JP2008230181A - Method for temperature control and cooling apparatus for servo amplifier for electric injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for temperature control for a cooling apparatus for the servo amplifier for an electric injection machine and a cooling apparatus for the servo amplifier for an electric injection machine which prevent occurrence of dew condensation. <P>SOLUTION: The cooling apparatus for the servo amplifier for the electric injection machine has cooling fin 1 cooled by an internal coolant installed in servo amplifier 2 which drives and controls servo motor 8, heat exchanger 30 which cools the internal coolant with an external coolant, and a control valve 40 arranged on external coolant feed pipe 25 in which the external coolant flows. temperature of the cooling apparatus is controlled by the opening and closing motion of control valve 40 based on the load on servo motor 8, the temperature of the external coolant T<SB>o</SB>, the temperature of the internal coolant T<SB>i</SB>and the temperature T<SB>a</SB>around cooling fin 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a temperature control method in a cooling device for a servo amplifier for an electric injection molding machine and a cooling device for a servo amplifier for an electric injection molding machine.

  As is conventionally known, an injection molding machine is composed of a mold opening / closing unit, an injection unit, and the like. The mold opening / closing unit consists of a fixed mold, a movable mold that opens and closes with respect to the fixed mold, an ejector device that projects the molded product, and the like. It consists of a screw driven by In the electric injection molding machine, a drive source for opening and closing the movable mold, a drive source for the ejector device, a drive source for rotating and plasticizing the screw, and a drive source for driving the screw in the axial direction The power source such as is composed of a servo motor.

  An IGBT (Insulated Gate Bipolar Transistor) that turns the current on and off based on a control signal output from the servo control device is used for controlling the servo motor. When the IGBT is switched to pass a current, the IGBT generates heat during switching and conduction.

  By the way, the servo motor as described above is also used in NC machine tools, industrial robots, etc., but the output of the servo motor used in the electric injection molding machine is the servo used in the NC machine tools etc. It is much larger than that of a motor and requires a servo amplifier including at least four IGBTs and an AC / DC converter.

  When the output of the servo motor reaches 15 kw, the heat generated in the IGBT is generated as much as 1000 w by driving only one servo motor. Since IGBT is weak against heat and breaks when the junction temperature exceeds 150 ° C, it must be used with an upper limit of about 120 ° C. Cooling of servo amplifiers or power semiconductors including IGBTs is an important problem for electric injection molding machines.

  For such a problem, Patent Document 1 discloses a cooling device for a servo amplifier for an electric injection molding machine as shown in FIG.

  The cooling device disclosed in Patent Document 1 includes a metal cooling plate 101 attached to a servo amplifier 100 including an IGBT, a reserve tank 102 for storing a coolant, and a heat exchanger 103 that cools the coolant with cold water. It has.

  The coolant in the reserve tank 102 is cooled to a predetermined temperature by the heat exchanger 103, and the coolant in the reserve tank 102 cooled to the predetermined temperature circulates between the cooling plate 101 and the reserve tank 102, and the servo amplifier 100. The servo amplifier included is cooled.

  This cooling device measures the ambient temperature Ta and the internal coolant temperature Ti of the cooling plate 101 and sets the control valve 104 at Ta-Ti> 5 ° C., as shown in the flowchart of FIG. The control valve 104 was turned ON (external cooling liquid was passed) when Ta-Ti ≦ 5 ° C. was set to OFF (external cooling liquid was stopped).

  However, in the case of the method disclosed in Patent Document 1, the control valve 104 is operated when the external coolant temperature is considerably lower than the ambient temperature Ta and the load on the servo motor 105 is reduced because the operation of the injector is stopped. After that, there is a delay time until the internal coolant temperature Ti changes. For this reason, the internal coolant temperature Ti is too low, and the cooling plate 101 may be condensed.

  In order to prevent condensation, it is also possible to adopt an air cooling method. In the case of the air-cooled type, no condensation occurs, so there are no problems such as electric leakage due to water droplets or short circuit. Further, the IGBT is cooled only by sucking and discharging the outside air, and no cooling heat medium is required.

