JP5239732B2 - Clamping device - Google Patents

Description

  The present invention relates to a mold clamping device for a die casting machine, an injection molding machine or the like.

  In die-casting machines for forming aluminum, a fixed mold placed on a fixed fixed platen (board) is combined with a movable mold installed on a movable movable platen (board), and the fixed mold and movable mold are combined with a mold clamping device. After the mold is clamped, a molten metal such as aluminum is injected into the cavity between the molds. The movable mold is moved by a relatively long mold closing distance with a small stroke (small force) mechanism with a large stroke, and then moved with a large capacity clamping cylinder with a small stroke, and then clamped. Procedure for fitting the half nut provided on the movable platen to the tie bar (formed in a tooth shape or threaded shape) to which the mold clamping cylinder is connected when the mold closing operation by the large stroke mechanism is shifted to the mold clamping cylinder. Is required. The half nut is generally fitted to the tie bar by meshing the tooth-like portions. However, since the dimensions change depending on the mold, it is necessary to position the half nut with respect to the tie bar.

  Various proposals have been made for positioning the tie bar with respect to the half nut by adjusting the intermediate position of the piston in the clamping cylinder. For example, Patent Document 1 proposes a device in which a small hydraulic sub-cylinder is provided so as to be in series with a mold-clamping hydraulic cylinder, and positioning can be finely adjusted. However, this document does not disclose a hydraulic circuit or a supply method for supplying hydraulic oil to the hydraulic sub-cylinder.

  Patent Document 2 discloses a method of controlling the rotational speed of a hydraulic pump and positioning it at a desired position while slowly moving a tie bar. However, in order to use this method, it is necessary to provide a hydraulic pump and a motor for each of a plurality of tie bars, which has the disadvantages that the structure is complicated and the cost is increased.

  Further, in Patent Document 3, a constant flow rate of hydraulic oil discharged from a hydraulic source is supplied to a mold clamping hydraulic cylinder via a direction switching valve to move a tie bar. A method is disclosed in which when the tie bar moves to a desired position, the direction switching valve is operated to stop the supply of hydraulic oil and position the tie bar. However, in this method, when one hydraulic power source is used, the hydraulic oil discharged from the hydraulic power source is branched in the middle, and the hydraulic oil is supplied to a plurality of tie bars. The piston packings installed in the pistons of the clamping cylinder connected to the tie bar have different sliding resistances, and therefore there is a difference in the moving speed of the tie bar.

  For this reason, a difference also occurs in the time to reach the desired position. Therefore, when one tie bar reaches the desired position and the direction switching valve is closed, the flow rate of the hydraulic oil supplied to the other mold clamping hydraulic cylinders Increases the speed of movement. If the moving speed of the tie bar during the positioning is increased, the positioning accuracy is deteriorated, so that a problem is easily caused in the meshing with the half nut. In order to avoid this, if the gap between the teeth is increased, the time for the piston to move during mold clamping is increased, leading to an increase in cycle time.

In order to avoid the drawbacks of the above-mentioned conventional scheme, a conventional hydraulic circuit as shown in FIG. 3 is considered.
In the conventional hydraulic circuit (140) shown in FIG. 3, in the mold clamping device having four mold clamping cylinders, the position of the mold clamping cylinder is detected, and the flow rate of hydraulic oil supplied to the mold clamping cylinder is adjusted. Thus, the half nut and the tie bar can be fitted by adjusting the moving speed of the mold clamping cylinder and performing the stop positioning of the mold clamping cylinder. The conventional mold clamping apparatus shown in FIG. 3 includes four mold clamping cylinders (25), and the reciprocating motion of each mold clamping cylinder (accordingly, mold clamping and strong mold opening) is an electric motor having a constant rotational speed. The operation is performed by supplying hydraulic oil via each electromagnetic valve (44) by a hydraulic pump 142 driven by a motor 141. Since the hydraulic pump 142 is driven by the electric motor 141 having a constant rotation speed, the hydraulic oil is supplied at a substantially constant flow rate. The four mold clamping cylinders (25) are connected in parallel to the hydraulic pump 142, and the hydraulic oil is supplied at substantially the same flow rate, but to be exact, the difference in sliding resistance and pipe resistance of the piston packing is different. As a result, the flow rate of hydraulic oil supplied to each mold clamping cylinder (25) varies.

