JP2013000947A - Workpiece forming mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a workpiece forming mold that can shorten the cycle time of workpiece molding by raising the temperature of a molding surface of a metal mold speedily and uniformly up to the mold removal temperature of resin to be molded, and also shortening the cooling time of the metal mold having been heated.SOLUTION: A workpiece forming mold 10 includes a pair of molding molds (a first molding mold 11 and a second molding mold 12) for molding a workpiece by heating and cooling, and a pair of cooling molds ( a first cooling mold 13 and a second cooling mold 14) which have cooling means (a cooling pipe 131 and a cooling pipe 141), and are arranged on reverse surface sides of respective molding surfaces of the pair of molding molds, respectively. When the pair of molding molds are heated, the pair of molding molds are heated by induction heating while the pair of molding molds and the pair of cooling molds are apart from each other, and when the pair of molding molds are cooled, the pair of molding molds are cooled and clamped as the pair of molding molds and the pair of cooling molds abut against each other.

Description

  The present invention relates to a workpiece molding die. More specifically, the present invention relates to a work mold that separates a mold and a cooling mold and heats only the mold using induction heating.

  Conventionally, a technique for heating a processing means and processing a material with a high-temperature processing means is known. For example, in resin molding, a mold is heated, and a material is pressure-molded with a high-temperature mold. After the pressure molding, the molded product is cooled in the mold until it reaches a temperature at which the molded product does not deform when the molded product is taken out from the mold.

  Thus, in the technique of processing a material with a high-temperature mold, heating and cooling are repeatedly performed. Therefore, in order to shorten the cycle time, a technique for rapidly heating the mold is necessary. As a technique for rapidly heating the mold, a technique using induction heating is known.

  By the way, when a workpiece having a complicated shape such as a resin molding die is heated by induction heating, there are a portion where eddy current is likely to concentrate and a portion where it is difficult to concentrate, so that the heating method is biased. Therefore, in order to prevent uneven heating, a magnetic compound having a Curie temperature is included in a part of the heating zone including the molding surface of the mold so that the temperature of the molding surface does not rise above the Curie temperature. A technique is disclosed (see Patent Document 1).

  In addition, as a technique for cooling a rapidly heated mold using induction heating, a technique for providing a cooling water passage in the mold and circulating the cooling water during cooling is known (see Patent Document 2).

Special table 2007-535786 gazette JP 2011-020390 A

  Here, in the technique of Patent Document 1, even when the Curie temperature is reached and the magnetic compound does not generate Joule heat, an eddy current is generated in a portion of the heating zone where the magnetic compound does not exist. As the Joule heat is transferred, the molding surface continues to be heated. Therefore, it has been difficult to raise the temperature of the molding surface uniformly.

  Further, in order to cool the rapidly heated mold in the technique of Patent Document 1, it is necessary to circulate the cooling water in the heated mold as in the technique of Patent Document 2, but during the heating, the cooling water The circulation of the cooling water is stopped and the circulation of the cooling water starts after heating. Therefore, the cooling water is warmed by the mold for a while from the start of cooling, and thus it takes time for cooling.

  The present invention has been made in view of the above, and its purpose is to quickly and uniformly raise the temperature of the molding surface of the mold to a temperature equal to or higher than the demolding temperature of the molding resin and to cool the heated mold. An object of the present invention is to provide a workpiece molding die that can shorten the cycle time of workpiece molding by advancing the time.

  In order to achieve the above object, a workpiece molding die according to the present invention (for example, a workpiece molding die 10 described later) includes a pair of molding dies (for example, a first molding die 11 described later and a workpiece molding die described later). A second mold 12) and a cooling means (for example, a cooling pipe 131 and a cooling pipe 141, which will be described later), and a pair of cooling molds (for example, the rear surfaces of the molding surfaces of the pair of molds, respectively) A first cooling mold 13 and a second cooling mold 14), which will be described later, and when the pair of molds are heated, the pair of molds and the pair of cooling molds are separated from each other. The mold is heated by induction heating, and at the time of cooling the pair of molds, the pair of molds and the pair of cooling molds come into contact with each other to cool and clamp the pair of molds. Features.

