JPH0562582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an annealing treatment method and apparatus for removing internal stress generated during molding of synthetic resin molded products such as moldings to be attached to automobiles, for example.

[Prior art] Synthetic resin molded products (hereinafter referred to as workpieces) are
While cooling from the high temperature state during molding to room temperature,
Thermal stress is generated due to differences in the cooling rate of each part,
It causes shape changes such as warping and twisting. Especially when the workpiece is long, such as molding for automobiles, the deformation is noticeable, and in order to correct this,
Annealing treatment is being performed.

FIG. 10 is a front view showing a conventional annealing processing apparatus. In the figure, reference numeral 1 denotes a conveyor that continuously rotates and conveys a workpiece 2, and a high-frequency dielectric heating section 3 is provided in the center of the conveyor 1. The high-frequency dielectric heating section 3 has a high-voltage electrode bar 4 placed above the conveyor and a ground electrode bar 5 placed below the conveyor, so that the conveyor 1 and the work 2 can pass between them. They face each other at a certain distance.

In order to remove thermal stress from a workpiece using this annealing processing device, first, the workpiece 2, which has been cooled to a predetermined temperature after forming, is sequentially moved from the entrance of the conveyor 1 with the longitudinal direction of the workpiece 2 aligned with the traveling direction of the conveyor 1. Send it in.

The workpiece 2 placed on the conveyor 1 and sent to the annealing processing apparatus passes through the high-frequency dielectric heating section 3 one after another from one end. High-frequency dielectric heating is performed by an electric field, and internal stress generated during molding is removed. After this, from conveyor 1 to work 2
The sample is taken out, fixed to prevent deformation, and then cooled to a predetermined temperature.

In the figure, 6 is a conductor that connects the high-voltage electrode bar 4 to a matching box (not shown), and 7 is a conductor that similarly connects the earth electrode bar 5 to the ground (not shown).

[Problem that the invention seeks to solve]

However, in such conventional annealing processing methods and apparatuses, even if the workpiece 2 is annealed without being cooled to a predetermined temperature,
Since the thermal stress cannot be removed, the workpiece 2 must be cooled to a predetermined temperature before being sent to the annealing apparatus. During cooling at this time and cooling after annealing, deformation such as warping or twisting may occur. To prevent this, the work 2 must be fixed so that it does not deform during cooling. There was a problem in that it required cooling, which made the process complicated.

The present invention is intended to solve the above-mentioned problems.It is possible to continuously feed a workpiece that is still at a high temperature after forming, and a series of cooling, reheating, and cooling processes are performed to remove internal stress. It is an object of the present invention to provide a method and apparatus for annealing a synthetic resin molded product, which can perform the steps continuously so as to maintain a predetermined shape.

[Means for solving problems]

The present invention provides the following method and apparatus for annealing a synthetic resin molded article.

In an annealing treatment method that removes the internal stress of a synthetic resin molded product that occurs during molding, (A) the synthetic resin molded product is tilted in a shaping mold after molding and before curing, and shaped by its own weight. (B) Process of cooling the synthetic resin molded product while keeping it in a fixed shape based on the side and bottom parts of the mold; (B) Process of applying high-frequency voltage between the high-voltage electrode and the ground electrode to heat the synthetic resin molded product using high-frequency dielectric heating. , and (C) Synthetic resin molding, which consists of the process of tilting the heated synthetic resin molded product again in the mold and cooling it while maintaining a constant shape based on the side and bottom parts of the mold due to its own weight. Product annealing treatment method.

A cooling chamber and a heating chamber, a high voltage electrode and a ground electrode provided in the heating chamber, a cooling chamber and a heating chamber, a conveyor that intermittently conveys the synthetic resin molded product through the cooling chamber, and a conveyor on which the synthetic resin molded product is placed. an intermediate electrode having a mold attached to a conveyor so as to move through the cooling chamber and heating chamber in an inclined state and to enter between the high-voltage electrode and the ground electrode in any position to perform high-frequency dielectric heating; Annealing equipment for resin molded products.