  For this reason, the conventional mold clamping apparatus of FIG. 3 includes a variable flow rate adjusting valve (147) in front of each electromagnetic valve (44) in order to equalize the flow rate of hydraulic oil supplied to each mold clamping cylinder (25). In this case, in order to ensure a sufficient supply flow rate, the flow rate of the hydraulic pump 142 is set larger than the total flow rate of each variable flow rate adjustment valve, and the excess flow rate is returned to the tank 43 via the electromagnetic relief valve 145. When each mold clamping cylinder (25) reaches a predetermined position, this is detected by the position detection sensor (51), the electromagnetic valve (44) is moved to the block position, and the mold clamping cylinder is stopped.

  In such a conventional mold clamping device of FIG. 3, it is necessary to provide the variable flow rate adjusting valve (147) upstream of each electromagnetic valve (44), and the adjustment is troublesome. Further, as described above, the surplus hydraulic oil generates heat when returning to the tank via the electromagnetic relief valve 145 during loading, causing energy loss.

Japanese Patent No. 3595367 JP 2002-225103 A JP 2005-297020 A

  When operating pistons in a plurality of mold clamping cylinders, even if there is a variation in sliding resistance or pipe resistance in each, fitting is achieved by appropriately controlling the moving speed and stop position. An object of the present invention is to provide a mold clamping device having a simple hydraulic circuit capable of minimizing the gap between the portions and eliminating the cycle loss. Furthermore, another object of the present invention is to provide a mold clamping device that eliminates energy loss that occurs when pressure oil that has been throttled by a flow control valve and is not used returns to the tank, and can save energy.

  In the first embodiment of the present invention, the mold clamping device (50) is provided with a movable mold (5) attached to the movable platen (4) and a fixed attached to the fixed platen (2) in order to achieve the above-described object. A plurality of clamping cylinders (25) for applying a clamping force to the mold in cooperation with the tie bar (10) and the half nut (22) after the mold (3) is closed, which can reciprocate. A mold clamping cylinder (25) having a piston (27) therein, a hydraulic circuit (40) for supplying hydraulic oil to the mold clamping cylinder (25) and returning the hydraulic oil, and a hydraulic circuit (40). A control device (60) for adjusting the mold clamping force of the mold clamping cylinder (25), the moving speed and stop position of the piston (27), and a position detection sensor (51) for detecting the position of the piston (27). And comprising. The piston (27) inside the mold clamping cylinder (25) is connected to the tie bar (10) and can be interlocked. The fitting position of the tie bar (10) and the half nut (22) is adjusted by moving the piston (27) in the clamping cylinder (25) by supplying hydraulic oil, stopping the supply of hydraulic oil, This can be implemented by stopping (27) at a predetermined position and positioning. The hydraulic circuit (40) includes a single hydraulic pump unit (35) and a plurality of solenoid valves (44) for switching the supply direction of hydraulic oil to each clamping cylinder (25) and stopping the supply. The discharge flow rate of the hydraulic pump unit (35) is variable. The discharge flow rate of the hydraulic pump unit (35) is adjusted to decrease by a predetermined flow rate when one of the plurality of pistons (27) reaches the fitting position of the tie bar (10) and the half nut (22) and stops. After that, when the other piston (27) reaches the fitting position, it is adjusted so as to decrease by a predetermined flow rate sequentially.

  The piston (27) inside the mold clamping cylinder (25) may be connected to the half nut (22) so as to be interlocked. In a preferred embodiment, the predetermined flow rate to be reduced is a constant amount, and is a value obtained by dividing the flow rate when all the clamping cylinders (25) are simultaneously operated by the number of clamping cylinders (25). It is preferable.

  The hydraulic pump unit (35) preferably includes a hydraulic pump (42) and an electric motor (41) with a variable rotation speed that drives the hydraulic pump (42), such as a servo motor. The number of the plurality of mold clamping cylinders (25) is preferably four.

  In a second aspect of the present invention, a method for controlling a mold clamping device is provided, which comprises operating either a half nut (22) or a tie bar (10) and a piston (27). To adjust the discharge flow rate of the hydraulic pump unit (35) according to the number of the clamping cylinders (25) in operation. An adjustment procedure. In the adjustment procedure, the discharge flow rate of the hydraulic pump unit (35) is equal to the predetermined flow rate when one of the plurality of mold clamping cylinders (25) reaches the fitting position of the tie bar (10) and the half nut (22) and stops. Adjusted to decrease only.

  In the above description of the present invention, symbols or numbers in parentheses () are attached to show correspondence with the embodiments described below.