  According to the present invention, at the time of induction heating, the pair of molds and the pair of cooling molds are separated from each other, so that the molds are not deprived of heat by the cooling molds. Further, the temperature of the cooling mold can be lowered in advance without stopping the cooling means. Therefore, since the mold can be heated quickly and uniformly, and the cooling can be performed in a short time and uniformly, the work molding cycle time can be shortened.

  In this case, it is preferable that the shape of the contact surface of the pair of molding dies with the pair of cooling dies is an uneven shape along the shape of the molding surface of the pair of molding dies.

According to this invention, since the shape of the contact surface of the molding die with the cooling die is an uneven shape along the shape of the molding surface, the thickness of the molding die can be made uniform. Therefore, since heating by heat transfer can be made more uniform, the molding surface can be heated more uniformly.
Moreover, according to this invention, since the distance between a molding surface and a cooling die can be made uniform, a molding surface can be cooled more uniformly. That is, heating and cooling of the molding surface can be performed more uniformly.

Furthermore, since the molding surface is uniformly heated, the resin temperature in the cavity during resin injection can be increased, and the fluidity of the resin can be improved, so that the thickness of the molded product (workpiece) can be reduced. The number of gates can be reduced, and welds (streaks that look like cracks that occur on the surface of the molded product) and flow marks (phenomenon of appearance defects that cause a ring-shaped wave pattern around the gate on the surface of the molded product) This can improve molding defects.
In addition, by uniformly cooling the molding surface, sink marks (depressions generated on the surface of the molded product) and deformation due to shrinkage differences can be prevented.

  According to the present invention, the temperature of the molding surface of the mold is rapidly and uniformly raised to a temperature equal to or higher than the demolding temperature of the molding resin, and the cooling time of the heated mold is shortened, so that the cycle time of the workpiece molding is increased. It is possible to provide a work mold that can speed up the process.

It is a mimetic diagram showing composition of a work forming system containing a work forming die concerning one embodiment of the present invention. It is a figure which shows the structure of the workpiece shaping | molding system containing the cross-sectional view of the workpiece shaping die which concerns on the said embodiment. It is a figure which shows the structure of the workpiece shaping | molding system containing the cross-sectional view of the workpiece shaping die which concerns on the said embodiment. It is a figure which shows the structure of the workpiece shaping | molding system containing the cross-sectional view of the workpiece shaping die which concerns on the said embodiment. It is a figure which shows the structure of the workpiece shaping | molding system containing the cross-sectional view of the workpiece shaping die which concerns on the said embodiment. It is a figure which shows the magnetic characteristic of the magnetic material which concerns on the said embodiment. It is a figure which shows the temperature change of the shaping | molding die concerning the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a configuration of a workpiece forming system including a workpiece molding die according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a workpiece forming system including a cross-sectional view of a workpiece molding die according to an embodiment of the present invention.

The workpiece molding system 1 according to the present embodiment heats a mold using induction heating, clamps the mold together with a cooling mold, and then performs resin injection molding while cooling the mold.
The configuration of the workpiece forming system 1 will be described.
The workpiece molding system 1 includes a workpiece molding die 10, an injection device 20 connected to the workpiece molding die 10, and a pair of high-frequency coils 30, 30 arranged so as to face the workpiece molding die 10. , A pair of high-frequency power sources 40, 40 for applying a high-frequency current to the pair of high-frequency coils 30, 30 and a plurality of molds constituting the workpiece molding die 10 (first molding die 11, second molding die 12, which will be described later, And a mold control mechanism 50 for controlling the advance and retreat of the first cooling mold 13), an injection device 20, a pair of high-frequency power supplies 40 and 40, and a control device 60 for controlling the mold control mechanism 50.

