JP2009226778A - Surface-like carbon heater for metallic mold, process for manufacturing the same and metallic mold apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat carbon heater excellent in temperature rising speed characteristic and to provide a metallic mold apparatus which is provided with the heater and which can efficiently produce a molding having no welding line. <P>SOLUTION: The metallic mold apparatus is provided with a heater unit 4 which uses the flat carbon heater CH as a heat source and a heater accommodation part 27 for accommodating the heater unit 4 is provided at least at one among a mobile mold 1 and a fixed mold 2 corresponding to the mobile mold. The heater accommodation part 27 is located at a position facing a product molding part 3 which is formed between the mobile mold 1 and the fixed mold 2 by holding a thermally conductive heat transfer wall 24b heated by the heater unit 4. The heater unit 4 can move between a position which is in contact with the heat transfer wall 24b and a position which is remote from the heat transfer wall 24b. Moreover the flat carbon heater CH is constituted by burying a resistance exothermic body 43 composed of a carbon line in a flat heat-resistant plate 42 having an electrical insulation property and a thermal conductivity property and electrically conductive connection of a lead wire 44 is carried out to both end parts 43a, 43a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a planar carbon heater having an excellent temperature rise rate performance in which the surface temperature rises rapidly when energized, a method for efficiently producing the same, and the generation of a weld line is suitably prevented by using the heater. The present invention relates to a mold apparatus that can be used.

  Conventionally, various methods are known as a molding method using a mold, and hair-like lines called weld lines may be generated in a molded product mainly in injection molding. This weld line is generated when the molten material in the mold flows and joins around the part that becomes the hole or window of the molded product, and it does not matter so much in terms of strength, but the type of resin, etc. Depending on the case, the strength reduction may become so large that it cannot be ignored, and the aesthetics of the product will be greatly impaired.

  For this reason, conventionally, in order to prevent the occurrence of a weld line, after the molten material is filled in the mold, the mold is heated by a heater provided therein to remelt the molten material that is being cured. (For example, Patent Document 1).

  Ceramic heaters and carbon heaters are generally well known as heaters, but conventional carbon heaters enclose a carbonaceous heating element in a glass tube and connect the lead wire connected to the carbonaceous heating element to glass. It is pulled out of the pipe (for example, Patent Document 2).

JP 2007-223168 A JP 2006-286372 A

  Here, in Patent Document 1, it is possible to prevent the occurrence of a weld line by re-melting the molten material filled in the mold cavity by energizing the ceramic heater built in the mold and heating the mold. Although it is possible to cool the mold after remelting and proceed to the next molding process, it takes time until the surface of the ceramic heater reaches the specified temperature after the energization of the ceramic heater, shortening the molding cycle time. It was a big obstacle to plan.

  On the other hand, in the conventional carbon heater as disclosed in Patent Document 2, it is customary to enclose an inert gas in a glass tube in order to prevent heating deterioration of the carbonaceous heating element, which makes it difficult to manufacture the product. There is a drawback that the cost is high and the glass tube enclosing the carbonaceous heating element may be damaged by impact, making it difficult to use as a drive system.

  The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a novel carbon heater excellent in durability that can be easily manufactured at a high temperature rise rate, and a weld including the heater. An object of the present invention is to provide a mold apparatus capable of efficiently producing a molded product without a line.

In order to achieve the above-described object, the present invention provides a planar carbon heater CH for a mold,
A resistance heating element comprising a carbon wire that has a predetermined linear pattern and extends in a plane parallel to the plate surface of the heat-resistant plate inside a flat heat-resistant plate 42 having electrical insulation and thermal conductivity. 43 is embedded without contacting with an oxidizing atmosphere, and lead wires 44 are conductively connected to both end portions 43a and 43a of the resistance heating element 43, respectively.

  In addition, a metal terminal 45 having a U-shaped cross section is attached to both ends 43 a and 43 a of the resistance heating element 43, and the lead wire 44 is connected to both ends 43 a of the resistance heating element 43 through the metal terminal 45. , 43a are conductively connected.

  Further, split grooves 43b are formed in both end portions 43a and 43a of the resistance heating element 43 along the axial direction thereof, and each end of the lead wire 44 is formed as a flat plate-like connection terminal portion 44a. It is characterized by being inserted into the groove 43b.

