JP2016040081A - Electromagnetic induction heating type mold device for molding and vulcanizing rubber packing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold device for molding and vulcanizing a rubber packing by which a high-quality packing product can be produced with high productivity without causing heat deformation of a mold body or the molding and vulcanizing apparatuses while achieving energy saving.SOLUTION: A mold device for molding and vulcanizing a rubber packing is composed of: a magnetic metal layer constituting a mold body and also a mold cavity surface, and comprising a nickel alloy or an iron alloy; a mold support layer which is a nonmagnetic or feeble magnetic insulator layer disposed opposite the mold cavity surface of the magnetic metal layer and supports the mold body; and an electromagnetic induction coil disposed in the mold support layer. The device is configured so as to heat the mold body directly and transmit a molding pressure to the mold body via the mold support layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a mold apparatus for molding / vulcanizing rubber packing, and more particularly to an electromagnetic induction heating mold apparatus for molding / vulcanizing rubber packing.

  The rubber packing is manufactured by heating and vulcanizing a rubber molded body having a predetermined cross-sectional shape. Whether the rubber packing is prepared by separately preparing a molding apparatus and a vulcanizing apparatus and performing each process separately. Alternatively, it is produced by performing molding and vulcanization simultaneously or continuously. From the viewpoint of productivity, it is excellent to perform vulcanization using the same mold apparatus at the same time as molding or subsequently.

  By the way, a rubber packing molding die apparatus that performs molding and vulcanization with the same die is composed of a die and a hot plate provided on the back surface thereof, and heats the die by heat from the hot plate. Molding and vulcanization. However, if it is used for a long time at the vulcanization temperature (150 to 210 ° C.), it will be affected by the hot plate, and the middle part of the mold will be deformed to medium-high, that is, the center part will be worn away, and the temperature distribution in the mold will be This will cause defective mold temperature rise and product quality problems. Furthermore, the parallelism of the hot plate on the back side of the mold is also distorted, and the mold deformation due to non-uniformity in the transmission of molding pressure will not be performed uniformly, which requires correction by polishing the hot plate. .

  Further, conventionally, the heating means of the hot plate is generally a cartridge type electric heater or steam, but they are inefficient in heating the mold and require a large amount of power and time. Furthermore, it takes time to preheat the mold, which impedes the productivity of rubber packing molding.

  Non-Patent Document 1 discloses a hot plate heating method used as a general method of rubber packing molding, but the mold used for a long time for molding and vulcanization is in the state of the hot plate (parallelism, wear). Is influenced by.

FIG. 5 is a schematic diagram of a rubber packing molding die apparatus described in Non-Patent Document 1, in which a hot plate 42 is disposed on the upper and lower surfaces of a mold 40 which is schematically shown by integrating an upper mold and a lower mold. In addition, a heating temperature for the mold 40 is secured by a heater 44 (shown schematically by a broken line) incorporated therein. Each hot plate 42 is supported by a fixed platen 50 from above and a movable platen 52 from below via a heat insulating material 46, and at the time of molding, a required molding pressure is applied via a piston 54 from below. .
In the case of compression molding such as rubber packing molding, there are many plate-shaped molds whose dimensions in the thickness direction are small with respect to the projection surface, so that they are easily affected by the heat plate 42. For example, in order to heat transfer and heat the mold 40, when pressurizing between the upper mold and the lower mold with a hot plate 42 heated to the vulcanization temperature, the outer periphery of the mold is fixed by the applied pressure. If so, the thermal expansion of the mold 40 is constrained, so that a thermal stress is generated. The influence of the thermal stress is directed toward the inside of the mold and expands in the thickness direction, so that the central portion is curved.

  In FIG. 5, the white arrow indicates the direction of heat dissipation in the direction of the arrow, and also indicates the amount of heat dissipation by the thickness of the arrow. Is cooled to a low temperature. There is also an influence due to the position of the heater 44 serving as a heat source of the hot plate 42, and the difference in thermal expansion from this outer peripheral part is involved in the mold deformation. In this way, if the mold is deformed and the contact between the mold and the hot plate becomes insufficient, the thermal conductivity changes, and the temperature distribution in the mold changes, resulting in a misalignment in the parallelism of the hot plate. become.