[Effect]

In the method and apparatus for annealing synthetic resin molded products of the present invention, the workpiece before being cooled and hardened after molding is placed on an intermediate electrode having a shaping die and is intermittently conveyed by a conveyor, and the shaping die is held in a cooling room. After cooling the workpiece while keeping it in a constant shape based on the side and bottom parts of the shaping die by its own weight, the intermediate electrode with the shaping die is held in any position and the high voltage electrode is tilted. and the earth electrode, apply high frequency voltage to perform high frequency dielectric heating, and tilt the molded product again with the shaping mold to maintain a constant shape based on the side and bottom parts of the shaping mold by its own weight. Cooling removes internal stress and prevents warping and twisting of the workpiece.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings. FIG. 1 is a perspective view of the annealing processing apparatus of the embodiment, FIG. 2 is a sectional view thereof, FIGS. 3 and 4 are partially enlarged views thereof, FIG. 5 is a perspective view of the chain, and FIG. Figures and A direction arrow view of Figure 4, No.
8 and 8 are enlarged views of part B in FIG. 4, and FIG. 9 is a view taken in the direction of arrow C in FIG. 7, and the same reference numerals as in FIG. 10 indicate the same or corresponding parts.

The annealing processing apparatus shown in its entirety in FIGS. 1 and 2 has a substantially box-shaped main body 11, the interior of which is divided into a cooling chamber 12 and a heating chamber 13 by a partition plate 14. A supply section 15 for feeding the workpiece 2 and a discharge section 16 are formed at the end of the apparatus main body 11 on the cooling chamber 12 side, and a conveyor 17 for discharging the workpiece 2 from the discharge section 16 communicates with a pedestal 18 .

Inside the device main body 11, there are two
Two chains 21 and 22 are stretched between the set of sprocket wheels 19 and 20, and the workpiece 2 is transported to the supply section 1.
A conveyor 1 is formed which conveys the material from 5 through a cooling chamber 12, a heating chamber 13, and a cooling chamber 12 to a discharge section 16. The conveyor 1 drives the sprocket foil 1 through a chain 24 by a drive unit 23 that is installed below the heating chamber 13 and includes a speed reducer, a motor, etc.
9 and 20 are driven intermittently, the vehicle travels intermittently. The intermittent drive of the conveyor 1 is performed by a photoelectric switch 25, which controls the drive unit 2 according to the movement of the workpiece 2.
This is achieved by repeating the rotation and stopping of step 3. The sprocket wheels 19, 20 rotate clockwise, and the conveyor 1 runs from the cooling chamber 12 to the heating chamber 13 on the upper side, and from the heating chamber 13 to the cooling chamber 12 on the lower side. The chains 21 and 22 stretched between the sprocket wheels 19 and 20 are secured by a chain stay (not shown) to prevent them from sagging or shaking during driving.
The track is supported from below.

The cooling chamber 12 has a cooling device 26 provided below it.
The temperature is kept below a certain level by blowing in low-temperature compressed air. Heating chamber 1
3 is equipped with a high-frequency dielectric heating section 3, and the temperature is always maintained at a constant temperature by infrared lamps 27 provided at the front and rear of the heating section 3. These cooling chamber 12 and heating chamber 13 are surrounded by a partition plate 14 made of a heat insulating material such as glass wool. In the figure, 28 is a window for visually checking the internal state of the heating chamber 13.

Two chains 21 and 22 stretched in parallel
A plurality of brackets 31 are provided to protrude inwardly at regular intervals, and bearings 32 are each fixed to the upper surface of the brackets 31. And an intermediate electrode bar 33 having a shaping mold on which the workpiece 2 is placed.
A shaft 34 is rotatably supported by a bearing 32 on the same axis at both ends of the conveyor 1 . One end of the shaft 34 is further extended outward from the bearing 32, and a lever-shaped weight 35 is pivotally attached to the upper surface of the intermediate electrode bar 33 at a constant inclination. Bearings 32 on both sides that pivotally supported the intermediate electrode bar 33
The chains 21, 22 and the shaft 34 are installed at right angles so that they are in the same phase with respect to the traveling direction of the chains 21, 22. This shaft 34 is preferably made of a pipe to reduce weight.