Furthermore, the present invention provides a method for producing the above-described planar carbon heater CH for molds,
In a cavity 6C formed between a pair of upper and lower molds 6A and 6B, a fixed resistance heating element 43 made of carbon wire having a predetermined linear pattern and developed in a planar shape is disposed, and the resistance heating is performed. After the body 43 is parallel to the bottom surface of the cavity 6C and supported at a middle position in the height direction of the cavity 6C, the pair of upper and lower molds 6A and 6B are closed, and the cavity 6C is electrically insulated by heating. In addition, the ceramic slurry is filled with a ceramic slurry that becomes a cured product having thermal conductivity, and then the ceramic slurry is heated and cured while the upper and lower pair of molds 6A and 6B are closed, so that the resistance heating element 43 comes into contact with the oxidizing atmosphere. The flat heat-resistant plate 42 is embedded in a state where it is not used.

  In the above method, before placing the resistance heating element 43 in the cavity 6C, the lead wires 44 are connected to both end portions 43a, 43a, and the ceramic slurry is filled when the ceramic slurry is filled into the cavity 6C. It is preferable to cover the connecting portion of the lead wire 44 with a rally.

  Further, the present invention is a mold apparatus including a heater unit 4 having the planar carbon heater CH for mold as a heat source, and a refrigerant is provided to at least one of the movable mold 1 and the fixed mold 2 corresponding to the movable mold. A cooling passage 26 for circulation and a heater accommodating portion 27 for accommodating the heater unit 4 are provided, and the heater accommodating portion 27 sandwiches a heat conductive heat transfer wall 24b heated by the heater unit 4. The heater unit 4 is connected to the heater moving mechanism 5 and is in contact with the heat transfer wall 24b, and is located at a position facing the product molding portion 3 formed between the movable mold 1 and the fixed mold 2. It is possible to move between positions separated from the heat transfer wall 24b.

  According to the planar carbon heater for molds according to the present invention, a plane parallel to the plate surface of the heat-resistant plate having a predetermined linear pattern inside the flat heat-resistant plate having electrical insulation and thermal conductivity. Because the resistance heating element consisting of carbon wire that expands in a plane inside is buried without being in contact with the oxidizing atmosphere, the carbon resistance heating element is not exposed to the atmosphere, so that it is difficult for heat deterioration to proceed. Moreover, since the resistance heating element is protected from external force by the heat-resistant plate, it can be used by being attached to the drive system.

  The planar carbon heater for molds according to the present invention has low power consumption and excellent temperature rising speed characteristics, and can rapidly increase the surface temperature when energized.

  In addition, the lead wire is conductively connected to both ends of the resistance heating element via a metal terminal having a U-shaped cross section, or one end of the lead wire is connected to the resistance heating element as a flat plate-like connection terminal portion. Since it is inserted into the split grooves formed at both ends, the lead wires can be connected well without poor conduction.

  On the other hand, according to the method according to the present invention, the planar carbon heater for a mold as described above can be efficiently manufactured. In particular, the lead wire is connected to both ends of the resistance heating element, and when the ceramic slurry is filled into the cavity, the connecting portion of the lead wire is covered with the ceramic slurry. Defects and lead wires do not come off during use, and leakage and short circuit can be prevented.

  Furthermore, since the mold apparatus according to the present invention includes a heater unit that uses the planar carbon heater for molds as a heat source, the molding material in the mold is heated by the heater unit to prevent generation of a weld line. In addition, the molding material can be rapidly heated in accordance with the temperature rise rate performance of the planar carbon heater for molds, so the molding cycle time can be shortened and molded products without weld lines can be mass-produced efficiently. It contributes a lot.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing a mold apparatus according to the present invention. In FIG. 1, the mold apparatus includes a movable mold 1 (core mold) and a corresponding fixed mold 2 (cavity mold) for injection molding.

  The movable mold 1 includes a mold plate 12 attached to the movable platen 11 and a core 13 incorporated in the mold plate 12, and faces the fixed die 2 by a mold clamping cylinder (not shown) connected to the movable platen 11. To be moved to. On the other hand, the fixed mold 2 is located on the back side of a cavity plate 24 in which a concave cavity 24 a corresponding to the core 13 is formed via a heat insulating plate 23 inside an outer frame 22 attached to the fixed platen 21. A back plate 25 is incorporated.

  According to the mold apparatus, when the movable mold 1 moves, the movable mold 1 and the fixed mold 2 are opened and closed. When the mold is clamped (when the movable mold 1 and the fixed mold 2 are closed together), A product molding part 3 having a predetermined shape constituted by the core 13 and the cavity 24a is formed between the both parts 1 and 2, and a molten material (mainly thermoplastic resin) from an injection device (not shown) is formed in the product molding part 3. Is to be injected.

