JPH03138111A - Method and apparatus for producing synthetic resin molding - Google Patents

Abstract

PURPOSE:To enable various molded articles to be molded automatically through a cast method by performing the pre-heating of a mold and casting, heating and demolding of synthetic resin liquid and discharging two kinds of synthetic resin liquid respectively at a certain flow content and flow rate and then mixing them so as to be cast-molded into the mold. CONSTITUTION:A number of the same or different molds 11 are circulated on a circulating conveyer and two kinds of original liquid are forwarded respectively to a mixing heat 18 at a predetermined certain flow rate and then mixed at a predetermined mixing rate and thereafter cast immediately into a pre-heated circulating mold 11. And, after passed through a primary curing bath 7 which is kept at a predetermined curing temperature and then demolded therefrom, it is cured temporarily to the cured degree in which any deformation never occurs and then demolded therefrom wherein the mold 11 is used circulatively and further the primary cured molded article is still cured in a secondary curing bath which is kept at a predetermined curing temperature. Whereby a casting work can be automized and even in the case of mixing and manufacturing various kinds of molded articles, a predetermined content of synthetic resin liquid can be cast correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and an apparatus for molding a synthetic resin molded article by casting a thermosetting resin such as a polyurethane resin into a mold.

[Conventional technology]

Conventionally, two types of synthetic resin stock solution, such as polyurethane resin, were mixed, poured into a mold, heated, reacted, and cured to obtain a relatively large molded product. The general method is to pour the stock solution into a mixing tank at a certain rate and mix it, then manually inject this mixed liquid into a mold, then transport the mold into a heating chamber, heat it for a certain period of time, harden it, and remove it from the mold. It is being done.

[Problem that the invention seeks to solve]

In the above-mentioned conventional molding method, the resin mixture is poured manually, resulting in poor work efficiency.Even if you try to automate this process, it will be difficult to mix and manufacture molded products of various shapes and sizes. Since the amount of casting resin varies depending on the mold, it has been difficult to automate the molding process.

When mixing and casting two kinds of synthetic resin stock solutions, if the mixing ratio deviates from the specified mixing ratio, there is a risk that the quality of the synthetic resin molded product will deteriorate, but the mixing ratio should be kept at the specified mixing ratio. It is difficult to do this, and if time elapses between mixing and casting, there is a risk that the quality of the molded product will deteriorate.

Furthermore, when casting a mixture of synthetic resin stock solutions, air bubbles are likely to enter, and once air bubbles are introduced in a highly viscous mixed liquid, the air bubbles cannot be removed, and molded products containing air bubbles become defective.

Accordingly, an object of the present invention is to provide a molding method and apparatus for automatically molding various molded products by a casting method.

Another object of the present invention is to provide a molding method and apparatus that can accurately maintain the mixing ratio of a synthetic resin stock solution at a predetermined mixing ratio and obtain a high-quality molded product without air bubbles.

[Means for solving problems]

In order to achieve the above object, the inventors of the present invention have conducted intensive research and have found that a large number of molds are continuously moved and circulated by a conveyor system, and in the middle of the process, the molds are preheated, synthetic resin liquid is poured, In addition to heating and demolding, two types of synthetic resin stock solutions are discharged and mixed at a fixed flow rate and flow rate ratio, and simultaneously poured into a mold, and the injection amount is controlled by the injection time. , discovered that the molding process can be automated, and also that when injecting the resin mixture stock solution into the mold from the casting machine, the head difference between the discharge port of the casting machine and the mold is kept below a certain level, and the viscosity is high. The inventors have discovered that by adjusting the drop point of the stock solution on the mold, it is possible to completely prevent air bubbles from entering the cast resin solution, and have completed the present invention.

In other words, two types of stock solutions are mixed and the mixed solution is poured into a mold.
In a thermoplastic resin molding method in which a thermoplastic resin is heated, reacted, and cured, a large number of identical or different molds are circulated on a circulation conveyor system, and the two stock solutions are each delivered to a mixing head in a predetermined constant flow mold. After mixing at a predetermined mixing ratio, the mold is immediately poured into the preheated circulating mold, passed through a primary curing tank kept at a predetermined curing temperature, and is primarily cured to a hardness that does not deform in the demolding machine. A method for molding a synthetic resin molded article, which comprises molding, circulating the mold, and further curing the primary-cured molded product in a secondary curing tank maintained at a predetermined curing temperature. This is the summary.