  However, air has a small heat capacity, and in order to cool an IGBT for an electric injection molding machine, a large amount of cooling air must be taken in, and the IGBT terminal portion is contaminated by dust or the like contained in the large amount of air. In addition, the duct for sucking a large amount of cooling air becomes large, and there is a disadvantage that the control panel becomes large. Furthermore, there are problems such as a noise problem of the cooling fan, a problem that it becomes difficult to calculate the cooling capacity, and a weight problem due to an increase in size of the cooling fan.

Accordingly, an object of the present invention is to provide a temperature control method in a cooling device for a servo amplifier for an electric injection molding machine and a cooling device for the servo amplifier for an electric injection molding machine that can prevent the occurrence of condensation.
JP 2006-177601 A

  In order to achieve the above object, the temperature control method of the present invention includes a cooling fin that is cooled by an internal cooling liquid attached to a servo amplifier that drives and controls a servo motor, and a heat exchanger that cools the internal cooling liquid by an external cooling liquid. And a control valve provided in an external coolant supply pipe through which the external coolant flows, in a temperature control method in a servo amplifier cooling device for an electric injection molding machine, the load of the servo motor, the temperature of the external coolant, the internal cooling The control valve is controlled to open and close based on the temperature of the liquid and the temperature around the cooling fin.

  As described above, the temperature control method of the present invention controls the opening and closing of the control valve based on the temperature of the internal cooling liquid and the temperature around the cooling fin, as well as the load of the servo motor and the temperature of the external cooling liquid. For this reason, it is possible to prevent the internal cooling liquid from being overcooled by the external cooling liquid when the load on the servo motor is reduced, and thus it is possible to prevent the condensation from occurring on the cooling fins.

  Further, the temperature control method of the present invention provides a temperature difference between the temperature of the internal cooling liquid and the temperature of the external cooling liquid and the temperature around the cooling fin and the internal temperature when the load of the servo motor is smaller than a predetermined threshold value. The opening / closing of the control valve may be controlled based on a temperature difference from the temperature of the coolant. In this case, the temperature difference between the temperature of the internal cooling liquid and the temperature of the external cooling liquid is larger than the first temperature difference, and the temperature difference between the temperature around the cooling fin and the temperature of the internal cooling liquid is The control valve may be closed when it is larger than the second temperature difference. Alternatively, the temperature difference between the temperature of the internal coolant and the temperature of the external coolant is equal to or less than the first temperature difference, and the temperature difference between the temperature around the cooling fin and the temperature of the internal coolant is the third. The control valve may be closed when the temperature difference is larger.

  A cooling device for a servo amplifier for an electric injection molding machine according to the present invention includes: a pipe through which an internal coolant that cools cooling fins attached to a servo amplifier that drives and controls a servo motor; a heat exchanger that cools the internal coolant; A pipe through which the external coolant supplied to the heat exchanger flows, a control valve provided in the pipe through which the external coolant flows, a current sensor for detecting the current supplied to the servo motor, and the temperature of the external coolant. External coolant temperature sensor to detect, ambient temperature sensor to detect the temperature around the cooling fin, internal coolant temperature sensor to detect the temperature of the internal coolant, current sensor, external coolant temperature sensor, ambient temperature sensor And a controller that controls opening and closing of the control valve based on the detection value of the internal coolant temperature sensor.

  As described above, the cooling device of the present invention has a controller that controls opening and closing of the control valve based on the temperature of the internal cooling liquid and the temperature around the cooling fin, as well as the load of the servo motor and the temperature of the external cooling liquid. For this reason, it is possible to prevent the internal cooling liquid from being overcooled by the external cooling liquid when the load on the servo motor is reduced, and thus it is possible to prevent the condensation from occurring on the cooling fins.

  In addition, since the cooling device of the present invention is liquid-cooled, contamination due to dust contained in the cooling air, a large duct and control panel for sucking the cooling air, noise problems of the cooling fan, cooling capacity There are no problems in the air-cooling system, such as problems that make calculation difficult and weight problems due to the larger cooling fan.

  According to the present invention, the opening / closing of the control valve is controlled based on the temperature of the internal cooling liquid and the temperature around the cooling fin, as well as the load of the servo motor and the temperature of the external cooling liquid. For this reason, it is possible to prevent the internal cooling liquid from being overcooled by the external cooling liquid when the load on the servo motor is reduced, and thus it is possible to prevent the condensation from occurring on the cooling fins.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating a cooling device for a servo amplifier for an electric injection molding machine according to the present embodiment.