  In particular, the fixed mold 2 is provided with a cooling passage 26 for circulating a refrigerant (cooling water) therein and a heater accommodating portion 27 for accommodating a heater unit 4 described later. Among these, the cooling passage 26 is formed so as to surround the heater accommodating portion 27 between the cavity plate 24 and the back plate 25, and both ends thereof are opened to the outside through the side surface of the outer frame 22. . The cooling passage 26 communicates with an external refrigerant tank (not shown), and the refrigerant is circulated between the refrigerant tank and the fixed mold 2.

  On the other hand, the heater accommodating portion 27 is a square hole that penetrates the back plate 25 at a position corresponding to the product forming portion 3, and the peripheral wall thereof is formed by a heat insulating plate 27a. The outer frame 22 and the stationary platen 21 are provided with holes communicating with the heater accommodating portion 27, and the heater unit 4 in the heater accommodating portion 27 and the stationary platen 21 via a rod 51 inserted into the hole. Are connected to a plate 52 parallel to each other. The plate 52 is connected to the stationary platen 21 via an expansion / contraction actuator 53 such as a fluid pressure cylinder or an electromagnetic solenoid, and moves the heater unit 4 in the opening direction of the heater accommodating portion 27 (vertical direction in FIG. 1). The heater moving mechanism 5 is configured. Here, a cylinder direct connection structure, a cam mechanism, or the like may be employed as the heater moving mechanism 5.

  The cavity plate 24 is a heat conductive wall 24b that is heated by the heater unit 4 between the surface in contact with the back plate 25 and the cavity 24a, and through the heat transfer wall 24b. Heat conduction is performed from the heater unit 4 to the molten material (molding material) in the product molding section 3. In particular, the heater unit 4 has a heating head h whose end portion directed toward the cavity plate 24 generates heat at a high temperature, and the heating head h moves to the cavity plate 24 (transmission) by the movement of the heater unit 4 by the heater moving mechanism 5. It contacts or is separated from the hot wall 24b).

  Here, the configuration of the heater unit 4 will be described. FIG. 2 is a plan view showing the internal structure of the heater unit, and FIG. 3 is a side view of the unit. As is apparent from these drawings, in this example, the heater unit 4 is configured by incorporating two planar carbon heaters CH serving as heat sources in a flat plate-shaped heat-resistant housing 41 adjacent to each other.

  The heat-resistant casing 41 includes a case main body 41a that holds the planar carbon heater CH for molds integrally with the heating head h, and a cover 41b that holds the heater CH. Mold surface carbon heaters CH and CH are in contact with each other. Further, a pair of lead wires 44 each having an insulating coating are drawn out from the planar carbon heater CH for molds so that the lead wires 44 are connected to a power source via a control device (not shown). It has become. The lead wire 44 is drawn out of the fixed mold 2 with the outer periphery of the rod 51 shown in FIG. 1 being drawn, but the lead wire 44 may be passed through the rod 51 as a hollow shaft.

  FIG. 4 is a plan view showing the internal structure of the planar carbon heater CH for molds, and FIG. 5 shows an enlarged cross section taken along line XX of FIG. As is apparent from these drawings, the planar carbon heater CH for molds is configured by embedding a resistance heating element 43 made of carbon wire in a flat heat-resistant plate 42 so as not to contact an oxidizing atmosphere. . Among these, the heat-resistant plate 42 is made of an inorganic material having electrical insulation and thermal conductivity, and the resistance heating element 43 is flattened in a plane parallel to the plate surface.

  On the other hand, the resistance heating element 43 is a fixed shape cut out from a carbon plate into a predetermined linear pattern (comb shape in the illustrated example), and the continuous section has a rectangular cross section as shown in FIG. In this example, the heat-resistant plate 42 and the resistance heating element 43 are flat, but they may be curved or bent.

  Further, both end portions 43a and 43a of the resistance heating element 43 are wide and formed in parallel so as to be close to each other, and the lead wires 44 for energization are conductively connected to the both end portions 43a and 43a, respectively. Yes. In particular, as shown in FIG. 6, both end portions 43a and 43a of the resistance heating element 43 are formed with split grooves 43b and 43b whose one ends are opened to the outside along the axial direction, respectively. Corresponding to 43b, each end of the lead wire 44 is a flat-plate-like connecting terminal portion 44a that is not coated with an insulating coating. Each lead wire 44 is fixed with a carbon adhesive (for example, ST-201 manufactured by Nisshinbo Co., Ltd.) by inserting the connecting terminal portion 44a into the dividing groove 43b, and the connecting portion is not short-circuited. As shown in FIG. 4, the heat-resistant plate 42 is coated together with the resistance heating element 43.

