JP2009023192A - Mounting structure of heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniform heating characteristics by a mica heater. <P>SOLUTION: The plate type mica heater 2 having a mounting screw hole is mounted to a metallic mold 1 as a heated target by a screw 13 while a metal-made dispersion plate 5 for dispersing heat is interposed therebetween, and the heat from the mica heater 2 is dispersed by the dispersion plate 5 having excellent heat conductivity, and the metallic mold 1 is uniformly heated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heater mounting structure, and more particularly to a plate-type mica heater mounting structure.

  Conventionally, as a temperature control method for reducing interference between control points when controlling a temperature of a controlled object such as a mold at multiple points, a plurality of detected temperatures corresponding to a plurality of control points are There is a method (hereinafter also referred to as “gradient temperature control”) that converts the average temperature into a temperature difference (gradient temperature) based on a plurality of detected temperatures and controls the average temperature and the gradient temperature as control amounts (hereinafter also referred to as “gradient temperature control”). Patent Document 1).

  FIG. 6 is a configuration diagram when the gradient temperature control method is applied to two-channel temperature control.

  The detected temperatures at the two control points of the controlled object 30 are converted by the mode converter 31 into an average temperature that is an average value of both detected temperatures and a gradient temperature that is a temperature difference between the detected temperatures, and the average temperature and the target average temperature. Or a deviation between the gradient temperature and the target gradient temperature is input to each PID control unit 32.

  Each PID control unit 32 calculates and outputs an operation amount so as to eliminate an average temperature deviation or a gradient temperature deviation. In the precompensator 33, only the gradient temperature reacts to a change in the gradient temperature manipulated variable. The control output is distributed to control the output so that the response to the average temperature is small, and conversely, the response to the gradient temperature is small with respect to the change in the control amount of the average temperature. The temperature of the controlled object 30 is controlled.

  Conventionally, in order to control each of the two points to be controlled individually, the control of one point has an effect on the control of the other point, making it difficult to control with high accuracy. In the gradient temperature control, high-precision control is enabled by controlling the average temperature at two points and the gradient temperature, which is the temperature difference between the two points, as control amounts.

Such tilt temperature control reduces interference and enables uniform temperature control. For example, when molding precision parts such as optical lens parts, if the mold temperature is controlled at multiple points, If the heating characteristics of the plurality of heaters for heating the mold are not uniform, it is difficult to make the mold temperature sufficiently uniform, especially in the molding of small precision parts. .
Japanese Patent No. 3278807

  Conventionally, a relatively inexpensive mica heater has been used as a plate heater for heating a mold.

  For example, as shown in FIG. 7A, the mica heater winds a heating wire 7 made of nichrome wire or the like around a plate-like core member 6 formed of mica, and as shown in FIG. The upper and lower surfaces are sandwiched between mica 8 and 9 and incorporated in a metal case 10.

  In such a mica heater, for example, screw holes are formed to be attached to a mold to be heated with screws, but as shown in FIG. 8, for example, a core material in which screw holes 12 are formed in two places. 6. It is not easy to uniformly wind the heating wire 7 while avoiding the screw holes 12, and it is particularly difficult with a small heater having a size of about 5 cm. Thus, if the winding of the heating wire 7 becomes non-uniform on the left and right, the heating characteristics of the mica heater become non-uniform due to this.

  As shown in FIG. 9, the mica heater in which the screw holes 12 are formed is attached to the left and right central positions of the upper surface of the mold 1 with screws 13 to heat the mold 1, and an image of the thermography at that time is As shown in FIG.

  10A is a thermographic image showing the temperature distribution in front of the mold 1, and FIG. 10B shows the same temperature zone (isothermal zone) of the image in black.

  As shown in FIG. 10, it can be seen that the center of the upper portion where the mica heater is attached has a high temperature, and the isothermal zone spreads semicircularly downward from the center.

