JPH04151812A - Resin molding method - Google Patents

Abstract

PURPOSE:To set up optimum mold release timing thereby enabling a molded product of excellent quality to be manufactured efficiently by a method wherein the resin setting state is judged according to the temperature of a mold resin and the fluctuation in the heating temperature by a heating means. CONSTITUTION:A molding tool 1 containing a molded product is contained in a heating furnace 4 and after pouring a resin 3 into the molding tool 1, the heating furnace 4 is heated by a heater 5 to heat the resin 3 in the molding tool 1. At this time, the temperature t1 is detected by a temperature sensor 6 while the temperature t2 in the heating furnace 4 is detected by another temperature sensor 7. Next, assuming the difference between the temperature t1 and the temperature t2 to be t, the completion time ( t=0) of the primary setting step of the resin 3 is judged according to the fluctuation of the t by a control device 8 to light a pilot lamp 10 at the completion time of the primary setting step. Through these procedures, the setting completion time of the resin 3 can be judeged precisely so that the optimum mold release timing may be set up thereby enabling a molded product of excellent quality to be manufactured efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a resin molding method for molding a molded object with a thermosetting resin.

(Prior Art) When manufacturing a molded coil in which a molded object, such as a coil, is molded with a resin, a thermosetting resin such as an epoxy resin is generally used as the molding resin.

When manufacturing a molded coil using such a thermosetting resin, it is generally performed as follows. first,
A coil to be molded is placed in a mold, and this mold is placed in a heating furnace.

Then, a thermosetting resin is injected into the mold, and the mold is heated by a heater in a heating furnace to heat and harden the mold resin. At this time, the heat curing of the mold resin is performed separately into secondary curing (semi-curing) and secondary curing (after-curing). - Secondary curing is performed with the mold assembled, and secondary curing is performed with the mold removed (released).

(Problem B to be Solved by the Invention) By the way, when manufacturing a molded coil using the method described above, it is extremely important to determine when to release the mold, that is, to set the timing for releasing the mold. If the timing of mold release is too early, there is a risk that the molded product may be deformed due to insufficient curing of the resin, or internal peeling or cracking may occur due to insufficient strength or adhesive strength. If the timing is too late, not only will energy for heating be wasted, but residual stress will remain in the resin of the molded product, which may reduce crack resistance.

Conventionally, the timing of mold release has generally been controlled by a preset time that takes into consideration the characteristics of the resin, the size and weight of the molded product, and the like. However, when molding a wide variety of products, the heat capacity, heat dissipation characteristics, curing heat generation 1, etc. change depending on the type, size, and shape of the molded object, as well as the type and thickness of the molding resin. However, it was not possible to set the optimal timing for each product. Therefore, in the conventional method, the timing of mold release is not necessarily optimal, and there are many problems as described above.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a resin molding method that can optimally set the timing of mold release and efficiently produce molded products of good quality.

[Structure of the Invention (Means for Solving the Problems)] The present invention accommodates a molded object in a mold, injects a thermosetting resin, and heats and hardens the resin with a heating means. In the method of molding the object to be molded, the temperature of the molding resin and the heating temperature by the heating means are measured when the resin is heated and cured, and the cured state of the resin is determined based on the temperature change. It has some characteristics.

(Function) When the resin is heated and cured, the temperature of the resin becomes higher than the heating temperature by the heating means due to the reaction heat accompanying the start of the curing reaction, reaches the highest value near the peak of the reaction, and then, There is a tendency for the temperature to gradually decrease and become equal to the heating temperature by the heating means. Therefore, by measuring the temperature of the resin at this time and the heating temperature by the heating means and comparing the temperature difference between them, it is possible to determine whether the resin has completely cured, that is, to set the optimal timing for releasing from the mold. be able to.

(Example) Hereinafter, a first example in which the present invention is applied to a method for manufacturing a molded coil will be described with reference to FIGS. 1 and 2.

First of all, FIG. 1 shows a mold 1 in which a dull coil 2 to be molded is housed and a thermosetting resin 3 such as an epoxy resin.
The injection state is shown.

The mold] is housed in a heating furnace 4 so as to be removable therein, and the inside of this heating furnace 4 is heated by a heater 5 serving as a heating means. A temperature sensor 6 is closely attached to the outer surface of the mold 1, and a temperature sensor 7 is also installed inside the heating furnace 4.
are installed, and both temperature sensors 6.7 are connected to a control device 8 comprising a microcomputer. The control device 8 controls the temperature inside the heating furnace 4 by controlling the heater 5 via the power source 9, and
It has a function of determining the hardening state of the resin 3 based on the detection signals from both temperature sensors 6 and 7, as described later.
When it is determined that the primary curing of the resin 3 has been completed, the display lamp ]0 is turned on.

