JP5199990B2 - Molding machine hydraulic oil temperature raising method - Google Patents

Description

  The present invention relates to a hydraulic oil temperature raising method for a molding machine in which hydraulic oil discharged from a hydraulic pump is caused to generate heat by passing through a specific flow path portion having a large flow resistance to raise the temperature of the hydraulic oil.

  Conventionally, when operating a hydraulic drive unit including a hydraulic pump that is rotationally driven by a drive motor, when the temperature of the hydraulic oil is lower than a target temperature, the hydraulic oil is operated at least from the oil distribution pipe unit by operating the hydraulic pump in advance. As the temperature raising device that passes the specific flow path portion where the flow resistance is increased and raises the temperature of the hydraulic oil by heat generation at this time, the hydraulic oil temperature raising device disclosed in Patent Document 1 is known. .

  The temperature raising device disclosed in Patent Document 1 includes a pump for sending hydraulic oil from a tank, a flow rate control unit for controlling the amount of pumped oil by a control signal, and a hydraulic circuit on the pump sending side. A throttle part that is provided in the middle and raises the temperature of the hydraulic oil that passes therethrough by reducing the cross-sectional area of the hydraulic oil, an input part for inputting the pumping oil amount, and the input part The control unit sends a control signal to the flow rate control unit in accordance with the pump delivery oil amount inputted in this manner, and controls the pump delivery oil amount via the flow rate control unit. It is called a power match type temperature raising device that raises the temperature of hydraulic oil using the pressure difference.

JP-A-5-169510

  However, the conventional hydraulic oil temperature raising device described above also has the following problems to be solved.

  First, since the pumping oil amount (per unit time) is input from the input unit and hydraulic oil is supplied based on this sending oil amount when the temperature rises, the sending oil amount can be set to an arbitrary size. Although it can be set, the amount of oil to be delivered at the time of temperature rise is controlled to be constant so as to be the amount of oil to be set, so there is a problem to be solved with the control method. That is, since the fluidity of the hydraulic oil increases as the temperature increases, the flow resistance decreases and the temperature rise efficiency increases when the temperature rises to some extent even if the amount of oil to be delivered is set with the temperature being low and the viscosity being high. descend. As a result, the temperature rise time becomes long, and it is disadvantageous from the viewpoint of energy saving.

  Second, since the amount of oil to be sent is set by the operator, there is an advantage that it can be set to any size depending on the form of the molding machine, the type of hydraulic oil used, the usage environment, etc. The operator is required to have appropriate skills, and setting is not easy for beginners. In the end, not only is it difficult to set an appropriate amount of oil to be sent, but there is also annoyance associated with setting (input) such as the need to reset the amount of oil to be sent due to changes in conditions, environment, and the like.

  An object of the present invention is to provide a method for raising the operating oil temperature of a molding machine that solves the problems existing in the background art.

  In order to solve the above-described problem, the present invention operates the hydraulic drive unit 4 including the hydraulic pump 3 that is rotationally driven by the drive motor 2. When the hydraulic oil temperature is lower than the target temperature Ths, the hydraulic pump 3 The hydraulic oil discharged from the hydraulic pump 3 is caused to generate heat by passing through a specific flow path portion Ls having a flow resistance larger than that of at least the oil distribution pipe portion L. In the hydraulic oil temperature raising method of the molding machine M, a variable discharge hydraulic pump 3s that can control at least the discharge flow rate of the hydraulic oil by variably controlling the rotational speed of the drive motor 2 is used as the hydraulic pump 3. A target load amount Trs is set for the drive motor 2, and the load amount of the drive motor 2 is the target load amount Tr until the temperature of the hydraulic oil reaches the target temperature Ths when the hydraulic oil is heated. So that, characterized by variably controlling the rotational speed of the drive motor 2.

  In this case, according to a preferred aspect of the invention, the rotational torque Tr [%] of the drive motor 2 can be used as the load amount. Further, the target load amount Trs can be set to 60% or more of the maximum load amount Trp in the drive motor 2, and the target load amount Trs is set to the drive time of the drive motor 2 when the hydraulic oil is heated. On the other hand, it can be set to one stage or multiple stages. On the other hand, the variable discharge hydraulic pump 3s has a setting function of a plurality of fixed discharge flow rates Qs and Qm having different maximum discharge flow rates, and the fixed discharge flow rate Qs with respect to at least the first stage target load amount Trsf of the multi-stage target load amount Trs. Can be set smaller than the fixed discharge flow rate Qm in the latter stage. On the other hand, the internal flow path of the switching valve 5 can be used for the specific flow path portion Ls, and this switching valve 5 is used in combination with a switching valve that is used for other than when the temperature rises. By switching 5 to the temperature raising position a, the hydraulic oil supplied from the variable discharge hydraulic pump 3s can be returned to the oil tank 6.