  As shown in FIG. 9, the mica heater is attached at the center position of the upper side of the mold. Compared to the left and right of the isothermal zone displayed in black in FIG. 10B, the upper end of the right isothermal zone. In the section, different temperature zones are widely present on the right side, whereas almost no different temperature zones exist in the upper end portion of the left isothermal zone.

  As described above, in the mica heater, there is a problem that the heating characteristics become non-uniform due to non-uniform winding of the heating wire 7 and the temperature distribution of the mold 1 to be heated becomes non-uniform.

  The present invention has been made in view of the above-described points, and an object thereof is to make uniform the heating characteristics of the mica heater.

  (1) The heater mounting structure of the present invention is a structure in which a plate-type mica heater in which mounting holes are formed is attached to a heating target, and heat is diffused between the mica heater and the heating target. A metal diffusion plate is interposed.

  According to the heater mounting structure of the present invention, a metal diffusion plate is interposed between the plate-type mica heater and the object to be heated, so even if the heat generation of the mica heater is non-uniform, heat is diffused by the diffusion plate. And heating uniformly.

   (2) In one embodiment of the heater mounting structure of the present invention, the diffusion plate is made of any one of stainless steel, copper, aluminum, silver, or alloys thereof.

  The diffusion plate is preferably made of a metal material having high thermal conductivity, such as stainless steel, copper, aluminum, silver, or alloys thereof, such as beryllium copper or brass.

  According to this embodiment, since the diffusion plate is made of a metal having high thermal conductivity such as stainless steel, copper, aluminum, silver and alloys thereof, the heat generated from the mica heater is efficiently diffused, and the heating target is made uniform. Can be heated.

   (3) In another embodiment of the heater mounting structure of the present invention, the mica heater has a heater body in which a heating wire is wound around a core material made of mica having the hole so as not to block the hole. I have.

  According to this embodiment, even when the winding of the heating wire around the core material is non-uniform and the heat generation of the mica heater becomes non-uniform, heat can be uniformly diffused by the diffusion plate.

   (4) In still another embodiment of the heater mounting structure of the present invention, the object to be heated is a mold, and the mounting holes are screw holes, and a plurality of holes are formed.

  According to this embodiment, the plate-type mica heater can be easily attached to and removed from the mold with the screws.

   (5) In the embodiment of the above (4), a plurality of the mica heaters are attached to the side surface of the mold.

  According to this embodiment, a plurality of mica heaters can be attached to the mold and applied to multipoint temperature control.

  According to the present invention, since the metal diffusion plate is interposed between the plate-type mica heater and the object to be heated, even if the heat generation of the mica heater is not uniform, the heat is diffused by the diffusion plate, and the object to be heated Can be heated uniformly.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a temperature control system including a heater mounting structure according to one embodiment of the present invention.

  The temperature control system includes a mold 1 as a control target, a heater 2 that heats the mold 1, and a temperature regulator 3 that controls energization of the heater 2 to control the temperature of the mold 1. ing.

The mold 1 of this embodiment is, for example, a mold on the fixed side or movable side of an injection molding machine.
FIG. 2 is a front view showing the arrangement of the mold 1 and the heater 2 of FIG. A concave portion (not shown) for forming a cavity is formed on the surface of the mold 1, but is omitted in FIG. 2.

In the vicinity of the surface of the mold 1, eight temperature sensors 4 a to 4 h that respectively detect the temperatures of the eight control points A to H are arranged along the same circumference from the center of the mold 1. ing.
Nine plate heaters 2-1, 2-2a, 2-2b, 2-3, 2-4a, 2-4b, 2-5, 2-in total, three on each side of the mold 1 respectively. 6a, 2-6b, 2-7, 2-8a, 2-8b are respectively attached via metal diffusion plates 5 described later.