  The cooling device of this embodiment is a device for cooling a plurality of servo amplifiers 2 for an electric injection molding machine. The plurality of servo amplifiers 2 are composed of an ejector servo amplifier, a mold opening / closing servo amplifier, a plasticizing servo amplifier, an injection servo amplifier, and the like, and each includes an IGBT. Each servo amplifier 2 drives and controls each servo motor 8 such as an ejector servo motor, a mold opening / closing servo motor, a plasticizing servo motor, and an injection servo motor. Each servo amplifier 2 is provided with a cooling fin 1 made of a good heat conductor such as an aluminum alloy.

  The cooling fins 1 are circulated and supplied with the coolant in the reserve tank 10. The cooling device of the present embodiment also includes a refrigeration cycle (not shown), and the coolant obtained in this refrigeration cycle is heat-exchanged by the heat exchanger 30.

  One cooling fin 1 includes a pair of plate members and two internal cooling liquid pipes 3 reciprocating in the cooling fin 1. That is, the pair of plate members are extruded by, for example, an aluminum alloy so as to have a predetermined width and a predetermined length, and a groove having a predetermined diameter in the axial direction on the mating surface. Then, two internal cooling liquid pipes 3 made of a metal pipe, for example, a copper alloy are set in these concave grooves, and the mating surfaces of the pair of plate members are joined by brazing. Thereby, the cooling fin 1 with which the two internal cooling liquid pipe | tubes 3 were contacted closely between a pair of board | plate materials is obtained.

  One end side of the two internal coolant pipes 3 thus obtained is connected to the internal coolant supply pipe 4, and the other one end side of the two internal coolant pipes 3 is returned to the internal coolant. Each is connected to a pipe 6. On the other hand, the other end sides of the two internal coolant pipes 3 are connected to each other by a return pipe 5 outside the cooling fins 1. As a result, the coolant supplied from the internal coolant supply pipe 4 reciprocates between the cooling fins 1.

Further, the ambient temperature sensor 52 for detecting the ambient temperature T _a is provided in place of the vicinity of the cooling fins 1.

  Although the cooling source provided in the electric injection molding machine can be used as the cooling source for obtaining the cooling liquid, a refrigeration cycle (not shown) is applied in the present embodiment. As conventionally known, the refrigeration cycle includes a compressor for compressing a refrigerant, a condenser, a capillary tube, an evaporator, and the like, which are connected by a refrigerant pipe. The evaporator of the refrigeration cycle and the heat exchanger 30 are connected by an external coolant supply pipe 25 and an external coolant return pipe 26. These tubes 25 and 26 are connected to a first import 31 and a first outport 32 of the heat exchanger 30, respectively.

A control valve 40 which is ON / OFF controlled by the controller 60 to the external coolant supply pipe 25, the external coolant temperature sensor 51 for detecting an external cooling fluid temperature T _o of the external cooling liquid supply pipe 25 is provided . In the present embodiment, the control valve ON means a state in which the control valve 40 is opened to allow the external coolant to flow, and the control valve OFF means that the control valve 40 is closed to stop the external coolant from flowing. Means state. In other words, when the control valve 40 is turned ON, the external coolant is passed and the internal coolant is cooled by the heat exchanger 30, and when the control valve 40 is turned OFF, the external coolant is passed. The cooling of the internal coolant in the heat exchanger 30 is stopped.

  On the other hand, the internal coolant return pipe 6 is connected to the second import 34 of the heat exchanger 30, and the return pipe 6 ′ connected to the reserve tank 10 is attached to the second outport 35.

The internal coolant supply pipe 4 is provided with a pump 7. The pump 7 sucks the internal coolant stored in the reserve tank 10 and supplies it to the servo amplifier 2 side. The reserve tank 10, the internal coolant temperature sensor 53 for detecting the internal coolant temperature T _i of the internal coolant.