Another aspect of the present invention is a conveyor system in which a large number of molds are placed, circulated and conveyed, a preheating tank that preheats the molds moving on the conveyor system to a predetermined temperature, and a conveyor system that exits the preheating tank. a stop position adjustment mechanism that stops the upper mold at a predetermined position in the casting position and raises and lowers it to a predetermined height;
a casting machine that mixes and immediately injects two kinds of synthetic resin stock solutions into the mold stopped at the casting position; a primary curing tank heated to a predetermined curing temperature through which the mold passes after casting; The gist of the present invention is a continuous molding apparatus for synthetic resin molded bodies, which is equipped with a demolding device for demolding the molded product from the mold that has exited the primary curing tank.

Synthetic resins used in the present invention include polyurethane resins,
Any thermosetting synthetic resin that can be cured by mixing two stock solutions such as unsaturated polyester resin, epoxy resin, silicone resin, heating and reacting the mixture can be used.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view schematically showing an example of an apparatus used in the method of molding a synthetic resin molded article of the present invention.

Reference numeral 1 denotes a conveyor system for circulating molds, which includes two top roller type chain conveyors 2.3 arranged to convey molds in parallel and in opposite directions; It consists of a conveyor 4.5 connecting .3.

The chain conveyor 2.3 is installed so that the articles to be transported pass through a preheating tank 6 and a primary curing tank 7, each of which is a tunnel-shaped heating tank. Reference numeral 8 denotes a metal fittings preheating conveyor, which is disposed so as to pass through a tunnel-shaped metal fittings preheating tank 29. This metal fittings preheating conveyor 8 is used to preheat metal fittings when molding a solid tire by embedding metal fittings and integrally molding a synthetic resin, such as when molding a tire by embedding rim metal fittings. used.

Reference numeral 9 denotes a magnet crane that conveys a steel fitting 10 from the end of the fitting preheating conveyor 8 into a mold 11 on the chain conveyor 2.

Reference numeral 12 denotes a mold injection station, which uses horizontal and vertical position adjustment mechanisms to accurately adjust the position of the mold during pouring, as will be described later. Reference numeral 13 is a casting machine that mixes two kinds of synthetic resin stock solutions and immediately casts the mixture. Each switching valve 16
．． The mixture is delivered to a mixing head 18 through a mixing head 17, mixed, and poured into a mold 11 through a discharge port 19. Switching valve 16.1
7 are three-way valves that respectively switch the liquid discharge direction to the flow path to the mixing head 18 and the return flow path 20.21 to the storage tank 14.15, and both switching valves 16.17 are switched in the same direction at the same time. It is now possible to

Reference numeral 22 denotes a demolding device for demolding the molded product from the mold 11 that has exited the primary curing tank 7, which includes a method of pinching and pulling out the molded product from within the mold 11, a method of extruding the molded product from the back side of the mold, This can be done by a known method such as a method of attracting and pulling out the metal fitting 10 embedded in the molded product using an electromagnet.

3 and 4 are a plan view and a front sectional view showing an example of the mold 11 for molding a solid tire.

Each mold 11 is fixed on the same flat mold stand 23,
A bar code 24 indicating the type of mold is attached to the back side of the mold. Place the upper lid 25 on the rim fitting 10 in the mold 11,
A positioning pole 26 is provided protrudingly on the upper lid 25. The positioning pole 26 may be provided protrudingly on the main body of the mold 11.

A barcode reading device 30 is provided at the bottom of the conveyor 4, and as shown in FIG. A horizontal position detection sensor 27 and a vertical position detection sensor 28 are provided to detect horizontal and vertical positions.

In order to manufacture, for example, a solid tire made of polyurethane resin by the method of the present invention, first, a large number of molds 1 are placed on the annular conveyor system 1, each placed on a mold stand 23.
1 in a row. Each mold 11 may be the same mold 11 or may be a different mold 11. The surface of the rim metal fitting 10, which is embedded in the resin and integrally formed, is sandblasted in advance according to a conventional method, and in order to improve adhesion to the polyurethane resin, the surface is repeatedly coated with adhesive and dried two to three times. . The different types of rim fittings 10 that have been pretreated in this manner are stored in a fitting supply shelf or the like, and
Consistent with the order of arrangement of molds on conveyor system 1,
To surely supply metal fittings 10 that fit each mold 11.

For example, as shown in FIG. 1, the metal fitting supply shelf 31 is provided with a separate metal fitting storage section 32 for each mold, each metal fitting storage section 32 is provided with an indicator lamp 33, and the molds on the conveyor system 1 are
A computer that stores the arrangement order lights up the display lamp 33 to indicate the order in which the metal fittings 10 should be taken out from each of the metal fitting supply shelves 31 and the metal fitting storage sections 32, and the worker takes out the metal fittings 10 in accordance with the order and preheats the metal fittings. Even when mixing and molding multiple types of molded products at the same time by placing them on a conveyor 8, the mold 11 and the metal fittings 1
Combinations of 0 can be made without error.