The workpiece molding die 10 includes a first molding die 11, a second molding die 12, a first cooling die 13, a second cooling die 14, and a guide portion 15.
The first mold 11 and the second mold 12 that are a pair of molds are arranged to face each other, and the opposing surfaces of the first mold 11 and the second mold 12 are the molding surfaces of the workpiece. It becomes. Moreover, about the 1st cooling mold 13 and the 2nd cooling mold 14 which are a pair of cooling molds, the 1st cooling mold 13 is arrange | positioned at the back surface side of the molding surface of the 1st shaping | molding die 11, and the 2nd cooling mold 14 is The second mold 12 is disposed on the back side of the molding surface.
Further, the shape of the contact surface of the first mold 11 with the first cooling mold 13 is a shape recessed toward the second mold 12 along the shape of the molding surface of the first mold 11. The shape of the contact surface of the second mold 12 with the second cooling mold 14 is a convex shape toward the second cooling mold 14 along the shape of the molding surface of the second mold 12.

Further, the first cooling mold 13 and the second cooling mold 14 are respectively formed with a cooling pipe 131 and a cooling pipe 141 as cooling means for cooling the cooling mold, and the cooling water is passed through these cooling pipes. Thus, the first cooling mold 13 and the second cooling mold 14 can be always kept in a cooled state. A plurality of cooling pipes 131 and cooling pipes 141 are formed.
Furthermore, the first mold 11, the second mold 12, the first cooling mold 13, and the second cooling mold 14 are connected via a guide portion 15, and the guide portion 15 is connected to the first mold 11. The second mold 12 and the first cooling mold 13 are guided forward and backward. The second cooling mold 14 is fixedly disposed together with the injection device 20, and the second cooling mold 14 itself does not move.
Further, the advance / retreat of the molds is controlled by a mold control mechanism 50 controlled by the control device 60. In addition, the guide part 15 is comprised with the insulator.
Furthermore, the first mold 11 and the second mold 12 are made of a magnetic material having a Curie temperature higher than the glass transition temperature (or melting point) of the resin to be molded.

Here, the Curie temperature will be described with reference to FIG.
FIG. 6 is a diagram showing the magnetic characteristics of a general magnetic material. Specifically, FIG. 6 is a diagram showing the relationship between the temperature and the magnetic permeability of a general magnetic material. Here, the magnetic permeability is a material constant representing the state of magnetization of the magnetic material, and means the ratio between the magnetic flux density and the strength of the magnetic field. As shown in FIG. 6, the magnetic material has a characteristic that the magnetic permeability is high below a predetermined temperature, and the magnetic permeability rapidly decreases when the temperature exceeds the predetermined temperature.
The predetermined temperature at this time is called the Curie temperature, and is a temperature unique to each magnetic material in which the ferromagnetic material transitions to the paramagnetic material. Examples of the magnetic material having such magnetic characteristics include various magnetic shunt alloys that are alloyed while maintaining the above magnetic characteristics, in addition to simple substances such as iron, cobalt, and nickel. According to this magnetic shunt alloy, a magnetic material having a desired Curie temperature is obtained, and the first mold 11 and the second mold 12 can be controlled to be heated to a desired temperature.

Next, the operation of the workpiece forming system 1 will be described with reference to FIGS.
In the state shown in FIG. 2, the first mold 11 and the second mold 12 are heated by induction heating. In the induction heating, the control device 60 controls the pair of high-frequency power sources 40 and 40 to pass a high-frequency current through the pair of high-frequency coils 30 and 30, so that the magnetic flux penetrating the first mold 11 and the second mold 12. Is generated. Due to this magnetic flux, eddy currents are generated in the first mold 11 and the second mold 12 and are rapidly heated.