  Note that a metal terminal 45 having a U-shaped cross section as shown in FIG. 7 is used to connect the lead wire 44, and the metal terminal 45 is clamped to both end portions 43 a and 43 a of the resistance heating element 43, and the lead wire 44 is attached thereto. May be connected.

  Next, the manufacturing method of the planar carbon heater for metal mold | die comprised as mentioned above is demonstrated. FIG. 8 shows a mold used for manufacturing the planar carbon heater CH for a mold, which is composed of an upper mold 6A and a lower mold 6B, and a concave mold for molding the heat-resistant plate 42 therebetween. A cavity 6C is formed.

  In this example, a stripper plate 61 is provided on the upper part of the lower mold 6B, and a cavity 6C is formed inside thereof. Further, a receiving plate 63 is connected to the back side of the lower die 6B through an extendable actuator 62 so as to be freely opened and closed, and the stripper plate 61 and the ejector plate 65 are connected through an ejector pin 64 penetrating the receiving plate 63. Has been. Further, a plurality of positioning pins 66 (only one is shown in FIG. 8) are incorporated in the lower mold 6B so as to be slidable in the axial direction, and their tips protrude into the cavity 6C. ing. The positioning pin 66 is urged toward the cavity 6 </ b> C by a spring built in the receiving plate 63.

  On the other hand, the upper die 6A is provided with a gate 67 leading to the cavity 6C, and at several locations corresponding to the cavity 6C, a pressing pin 68 (one in FIG. 8) is biased toward the cavity 6C. Only one is shown).

  And according to this example, when manufacturing the planar carbon heater CH for molds configured as described above, the cavity formed in the lower mold 6B with the upper mold 6A and the lower mold 6B first opened. A resistance heating element 43 made of regular carbon having a predetermined linear pattern prepared in advance is placed in 6C. The resistance heating element 43 is positioned at a fixed position by a positioning pin 66 as shown in FIG. 9, and is supported at an intermediate position in the height direction of the cavity 6C in a state parallel to the bottom surface of the cavity 6C. Further, as shown in FIG. 9, lead wires 44 are connected in advance to both ends of the resistance heating element 43 arranged in the cavity 6C by the method shown in FIG. 6 or FIG.

  When the arrangement of the resistance heating element 43 in the cavity 6C is completed, the upper mold 6A and the lower mold 6B are closed, whereby the resistance heating element 43 is moved by the positioning pin 66 and the pressing pin 68 as shown in FIG. It is sandwiched from above and below and is restrained at a fixed position in the cavity 6C.

  Therefore, the ceramic slurry formed with the heat-resistant plate 42 is filled into the cavity 6 </ b> C through the gate 67. The ceramic slurry becomes a cured product having electrical insulation and thermal conductivity when heated, and includes an inorganic adhesive mainly composed of silica or the like (for example, Sumicelam S-17D manufactured by Asahi Chemical Industry Co., Ltd.). ) Can be suitably used. Then, after filling the ceramic slurry, the ceramic slurry is heat-cured (for example, 150 ° C./30 minutes) by energizing a heating wire (not shown) built in both the upper die 6A and the lower die 6B while being closed. As a result, the planar carbon heater CH for molds as described above is obtained.

  After the ceramic slurry is hardened, the upper die 6A and the lower die 6B are opened, and then the lower die 6B and the receiving plate 63 are opened by the telescopic actuator 62, and the positioning pins 66 are removed from the cavity 6C, so that the stripper plate 61 is removed. By pushing up, the completed planar carbon heater CH for mold can be taken out from the cavity 6C. In addition, in the obtained planar carbon heater CH for molds, dents are formed at the positions of the positioning pins 66 and the pressing pins 68. The dents are later filled with the same ceramic slurry as described above. It is blocked.

  Here, when the surface temperature of the mold planar carbon heater CH obtained as described above was energized and its surface temperature was measured, the applied voltage was 100V, 50V, as shown in FIG. It was confirmed that both 30V and 20V have excellent temperature increase rate characteristics.