On the other hand, depending on the capacity of each mold 11 arranged in the conveyor system 1, the average injection time into the molds 11 is determined by the conveyor 4.
The discharge amount of each of the two kinds of stock solutions is adjusted so that the cycle time of the movement of the mold 11 passing over the mold 5 is approximately equal to or shorter than this, and the mixing ratio of the two solutions is adjusted to a predetermined mixing ratio. Adjust so that the ratio is the same. - Once the discharge amount of each stock solution is adjusted accurately, even if the discharge direction is switched by the switching valve 16 or 17, the mixed liquid discharged from the discharge port 19 of the casting @ 13 will always have a constant mixing ratio and discharge flow. Keep l.

According to the arrangement order of the molds 11 by the method described above, the corresponding metal fittings 10 are preheated in the metal fitting preheating tank 29, and the steel rim metal fittings 10, which have been preheated to a predetermined temperature of about 100°C, are placed on the chain conveyor 2 by the magnetic crane 9. It is placed in the mold 11 and sent into the preheating tank 6.

The mold 11 and the metal fittings 10, which have passed through the preheating tank 6 for about 20 minutes, are preheated to a predetermined temperature of about 100°C.

The mold 11 that has left the preheating tank 6 is conveyed to the injection station 12 by the conveyor 4, but on the way, the barcode 24 attached to the bottom surface of the mold 11 is read by the barcode reading device 3.
0, input the number into the resin injection amount control computer, and calculate the required resin mixture based on the resin injection amount required for each mold 11 and the discharge flow rate data of the casting machine 13, which are stored in advance in the computer. Calculate the injection time of the stock solution.

A horizontal position detection sensor 27 installed on the side of the injection station 12 detects the pole 26 and places the mold 1 in a predetermined position.
1 is stopped, and then the mold stand 23 is raised by a lifting device such as a hydraulic cylinder until the vertical position detection sensor 28 detects the pole 26, and the mold 11 is stopped at a predetermined horizontal and vertical position. When injecting the liquid mixture from the discharge port 19 of the casting machine 13 into the mold 11, a pole 26 is pre-protruded at a position a certain distance in a certain direction from the optimal drop point where the mixture can be poured without introducing air bubbles. So,
The mold 11 is stopped in such a way that the drop point of the liquid mixture from the discharge port 19 is at an optimum position, which is a certain distance away from the pole 26 in the horizontal direction. The optimal falling point is mold 1
It varies depending on the shape and size of 1, the presence or absence of the upper lid 25, etc.
When using the disc-shaped upper lid 25, 1 from the periphery of the upper lid 25.
A position about 0 to 20 mm inside is preferable.

The stopping position of the mold 11 in the vertical direction is such that the drop from the discharge port 19 of the casting machine 13 to the drop point of the mixed liquid on the upper surface of the mold 11 or the upper surface of the upper lid 25 is 250 m+n or less, more preferably 20 m+n.
Adjust so that it is 0 mm or less. This preferred range of head difference varies depending on the type and viscosity of the synthetic resin stock solution.

By accurately switching the switching valves 16 and 17 according to the injection time calculated by the computer from the data of the barcode 24 read from each mold 11 and the discharge flow rate of the casting machine 13, a predetermined amount of the mixed liquid is poured accurately. Can be molded.

After the casting is completed, the mold stand 23 is automatically lowered to the original height by the lifting device, and is automatically loaded onto the chain conveyor 3 and sent into the primary curing tank 7. When the polyurethane resin is passed through a primary curing horizontal 7 maintained at about 100 to 110° C. for about 30 minutes, the polyurethane resin is cured to a hardness that allows demolding. Next, the cured molded product is demolded from the mold 11 by the demolding device 22 and transported to a secondary curing tank (not shown), where it is heated for about 110 min.
C. for 8 hours to completely cure.

After cleaning the demolded mold 11, a release agent is applied to the inner surface, and the next metal fitting 10 is placed on the mold 11 again, and the mold 11 is circulated and used in the same manner as described above.

The top roller type chain conveyor 2.3 used in the present invention automatically stops at that position and waits when the conveyed object has been conveyed to the end, or when the conveyed object has caught up with the preceding conveyed object. Shitsuru.

The mold 11 used in the present invention may be a single mold that is integral and indivisible, or may be a mold that can be divided into a plurality of pieces.