  According to the hydraulic oil temperature raising method of the molding machine according to the present invention by such a method, the following remarkable effects are achieved.

  (1) A variable discharge hydraulic pump 3 s that can control at least the discharge flow rate of hydraulic oil by variably controlling the rotational speed of the drive motor 2 is used as the hydraulic pump 3, and a target load is applied to the drive motor 2 in advance. The amount Trs is set, and when the temperature of the hydraulic oil rises, the rotational speed of the drive motor 2 is variably controlled so that the load amount of the drive motor 2 becomes the target load amount Trs until the temperature of the hydraulic oil reaches the target temperature Ths. Therefore, when the fluidity increases as the temperature of the hydraulic oil increases, the rotational speed of the drive motor 2 also increases. Therefore, it is possible to improve the temperature raising efficiency and shorten the temperature raising time and to further improve the energy saving.

  (2) Since the rotational speed of the drive motor 2 is variably controlled so that the load amount of the drive motor 2 becomes the target load amount Trs when the hydraulic oil is heated, the actual load amount becomes the target load amount Trs. Controlled. Therefore, once the target load amount Trs corresponding to the performance of the drive motor 2 is set in advance, the control is automatically performed thereafter, so that the troublesomeness associated with the setting (input) can be eliminated.

  (3) If the rotational torque Tr [%] of the drive motor 2 is used as the load amount according to a preferred embodiment, it can be easily detected from the drive current of the drive motor 2 and is incorporated into the control system of the drive motor 2. It is possible to easily and accurately control the rotational torque Tr.

  (4) If the target load amount Trs is set to 60 [%] or more of the maximum load amount Trp in the drive motor 2 according to a preferred aspect, an efficient temperature rise for the hydraulic oil including the setting of the maximum load amount Trp is included. It can be performed.

  (5) According to a preferred aspect, the target load amount Trs can be set in one stage or multiple stages with respect to the drive time of the drive motor 2 when the hydraulic oil is warmed up. The optimum number of stages can be set (selected), and in particular, if the number of stages is set, optimum temperature rise characteristics matched to the characteristics of the drive motor 2 and hydraulic oil can be set.

  (6) According to a preferred embodiment, the variable discharge hydraulic pump 3s is provided with a setting function for a plurality of fixed discharge flow rates Qs and Qm having different maximum discharge flow rates, and at least the first target load amount of the target load amount Trs set in multiple stages. If the fixed discharge flow rate Qs for Trsf is set to be smaller than the fixed discharge flow rate Qm at the subsequent stage, there is no possibility that an overload is applied to the drive motor 2, so that the drive motor 2 can be protected and the temperature raising operation is performed. Can be optimized further.

  (7) If the internal flow path of the switching valve 5 is used as the specific flow path portion Ls according to a preferred embodiment, a dedicated part for the specific flow path portion Ls is not necessary, which facilitates implementation and reduces costs. Can be planned.

  (8) According to a preferred embodiment, the switching valve 5 is used in combination with a switching valve that is used at times other than when the temperature is raised, and is switched from the variable discharge hydraulic pump 3s by switching the switching valve 5 to the temperature raising position a when the temperature is raised. If the hydraulic oil to be returned is returned to the oil tank 6, the number of parts can be reduced by using the switching valve together, and the cost can be reduced accordingly.

The flowchart for demonstrating the process sequence of the hydraulic-oil temperature rising method which concerns on suitable embodiment of this invention, The block diagram of the molding machine containing the hydraulic circuit in the hydraulic drive part which can implement the hydraulic oil temperature rising method, Block diagram of a control system of a molding machine that can implement the hydraulic oil temperature raising method, Hydraulic circuit diagram of a hydraulic drive unit for explaining the operation of the hydraulic oil temperature raising method, Characteristic diagram of temperature rise time versus rotational torque when using the same hydraulic oil temperature rise method, Other temperature rise time vs. rotational torque characteristic diagram when using the hydraulic oil temperature raising method according to a modified embodiment of the present invention, A flow chart for explaining a processing procedure of the hydraulic oil temperature raising method,

  Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of an injection molding machine (molding machine) M including a hydraulic drive unit that can implement the hydraulic oil temperature raising method according to the present embodiment will be described with reference to FIGS. 2 and 3.