  Therefore, according to the mold apparatus incorporating the heater unit 4 having the planar carbon heater CH for the mold as a heat source, the molding material (molten material) filled therein is rapidly heated, and there is no weld line. It can be expected to mass-produce high-quality molded products efficiently.

  Although the present invention has been described with reference to the drawings, the resistance heating element 43 made of carbon wire is not limited to the comb-shaped linear pattern as shown in the illustrated example, and can be formed in various linear patterns. For example, in order to form a cylindrical object (thick article), if the outer side of the mold has a curved surface along the cylindrical shape, if a heater along the curved surface is used, Rapid heating can also be performed easily. In addition, the mold apparatus according to the present invention can be configured by incorporating the heater unit 4 using the planar carbon heater CH as a heat source in the movable mold 1 or both the movable mold 1 and the fixed mold 2.

Schematic sectional view showing a mold apparatus according to the present invention The top view which shows the internal structure of the heater unit incorporated in the mold apparatus Side view of the heater unit The top view which shows the internal structure of the planar carbon heater for metal mold | dies which comprise the heater unit XX expanded sectional view of FIG. Explanatory drawing showing connection form of lead wire Explanatory drawing which shows the example of a change of the connection form of a lead wire Sectional drawing which shows an example of the metal mold | die used for manufacture of the planar carbon heater for metal mold | dies Explanatory drawing which shows the state which has arrange | positioned resistance heating element in a cavity Explanatory drawing which shows the state at the time of the filling of the ceramic slurry with respect to the inside of a cavity The graph which shows the temperature increase rate characteristic of the carbon heater of this invention, and the conventional ceramic heater

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable type 13 Core 2 Fixed type 24 Cavity plate 24a Cavity 24b Heat transfer wall 26 Cooling passage 27 Heater accommodating part 3 Product molding part 4 Heater unit 41 Heat-resistant housing CH Planar carbon heater 42 Heat-resistant plate 43 Resistance heating element 43b Split groove 44 Lead wire 44a Connection terminal section 45 Metal terminal 5 Heater moving mechanism 6A Upper mold 6B Lower mold 6C Cavity

Claims (6)

  Inside the flat heat-resistant plate having electrical insulation and thermal conductivity, a resistance heating element comprising a carbon wire having a predetermined linear pattern and extending in a plane in a plane parallel to the plate surface of the heat-resistant plate is provided. A planar carbon heater for a mold, which is embedded without being in contact with an oxidizing atmosphere, and has lead wires conductively connected to both ends of the resistance heating element.   A metal terminal having a U-shaped cross section is attached to both ends of the resistance heating element, and the lead wire is conductively connected to both ends of the resistance heating element via the metal terminal. Item 2. A planar carbon heater for a mold according to Item 1.   Split grooves are formed along the axial direction at both ends of the resistance heating element, and each one end of the lead wire is inserted into the split groove as a flat plate-like connection terminal portion. A planar carbon heater for a mold according to claim 1.   In a cavity formed between a pair of upper and lower molds, a fixed resistance heating element made of a carbon wire having a predetermined linear pattern and developed in a planar shape is disposed, and the resistance heating element is disposed in the cavity. After supporting the cavity in the middle of the cavity in the height direction in parallel with the bottom surface, the pair of upper and lower molds are closed, and the ceramic slurry becomes a cured product having electrical insulation and thermal conductivity by heating in the cavity. Then, the ceramic slurry is heated and cured while the pair of upper and lower molds are closed, and a flat heat-resistant plate embedded in a state where the resistance heating element is not in contact with the oxidizing atmosphere is formed. Manufacturing method of planar carbon heater for mold.   Before arranging the resistance heating element in the cavity, lead wires are connected to both ends thereof, and when the ceramic slurry is filled into the cavity, the connecting portion of the lead wire is also covered with the ceramic slurry. The method for producing a planar carbon heater for a mold according to claim 4, wherein:   It is a mold apparatus provided with the heater unit which uses the planar carbon heater for metal mold | dies in any one of Claims 1-3 as a heat source, A refrigerant | coolant is provided to at least one of a movable mold | type and a fixed mold | type corresponding to this movable mold | type. A cooling passage for circulation and a heater accommodating portion for accommodating the heater unit are provided, and the heater accommodating portion is fixed to the movable type and fixed with a heat conductive heat transfer wall heated by the heater unit interposed therebetween. The heater unit is located at a position facing the product forming part formed between the molds, and the heater unit is connected to a heater moving mechanism and is in contact with the heat transfer wall and a position separated from the heat transfer wall. A mold apparatus characterized by being movable.

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