  Furthermore, in mold vulcanization in the molding of rubber packing, rubber is heated and vulcanized by heat transfer from a mold. However, since rubber has a low thermal conductivity, it takes time to raise the temperature, and as a result, a long vulcanization time is required.

  By the way, it is known to employ electromagnetic induction heating as a heating means for a resin molding die, and in Patent Document 1, an electromagnetic induction coil is temporarily disposed in a cavity for heating a resin molding die. A heating method is disclosed.

  Patent Document 2 discloses an electromagnetic induction heating mold apparatus for molding a general resin, and according to this, a cavity surface is directly formed in an induction coil holding portion in which an electromagnetic induction coil is embedded. The magnetic metal part is joined. The idea of using electromagnetic induction heating as the heating means is the same as in Patent Document 1, but in Patent Document 2, the heating means is incorporated in direct contact with the mold.

  Patent Document 3 discloses a mold apparatus used for rubber vulcanization, which is a mold apparatus for heat vulcanization for heating and vulcanizing a preformed raw rubber, and a cavity that comes into contact with a green tire. The surface is made of aluminum or the like having a low magnetic permeability and excellent thermal conductivity.

“Troubles and Countermeasures in Molding”, Journal of Rubber Association, Vol. 82, No. 7 (2009) "Temperature examination in rubber injection molding machine" Toyoda Gosei Technical Report, 2001, Vo. 43, no. 1

JP-A-8-39571 JP 2012-2104040 A JP2012-25126A

  FIG. 1 is a graph showing the result of simulation calculation of the relationship between the filling material temperature in the mold and the vulcanization time of the product wall surface portion and the center portion, which is disclosed in Non-Patent Document 2.

  From FIG. 1 it can be seen that the mold must be heated to a certain temperature in order for vulcanization to occur simultaneously in the product surface and in the product center. In the figure, it is shown as acceleration time. However, when the heating temperature is too high, the heating rate is also increased. Therefore, the vulcanization proceeds excessively before the molding is completed, and the deterioration of the mechanical characteristics is inevitable.

  That is, from FIG. 1, if high temperature rubber can be filled in the mold, the time required for temperature rise of the rubber can be shortened, and further, the higher the vulcanization temperature, the higher the vulcanization speed. Can be seen to be shorter. However, the higher the vulcanization temperature, the more the surface part in contact with the mold is overcured, the inside is still not at the vulcanization temperature. The far part) remains porous, and in extreme cases, the rubber may not flow sufficiently inside the mold. The deterioration of the mechanical properties of the resulting rubber molded product is inevitable. In addition, there is a concern about problems such as so-called burning, in which the rubber surface is vulcanized early.

  Based on the above, measures to shorten the vulcanization time are as follows: (1) Use a flat vulcanized rubber that has a high vulcanization speed and a small difference in physical properties between the optimal vulcanized state and the overvulcanized state. (2) It is generally considered to use rubber having a fast vulcanization at the center, and (3) to preheat the mold to a temperature that does not scorch the rubber (initial vulcanization).

  Thus, the prior art does not disclose that electromagnetic induction heating is performed when molding and vulcanization are performed in the same mold in the production of rubber packing. Even when the induction heating method is employed as a mere heating means for resin molding shown in Patent Documents 1 and 2, no consideration has been given from the viewpoint of how to increase production efficiency.

  Moreover, there has been no known configuration for improving productivity when electromagnetic induction heating means is used as heating means in the two manufacturing stages of molding and vulcanization.

  In the above-mentioned Patent Document 3, an electromagnetic induction heating method is adopted as a heating means for vulcanization, but this is a vulcanization of a rubber product such as an automobile tire that has a very large cross-sectional thickness and varies greatly depending on the part. Therefore, the pressurized steam is used in combination, and the mold portion that comes into contact with the tire is made of a material having low thermal conductivity such as aluminum or copper and having excellent thermal conductivity.

  The present invention is intended to solve the above-described problems, and eliminates heat deformation of the mold body and the mold apparatus, thereby saving energy, and capable of manufacturing a high-quality product with high productivity. An object of the present invention is to provide an induction heating mold apparatus for use.