〔Effect of the invention〕

According to the method for molding a synthetic resin molded article of the present invention, it is possible to automate the casting work that was conventionally performed manually.
Even when various molded products are mixed and manufactured using different types of molds 11, it is possible to accurately cast a predetermined amount of the synthetic resin stock solution into the mold.

Two types of synthetic resin stock solutions can always be mixed at an accurate mixing ratio, and there is no risk of quality deterioration of molded products due to variations in the mixing ratio.

The position of the mold 11 at the injection station 12 is determined by the pole 26.
By detecting the horizontal and vertical position detection sensors 27 and 28 and adjusting the position to the optimum position, it is possible to completely eliminate the inclusion of air bubbles during casting.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the continuous casting apparatus for synthetic resin molded bodies of the present invention, FIG. 2 is an illustration of the casting machine and the mold position adjustment mechanism in the injection station, and FIGS. FIG. 4 is a plan view and a front sectional view showing an example of a mold 11 for molding a solid tire. 1 conveyor system, 213 chain conveyor, 4.5 conveyor, 6 preheating tank, 7 primary curing tank, 8 metal fittings preheating conveyor, 9 magnetic crane, 10 metal fittings, 11 mold, 12 injection station, 13 casting machine, 14. 15 storage tank, 16.17 switching valve, 18 mixing head, 19 discharge port, 20.21 return flow path,
22 demolding device, 23 mold stand, 2
4 Barcode, 25 Top lid, 26
Pole, 27 horizontal position detection sensor 28°/vertical position detection sensor 29/metal preheating tank, 30 barcode reader, 31 metal fitting supply shelf, 32 metal fitting storage section, 33
Display lamp.

Claims (7)

[Claims] (1) Mix two types of stock solutions and inject the mixed solution into the mold,
In a thermosetting resin molding method in which a thermosetting resin is heated, reacted, and cured, a large number of identical or different molds are circulated on a circulating conveyor system, and the two stock solutions are each sent to a mixing head at a predetermined constant flow rate. After mixing at a predetermined mixing ratio, it is immediately poured into the preheated circulation mold, passed through a primary curing tank kept at a predetermined curing temperature, and is primarily cured to a hardness that will not deform after demolding, and then demolded. . A method for molding a synthetic resin molded article, which comprises circulating the mold and further curing the primarily cured molded article in a secondary curing tank maintained at a predetermined curing temperature. (2) The amount of the mixed liquid injected into the mold is controlled by keeping the discharge flow rate from the mixing head to the mold constant and adjusting the injection time according to the capacity of the mold. 2. The method for molding a synthetic resin molded article according to claim 1, wherein the injection amount is adjusted. (3) Read the barcode attached to the mold, automatically calculate the injection time from the pre-stored capacity of the mold corresponding to the barcode and the discharge flow rate, and adjust the injection time. A method for molding a synthetic resin molded article according to claim 2. (4) A pole is provided protruding from the mold body or an upper lid that can be covered over the mold, and the horizontal and vertical positions of the pole are detected by a sensor to prevent air bubbles from being generated when the mixed liquid is injected into the mold. 2. The method for molding a synthetic resin molded article according to claim 1, wherein the injection is performed by adjusting the position of the mold to an optimal position. (5) A conveyor system on which a large number of molds are placed, circulated and transported, a preheating tank that preheats the molds moving on the conveyor system to a predetermined temperature, and molds on the conveyor system that exit the preheating tank. stopping the mold in place at the casting position;
A stop position adjustment mechanism that raises and lowers to a predetermined height, a casting machine that mixes two kinds of synthetic resin stock solutions and immediately injects the mixture into the mold stopped at the casting position, and a predetermined position through which the mold passes after casting. A continuous molding apparatus for synthetic resin molded articles, comprising a primary curing tank heated to a curing temperature and a demolding device for demolding the molded product from the mold after exiting the primary curing tank. (6) The casting machine includes a pump that discharges two types of synthetic resin stock solutions at predetermined flow rates, a mixing head that mixes the two types of discharged synthetic resin stock solutions, and a storage for each of the two types of discharged synthetic resin stock solutions. Two switching valves that switch between the return flow path to the tank and the flow path to the mixing head, a switching mechanism that switches both switching valves simultaneously, and a control mechanism that controls the switching time of the switching mechanism according to the capacity of the mold. 6. The continuous molding apparatus for synthetic resin molded bodies according to claim 5. (7) a barcode reading device that reads the barcode attached to the mold; a storage device that stores the capacity data of each mold and the discharge flow rate data of the casting machine corresponding to each read barcode; 7. The continuous molding apparatus for synthetic resin molded bodies according to claim 6, further comprising an arithmetic unit for calculating the necessary switching time for each mold from the capacity data and the discharge flow rate data.