pre-foamed particles having a large specific gravity, the weight of the resulting foamed resin molded product becomes heavy. On the contrary, when the same mold is filled with pre-foamed particles having a small specific gravity, the weight of the foamed resin molded product becomes light. Thus, when the filling weight of the pre-foamed particles changes between each molding cycle, there is a problem that the product weight of the foamed resin molded product is not stable.

[0006] In consideration of the variation in the specific gravity of the pre-expanded particles, a certain range is often provided for the product weight standard. However, if the variation in the product weight becomes large, there is a risk of falling outside this standard and becoming defective products. Also, if the product weight remains high above the product standard, raw material beads will be used more than necessary, resulting in increased manufacturing costs.

[0007] Conventionally, in order to stabilize the product weight regardless of the specific gravity difference of the pre-expanded particles, the cracking width in the cracking filling method has been adjusted. This is to increase or decrease the volume of the cavity by adjusting the cracking width of the mold, aiming to make the weight of the pre-expanded particles filled into the mold constant.

[0008] However, to determine the appropriate cracking width, the skill and proficiency of the operator are required. Also, the operation of adjusting the cracking width by the operator takes time, which may reduce productivity.

[0009] Patent Document 1 describes a molding method that measures the bulk specific gravity of pre-expanded particles conveyed from an aging silo and adjusts the cracking amount based on the measured information of the obtained bulk specific gravity. The foam molding machine used in this molding method is provided with an arithmetic means for obtaining the cracking amount of the mold to make the filling weight of the pre-expanded particles into the cavity constant based on the measured information of the bulk specific gravity of the pre-expanded particles, and a control means for controlling the drive of the moving mechanism of the moving mold to adjust the cracking amount according to the calculation result.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, even if the cracking width is adjusted during the filling process, it may not be possible to completely prevent defective product weights. In addition, for the purpose of stabilizing the product weight below the standard range, finer mold control may be desired in some cases.

[0012] The weight inspection of the released foamed resin molded product is performed by a product inspector on the downstream side of the manufacturing process. The weight inspection is carried out, for example, at the first molding before starting the continuous operation of the molding cycle or during regular quality checks during continuous operation.

[0013] When the product inspector determines that the measured product weight is out of the target and the cracking width needs to be adjusted, the product inspector requests the operator in charge of controlling the molding machine to adjust the cracking width. The operator who receives the adjustment request operates the touch panel of a control means such as a programmable logic controller (PLC) that controls the behavior of the molding machine to adjust the cracking width.

[0014] For this reason, a time lag occurred from when the product inspector recognized the need to adjust the cracking width until the actual adjustment was made. In particular, when the distance between the product inspector and the operator was far, such as when the floors for product inspection and the molding machine were different, the adjustment request was made using a telephone or the like, and the adjustment was not in time, and products that deviated from the product weight standard sometimes came out. Thus, in the conventional operation, there were problems such as time loss, stagnation of inspection work, and reduction of work efficiency, and there was room for improvement.

[0015] Note that Patent Document 1 does not describe or suggest any countermeasures when the need to adjust the cracking width in subsequent cycles is recognized on the downstream side of the manufacturing process.

[0016] An object of the present invention is to provide a manufacturing method and a manufacturing apparatus for a foamed resin molded product that can solve the above-described conventional problems, stabilize the product weight of the foamed resin molded product, and improve work efficiency.

Means for Solving the Problems

[0017] In order to solve the above problems, a method for manufacturing a foamed resin molded product is provided, in which pre-expanded particles are filled into a cavity formed by a pair of molds provided in a molding machine, heat-molded in the mold, and after cooling treatment, the mold is opened to take out the foamed resin molded product. The method includes: automatically measuring the specific gravity of the pre-expanded particles transferred from an aging silo to the molding machine, calculating an appropriate value of the cracking width of the mold from the obtained specific gravity value and performance data including past product weights, and filling the pre-expanded particles after adjusting the cracking width based on the appropriate value; measuring the weight of the foamed resin molded product taken out of the mold and transferred downstream after molding in the mold, and if the measured weight value is out of the target range, readjusting the cracking width from the downstream side using a remote operation terminal device.