  Here, according to the present invention, the deformation prevention of the mold can be solved by heating the cavity surface uniformly and quickly by using the mold body as a heating element, while the deformation of the entire mold apparatus is achieved. Prevention can be solved by partitioning the mold and the induction coil unit constituting the heating element with an insulator layer and thermally insulating the induction coil unit with the insulator layer.

  From the viewpoint of manufacturing rubber packing, energy saving and high productivity can be achieved by using electromagnetic induction heating means, ensuring a molding temperature with short heating, and enabling vulcanization in a short time. Since the mold body constitutes a heating element, and because electromagnetic induction heating is used, the entire mold is heated uniformly in a short time, so that the flow during molding of the input rubber is sufficient. Since it can be secured and only a short vulcanization time is required, quality degradation is not significant.

  In the case of rubber packing, the upper and lower molds each have a thickness of several tens of millimeters at most, and most of them are usually 30 mm or less. Further, in the case of electromagnetic induction heating, the so-called heating depth can be changed by changing the frequency of electromagnetic waves. Therefore, according to the present invention, even when the mold is developed flat like a rubber packing molding mold, the whole can be rapidly and uniformly heated efficiently.

  Furthermore, according to the present invention, the mold body can be supported by the insulator layer, and the heat-insulating protection of the induction heater unit, that is, the induction coil unit, can be performed. By transmitting from the mold to the mold, the mold that constitutes the electromagnetic induction heating element and the induction heater unit can be completely thermally and mechanically isolated.・ Mechanical deformation can be largely prevented.

  In the present invention, in order to efficiently realize electromagnetic induction by the induction coil in the mold body, the insulator is made of a nonmagnetic material or a weak magnetic material.

  That is, the present invention constitutes a mold body and a magnetic metal layer made of nickel alloy or iron alloy constituting a mold cavity surface, and is disposed on the opposite side of the mold cavity surface of the magnetic metal layer. A non-magnetic material or a weak magnetic insulator layer, the mold support layer configured to support the mold body, and an electromagnetic induction coil embedded in the mold support layer. An electromagnetic induction heating mold apparatus for rubber packing molding and vulcanization, wherein molding pressure is transmitted to a mold body through a layer.

  According to the present invention, in the case of manufacturing rubber packing, only the mold body, which is a magnetic metal layer, is directly heated by electromagnetic induction, so that it is possible to shorten the mold heating time, vulcanization time and power consumption. Thus, total productivity improvement and energy saving can be realized. Furthermore, by installing the induction coil unit in the insulator layer having low heat conduction, it is possible to reduce the thermal deformation of the mold and the molding machine, and to improve the yield by stable molding.

FIG. 1 is a graph showing the relationship between the temperature of the central portion and the temperature of the surface portion of a solid rubber product that is a filling material in a mold. FIG. 2 is a schematic cross-sectional view of a rubber packing molding / vulcanizing mold apparatus according to the present invention. FIG. 3 is a schematic cross-sectional view showing another aspect of the mold apparatus according to the present invention. FIG. 4 is a graph showing the relationship between the heating time and the heating temperature when performing vulcanization by the step method using the mold apparatus according to the present invention. FIG. 5 is a schematic explanatory view of a conventional molding / vulcanizing mold apparatus.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic explanatory view showing a configuration example of an electromagnetic induction heating mold apparatus for rubber packing molding / vulcanization (sometimes simply referred to as a molding / vulcanizing apparatus in the present specification) according to the present invention.

  A molding / vulcanizing apparatus 1 according to the present invention comprises a mold body 2 and a magnetic metal layer 4 made of a nickel alloy or an iron alloy constituting a mold cavity surface 3, and the magnetic metal layer 4. A non-magnetic material or weak magnetic insulator layer 5 disposed on the opposite side of the mold cavity surface 3, and a mold support layer 6 that supports the mold body, and is disposed in the mold support layer. And an electromagnetic induction coil 7.