  Nine heaters 2-1, 2-2 a, 2-2 b, 2-3, 2-4 a, 2-4 b, 2-2 attached to each side surface of a square mold 1 having a side of about 20 cm, for example. 5, 2-6a, 2-6b, 2-7, 2-8a and 2-8b, heaters 2-2a and 2-2b at four corners of a square; 2-4a and 2-4b; 6a, 2-6b; 2-8a, 2-8b are two heaters 2-2a, 2-2b; 2-4a, 2-4b; 2-6a, 2-6b; 2-8a, 2-8b, respectively. The heaters 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8 controlled individually are temperature sensors 4a to 4h. In this embodiment, eight channels of temperature control are performed.

  The temperature controller 3 in FIG. 1 includes eight heaters 2-1, 2-2, 8 via SSR (not shown) based on the detected temperatures of the temperature sensors 4 a to 4 h at the control points A to H. The energization of 2-3, 2-4, 2-5, 2-6, 2-7, 2-8 is controlled.

  The temperature controller 3 of this embodiment does not individually control the temperature for each channel, but uses the temperature control method disclosed in the above-mentioned Patent Document 1 or the like.

  As described above, this temperature control method converts a plurality of detected temperatures corresponding to a plurality of control points into, for example, an average temperature of a plurality of detected temperatures and a temperature difference (gradient temperature) based on the plurality of detected temperatures. The temperature is controlled using the average temperature and the gradient temperature as control amounts.

  FIG. 3 is a block diagram showing the configuration of the gradient temperature control in the temperature controller 3 of this embodiment.

  The temperature controller 3 of this embodiment converts the input temperatures PV1 to PV8 from the eight temperature sensors 4a to 4h into one average temperature (average PV) and seven gradient temperatures (gradient PV1 to gradient PV7). The operation amount is calculated based on the mode converter 14 and the deviation between each temperature (average PV, slope PV1 to slope PV7) from the mode converter 14 and the target temperature (average SP, slope SP1 to slope SP7). The eight PID control units 15 and the operation amount from each PID control unit 15 are distributed so that the influence of the control by each PID control unit 15 on the control by the other PID control unit 15 is eliminated or reduced. And a pre-compensation unit 16 that provides control outputs MV1 to MV8 to the heaters 4 to 11, respectively.

  The mode conversion unit 14 converts the eight input temperatures PV1 to PV8 into an average temperature (average PV) that is an average value thereof and, for example, a temperature difference (PV1-PV2, PV2-PV3, PV3-PV4) between adjacent input temperatures. ,..., PV7-PV8) are converted into seven gradient temperatures (gradient PV1 to gradient PV7).

  Note that the gradient temperature is not limited to the temperature difference with the adjacent input temperature. For example, the temperature difference between the average temperature (average PV) and each input temperature (PV1-average PV, PV2-average PV, PV3-average). PV, ... PV7-average PV). Thus, by using the temperature difference between each input temperature and the average temperature as the gradient temperature, it becomes possible to control the temperature of the symmetrical mold more evenly.

  For the target temperature SP, the difference between the target average temperature (average SP), which is the average value of the set temperatures (target temperatures) SP1 to SP8 of the eight control points A to H, for example, the adjacent set temperature (SP1- SP2, SP2-SP3, SP3-SP4,... SP7-SP8) are set as seven target gradient temperatures (gradient SP1 to gradient SP7).

  Each PID control unit 15 performs a PID calculation so as to eliminate a deviation between the input temperature PV and the target temperature SP, and outputs an operation amount.

  The pre-compensation unit 16 decomposes the operation amount from the PID control unit 15 and has the same configuration as the configuration disclosed in Patent Document 1 and the like, and the distribution ratio matrix of the pre-compensation unit 16 Gc is the pre-compensation matrix, and the mode conversion matrix Gm is a matrix for converting the detected temperatures (PV1 to PV8) by the above-described mode converter 14 into gradient temperatures (gradients PV1 to PV7) and average temperatures (average PV). If the interference matrix, which is information indicating the degree of interference, is Gp, the pre-compensation matrix Gc can be obtained as an inverse matrix as follows.