The intermediate electrode bar 33 has a structure in which a shaping die 36 is attached from the top. The shaping mold 36 has a bottom part 40 made of a core plate in which a sheet-like polytetrafluoroethylene layer 39 is formed on an aluminum plate 38.
Side parts 37a and 37b are constructed to rise from both sides. The workpiece 2 is accommodated in a space formed by the bottom part 40 and side parts 37a and 37b of the shaping mold 36.

The heating chamber 13 and the supply section 15 are provided with guide stands 41 and 42 that tilt the weight 35 to place the intermediate electrode bar 33 in a horizontal position, and in other parts, the weight 35 hangs vertically. As a result, the intermediate electrode bar 33 is inclined. The discharge section 16 is provided with a guide stand 43 that keeps the weight 35 horizontal and tilts the intermediate electrode bar 33 in the opposite direction.

The high-frequency dielectric heating section 3 includes a high-voltage electrode bar 4 and a ground electrode bar 5, which are arranged between the infrared lamps 27 of the heating chamber 13 and sandwiching the intermediate electrode bar 33 of the conveyor 1 from above and below. A conductor 6 connected to the ground electrode bar 4 is connected to a matching box (not shown) for adjusting the incident voltage and reflected voltage, and a conductor 7 connected to the ground electrode bar 5 is connected to the ground.

The high-voltage electrode bar 4 is attached to a guide bar 44 and lowered by a fluid pressure cylinder 45. Push plates 46 are provided at the bottom of both ends of the guide bar 44, and push plates 46 are provided at both ends of the intermediate electrode bar 33. The received plate 47 is pressed down and pressed against the pedestal 48.

The intermediate electrode bar 33 is positioned by the photoelectric switch 25 so as to stop between the high voltage electrode bar 4 and the earth electrode bar 5. At this time, the weight 35 is placed on a spring 49 provided on the guide stand 41. It is becoming located. The spring 49 normally holds the weight 35 on the reference plane of the guide stand 41 as shown in FIG. 7, but when pushed by the drive of the fluid pressure cylinder 45, it descends as shown in FIG. Thus, the intermediate electrode bar 33 is brought into contact with the ground electrode bar 5.

Insertion guides 50 and 51 protrude in a curved manner toward the supply section 15 side of the high-voltage electrode bar 4 and the earth electrode bar 5, and a protective layer 52 of sheet-like polytetrafluoroethylene or the like is applied to the surface of the intermediate electrode. It is designed to facilitate the entry of the bar 33.
53 is a thermosensor for controlling the heating temperature by the infrared lamp 27, and 54 is a defect marking machine that operates in conjunction with a radiation thermometer 55 that measures the outer surface temperature of the workpiece 2.

In the annealing treatment method using the above-mentioned annealing treatment apparatus, in the supply section 15, the bottom surface 4 of the shaping die 36 of the intermediate electrode bar 33 of the conveyor 1 that moves intermittently
0, the workpiece 2 immediately after molding is placed on it. The lower end of the weight 35 of the supply section 15 is pushed down by the guide stand 42 and tilted rearward in the traveling direction (X), keeping the intermediate electrode bar 33 horizontal to improve workability.

Passing through the guide stand 42 of the supply section 15,
When entering the cooling chamber 12, the intermediate electrode bar 33 tilts due to the weight of the weight 35, so the workpiece 2 placed on the shaping mold 36 moves downward due to its own weight, and the side surface 37a
comes into contact with. As a result, the workpiece 2 is held in a constant shape with respect to the side surface 37a and the bottom surface 40 of the shaping die 36, and the linearity of the workpiece 2 is maintained. In this state, the workpiece 2 passes through the cooling chamber 12,
Cool and harden.