  That is, the mold bodies 2 and 2 provided on the fixed side and the movable side are supported by the insulator layers 5 and 5 provided on the fixed side and the movable side, respectively. These insulator layers constitute a kind of casing, and the induction coils 7 and 7 protected by the induction coil cover 8 are arranged inside thereof. Although the induction coils 7 and 7 may be embedded in the insulator layer, in the illustrated example, the induction heating coil unit is detachably provided in the housing, so that maintenance and inspection are easy.

  The mold body and the insulator layer thus arranged are respectively supported by the fixed platen 11 and the movable platen 12 via the mounting plates 10 on the movable side and the fixed side, respectively. It is pressed by a piston that does not perform molding and vulcanization.

  Here, according to the electromagnetic induction heating mold apparatus for rubber packing molding and vulcanization according to the present invention, the mold body constituting the mold cavity surface and the mold cavity surface are arranged on the opposite side of the mold cavity surface and By forming a mold support that supports the mold body and an electromagnetic induction coil disposed in the mold support layer, the molding pressure can be transmitted to the mold body via the mold support. Therefore, the configuration of the entire mold apparatus is simplified and the operation becomes easy. In particular, the molding of a product having a shape like a rubber packing is advantageous in that uniform and rapid heating can be performed on the entire product.

  In the illustrated embodiment, the molds 2 and 2 are supported between the fixed platen 11 and the movable platen 12 via the upper and lower insulator layers 5 and 5. Since the opposite sides are supported by the platens 11 and 12, respectively, the pressure required for molding the mold is transmitted from the platens 11 and 12 to the molds 2 and 2 through the insulator layers 5 and 5, respectively. The structure of the mold device is simplified. Inside the insulator layers 5 and 5, electromagnetic induction coils 7 and 7 are detachably accommodated, and the mold body provided so as to be sandwiched between them is quickly heated to the vulcanization temperature. Demonstrate.

  In the illustrated example, the rubber packing has a ring shape with a circular cross section, but the cross sectional shape may be a rectangle or may be a flat plate as a whole. A common shape characteristic of rubber packing molding and vulcanization molds is that the thickness is very small in the plane direction, but as a characteristic of electromagnetic induction heating, the mold surface as a boundary surface, especially the cavity surface Therefore, the entire rubber packing, which is a molded product, is heated rapidly and uniformly, and the temperature control of vulcanization can be precisely and accurately performed. In this respect, the rubber packing targeted by the present invention can make full use of the characteristics of electromagnetic induction heating, as compared with a molded product that is thick or has a thickness change locally.

  In particular, in the case of the present invention, preferably, the insulator layer is composed of a box-shaped member that constitutes a casing that accommodates the induction heating unit, so that stable heating and heat insulation are possible.

  The material constituting the mold body is a magnetic metal, that is, a magnetic metal, and is not particularly limited as long as the mold cavity surface can be formed, but is preferably selected from a nickel alloy and an iron alloy. Examples of nickel alloys include permalloy and Ni-base super heat-resistant alloys. Examples of iron alloys include general structural rolled steel, mechanical structural carbon steel, structural alloy steel, carbon tool steel, bearing steel, and stainless steel. Illustrated.

  The insulator layer is composed of a non-magnetic material or a weak magnetic insulator. Examples of the insulator include a ceramic material such as a fine ceramic material, a super plastic such as a fluororesin (PTTE resin), a phenol resin, and an epoxy resin. The insulating material layer is selected from an engineering material and a glass material, and the insulator layer is mechanically or metallurgically bonded to the mold body. This insulator layer is required to have high rigidity against compression at high temperatures, and is preferably made of ceramics. Specifically, various ceramic materials such as oxide, carbide and nitride are exemplified.

  The rubber packing molding and vulcanizing apparatus according to the present invention comprises these two or more composite layers, and a product is molded on the surface of the magnetic metal layer.

  Note that explosive pressure bonding, diffusion bonding, brazing, or the like may be used as a metallurgical bonding method between the magnetic metal layer and the insulator layer.

  According to the present invention, a heater for electromagnetic induction heating may be installed in an insulator layer in a mold, and may be configured to have an independent structure as an induction heating unit. By exchanging only the layer, that is, the mold body, it is possible to easily convert to a different product type. In that case, the mold base layer and the insulator layer may be bonded to each other by appropriate mechanical means such as bolt fastening so as to be detachable.