  In FIG. 2, M is an injection molding machine, and includes an injection device Mi and a mold clamping device Mc. The mold clamping device Mc is slidably loaded on a fixed platen 11 fixed to a molding machine bed (not shown), a plurality of tie bars 12... Installed on a pressure receiving plate (not shown) from the fixed platen 11, and the tie bars 12. A movable platen 13 is provided. Further, the clamping cylinder 14 is fixed to the pressure receiving plate, and the piston 15 built in the clamping cylinder 14 is coupled to the movable platen 13. Then, the fixed mold Cc is attached to the fixed platen 11 and the movable mold Cm is attached to the movable platen 13. The fixed mold Cc and the movable mold Cm constitute a mold C. Thereby, if the mold clamping cylinder 14 is driven and controlled, and the movable platen 13 (movable mold Cm) is moved forward or backward, the mold C can be closed (clamped) or opened. The injection device Mi can inject and fill the molten resin into the cavity of the mold C by making the injection nozzle Min touch the mold C (fixed mold Cc).

  Further, the mold clamping device Mc includes a hydraulic drive unit 4 including a mold clamping cylinder 14, and the hydraulic drive unit 4 is controlled by a molding machine controller 71. The hydraulic drive unit 4 includes a variable discharge hydraulic pump 3 s (hydraulic pump 3) and a hydraulic circuit 21 serving as a hydraulic drive source. The hydraulic pump 3s includes a pump body 23 and a servo motor 2s (drive motor 2) that rotationally drives the pump body 23. As the servo motor 2s, an AC servo motor connected to the output port of the molding machine controller 71 is used. The servo motor 2s is provided with a rotary encoder 2e for detecting the rotation speed of the servo mode 2s, and this rotary encoder 2e is connected to a sensor input port of the molding machine controller 71.

  The pump body 23 is constituted by a swash plate type piston pump. Therefore, the pump body 23 includes the swash plate 25. If the inclination angle (swash plate angle) of the swash plate 25 is increased, the stroke of the pump piston in the pump body 23 is increased, the discharge flow rate is increased, and the swash plate is increased. If the angle is made smaller, the stroke of the pump piston becomes smaller and the discharge flow rate decreases. Therefore, by setting the swash plate angle to a predetermined angle, a fixed discharge flow rate at which the discharge flow rate (maximum discharge flow rate) is fixed to a predetermined size can be set. In the example, two fixed discharge flow rates, that is, a fixed discharge flow rate Qs having a small flow rate and a fixed discharge flow rate Qm having a large flow rate can be set. The small fixed discharge flow rate Qs can be set to a standard discharge flow rate, and the large fixed discharge flow rate Qm can be set to about twice the small fixed flow rate Qs. In particular, the large fixed discharge flow rate Qm is a value that does not adversely affect the servo motor 2s in the time required to raise the temperature from the lowest possible temperature of the hydraulic oil to the target temperature (usually around 40 ° C.). It can be set in consideration of this. Further, a control cylinder 26 and a return spring 27 are attached to the swash plate 25, and the control cylinder 26 is connected to a discharge port of the pump body 23 via a switching valve (electromagnetic valve) 28, a throttle 29, and a check valve 30. Connecting. Thereby, the angle of the swash plate 25 (swash plate angle) can be changed by the control of the control cylinder 26.

  The suction port of the pump body 23 is connected to the oil tank 6, and the discharge port of the pump body 23 (hydraulic pump 3 s) is connected to the hydraulic circuit 21. As described above, if the variable discharge hydraulic pump 3 s capable of controlling the discharge flow rate by changing the rotation speed of the servo motor 2 s is used for the hydraulic pump 3, energy saving and running can be improved by inverter control for the hydraulic pump 3 s. Cost can be reduced. On the other hand, 72 is a hydraulic oil temperature sensor that detects the temperature of the hydraulic oil attached to the oil tank 6, and 73 is a pump pressure sensor that detects the discharge pressure of the hydraulic pump 3 s, each connected to the sensor input port of the molding machine controller 71. To do.