When the intermediate electrode bar 33 carrying the workpiece 2 enters the heating chamber 13, the weight 3 is lifted by the guide stand 41.
5 is tilted, the intermediate electrode bar 33 maintains a horizontal position, and the workpiece 2 is heated by the infrared lamp 27 at the entrance, so that the surface and internal temperatures are approximately equal. After being positioned by the photoelectric switch 25, the intermediate electrode bar 33 accurately enters between the high voltage electrode bar 4 and the ground electrode bar 5 of the high frequency dielectric heating section 3 and stops there.

In this state, when the fluid cylinder 45 is driven and the high voltage electrode bar 4 is lowered, the intermediate electrode bar 33 is pushed by the push plate 46 and lowered within the clearance between the chains 21 and 22, and comes into contact with the pedestal 48. Stops in place. In this state, the intermediate electrode bar 3
Since the workpiece 2 on 3, the high voltage electrode bar 4 and the earth electrode bar 5 are parallel and the distance is constant,
When a high frequency wave of a predetermined voltage is applied, dielectric heating is always performed under the same conditions, and the workpiece 2 is uniformly heated to the same temperature. At this time, it is preferable that the intermediate electrode bar 33 and the earth electrode bar 5 come into contact with each other, but high-frequency current can be passed even if they do not come into contact with each other.

After performing high-frequency dielectric heating for a predetermined period of time, the fluid cylinder 45 rises, the intermediate electrode bar 33 returns to its normal position, and starts running again. The surface temperature of the workpiece 2 is measured by a radiation thermometer 55, and those exceeding the allowable range are marked by a defective product marking machine 54 and determined when the workpiece is taken out.

Furthermore, while running inside the heating chamber 13, the infrared lamp 2
After being maintained in a heated state by 7, the weight 35 leaves the guide stand 41 and the work 2 is tilted.
It enters the cooling chamber 12 in a state where it has been shaped by the shaping die 36 under its own weight. In the cooling chamber 12, the workpiece 2 is gradually cooled and hardened by cooling air from the cooling device 26, and internal stress is removed.

Next, when the chains 21 and 22 reach the discharge part 16, the weight 35 is tilted more deeply by the high guide stand 43 provided in the discharge part 16, the intermediate electrode bar 33 is reversed, and the workpiece 2 is moved downward. It is dropped onto the conveyor 17 and taken out onto the pedestal 18.

In the above description, the workpiece 2 is preferably made of a material with large dielectric loss, such as polyvinyl chloride or methyl methacrylate resin. On the other hand, as the material on which the workpiece 2 is placed, it is preferable to use a material with low dielectric loss and low coefficient of friction, such as polytetrafluoroethylene. Although a core plate is used for the bottom surface portion 40 of the shaping mold 36, if the tip of the workpiece 2 is not curved, there is no need to use a core-like plate, and the upper surface of the intermediate electrode bar 33 is It may also be the bottom portion 40.

The heating temperature changes when the distance between the surface of the workpiece 2 and the high-voltage electrode bar 4 changes, so the workpiece 2 is made parallel to the high-voltage electrode bar 4. However, if the cross section of the workpiece 2 changes, Based on the surface. Further, when the workpiece 2 has a radius in the axial direction or the width direction, uniform heating can be performed by matching the shape of the intermediate electrode bar 33 or (and) the high voltage electrode bar 4 to the shape of the workpiece 2. If the wall thickness of the workpiece 2 differs in the plane direction of the intermediate electrode bar 33, a difference will occur in the amount of heat generated, so the high voltage electrode bar 4 is It is desirable to change the cross-sectional shape of.

In the above embodiment, the intermediate electrode bar 33 is inserted between the high voltage electrode bar 4 and the ground electrode bar 5 in a horizontal position, but the intermediate electrode bar 33 may be inserted in any position, for example, in an inclined position. In this case, after entering the high voltage electrode bar 4 and the earth electrode bar 5
High frequency dielectric heating can be performed by bringing the fluid pressure cylinder 45 closer to the fluid pressure cylinder 45 or the like.