Gc = (Gm · Gp) ⁻¹
When each of the eight control points A to H is individually controlled, a certain control point influences another control point, that is, it is difficult to perform high-precision temperature control due to interference. In the temperature control, the average temperature and the gradient temperature based on the detected temperatures at the eight control points A to H are controlled as control amounts, so that highly accurate temperature control with reduced influence of interference becomes possible.

  The heaters 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8 in this embodiment are plate-type plates having the same configuration as that shown in FIG. Because it is a mica heater and the heating wire is wound while avoiding the screw holes for mounting, the winding of the heating wire is uneven on the left and right, and this causes heat generation to be uneven on the left and right. There are challenges.

  Therefore, in this embodiment, as shown in FIG. 2, each of the heaters 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, and gold A metal diffusing plate 5 that diffuses heat is interposed between the mold 1 and the mold 1 and is attached by screws (not shown).

  The diffusion plate 5 is made of, for example, stainless steel, and the heating surface of each heater 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8. And substantially the same area. The length of one side of the diffusion plate 5 is, for example, about 5 cm, and the thickness is, for example, about 2 cm.

  FIG. 5 shows an image of thermography in which the mica heater 2 is attached to the upper side surface of the mold 1 with the screw 13 and the mold 1 is heated as shown in FIG.

  FIG. 5 (a) is a thermographic image showing the temperature distribution in front of the mold, and FIG. 5 (b) shows the same temperature zone (isothermal zone) in black. It is a figure corresponding to an example.

  In the conventional example of FIG. 10B described above, the temperature distribution is biased to the left, as is apparent when comparing the left and right of the isothermal zone.

  On the other hand, in the embodiment in which the diffusion plate 5 is interposed, the right or left side of the upper end portion of the right isothermal zone is compared when the left and right of the isothermal zone displayed in black in FIG. It can be seen that there are almost no different temperature zones on the left side of the upper end of the temperate zone, and the left and right are heated uniformly.

  As described above, heat is diffused by the diffusion plate 5 so that the mold 1 can be heated uniformly, and the temperature of the mold 1 can be made uniform in combination with the gradient temperature control.

  In the above-described embodiment, the present invention is applied to the gradient temperature control. However, the present invention is not limited to the gradient temperature control, but can be applied to normal temperature control.

  The present invention is useful for multipoint temperature control and the like.

It is a schematic structure figure of a system provided with the attachment structure concerning one embodiment of the present invention. It is a front view which shows the metal mold | die and heater of FIG. It is a block diagram of the principal part of the temperature controller of FIG. It is a front view which shows the attachment state of the heater and diffusion plate with respect to a metal mold | die. It is a thermographic image which shows the temperature distribution of the metal mold | die of FIG. It is a block diagram of inclination temperature control. It is a figure which shows the structure of a mica heater. It is a figure which shows the heater main body in which the screw hole was formed. It is a front view which shows the attachment state of the heater with respect to a metal mold | die. 10 is a thermographic image showing the temperature distribution of the mold of FIG. 9.

Explanation of symbols

1 Mold 2 Heater (Mica heater)
3 Temperature controller 4a to 4h Temperature sensor 14 Mode converter 15 PID controller 16 Precompensator

Claims (5)

A plate-type mica heater in which a mounting hole is formed is attached to a heating target,
A heater mounting structure characterized in that a metal diffusion plate for diffusing heat is interposed between the mica heater and the object to be heated.   The heater mounting structure according to claim 1, wherein the diffusion plate is made of any one of stainless steel, copper, aluminum, silver, or alloys thereof.   The heater mounting structure according to claim 1, wherein the mica heater includes a heater body in which a heating wire is wound around a core material made of mica having the hole so as not to block the hole.   The heater mounting structure according to any one of claims 1 to 3, wherein the heating target is a mold, and the mounting holes are screw holes, and a plurality of the mounting holes are formed.   The heater mounting structure according to claim 4, wherein a plurality of the mica heaters are mounted on a side surface of the mold.