  As shown in FIG. 2, the hydraulic circuit 21 includes a switching valve main circuit 32 and a switching valve (electromagnetic valve) 33 for switching main operations including a mold opening / closing operation and a mold clamping operation of the mold clamping device Mc, and a sub tank 45 described later. A four-way switching valve (electromagnetic valve) 5 for switching the prefill valve 46 is provided. In this case, the four-way selector valve 5 has not only the positions n and b used when controlling the operation of the mold clamping device Mc, but also the temperature raising position a used when the hydraulic oil temperature raising method according to the present embodiment is performed. The internal flow path of the four-way switching valve 5 when switching to the temperature raising position a has a specific flow in which the flow resistance increases with respect to the oil feeding pipe L connected to the four-way switching valve 5. It becomes the road portion Ls. Thus, if the flow path part Ls uses the internal flow path of the four-way switching valve 5, a dedicated part for the flow path part Ls that increases the flow resistance becomes unnecessary, and the implementation can be facilitated. Further, the four-way switching valve 5 is used in combination with a switching valve that is used at times other than when the temperature is raised, and is supplied from the variable discharge hydraulic pump 3s by switching the four-way switching valve 5 to the temperature raising position a when the temperature is raised. If the hydraulic oil is returned to the oil tank 6, the number of parts can be reduced by using the switching valve together with the cost reduction. The switching valve main circuit 32 includes a pilot switching valve (electromagnetic valve), a direction switching valve (electromagnetic valve), and the like. Furthermore, 34 and 35 are check valves, 36 is a throttle, 74 is a cylinder pressure sensor, and the above circuit components are connected as shown in FIG. Further, the switching valve main circuit 32 and each switching valve (solenoid valve) 33, 5... Are connected to the control output port of the molding machine controller 71. As a result, the entire operation of the hydraulic circuit 21 is resequence controlled by the molding machine controller 71.

  The mold clamping cylinder 14 includes a cylinder body 41 and a piston 15 built in the cylinder body 41. The piston 15 also serves as the high-speed cylinder portion 43, and a booster ram 44 protruding forward from the rear end of the cylinder body 41 is inserted into the oil chamber of the high-speed cylinder portion 43. Further, the cylinder body 41 is provided with a sub tank 45, and a prefill valve 46 for connecting or blocking the sub tank 45 and the rear oil chamber 14r is provided between the sub tank 45 and the rear oil chamber 14r. The oil tank 6 is connected via 47. Therefore, this mold clamping device Mc constitutes a booster ram type mold clamping mechanism.

  Thus, when the mold is opened as an example of the operation of the mold clamping device Mc, the hydraulic oil discharged from the hydraulic pump 3s is supplied to the front oil chamber 14f of the mold clamping cylinder 14 via the switching valve main circuit 32 and the switching valve 33. Then, the piston 42 moves backward to open the mold. At this time, since the hydraulic oil of the hydraulic pump 3s is applied to the prefill valve 46 via the four-way switching valve 5, the prefill valve 46 is opened, and the hydraulic oil in the rear oil chamber 14r of the mold clamping cylinder 14 is It flows into the sub tank 45. Further, the hydraulic oil flowing out from the high speed cylinder portion 43 is returned to the oil tank 6 via the switching valve main circuit 32.

  The molding machine controller 71 has a computer function including a CPU, a memory, a power supply unit, and the like. The molding machine controller 71 is responsible for overall control and a control program for executing the hydraulic oil temperature raising method according to the present embodiment. FIG. 3 is a functional block diagram of a control system used when executing the hydraulic oil temperature raising method according to the present embodiment. Reference numeral 51 denotes a deviation calculation unit, and the pressure command value Ps or the torque target value Trs [%] is selectively given to the non-inverting input unit via the input switching unit 52. In this case, the torque target value Trs is set with respect to the rotational torque Tr of the servo motor 2s, and is the target load amount set by the present embodiment. Thus, the rotational torque Tr [%] can be used as the load amount of the servo motor 2s. If the rotational torque Tr is used as the load amount, it can be easily detected from the drive current of the servo motor 2s, and by incorporating it in the control system of the servo motor 2s, the rotational torque Tr can be controlled easily and accurately. For this reason, when setting the torque target value Trs, it can be input from, for example, a setting screen displayed on a display attached to the molding machine controller 71. The set torque target value Trs is given to the deviation calculating unit 51 via the input switching unit 52. The magnitude of the torque target value Trs is set as a percentage with the maximum value being 100 [%].

  On the other hand, the reverse input unit of the deviation calculation unit 51 is connected to the pressure detection value Pd detected by the pump pressure sensor 73 or the like or the detected rotational torque Tr of the servo motor 2s (torque detection value Trd) via the input switching unit 54. ) Is selectively given. In this case, a drive current (current detection value Id), which is a load current, is detected by the current detection unit 56 from the servo amplifier 55 to which the servo motor 2s is connected, and the current detection value Id is further converted into torque by the torque conversion unit 57. It is converted into a detection value Trd [%].