-According to the mold clamping device of the present invention, by obtaining stable stopping accuracy at the fitting position, the fitting between the tie bar and the half nut can be operated without malfunction.
-Since the gap between the fitting parts can be reduced, cycle loss due to the mold clamping force generation operation can be minimized.
-Since the discharge flow rate of the hydraulic unit, particularly the rotational speed of the hydraulic pump, can be controlled to the required amount, energy can be saved by eliminating the return amount of hydraulic oil to the tank.

Hereinafter, a mold clamping device 50 according to a first embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 schematically show a first embodiment of a die-casting machine for a die-casting machine and its hydraulic circuit according to the present invention, and FIG. 1 shows a die-casting machine including the mold-clamping device of the present invention. FIG. 2 schematically shows a first embodiment of the hydraulic circuit of the mold clamping device of the present invention.
First, the configuration of the die casting machine will be described with reference to FIG.

  As shown in FIG. 1, a fixed platen (board) 2 that supports a fixed mold 3 is fixed to an end portion of the machine base 1, and a movable platen (supporting a movable mold 5) is supported on the machine base 1. A panel 4 is disposed so as to be movable forward and backward with respect to the fixed platen 2 via a movable platen support member 6a. A mold opening / closing device 24 is attached to the lower end of the movable platen 4 to open and close the mold by moving the movable platen 4 forward and backward with respect to the fixed platen 2 on the movable platen support member 6a. FIG. 1 shows the mold clamping device 50 with the mold opened.

  Tie bar insertion holes 7 and 8 are formed at the four corners of the fixed platen 2 and the movable platen 4, and the tie bars 10 are inserted through the insertion holes 7 and 8. A tie bar cover 10 a is attached to the tie bar insertion holes 7 and 8 of the movable platen 4, and a support 10 b for supporting the tie bar 10 is disposed behind the lower tie bar insertion hole 8. The upper tie bar 10 is close to the end on the movable platen side, and the lower tie bar 10 is a split nut of a half nut (split nut device) 22 connected to the tie bar insertion holes 7 and 8 at the intermediate portion. Engagement portions 10x and 10y that are engaged with each other are formed. The fixed platen side end of the tie bar 10 includes an engaging portion 10z formed with a spiral groove that engages with the nut of the fixed nut device 23, and the tie bar 10 and the piston 27 are connected.

  In the tie bar insertion hole 7 of the fixed platen 2, a piston 27 is incorporated, a mold clamping cylinder 25 (pressing means) having oil chambers 28 and 29 is arranged, and a fixed nut device 23 is attached to the end of the piston 27. It becomes the composition. Further, the mold clamping cylinder 25 is provided with a port 25 a for supplying and discharging hydraulic oil (pressure oil) in the oil chamber 28. After the mold opening / closing device 50 is driven and the mold is closed and the tie bar 10 and the half nut 22 are fitted, the hydraulic pump unit 35 is operated to supply the hydraulic oil to the oil chamber 28, and the hydraulic oil is discharged from the oil chamber 29. Then, the piston 27 is driven. By driving the piston 27, the solid nut device 23 that is tightly connected to the end portion of the piston 27 and engaged with the engaging portion 10 z of the tie bar 10 is provided on the side opposite to the die mounting surface of the fixed platen 2 ( Since the driving force is received in the direction (right direction in FIG. 1), the movable platen 4 after mold closing is further pressed by the fixed platen 2, and the mold clamping operation is performed following the mold closing operation.

As described above, in the embodiment shown in FIG. 1, the mold clamping cylinder 25 is disposed in the tie bar insertion holes 7 and 8 of the fixed platen 2 and the tie bar 10 is driven in the mold clamping direction to clamp the mold. For example, the tie bar insertion holes 7 and 8 part of the fixed platen 2 are fixed to the side opposite to the die mounting surface, and the tie bar insertion holes 7 and 8 part of the movable platen 4 are fixed. A mold clamping cylinder 25 is disposed between the mold mounting surface side and the half nut 22, the half nut 22 and the tie bar 10 are connected, and the tie bar 10 is driven to the half nut side (left direction in FIG. 1) to clamp the mold. It is good also as composition which makes force act.
Further, in FIG. 1, the half nut 22 is installed on the movable platen 4 side. However, the half nut 22 may be installed on the stationary platen 2 side, and the mold clamping cylinder 25 and the half nut 22 may be used. May be possible arrangements other than those described above with respect to the stationary platen 2 and the movable platen 4.