[0018] Also, it is preferable that the molding performance data is accumulated with the specific gravity value and the cracking width of the pre-expanded particles in one cycle of molding operation associated for each type of mold.

[0019] In the readjusting step, it is preferable that a new appropriate value of the cracking width is calculated by an operator on the downstream side inputting the weight value into the remote operation terminal device, and the cracking width is adjusted based on the calculated new appropriate value.

[0020] A manufacturing apparatus for a foamed resin molded product is provided, which fills pre-expanded particles into a cavity formed by a pair of molds provided in a molding machine, heat-molds in the mold, and after cooling treatment, opens the mold to take out the foamed resin molded product. The molding machine is provided with a specific gravity measuring device for automatically measuring the specific gravity of the pre-expanded particles transferred from an aging silo, a calculating means for calculating an appropriate value of the cracking width of the mold from the specific gravity value measured by the specific gravity measuring device and performance data including past product weights, a control means for adjusting the cracking width based on the appropriate value calculated by the calculating means, and a remote operation terminal device capable of readjusting the cracking width from the downstream side based on the weight value of the demolded foamed resin molded product.

Advantages of the Invention

[0021] In the present invention, it is possible to provide a method and an apparatus for manufacturing a foamed resin molded product that can stabilize the product weight of the foamed resin molded product and improve the working efficiency.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0023] The following shows modes for carrying out the invention.

[0024] (Configuration of the Manufacturing Apparatus) The configuration of the manufacturing apparatus for the foamed resin molded product is shown. As shown in FIG. 1, the manufacturing apparatus for the foamed resin molded product of the embodiment includes a fixed mold 10 and a movable mold 20. The movable mold 20 is opened and closed with respect to the fixed mold 10 by a drive mechanism 21 such as a cylinder. The cavity C is formed by these fixed mold 10 and movable mold 20.

[0025] The manufacturing apparatus for the foamed resin molded product of the embodiment includes a feeder 30 for filling the cavity C with pre-expanded particles and a service hopper 40 connected to the feeder 30. In the embodiment, the pre-expanded particles are transferred from an aging silo (not shown) to the service hopper 40 and supplied from the service hopper 40 to the cavity C via the feeder 30. FIG. 1 shows a state where the cavity C is filled with pre-expanded particles.

[0026] In the service hopper 40 of the embodiment, a specific gravity measuring device 50 for measuring the specific gravity of the pre-expanded particles is provided. The specific gravity measuring device 50 of the embodiment is a device that can automatically sample a part of the pre-expanded particles supplied inside the service hopper 40 and measure its specific gravity.

[0027] The specific gravity measuring device 50 of the embodiment includes a measuring container having a measuring space with a fixed volume (not shown), a weighing scale for measuring the weight of the pre-expanded particles in the measuring container, and an arithmetic unit for calculating the specific gravity of the pre-expanded particles from the obtained weight value. The pre-expanded particles after weight measurement are recovered into the service hopper 40 and filled into the cavity C. Note that the specific gravity measuring device 50 is not limited to the above-described configuration, and various known devices can be used.

[0028] The manufacturing apparatus for the foamed resin molded product of the embodiment further includes a database DB, an arithmetic means 60, a control means 70, and a remote operation terminal device 80.

[0029] The database DB stores the molding performance data in past molding cycles. The database DB of the embodiment includes, in addition to the specific gravity value data of the used pre-expanded particles and the cracking width data in the molding cycle, the types of molds and raw material beads used, the pre-expansion conditions of the raw material beads, etc., and these data are stored in association with each type of mold. Also, when physical property data such as the weight of the manufactured foamed resin molded product is measured, it is preferable that these physical property data are also accumulated in the database DB.

[0030] The arithmetic means 60 is an information processing device that calculates an appropriate cracking width from the specific gravity value of the pre-expanded particles measured by the specific gravity measuring device 50 and the performance data of the database DB. The arithmetic means 60 of the embodiment is built into a personal computer, but is not limited thereto, and may be built into the PLC that serves as the control means 70.