  On the other hand, the processing system from the output unit of the deviation calculating unit 51 to the servo amplifier 55, that is, the other processing system excluding the above-described change of the processing system on the input unit side of the deviation calculating unit 51 is an existing pressure control system ( PID control system) 50c. 58 is an integrator, 59 is a computing unit that outputs an 1 / integral value, 60 is an integration limiter, 61 is an adder / subtracter, 62 is a delay unit, 63 is a differentiator, 64 is a subtractor, 65 is a proportional gain setting device, 66 Is a speed limiter, 67 is a reverse speed limiter, Vs is a speed command value given to the speed limiter 66, and Vc is a speed control command value output from the speed limiter 66. Therefore, the deviation output obtained from the output unit of the deviation calculating unit 51 is PID compensated in the pressure control system 50c, and the servo motor 2s is driven by supplying the motor drive current based on the obtained speed control command value to the servo motor 2s. Then, feedback control is performed so that the torque detection value Trd becomes the torque target value Trs or the pressure detection value Pd becomes the pressure command value Ps. Therefore, the hydraulic oil temperature raising method according to the present embodiment can be implemented by changing a part of the pressure control system Cp provided in the injection molding machine M.

  Next, an outline (principle) of the hydraulic oil temperature raising method according to the present embodiment will be described with reference to FIG.

  First, the principle of the hydraulic oil temperature raising method according to the present embodiment uses, as a basic requirement, a variable discharge hydraulic pump 3s that can variably control the rotation speed of the servo motor 2s to control at least the discharge flow rate of the hydraulic oil. . A torque target value Trs, which is a target load amount, is set in advance for the servo motor 2s, and the torque detection value Trd, which is a load amount of the servo motor 2s, becomes the torque target value Trs when the operating oil is heated. As described above, the rotational speed of the servo motor 2s is variably controlled.

  For this reason, the torque target value Trs is set in advance from a setting screen or the like displayed on a display attached to the molding machine controller 71. In this case, the magnitude of the torque target value Trs is set as a percentage with the maximum torque being 100%. The torque target value Trs is preferably set to 60% or more of the maximum torque (maximum load amount) in the servo motor 2s. Thereby, including the setting of the maximum load amount, it is possible to efficiently raise the temperature of the hydraulic oil.

  In FIG. 5, Trd1 indicated by a solid line indicates, as an example, a case where the torque target value Trs is set to 70 [%] and constant torque control (one-stage control) is performed on the rotational torque. In this case, the rotational torque is controlled to 70% from the start of the temperature rise, and the control is stopped when the temperature of the hydraulic oil reaches the target temperature Ths (40 ° C) after 18 minutes. Shows the state. In addition, Trdr indicated by a dotted line in the figure indicates a case where constant torque control for rotational torque is not performed, that is, when the amount of oil to be sent is set (controlled) as in the background art described above, or the discharge pressure is constant. In this case, if the temperature of the hydraulic oil increases and the viscosity gradually decreases, the rotational torque Tr (load amount of the servo motor 2s) also increases. The temperature gradually decreases, and as a result, the control is stopped when the temperature of the hydraulic oil reaches the target temperature Ths after 20 minutes. Further, Trd2 indicated by an imaginary line indicates a state in which the control is stopped by setting the torque target value Trs to 100 [%] and, after 13 [minutes], the temperature of the hydraulic oil reaches the target temperature Ths. . Therefore, setting the torque target value Trs to 100 [%] can raise the temperature in the shortest time, but actually, the control with 100 [%] is performed from the initial stage when the viscosity of the hydraulic oil is high. Therefore, an excessive load is applied to the thermomotor 2s, which is not preferable. For this reason, a modified embodiment in the case of setting to 100 [%] will be described later with reference to FIGS.

  Next, a specific processing procedure of the hydraulic oil temperature raising method according to the present embodiment will be described according to the flowchart shown in FIG. 1 with reference to FIGS.

  First, the operation switch of the injection molding machine M is turned on (step S1). Thereby, the molding machine controller 71 takes in the temperature of the hydraulic oil detected by the hydraulic oil temperature sensor 72 (step S2). Then, it is determined whether or not the temperature of the hydraulic oil is equal to or higher than the target temperature Ths [° C.], and if it is equal to or higher than the target temperature Ths [° C.], the operation in the normal production mode is performed without performing the temperature increase process for the hydraulic oil. Start (steps S3 and S10).