  In FIG. 1, reference numeral 30 denotes an injection device that injects and fills molten metal, which is a molding material, into a mold while the mold is clamped. The injection plunger 31 is driven by an injection cylinder together with a plunger tip (not shown) attached to the tip of the plunger 31 to advance and inject molten metal into the mold.

  FIG. 2 shows a system diagram of the hydraulic circuit 40 of the first embodiment of the present invention for driving the die-casting machine clamping device 50 described above. The hydraulic circuit 40 includes a hydraulic pump 42 that is driven by an electric motor 41. The hydraulic pump 42 sucks the hydraulic oil stored in the hydraulic tank 43 and supplies the hydraulic oil to the four mold clamping cylinders 25 through the respective electromagnetic valves 44. The electric motor 41, the hydraulic pump 42, the hydraulic tank 43 and the like constitute a hydraulic pump unit 35. As described above, the mold clamping cylinders 25 accommodate the pistons 27 that are engaged with the tie bars 10 via the fixing nut devices 23. The hydraulic oil is supplied to the oil chamber 28 or 29 of the mold clamping cylinder 25, thereby pressing the piston 27 and moving the piston 27 left or right. As a result, the tie bar 10 is reciprocated. Thus, mold clamping and strong mold opening of the mold clamping device 50 are performed.

  The solenoid valve 44 has three positions. When the solenoid valve 44 is on the left side in FIG. 2 (b solenoid excitation), hydraulic oil is supplied to the oil chamber 29 on the right side of the clamping cylinder 25 (the oil chamber 28 When the hydraulic oil returns to the hydraulic tank 43), the piston 27 (that is, the tie bar 10) is moved leftward in FIG. 1 (strong mold opening direction), and when it is on the right side in FIG. Hydraulic oil is supplied to the oil chamber 29 on the left side of the clamping cylinder 25, and the piston 27 (that is, the tie bar 10) is moved rightward in FIG. 1 (clamping direction), and the neutral position of the solenoid valve 44 (solenoid demagnetization). ) Stops the piston (the oil chamber 28 communicates with the tank and the oil chamber 29 is blocked). The branch line from the discharge side line of the hydraulic pump 42 is provided with a relief valve (or safety valve) 45. When the pressure of the discharge line becomes a predetermined pressure or more, such as when an abnormality occurs, It returns to the hydraulic tank 43 through the valve 45.

  The mold clamping device 50 further includes a position detection sensor 51 for detecting the position of the tie bar 10 (or the piston 27) corresponding to each mold clamping cylinder 25. The position detection sensor 51 can detect the stroke of the tie bar 10 and can detect a position (fitting position) where the engaging portion 10x of the tie bar 10 and the half nut 22 can be fitted. Accordingly, when the position detection sensor 51 detects the fitting position while exciting the electromagnetic valve 44 and moving the piston 27, the signal is sent to the control device 60 of the mold clamping device 50. 44 is demagnetized to stop the piston 27, thereby positioning the engaging portion 10 x of the tie bar 10 and stopping it at a position where it can be fitted to the half nut 22.

Next, the operation of the mold clamping device 50 of the present embodiment will be described below.
In the present embodiment, the electric motor 41 is a type capable of controlling the rotational speed of a servo motor, an inverter-controlled AC electric motor, or a DC motor. Therefore, since the rotational speed of the electric motor 41 is variably controlled by controlling the electric motor 41 with the control device 60, the rotational speed of the hydraulic pump 42 is also variable, and the hydraulic pump 42 (ie, the hydraulic unit 35) The discharge flow rate is variable. Since the discharge flow rate of the hydraulic pump 42 is variable, the moving speed (stroke speed) of the tie bar 10 can be controlled to an arbitrary value. In the mold clamping stage, the hydraulic pump 42 is operated at a high speed until each tie bar reaches a predetermined position, and then the hydraulic pump 42 is controlled to move the tie bar 10 at a low speed. Even in this case, in fact, the moving speed of each tie bar 10 varies due to differences in sliding resistance, pipe resistance, and the like with respect to each mold clamping cylinder 25.