At the time of induction heating, as shown in FIG. 2, the first mold 11 and the second mold 12 are separated from the first cooling mold 13 and the second cooling mold 14. Moreover, the 1st shaping | molding die 11 and the 2nd shaping | molding die 12 are spaced apart.
When the temperature of the first molding die 11 and the second molding die 12 reaches the Curie temperature of the magnetic material by induction heating, the ferromagnetic material transitions to a paramagnetic material, and the magnetic permeability rapidly decreases. Therefore, no eddy current is generated and heating of the mold is stopped. Thereafter, mold clamping is performed.

Clamping is performed as follows. That is, the first mold 11, the second mold 12, and the first cooling mold 13 are moved in the direction of the second cooling mold 14 to bring the first mold 11 and the second mold 12 into contact with each other, Further, the first mold 11 and the first cooling mold 13 are brought into contact with each other, and the second mold 12 and the second cooling mold 14 are brought into contact with each other. The state after contact is shown in FIG.
At this time, as shown in FIG. 3, a cavity 16 for forming a workpiece (for example, a resin molded product) is formed between the first mold 11 and the second mold 12.

When the mold clamping is completed, injection of resin from the injection device 20 into the cavity 16 is started.
The resin is injected from a nozzle (not shown) of the injection device 20 through sprues, runners, and gates (not shown) formed in the second cooling mold 14 and the second molding die 12. Resin flows in.
Since the first cooling mold 13 and the second cooling mold 14 are always in a cooled state, when the mold clamping is completed, the cooling of the first molding mold 11 and the second molding mold 12 is started promptly. Therefore, it is preferable to inject the resin until the temperature of the first mold 11 and the second mold 12 decreases to the glass transition temperature (or melting point) of the resin.
This is because if the resin is injected after the temperature is lowered to the glass transition temperature (or melting point) of the resin, the fluidity of the resin is lowered.

FIG. 4 is a diagram illustrating a state in which resin is injected and holding pressure cooling is performed.
According to FIG. 4, the resin is injected into the cavity 16 (see FIG. 3) by an amount necessary for forming the work, and the work W is formed. In this state, holding pressure cooling is performed to complete the forming of the workpiece W.

When the forming of the work W is completed, as shown in FIG. 5, the first forming mold 11 and the first cooling mold 13 are moved in the opposite direction to the second forming mold 12 to open the mold, and the work W is taken out.
When the workpiece W is taken out, the first molding die 11, the second molding die 12, and the first cooling die 13 are moved to the positions shown in FIG.

With reference to FIG. 7, the temperature change of a shaping | molding die is demonstrated. FIG. 7 is a view showing a temperature change of the mold.
When the mold is heated by induction heating, the temperature of the mold increases until the Curie temperature of the magnetic material is reached. Thereafter, the mold is clamped, but until the mold clamping is completed, the cooling mold does not come into contact with the mold, so the temperature drop is moderate. When the mold clamping is completed, the cooling mold comes into contact with the mold, so that the temperature decrease rate of the mold increases.
Since the injection of the resin into the cavity is performed after the completion of the mold clamping, the temperature of the molding die is lowered during the injection. For this reason, in order to prevent a decrease in the fluidity of the resin, it is preferable that the resin is injected before the temperature of the mold decreases to the glass transition temperature (or melting point) of the resin. When the injection of the resin is completed, the holding pressure cooling is performed until the molding of the workpiece is completed. When the temperature of the mold is lowered to the temperature at which the molding of the workpiece is completed, the mold is opened and the workpiece is taken out.

The workpiece molding die 10 according to the present embodiment has the following effects.
(1) According to this embodiment, at the time of induction heating, the first mold 11 and the second mold 12 are separated from the first cooling mold 13 and the second cooling mold 14, so that the mold is a cooling mold. I'm not deprived of heat. Further, the temperature of the cooling mold can be lowered in advance without stopping the flowing water to the cooling pipe 131 and the cooling pipe 141. Therefore, the first mold 11 and the second mold 12 can be heated quickly and uniformly and can be cooled in a short time and uniformly, so that the cycle time for molding the workpiece W can be shortened.