  On the other hand, when the temperature of the hydraulic oil is lower than the target temperature Ths (40 [° C.]), the temperature raising process is performed by the hydraulic oil temperature raising method according to the present embodiment. In this case, the molding machine controller 71 switches to control by the hydraulic oil temperature raising mode and outputs a switching command (switching command signal) (steps S3 and S4). Thereby, the four-way switching valve 5 shown in FIG. 2 is switched to the temperature rising position a shown in FIG. 4, and the input switching unit 52 shown in FIG. 3 is switched to the position where the torque target value Trs is input. The input switching unit 54 is switched to a position where the torque detection value Trd is input.

  Next, the servo motor 2s is driven to start the operation of the hydraulic pump 3s that is in the temperature raising operation (step S5). As a result, the hydraulic oil in the oil tank 6 circulates along the path indicated by the arrow Fo shown in FIG. That is, the hydraulic oil in the oil tank 6 is discharged from the hydraulic pump 3 s and reaches the four-way switching valve 5, and flows through the temperature rising position a in the four-way switching valve 5, and then passes through the check valve 35. And returned to the oil tank 6. At this time, the temperature rise position a in the four-way switching valve 5 becomes a specific flow path portion Ls in which the flow resistance is larger than that of the oil distribution pipe portions L connected to the four-way switching valve 5. Accordingly, the hydraulic oil generates heat due to a pressure difference when it flows through the temperature raising position a of the four-way switching valve 5, and functions as a power match type temperature raising device that raises the temperature of the hydraulic oil.

  On the other hand, in the pressure control system Cp shown in FIG. 3, a preset torque target value Trs is given to the non-inverting input unit of the deviation calculating unit 51 and is detected by the inverting input unit of the deviation calculating unit 51. Torque detection value Trd [%] is given. At this time, the drive current Id flowing through the servo motor 2s is detected by the current detection unit 56 from the servo amplifier 55, and the detected drive current Id is converted into the torque detection value Trd by the torque conversion unit 57. The Thereby, in the pressure control system Cp, feedback control is performed so that the torque detection value Trd becomes the torque target value Trs. Specifically, when the torque target value Trs is set to 70 [%], constant torque control is performed so that the actual rotational torque becomes 70 [%] (step S6). As a result, even if the rotational torque Tr (load amount of the servo motor 2s) gradually decreases due to the temperature of the hydraulic oil rising and the viscosity gradually decreasing, the servo motor 2s is controlled by the molding machine controller 71. The rotational torque Tr is maintained at 70 [%].

  When the hydraulic oil reaches the target temperature Ths (40 [° C.]), the molding machine controller 71 performs control to stop the power supply to the servo motor 2s and terminates the operation of the hydraulic pump 3s (steps S7 and S8). ). Further, the molding machine controller 71 cancels the hydraulic oil temperature raising mode (step S9). In this case, the molding machine controller 71 outputs a switching command (switching command signal) and switches the four-way switching valve 5 shown in FIG. 4 to return to the normal position n shown in FIG. Further, the input switching unit 52 shown in FIG. 3 is switched to the position where the pressure command value Ps is input, and the input switching unit 54 is switched to the position where the pressure detection value Pd is input. Thereby, the operation in the normal production mode is performed (step S10).

  Therefore, according to the hydraulic oil temperature raising method according to the present embodiment as described above, the variable discharge hydraulic pump capable of controlling at least the discharge flow rate of the hydraulic oil by variably controlling the rotation speed of the servo motor 2s in the hydraulic pump 3. 3s is used, and a torque target value Trs is set for the servo motor 2s in advance. When the temperature of the hydraulic oil rises, the rotational torque of the servo motor 2s becomes the torque target until the temperature of the hydraulic oil reaches the target temperature Ths. Since the rotation speed of the servo motor 2s is variably controlled so as to have the value Trs, when the fluidity increases as the temperature of the hydraulic oil increases, the rotation speed of the servo motor 2s also increases. Therefore, it is possible to improve the temperature raising efficiency and shorten the temperature raising time and to further improve the energy saving. Further, when the temperature of the hydraulic oil is increased, the rotational speed of the servo motor 2s is variably controlled so that the rotational torque of the servo motor 2s becomes the torque target value Trs. Therefore, once the torque target value Trs corresponding to the performance of the servo motor 2s is set once, control is automatically performed thereafter, so that the troublesomeness associated with setting (input) can be eliminated.