  However, if the tie bar 10 of the first mold clamping cylinder 25 first reaches a predetermined position, the position detection sensor 51 detects this to demagnetize the electromagnetic valve 44 corresponding to that mold clamping cylinder. Then, the tie bar 10 is stopped. At the same time, the discharge flow rate of the hydraulic pump 42 is decreased by a predetermined flow rate (for example, decreased by a constant flow rate to a discharge flow rate of 3/4). As a result, the remaining three tie bars 10 also move at the same low speed. If the flow rate of the hydraulic pump 42 is not reduced, the moving speed of the remaining tie bars 10 is increased and the stopping accuracy is lowered.

When the process further proceeds and the tie bar 10 of the second mold clamping cylinder 25 reaches the fitting position with the half nut 22, the position detection sensor 51 detects that and demagnetizes the solenoid valve 44. At the same time, the flow rate of the hydraulic pump 42 is further reduced by a predetermined flow rate (for example, it is reduced by a constant flow rate to a discharge flow rate of 1/2). As a result, the two tie bars 10 thereafter move at a low speed.
When the process further proceeds and the tie bar 10 of the third clamping cylinder 25 reaches the fitting position of the half nut 22, its position detection sensor 51 detects that, and demagnetizes its solenoid valve 44, At the same time, the flow rate of the hydraulic pump 42 is further reduced by a predetermined flow rate (for example, it is reduced by a constant flow rate to a discharge flow rate of 1/4).

When the tie bar 10 of the fourth mold clamping cylinder 25 reaches the fitting position of the half nut 22 and the position detection sensor 51 detects that, the electromagnetic valve 44 is turned off and the operation of the electric motor 41 is simultaneously performed. And stop the process.
If the step of matching the fitting position between the tie bar 10 and the half nut 22 is performed simultaneously during the step of opening the mold and taking out the product, it is preferable because the cycle time is shortened.

  In the second embodiment of the present invention, in the first embodiment, the electric motor 41 is, for example, an electric motor having a constant rotational speed, and the hydraulic pump 42 is, for example, a variable displacement type such as an axial piston type. The discharge flow rate of the hydraulic pump is variable. Other configurations of the second embodiment are basically the same as those of the first embodiment.

Next, effects and operations of the above embodiment will be described.
The following effects can be expected from the mold clamping apparatus according to the first embodiment of the present invention.
・ Variable control of the rotation speed of the electric motor (and hence the hydraulic pump) enables the piston and tie bar to be stroked to the desired predetermined position quickly and accurately. , And the cycle loss of the mold clamping operation can be minimized (the supply amount of hydraulic oil for increasing the pressure to the mold clamping pressure can be reduced).
・ Furthermore, since the speed of the electric motor (and hence the hydraulic pump) is controlled, heat is generated by returning excess hydraulic fluid from the relief valve to the hydraulic tank as in the case of speed control using a conventional flow control valve. In addition, energy loss can be prevented and energy saving can be achieved.

  With the mold clamping device according to the second embodiment of the present invention, the same effect as that of the first embodiment can be expected.

In the above description, the mold clamping device of the present invention has been described as having four mold clamping cylinders. However, the mold clamping device has another number of mold clamping cylinders such as two. There may be.
In the embodiment shown in FIG. 1, the opening / closing device 24 is shown as a mechanism like a ball screw type electric device, but this device may be another type such as a hydraulic cylinder type. .

  In the present embodiment, the present invention is applied to a die casting machine. However, the present invention may be applied to another molding apparatus such as an injection molding apparatus, and the application target of the present invention is not limited to a die casting machine. Absent.

  The above-described embodiment is an example of the present invention, and the present invention is not limited by the embodiment, but is defined only by matters described in the claims, and other embodiments than the above are also possible. It can be implemented.

FIG. 1 is a side view schematically showing a configuration of a die casting machine including a mold clamping device according to a first embodiment of the present invention. FIG. 2 is a system diagram of a hydraulic circuit of the mold clamping apparatus according to the first embodiment of this invention. FIG. 3 is a system diagram of a hydraulic circuit of a conventional mold clamping device corresponding to FIG.