In the above annealing process, the temperatures of the cooling chamber 12 and the heating chamber 13 are constant, the traveling speed of the workpiece 2 is also constant, and the high-frequency dielectric heating conditions are also constant, so that each workpiece 2 can be uniformly annealed. The internal stress is removed.

〔Effect of the invention〕

According to the present invention, after a synthetic resin molded product is tilted in a shaping mold and cooled while maintaining a constant shape based on the side and bottom parts of the shaping mold due to its own weight, high-frequency dielectric The mold was heated and tilted again together with the shaping mold to cool it while maintaining a certain shape based on the side and bottom parts of the shaping mold, so that the synthetic resin molded product could be annealed as is after molding. Furthermore, by keeping the annealing conditions constant and removing internal stress, it is possible to produce synthetic resin molded products shaped into a predetermined shape and having an excellent appearance.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an annealing processing apparatus according to an embodiment;
Fig. 2 is a sectional view thereof, Figs. 3 and 4 are partially enlarged views thereof, Fig. 5 is a perspective view of the chain, Fig. 6 is a view taken in the direction of arrow A in Figs. 3 and 4, and Fig. 7 Figures 8 and 8 are enlarged views of section B of Figure 4, and Figure 9 is an enlarged view of section B of Figure 4.
FIG. 10 is a front view of a conventional annealing processing apparatus. In each figure, the same reference numerals indicate the same or equivalent parts, 1 is the conveyor, 2 is the workpiece, 3 is the high frequency dielectric heating section, 4 is the high voltage electrode bar, 5 is the earth electrode bar, 11 is the device body, 12 is the cooling chamber , 13 is a heating chamber, 15 is a supply section, 16 is a discharge section, 21 and 22 are chains, 27 is an infrared lamp, 33 is an intermediate electrode bar, 35 is a weight, 36 is a shaping mold, 41, 42,
43 is a guide stand, 44 is a guide bar, 45
is a fluid pressure cylinder, and 49 is a spring.

Claims (1)

[Scope of Claims] 1. In an annealing treatment method for removing internal stress of a synthetic resin molded product that occurs during molding of the synthetic resin molded product, (A) the synthetic resin molded product is tilted in a shaping mold after molding and before curing. (B) Applying a high-frequency voltage between the high-voltage electrode and the ground electrode while holding the synthetic resin molded product in a desired position. In addition, there is a process of high-frequency dielectric heating, and (C) the heated synthetic resin molded product is tilted again in the mold and cooled while keeping it in a constant shape based on the side and bottom parts of the mold due to its own weight. A method for annealing synthetic resin molded products, which consists of the steps of: 2. The method according to claim 1, wherein the synthetic resin molded product is placed on an intermediate electrode having a shaping mold, transported, and subjected to cooling and high-frequency dielectric heating. 3. The method according to claim 1 or 2, wherein the synthetic resin molded product is subjected to high-frequency dielectric heating in a substantially horizontal position. 4 A cooling chamber and a heating chamber, a high-voltage electrode and a ground electrode provided in the heating chamber, a cooling chamber and a heating chamber, a conveyor that intermittently conveys the synthetic resin molded product through the cooling chamber, and a conveyor on which the synthetic resin molded product is placed. and an intermediate electrode having a shaped mold attached to a conveyor so as to move through the cooling chamber and heating chamber in an inclined state and to enter between the high voltage electrode and the earth electrode in any position to perform high frequency dielectric heating. Annealing equipment for synthetic resin molded products. 5. The apparatus according to claim 4, wherein the heating chamber has infrared lamps before and after the high voltage electrode and the earth electrode. 6. The device according to claim 4 or 5, wherein the intermediate electrode having a shaped mold is tiltable by a weight. 7. The device according to any one of claims 4 to 6, wherein the intermediate electrode having a shaped mold enters between the high voltage electrode and the earth electrode in a substantially horizontal position.