  Next, a hydraulic oil temperature raising method according to a modified embodiment of the present invention will be described with reference to FIGS. 6 and 7.

  In the above-described hydraulic oil temperature raising method, the case where the torque target value Trs serving as the target load amount is set in one step with respect to the drive time of the servo motor 2s when the hydraulic oil is raised is shown. In the hydraulic oil temperature raising method, as shown in FIG. 6, the torque target value Trs is set to two stages with respect to the driving time, specifically, the front stage is set to 70 [%] and the rear stage is set to 100 [%]. Is set. As described above, when the torque target value Trs is set to 100 [%], the temperature of the hydraulic oil can reach the target temperature Ths in the shortest time, but on the other hand, the hydraulic oil has a high viscosity. In the initial stage, the largest rotational torque (load amount) is applied to the servomotor 2s. Therefore, at the initial stage, the torque target value Trs is set to 70 [%] until the preset set time (illustrated 3 [minutes]) elapses from the start, and when the set time has elapsed. When tc is reached, the setting of the torque target value Trs is changed to 100 [%]. In this case, the set time until the time point tc is usually a time when the viscosity of the hydraulic oil is high, and even if the torque target value Trs is set to 100 [%], it is a time that does not adversely affect the servo motor 2s. Select.

  Further, two fixed discharge flow rates Qs and Qm having different maximum discharge flow rates are set in the variable discharge hydraulic pump 3s, and the initial torque target value Trsf (70 [%] in the torque target values Trsf and Trsr set in two stages is set. ], A small fixed discharge flow rate Qs is set, and a large fixed flow rate Qm is set for the subsequent torque target value Trsr (100 [%]).

  Therefore, the hydraulic oil temperature raising method according to the modified embodiment is performed along the flowchart shown in FIG. First, when the operation switch of the injection molding machine M is turned ON, the molding machine controller 71 takes in the temperature of the hydraulic oil detected by the hydraulic oil temperature sensor 72, and determines whether the temperature of the hydraulic oil is equal to or higher than the target temperature Ths. Judgment is made (steps S21, S22, S23). And if it is more than target temperature Ths, the driving | operation by a normal production mode will be started (step S24). On the other hand, when the temperature of the hydraulic oil is lower than the target temperature Ths, the control is switched to the hydraulic oil temperature increase mode, and the molding machine controller 71 outputs a switching command (switching command signal). As a result, the four-way switching valve 5 is switched to the temperature rising position a shown in FIG. 4, and the input switching unit 52 shown in FIG. 3 is switched to the position where the torque target value Trs is input, and the input switching unit. 54 is switched to a position where the torque detection value Trd is input. At this time, the switching valve (solenoid valve) 28 is switched, and the hydraulic pump 3s is switched to the small fixed discharge flow rate Qs (step S25).

  Next, the servo motor 2s is driven to start the operation of the hydraulic pump 3s (step S26). As a result, first, the constant torque control is performed so that the rotational torque Tr of the servo motor 2s becomes 70 [%] under the setting of the small fixed flow rate Qs (step S27). When the set time elapses, the hydraulic pump 3s is switched to a large fixed discharge flow rate Qm, the torque target value Trs is switched to 100 [%], and the rotational torque Tr of the servo motor 2s is , 100 [%], constant torque control is performed (steps S28, S29, S30).

  Thereafter, when the target temperature Ths is reached, the molding machine controller 71 performs control to stop the power supply to the servo motor 2s, and terminates the operation of the hydraulic pump 3s (steps S31 and S32). Further, the molding machine controller 71 cancels the hydraulic oil temperature raising mode (step S33). In this case, the molding machine controller 71 outputs a switching command (switching command signal) and switches the switching valve 5 shown in FIG. 4 to return to the normal position n shown in FIG. Further, the input switching unit 52 shown in FIG. 3 is switched to the position where the pressure command value Ps is input, and the input switching unit 54 is switched to the position where the pressure detection value Pd is input. Thereby, the operation in the normal production mode is performed (step S34).

  Therefore, according to the hydraulic oil temperature raising method according to such a modified embodiment type bear, the torque target value Trs is set to two stages, the first stage and the second stage, with respect to the drive time of the servo motor 2s when the hydraulic oil is heated. Therefore, it is possible to set an optimum temperature rise characteristic that matches the characteristics of the servo motor 2 and the hydraulic oil. Further, two fixed discharge flow rates Qs and Qm having different maximum discharge flow rates are set by the variable discharge hydraulic pump 3s, and the torque target value Trsf (70 [%]) preceding the torque target value Trs set in two steps is set. Since the small fixed flow rate Qs is set, there is no possibility that an overload is applied to the servo motor 2s, so that the drive motor 2 can be protected and the temperature raising operation can be further optimized.