Explanation of symbols

2 Fixed platen (board)
3 Movable platen (board)
4 fixed type 5 movable type 10 tie bar 22 half nut 23 solid nut device 25 mold clamping cylinder 27 piston 35 hydraulic pump unit 40 hydraulic circuit 41 electric motor 42 hydraulic pump 43 tank 44 solenoid valve 45 relief valve (or safety valve)
50 Clamping device 51 Position detection sensor 60 Control device

Claims (9)

After the movable die (5) attached to the movable platen (4) and the stationary die (3) attached to the stationary platen (2) are closed, in cooperation with the tie bar (10) and the half nut (22) A plurality of mold clamping cylinders (25) for applying a mold clamping force to the mold, the mold clamping cylinders (25) having pistons (27) that can reciprocate therein;
A hydraulic circuit (40) for supplying hydraulic oil to the mold clamping cylinder (25) and returning the hydraulic oil therefrom;
A control device (60) for controlling the hydraulic circuit (40) to adjust the clamping force of the clamping cylinder (25), the moving speed of the piston (27), and the stop position;
A position detection sensor (51) for detecting the position of the piston (27);
In a mold clamping device (50) comprising:
The piston (27) inside the mold clamping cylinder (25) is connected to the tie bar (10) and can be interlocked.
The fitting position of the tie bar (10) and the half nut (22) is adjusted by moving the piston (27) in the clamping cylinder (25) by supplying hydraulic oil and supplying hydraulic oil. It can be carried out by stopping and positioning the piston (27) at a predetermined position,
The hydraulic circuit (40) includes a single hydraulic pump unit (35) and a plurality of solenoid valves (44) for switching the supply direction of hydraulic oil to each mold clamping cylinder (25) and stopping the supply. The discharge flow rate of the hydraulic pump unit (35) is variable,
The discharge flow rate of the hydraulic pump unit (35) decreases by a predetermined flow rate when one of the plurality of pistons (27) reaches the fitting position of the tie bar (10) and the half nut (22) and stops. The mold clamping device is characterized in that, when the other piston (27) reaches the fitting position after that, the mold clamping device is adjusted so as to sequentially decrease by a predetermined flow rate.   The mold clamping device according to claim 1, wherein the piston (27) in the mold clamping cylinder (25) is connected to the half nut (22) to be interlocked.   The predetermined flow rate to be reduced is a constant amount, and is a value obtained by dividing the flow rate when all the mold clamping cylinders (25) are simultaneously operated by the number of the mold clamping cylinders (25). The mold clamping apparatus according to claim 1 or 2, wherein the mold clamping apparatus is characterized.   The hydraulic pump unit (35) comprises a hydraulic pump (42) and an electric motor (41) having a variable speed for driving the hydraulic pump (42). The mold clamping apparatus as described in any one of Claims.   5. The mold clamping apparatus according to claim 4, wherein the electric motor (41) is a servo motor.   The mold clamping device according to any one of claims 1 to 5, wherein the number of the plurality of mold clamping cylinders (25) is four. After the movable die (5) attached to the movable platen (4) and the stationary die (3) attached to the stationary platen (2) are closed, in cooperation with the tie bar (10) and the half nut (22) A plurality of mold clamping cylinders (25) for applying a mold clamping force to the mold, the mold clamping cylinders (25) having pistons (27) that can reciprocate therein;
A hydraulic circuit (40) for supplying hydraulic oil to the mold clamping cylinder (25) and returning the hydraulic oil therefrom, a hydraulic pump unit (35) having a variable discharge flow rate, and each of the mold clamping cylinders A hydraulic circuit (40) having a plurality of solenoid valves (44) for switching the supply direction of hydraulic oil to (25) and stopping the supply;
A control device (60) for controlling the hydraulic circuit (40) to adjust the clamping force of the clamping cylinder (25), the moving speed of the piston (27), and the stop position;
A position detection sensor (51) for detecting the position of the piston (27);
A method for controlling a mold clamping device (50) comprising:
In the method of controlling the mold clamping device (50), which operates the piston connected to one of the tie bar (10) and the half nut (22), the method includes:
A positioning procedure for moving one of the half nut (22) and the tie bar (10) by operating the piston (27) and stopping them at a predetermined position where they can be fitted;
An adjustment procedure for adjusting the discharge flow rate of the hydraulic pump unit (35) according to the number of the clamping cylinders (25) that are operating;
It has
In the adjustment procedure, the discharge flow rate of the hydraulic pump unit (35) is stopped when one of the plurality of mold clamping cylinders (25) reaches the fitting position of the tie bar (10) and the half nut (22). Then, the method is adjusted so as to decrease by a predetermined flow rate.   The predetermined flow rate to be reduced is a constant amount, and is a value obtained by dividing the flow rate when all the mold clamping cylinders (25) are simultaneously operated by the number of the mold clamping cylinders (25). 8. A method according to claim 7, characterized in that   The method according to claim 7 or 8, wherein the number of the plurality of mold clamping cylinders (25) is four.

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