[0031] The control means 70 is a device that controls the operation of the molding machine, and a PLC is used in the embodiment. In the embodiment, the control means 70 and the arithmetic means 60 are connected, and the control means 70 receives the information on the appropriate cracking width from the arithmetic means 60. The control means 70 controls the drive mechanism 21 to move the movable mold 20 so that the cracking width d between the fixed mold 10 and the movable mold 20 becomes the appropriate cracking width. The control means 70 that has adjusted the cracking width d performs control to fill the cavity C with the pre-expanded particles.

[0032] Further, the manufacturing apparatus for the foamed resin molded product of the embodiment includes a remote operation terminal device 80 capable of changing the set value of the cracking width d by remote operation. The remote operation terminal device 80 of the embodiment is a remote controller capable of remotely operating the control means 70 to rewrite the set value of the cracking width. The remote operation terminal device 80 may be a smartphone, a tablet terminal, a personal computer, or the like.

[0033] (Manufacturing process) Next, the manufacturing process of the foamed resin molded product of the present invention will be described with reference to FIG. 2.

[0034] (Steps S1 to S3) First, the raw material beads are pre-expanded in a pre-expander, transferred to an aging silo, and aged for a predetermined time. The aged pre-expanded particles are transferred to a service hopper 40 connected to the molding machine.

[0035] (Step S4) A part of the pre-expanded particles transferred to the service hopper 40 is supplied to the specific gravity measuring device 50, and the specific gravity is automatically measured. The measured specific gravity data is transmitted to the arithmetic means 60 and accumulated in the database DB.

[0036] (Step S5) The arithmetic means 60 collates the specific gravity data of the pre-expanded particles obtained from the specific gravity measuring device 50 with the molding achievement data in the database DB, and calculates the appropriate cracking width. The arithmetic means 60 in the embodiment extracts, from the past molding achievement data using the same mold as the mold filled with the pre-expanded particles, cases where pre-expanded particles with a specific gravity close to the specific gravity data were used, and refers to the cracking width in cases where data such as product weight is good among the extracted cases to derive the appropriate cracking width.

[0037] Note that the data used for calculating the appropriate cracking width by the arithmetic means 60 is not limited to the above-described configuration, and other elements may be considered.

[0038] (Step S6) The arithmetic means 60 outputs the information on the derived appropriate cracking width to the control means 70. The control means 70 performs control to operate the drive mechanism 21 based on the input information on the appropriate cracking width to open and close the movable mold 20, and adjusts so that the cracking width d becomes the appropriate cracking width.

[0039] (Step S7) After the control means 70 stops the movable mold 20 at a position where the cracking width d becomes the appropriate cracking width, it performs control to fill the cavity C with the pre-expanded particles from the service hopper 40 via the feeder 30.

[0040] (Step S8) When heated steam is supplied to the cavity C filled with the pre-expanded particles, the pre-expanded particles inside the cavity C are heated and foamed, the volume expands, and they fuse with each other. After the cavity C is heated for a predetermined time, the cavity C is cooled, the mold is opened, and the foamed resin molded product is taken out.

[0041] (Step S9) The product inspector inspects the taken-out foamed molded product. The inspection items include visual inspection for defects such as voids in the foamed resin molded product, measurement of the product weight, etc.

[0042] (Steps S10, S11) If the product weight of the foamed resin molded product is within the target range and no defects are found in other inspection items, mass production in Step S11 is started. If the product weight of the foamed resin molded product is out of the target range, proceed to Step S12.

[0043] (Step S12) If the product weight of the foamed resin molded product is out of the target range and it is necessary to readjust the cracking width d, the product inspector uses the remote operation terminal device 80 to readjust the cracking width d.

[0044] In the embodiment, the product inspector inputs the weight value of the foamed resin molded product into the remote operation terminal device 80 and accesses the arithmetic means 60. The arithmetic means 60 refers to the database DB and derives a new appropriate cracking width based on the input weight value. The arithmetic means 60 transmits the new appropriate cracking width to the control means 70, and the control means 70 executes the readjustment of the cracking width d. Thereby, in the embodiment, when the product inspector inputs the product weight from the downstream side, the cracking width d can be automatically readjusted.