  The preferred embodiment has been described in detail above, but the present invention is not limited to such an embodiment, and any method, configuration, numerical value, and the like may be arbitrarily selected without departing from the gist of the present invention. Can be changed, added, or deleted.

  For example, the case where the rotational torque Tr [%] of the drive motor 2 (servo motor 2s) is used as the load amount has been shown. However, if the load amount is indicated directly or indirectly, the pressure or the like Other physical quantities may be used. Moreover, although the servomotor 2s was illustrated as the drive motor 2, other various drive motors 2 are applicable. Furthermore, the set number of stages of the target load amount (torque target value) Trs may be set to three or more, or three or more different fixed discharge flow rates Qs. As described above, the optimum number of stages can be arbitrarily set (selected) according to the form and conditions of the molding machine M. On the other hand, although the case where the internal flow path of the four-way switching valve 5 is used as the specific flow path portion Ls is illustrated, any means may be used as long as it causes a pressure difference of the hydraulic oil, and if necessary. A separate throttle or the like may be connected to the temperature raising position a of the four-way switching valve 5. Moreover, although the switching valve 5 illustrated the case where it used together with the switching valve used except at the time of temperature rising, the case where the exclusive means which produces the pressure difference of hydraulic fluid is used is not excluded. Further, in the modified embodiment, the case where the control is switched from the preceding stage to the subsequent stage control at the time tc when the set time passes has been shown. However, the rotation speed of the servo motor 2c is monitored, and a preset rotation speed (for example, 2000 [rpm ]), The control may be switched from the former stage to the latter stage control.

  The hydraulic oil temperature raising method according to the present invention can be used for various molding machines including an injection molding machine and a hydraulic pump using a drive motor, and other various production machines.

  2: drive motor, 3: hydraulic pump, 3s: variable discharge hydraulic pump, 4: hydraulic drive unit, 5: switching valve, 6: oil tank, Tr: rotational torque of drive motor, L ...: oil distribution pipe unit, Ls : Specific flow path part, M: Molding machine, a: Temperature rising position

Claims (7)

  When operating a hydraulic drive unit including a hydraulic pump that is rotationally driven by a drive motor, when the temperature of the hydraulic oil is lower than a target temperature, the hydraulic pump is operated, and hydraulic oil discharged from the hydraulic pump is In the hydraulic oil temperature rising method for a molding machine that raises the temperature of the hydraulic oil by generating heat by passing through a specific flow path portion that has a flow resistance larger than at least the oil distribution pipe portion, the hydraulic pump is connected to the drive motor. Use a variable discharge hydraulic pump that can control at least the discharge flow rate of hydraulic oil by variably controlling the number of revolutions, set a target load amount for the drive motor in advance, and operate when the temperature of the hydraulic oil rises The rotational speed of the drive motor is variably controlled so that the load amount of the drive motor becomes the target load amount until the oil temperature reaches the target temperature. Hydraulic oil heating method for a molding machine for.   The method of claim 1, wherein a rotational torque of the drive motor is used as the load amount.   The method of claim 1 or 2, wherein the target load amount is set to 60% or more of the maximum load amount in the drive motor.   The hydraulic fluid for a molding machine according to any one of claims 1 to 3, wherein the target load amount is set to one stage or multiple stages with respect to a drive time of the drive motor when the hydraulic oil is heated. Heating method.   The variable discharge hydraulic pump is provided with a plurality of fixed discharge flow rate setting functions having different maximum discharge flow rates, and the fixed discharge flow rate for the target load amount of at least the first stage of the target load amount set in multiple stages is determined from the fixed discharge flow rate of the subsequent stage. The hydraulic oil temperature raising method for the molding machine according to claim 4, wherein the temperature is set to be smaller.   The hydraulic fluid temperature raising method for a molding machine according to any one of claims 1 to 5, wherein the specific flow path portion uses an internal flow path of a switching valve.   The switching valve is used in combination with a switching valve that is used except when the temperature is raised, and when the temperature rises, the switching valve is switched to a temperature raising position, thereby returning the hydraulic oil supplied from the variable discharge hydraulic pump to the oil tank. The method for raising the operating oil temperature of a molding machine according to claim 6.

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