  Thus, according to the present invention, by selecting a material having low thermal conductivity for the insulator layer, it is difficult to be affected by heat on the heated magnetic metal layer.

  FIG. 3 shows a further aspect of the present invention. The mold apparatus comprising the mold body, the mold support layer, and the electromagnetic induction coil provided on the mold body shown in FIG. 2 is treated as one unit. A plurality of units are installed at predetermined positions on one box plate 14, for example, a grid shape, a staggered shape, or a concentric shape. The example of illustration shows typically the example of a structure of one unit arranged in that way. The same members as those in FIG. 2 are denoted by the same reference numerals.

The member 16 that connects the upper and lower box plates 14 is a guide pin.
According to the present invention, by using an insulator layer, if an aluminum alloy or a titanium alloy is further used as a mounting plate and a box plate, the weight of the entire mold apparatus can be reduced, and at the same time, due to the heat shielding effect by the insulator. The molding press temperature can be lowered, and the press accuracy can be continuously maintained.

  Here, the heating itself by the electromagnetic induction heating method is not particularly limited as described in Patent Documents 1 and 2 described above, but desirably, it can be freely attached and detached by using it as a heater unit. Thus, maintenance and inspection can be facilitated, and the thermal insulation protection by the above-described insulator layer can be more effectively exhibited.

  As a feature of heating by the electromagnetic induction heating method, rapid heating and further adjustment of the heating depth can be easily performed by selecting the frequency, and furthermore, heating start and heating stop can be switched instantaneously, The effect can be exerted particularly in the molding vulcanization of the rubber packing, particularly in the step vulcanization as described later.

  Next, the mold apparatus by the electromagnetic induction heating method according to the present invention is particularly suitable for performing molding and vulcanization by the step method as described below. In this specification, it is referred to as “molding and vulcanization of rubber packing by the step vulcanization method”.

  That is, in another aspect, the present invention includes a step of initially heating a mold body (hereinafter sometimes simply referred to as “mold”) by electromagnetic induction heating method, and a rubber as a mold filling material is molded into a mold. At the same time, the mold is heated to a predetermined molding temperature by electromagnetic induction heating and molded. At this stage, the initial rubber is started, and then when the molding is finished, Steps to further increase the temperature by electromagnetic induction heating, steps to reach a predetermined temperature, maintain the temperature and complete vulcanization in the mold, and take out the molded / vulcanized product from the mold This is a method of molding and vulcanizing rubber packing consisting of stages.

  By performing the initial heating of the mold and heating at the molding stage by electromagnetic induction, it is possible to quickly heat, and the heating time for completing the vulcanization can be significantly reduced unexpectedly. The production efficiency of rubber packing is greatly improved.

  Molding and vulcanization of the rubber packing by the step vulcanization method using the molding and vulcanizing apparatus according to the present invention is performed in the relationship of temperature and time schematically shown in FIG. It is as follows.

(I) First stage heating In this stage, the mold is initially heated, and the mold is preliminarily heated at high speed by electromagnetic induction heating. In FIG. 4, this is the stage indicated as “heating time”. The time required for mold heating can be greatly shortened, and work efficiency and energy saving can be realized.

(Ii) First-stage mold vulcanization The rubber is put into the mold heated to the above-mentioned predetermined temperature and molded and vulcanized. FIG. 5 is a short flat stage following the “heating time” on the graph shown in FIG. 4. At this stage, molding is almost completed and vulcanization starts.

  At the stage (scorch time) in which rubber is poured into the mold, the vulcanization conditions (temperature and time) are set so as not to cause defects such as burning. Specifically, the temperature and time at which molding and vulcanization are preferably performed at the same time, that is, without time difference, are preferably set at the center and the surface of the rubber product.

  In the examples described later, the heating temperature for the first stage heating was set to 160 ° C., and the vulcanization time for the first stage type vulcanization was set to 10 seconds.

(Iii) Second stage heating Further, in order to complete vulcanization, the mold temperature is increased at high speed by electromagnetic induction heating. On the graph shown in FIG. 4, the “vulcanization time” is a temperature raising stage following the flat stage in a certain stage.
In the examples described later, the temperature raising time was 20 seconds.