[0045] Note that the above readjustment of the cracking width d may be configured such that the product weight input to the remote operation terminal device 80 is directly transmitted to the control means 70, and the control means 70 automatically adjusts the cracking width d based on the product weight.

[0046] Specifically, the readjustment based on the new appropriate cracking width is, for example, to decrease the cracking width d when the product weight is heavier than the target range, and to increase the cracking width d when the product weight is lighter than the target range.

[0047] Based on the readjusted cracking width d, the steps of Steps S7 to S10 are performed again. If the product weight of the foamed resin molded product is within the target range, proceed to mass production in Step S11.

[0048] (Step S13) After the forming cycle is made continuous and mass production is started, periodic quality checks are performed at predetermined time intervals. When the timing for quality check of the foamed resin molded product arrives, the processes after Step S9 are repeated.

[0049] With such a configuration, in the manufacturing method and manufacturing apparatus of the embodiment, it becomes possible for a product inspector to readjust the cracking width d by remote operation. Further, for both the operator of the control means 70 and the product inspector, an appropriate cracking width is automatically presented by the arithmetic means 60, so the determination of the cracking width d is less likely to depend on the skill level of the worker, and the personalization of the molding operation can be suppressed.

[0050] Also, in the present invention, it is possible to contribute to reducing defective products of the foamed resin product, and by stably setting the product weight below the product standard, raw material savings can be achieved, and the manufacturing cost can be reduced.

[0051] Thereby, in the present invention, it is possible to provide a manufacturing method and manufacturing apparatus for a foamed resin molded product capable of improving the working efficiency while stabilizing the weight of the foamed resin molded product.

[0052] As described above, the present invention has been described by taking the embodiment as an example, but the present invention is not limited to the above embodiment, and various aspects are possible.

Explanation of Signs

[0053] 10 Fixed mold 20 Movable mold 21 Driving mechanism 30 Feeder 40 Service hopper 50 Specific gravity measuring device 60 Arithmetic means DB Database 70 Control means 80 Remote operation terminal device

Claims

1. A method for manufacturing a foamed resin molded product, comprising filling a cavity formed by a pair of molds provided in a molding machine with pre-expanded particles, performing heat molding in the mold, opening the mold after cooling treatment, and taking out the foamed resin molded product, automatically measuring the specific gravity of the pre-expanded particles transferred from the aging silo to the molding machine, calculating an appropriate value of the cracking width of the mold from the obtained specific gravity value and performance data including past product weights, and adjusting the cracking width based on the appropriate value and then filling the pre-expanded particles; measuring the weight of the foamed resin molded product taken out from the mold and transferred downstream after molding with the mold, and when the measured weight value is out of the target range, readjusting the cracking width from the downstream side using a remote operation terminal device. A method for manufacturing a foamed resin molded product including a readjustment step.

2. The molding performance data is The method for manufacturing a foamed resin molded product according to claim 1, wherein for each type of mold, the specific gravity value and the cracking width of the pre-expanded particles in one cycle of the molding operation are associated and accumulated.

3. The readjustment step is A new appropriate value of the cracking width is calculated by an operator on the downstream side inputting the weight value into the remote operation terminal device, and the cracking width is adjusted based on the calculated new appropriate value. The method for manufacturing a foamed resin molded product according to claim 1 or 2.

4. A manufacturing apparatus for a foamed resin molded product, which fills a cavity formed by a pair of molds provided in a molding machine with pre-expanded particles, performs heat molding in the mold, opens the mold after cooling treatment, and takes out the foamed resin molded product, The molding machine is provided with a specific gravity measuring device for automatically measuring the specific gravity of the pre-expanded particles transferred from the aging silo, calculating means for calculating an appropriate value of the cracking width of the mold from the specific gravity value measured by the specific gravity measuring device and performance data including past product weights, Control means for adjusting the cracking width based on the appropriate value calculated by the arithmetic means; A manufacturing apparatus for a foamed resin molded product, comprising a remote operation terminal device capable of readjusting the cracking width from the downstream side based on the weight value of the released foamed resin molded product.

Images