  The controller 60, the external coolant temperature sensor 51, the ambient temperature sensor 52, and the internal coolant temperature sensor 53 are connected by signal lines a, b, and c, respectively, and the controller 60 detects from each temperature sensor. Detection values are input via signal lines a, b, and c. In addition, a detection value from a current sensor 9 that detects a current supplied to the servomotor 8 as a load of the servomotor 8 is input to the controller 60 via a signal line d. The controller 60 performs ON / OFF control of the control valve 40 based on each of the input detection values, that is, the external coolant temperature, the ambient temperature, the internal coolant temperature, and the load of the servo motor. A control signal from the controller 60 is transmitted to the control valve 40 via the signal line d.

  Next, ON / OFF control of the control valve 40 by the controller 60 will be described in detail using the control flowchart shown in FIG.

  First, the magnitude of the load on the servo motor 8 is determined based on whether or not the current value detected by the current sensor 9 exceeds a predetermined threshold value preset in the controller 60 (step S1). The predetermined threshold value based on the current value is a load threshold value, and the value is appropriately set according to the specifications of the servo amplifier 2 and the servo motor 8 to be used.

Current value detected by the current sensor 9 exceeds a predetermined threshold value, if it is determined that the load of the servo motor 8 is large, or the temperature difference between the ambient temperature T _a and the internal coolant temperature T _i is greater than 5 ° C. Judgment is made (step S2). When T _a −T _i > 5 ° C., the control valve 40 is turned OFF (step S3), and the flow of the external coolant is stopped. When T _a −T _i ≦ 5 ° C., the control valve 40 is turned on (step S4), and the external coolant is passed.

Current value detected by the current sensor 9 is less than the predetermined threshold value, if it is determined that the load of the servo motor 8 is small, the temperature difference between the inside coolant temperature T _i and the external coolant temperature T _o is 10 ° C. ( It is determined whether or not the difference is greater than the first temperature difference (step S5).

T _i -T _o> 10 ° C., Nachi Suwa, when the temperature difference between the inside coolant temperature T _i and the external coolant temperature T _o is greater than the first temperature difference, followed by ambient temperature T _a and the internal coolant It is determined whether or not the temperature difference from the temperature T _i is greater than 1 ° C. (second temperature difference) (step S6). If T _a −T _i > 1 ° C., that is, if the temperature difference between the ambient temperature T _a and the internal coolant temperature T _i is greater than the second temperature difference, the control valve 40 is turned OFF (step S7). Stop the flow of external coolant. On the other hand, when T _a −T _i ≦ 1 ° C., the control valve 40 is turned ON (step S8), and the external coolant is passed.

On the other hand, T _i -T _o ≦ 10 ° C., Nachi Suwa, when the temperature difference between the inside coolant temperature T _i and the external coolant temperature T _o is less than the first temperature difference, followed ambient temperature T _a and the internal It is determined whether the temperature difference from the coolant temperature T _i is greater than 3 ° C. (third temperature difference) (step S9). If T _a −T _i > 3 ° C., that is, if the temperature difference between the ambient temperature T _a and the internal coolant temperature T _i is greater than the third temperature difference, the control valve 40 is turned OFF (step S10), and the external Stop the coolant flow. On the other hand, when T _a −T _i ≦ 3 ° C., the control valve 40 is turned ON (step S11), and the external coolant is passed.

As described above, the cooling device of this embodiment, not only the temperature difference between the ambient temperature T _a and the internal coolant temperature T _i, the load status of the servo motor 8, the internal coolant temperature T _i and the external coolant temperature temperature difference between T _o, the temperature control in consideration of the temperature difference between the ambient temperature T _a and the internal coolant temperature T _i is made. Thus, the controller 60 of the cooling device of this embodiment, the ambient temperature T _a, not the internal coolant temperature T _i only, load situation and external coolant temperature T _o control valve in consideration of the servo motor 8 40 open / close control is performed. For this reason, it is possible to prevent the internal cooling liquid from being overcooled by the external cooling liquid when the load on the servo motor 8 is reduced, for example, when the operation of the injection machine is stopped, thereby preventing condensation on the cooling fin. can do. Thereby, dew condensation of the cooling fin 1 can be prevented, and occurrence of electric leakage, short circuit, etc. can be prevented beforehand.