(Iv) Second-stage vulcanization The vulcanization conditions for satisfying the characteristics of the rubber product are set.
In the examples described later, the vulcanization temperature at this time was 200 ° C., and the vulcanization time was 2 minutes. It is a flat stage on the graph following the above-mentioned second stage heating in FIG.

  In the rubber molding by the step molding / vulcanization method according to the present invention, the first stage, the second stage, and the heating and vulcanization are performed separately. Can be made significantly shorter than expected.

The rubber packing product molded and vulcanized under such vulcanization conditions satisfied the sealing performance.
In conventional heat transfer heating, the temperature rise time becomes long, and burning and insufficient mechanical properties occur. However, by using electromagnetic induction heating, the vulcanization temperature can be controlled in two steps (step vulcanization), and the vulcanization time can be shortened.

  Next, the operation of the present invention will be described more specifically with reference to examples.

Example In this example, a rubber packing molding / vulcanizing mold apparatus having the structure shown in FIG. 2 was used, and according to FIG. 4, the rubber packing was molded / stepped by electromagnetic induction heating under the following conditions. Vulcanization was performed.

(I) First stage heating The initial mold heating temperature was set to 160 ° C.

(Ii) First-stage vulcanization After the temperature rise, the rubber was put into a mold for molding, and at the same time, the vulcanization time was set to 10 seconds.

(Iii) Second stage heating Thereafter, the vulcanization temperature is raised to 200 ° C. The temperature raising time was about 20 seconds.

(Iii) Second-stage vulcanization After the temperature increase, the vulcanization time was set to 2 minutes.

  The total vulcanization time under the above vulcanization conditions was 2 minutes 30 seconds. In the prior art using the apparatus shown in FIG. 5, since the vulcanization time was 8 minutes, it can be seen that according to the present invention, a significant reduction of 5 minutes 30 seconds can be achieved. A significant improvement in productivity can be realized by using the molding vulcanizing apparatus according to the present invention.

  Rubber products molded under such vulcanization conditions have mechanical properties necessary for improving sealing performance such as (i) compression set, (ii) hardness, (iii) tensile strength, (iv) elongation, etc. Satisfied, the sealing performance was satisfactory.

On the other hand, when such step vulcanization is performed by the electrothermal heating method using the apparatus shown in FIG.
(1) It takes a long time to raise the temperature from 160 ° C. to 200 ° C., and the vulcanization time cannot be shortened.
(2) The vulcanization time at a high temperature becomes longer, resulting in burning and insufficient mechanical properties.

  In the present invention, since the vulcanization temperature is controlled in two stages and the heating is performed by induction heating, even if the vulcanization time is shortened, no deterioration in mechanical properties occurs.

DESCRIPTION OF SYMBOLS 1 Electromagnetic induction heating type die apparatus for rubber packing molding and vulcanization 2 Mold body 3 Mold cavity surface 4 Magnetic metal layer 5 Insulator layer 6 Mold support layer 7 Induction coil 10 Mounting plate 11 Fixed platen 12 Movable side Platen

Claims (3)

  A mold body constituting a mold cavity surface, a mold support disposed on the opposite side of the mold cavity surface to support the mold body, and an electromagnetic induction coil disposed in the mold support layer The mold body is composed of a magnetic metal layer made of nickel alloy or iron alloy, the mold support is composed of a nonmagnetic material or a weak magnetic insulator layer, and the mold body is directly An electromagnetic induction heating mold apparatus for rubber packing molding and vulcanization characterized by heating and transmitting a molding pressure to the mold body through the mold support.   2. The rubber packing molding / heating of claim 1, wherein the magnetic metal layer is one selected from general structural rolled steel, mechanical structural carbon steel, structural alloy steel, carbon tool steel, bearing steel, and stainless steel. Electromagnetic induction heating mold equipment for sulfur. The electromagnetic induction heating mold for rubber packing molding and vulcanization according to claim 1 or 2, wherein the insulator layer is composed of one kind selected from a super engineering plastic material, a ceramic material, and a glass material. apparatus.

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