(2) According to the present embodiment, the shape of the contact surface of the first mold 11 with the first cooling mold 13 is on the second mold 12 side along the shape of the mold surface of the first mold 11. The shape of the contact surface of the second mold 12 with the second cooling mold 14 is convex toward the second cooling mold 14 along the shape of the molding surface of the second mold 12. Since it is a shape, the thickness of the 1st shaping | molding die 11 and the 2nd shaping | molding die 12 can be made uniform. Therefore, since heating by heat transfer can be made more uniform, the molding surfaces of the first mold 11 and the second mold 12 can be heated more uniformly.
Further, according to the present embodiment, the distance between the molding surface of the first molding die 11 and the first cooling die 13 and the distance between the molding surface of the second molding die 12 and the second cooling die 14. Therefore, the molding surfaces of both molds can be cooled more uniformly. That is, heating and cooling of the molding surface can be performed more uniformly.

Furthermore, since the molding surface is uniformly heated, the resin temperature in the cavity 16 at the time of resin injection can be increased, and the fluidity of the resin can be improved, so that the workpiece W can be made thinner and the number of gates can be increased. In addition, molding such as welds (streaks that look like cracks that occur on the surface of the molded product) and flow marks (phenomenon of appearance defects that cause a ring-shaped wave pattern around the gate on the surface of the molded product). Defects can be improved.
In addition, by uniformly cooling the molding surface, sink marks (depressions generated on the surface of the molded product) and deformation due to shrinkage differences can be prevented.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, although the case where injection molding is performed has been described in the above embodiment, the present invention is not limited to this, and hot pressing may be performed. In the case of hot pressing, when the first mold 11 and the second mold 12 are uniformly heated, a workpiece is inserted between the first mold 11 and the second mold 12, and the first cooling is performed. Press molding is performed together with the mold 13 and the second cooling mold 14. Moreover, since the cavity 16 is unnecessary, it is preferable to process the mold so that the entire molding surfaces of the first mold 11 and the second mold 12 are in contact with each other.
Moreover, although the said embodiment demonstrated the case where the 1st shaping | molding die 11 and the 2nd shaping | molding die 12 were isolate | separated at the time of the induction heating of the 1st shaping | molding die 11 and the 2nd shaping | molding die 12, it is restricted to this. Instead, the first mold 11 and the second mold 12 may be connected. In this case, the eddy current does not flow through the closed circuit of each molding die, but circulates outside the connected first molding die 11 and second molding die 12, so there is no risk of interference and it is easier to flow. Become.

DESCRIPTION OF SYMBOLS 1 ... Work shaping | molding system 10 ... Work shaping | molding die 11 ... 1st shaping | molding die 12 ... 2nd shaping | molding die 13 ... 1st cooling die 14 ... 2nd cooling die 15 ... Guide part 16 ... Cavity 20 ... Injection apparatus 30 ... High frequency coil DESCRIPTION OF SYMBOLS 40 ... High frequency power supply 50 ... Mold control mechanism 60 ... Control apparatus 131 ... Cooling pipe 141 ... Cooling pipe W ... Workpiece

Claims (2)

A pair of molds for molding a workpiece by heating and cooling; and
A cooling means, and a pair of cooling molds disposed on the back side of each molding surface of the pair of molding dies, and
At the time of heating the pair of molds, the pair of molds is heated by induction heating in a state where the pair of molds and the pair of cooling molds are separated from each other,
When cooling the pair of molds, the pair of molds and the pair of cooling molds come into contact with each other to cool and clamp the pair of molds.   2. The workpiece forming according to claim 1, wherein a shape of a contact surface of the pair of forming dies with the pair of cooling dies is an uneven shape along a shape of a forming surface of the pair of forming dies. Mold.

Images