  In addition, since the cooling device of the present embodiment is liquid-cooled, dirt due to dust contained in the cooling air, large ducts and control panels for sucking cooling air, noise problems of the cooling fan, cooling capacity There are no problems in the air-cooling method, such as the problem that the calculation of the above becomes difficult and the problem of weight due to the enlargement of the cooling fan.

  In the present embodiment, the control valve 40 is exemplified by a binary value of ON / OFF, but the present invention is not limited to this, and a control valve capable of continuously varying the flow rate of the external coolant is used. You may do.

  The above-mentioned temperature differences are the most preferable examples for preventing condensation on the cooling fins, but may be changed as appropriate depending on the configuration of the electric injection molding machine, the configuration of the cooling device, and the usage environment. Good.

It is a figure which shows typically an example of the cooling device of the servo amplifier for electric injection molding machines of this invention. It is an example of the control flowchart of the cooling device of this invention. It is a figure which shows typically an example of the cooling device of the servo amplifier for the conventional electric injection molding machines. It is an example of the control flowchart of the conventional cooling device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling fin 2 Servo amplifier 3 Coolant liquid pipe 4 Internal coolant supply pipe 5 Return pipe 6 Internal coolant return pipe 7 Pump 8 Servo motor 9 Current sensor 10 Reserve tank 25 External coolant supply pipe 26 External coolant return pipe 30 Heat Exchanger 31 First import 32 First outport 34 Second import 35 Second outport 40 Control valve 51 External coolant temperature sensor 52 Ambient temperature sensor 53 Internal coolant temperature sensor 60 Controller T _a Ambient temperature T _i Internal coolant temperature T _o External coolant temperature

Claims (5)

A cooling fin (1) that is cooled by an internal coolant attached to a servo amplifier (2) that drives and controls the servo motor (8); and a heat exchanger (30) that cools the internal coolant by an external coolant. In the temperature control method in the cooling device of the servo amplifier for the electric injection molding machine having the control valve (40) provided in the external coolant supply pipe (25) through which the external coolant flows.
Based on the load of the servo motor (8), the temperature (T _o ) of the external coolant, the temperature (T _i ) of the internal coolant, and the temperature (T _a ) around the cooling fin (1), A temperature control method characterized by controlling opening and closing of the control valve (40). When the load of the servo motor (8) is smaller than a predetermined threshold, the temperature difference between the temperature of the internal coolant (T _i ) and the temperature of the external coolant (T _o ), and the cooling fin ( The temperature control method according to claim 1, wherein opening and closing of the control valve (40) is controlled based on a temperature difference between the ambient temperature (T _a ) of ₁ ) and the temperature (T _i ) of the internal coolant. The temperature difference between the temperature of the internal coolant (T _i ) and the temperature of the external coolant (T _o ) is greater than the first temperature difference, and the temperature around the cooling fin (1) The temperature control method according to claim 2, wherein the control valve (40) is closed when a temperature difference between (T _a ) and the temperature (T _i ) of the internal coolant is larger than a second temperature difference. The temperature difference between the temperature of the internal coolant (T _i ) and the temperature of the external coolant (T _o ) is equal to or less than a first temperature difference, and the temperature around the cooling fin (1) ( The temperature control method according to claim 2, wherein the control valve is closed when a temperature difference between T _a ) and the temperature of the internal coolant (T _i ) is larger than a third temperature difference. A cooling fin (1) attached to a servo amplifier (2) for driving and controlling the servo motor (8) and cooled by an internal coolant;
A heat exchanger (30) for cooling the internal coolant;
Pipes (25, 26) through which external coolant supplied to the heat exchanger (30) flows;
A control valve (40) provided in the pipe (25);
A current sensor (9) for detecting a current supplied to the servo motor (8);
An external coolant temperature sensor (51) for detecting the temperature (T _o ) of the external coolant;
An ambient temperature sensor (52) for detecting the ambient temperature (T _a ) of the cooling fin (1);
An internal coolant temperature sensor (53) for detecting the temperature (T _i ) of the internal coolant;
The opening and closing of the control valve (40) is controlled based on the detected values of the current sensor (9), the external coolant temperature sensor (51), the ambient temperature sensor (52), and the internal coolant temperature sensor (53). And a servo amplifier cooling device for an electric injection molding machine.

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