When manufacturing a molded coil with the above configuration, the mold 1 containing the coil 2 is first placed in the heating furnace 4, and the resin 3 is injected into the mold 1 in this state.

Then, in order to harden the resin 3, the heater 5 heats the inside of the heating furnace 4, thereby heating the resin 3 inside the mold. At this time, the temperature t1 of the resin 3 is detected by the temperature sensor 6 via the mold, and the temperature t2 inside the heating furnace 4 is detected by the temperature sensor 7. Heating furnace 4
The temperature within is the curing temperature t necessary to cure the resin 3.
s.

In this case, the temperature t of the resin 3 during heat curing of the resin 3
1 and the temperature t2 in the heating furnace 4 change as shown in FIG. That is, first, the temperature t2 in the heating furnace 4 or the curing temperature ts
After a while, the temperature t1 of the resin 3 becomes approximately equal to the temperature t2 in the heating furnace 4 (tl = t2), and therefore the temperature t1 of the resin 3 also reaches the curing temperature ts. After this state is maintained for a while, the temperature t1 of the resin 3 gradually becomes higher than the temperature t2 in the heating furnace 4 (1+>12) due to the heat generated by the curing reaction of the resin 3. Here, resin 3
If the difference between the temperature t in the heating furnace 4 and the temperature t2 in the heating furnace 4 is Δt, this Δt increases as the curing reaction of the resin 3 progresses, reaches a maximum near the peak of the reaction, and then gradually decreases. , eventually approaches 0. Since the primary curing of the resin 3 is completed when the heat generation associated with the curing reaction ends, it can be determined that the secondary curing is completed when the heat generation ceases (Δt=0). Therefore, in this case, the control device 8 controls the resin 3 based on the change in Δt.
It is determined when the primary curing is completed, and the indicator lamp 10 is turned on when the secondary curing is completed. The worker turns on the indicator lamp 1.
0 is lit, it can be known that the primary curing of the resin 3 has been completed. Based on the lighting of the indicator lamp 10, the mold 1 is removed and released, and then the secondary curing of the resin 3 is performed. conduct. Thereby, the timing of mold release can be optimized, and a molded product of good quality can be efficiently produced.

FIG. 3 shows a second embodiment of the present invention, which is different from the first embodiment described above, particularly in the detection means for detecting the temperature on the resin 3 side. That is, when the object to be molded is a conductor like the coil 2, the temperature of the coil 2 and, by extension, the temperature of the resin 3 can be calculated based on measuring the resistance between both terminals of the coil 2, so this method The temperature of the coil 2 is detected using the coil temperature detection device 1]. In this case, the temperature detected by the coil temperature detection device 11 corresponds to the temperature detected by the temperature sensor 6 (temperature 1+ of the resin 3) in the first embodiment. Therefore, the temperature detected by the coil temperature detection device] and the temperature detected by the heating furnace 4
Similarly to the first embodiment, the control device 8 can determine the point in time when the primary curing of the resin 3 is completed based on the temperature detected by the temperature sensor 7 that detects the temperature inside.

According to such a second embodiment, the coil temperature detection device 1
1 to detect the temperature of the coil 2, it is possible to measure a temperature closer to the temperature of the resin 3 itself, compared to detection by the temperature sensor 6 attached to the outer surface of the mold 1, and as a result, the primary curing of the resin 3 The completion point can be determined more accurately.

[Effects of the Invention] As is clear from the above description, according to the present invention, the point at which curing of the resin is completed can be accurately determined, so the timing of mold release can be set optimally, and high-quality molded products can be produced efficiently. It has the excellent effect of being easily manufactured.

[Brief explanation of the drawing]

Figures 1 and 2 show a first embodiment of the present invention, Figure 1 is a schematic diagram of the state in which the resin is heated and hardened, and Figure 2 shows changes in the temperature of the resin and the temperature in the heating furnace. FIG. Further, FIG. 3 shows the first embodiment showing the second embodiment of the present invention.
It is a figure equivalent figure. In the drawing, 1 is a mold, 2 is a coil (molded object), and 3 is a mold.
is a resin, 4 is a heating furnace, 5 is a heater (heating means), 6.7
8 is a temperature sensor, 8 is a control device, and 11 is a coil temperature detection device.

Claims (1)

[Claims] 1. In a method of molding an object to be molded by storing an object to be molded in a mold and injecting a thermosetting resin, and heating and hardening the resin with a heating means, the mold is A resin molding method characterized in that the temperature of the resin and the heating temperature by the heating means are measured, and the cured state of the resin is determined based on the temperature change.