Mold changer

Abstract

Mold changing device supplied with an injection molding machine (1), comprising: a first mold changing device (20) configured to generate a drive force for loading a mold (9) into the injection molding machine (1) and a second mold changing device (21) configured to generate a drive force for removing the mold (9) from the injection molding machine (1); wherein the first mold changing device (20) and the second mold changing device (21) each comprise the following: a conveying unit forming a linear transport path and a drag unit (48, 49) configured to move the form (9) along the transport path and a linear guide (47) configured to movably attach the drag unit (48, 49) a pair of power support units (44, 45) arranged along the electric drives (42, 43) and opposite each other wherein each of the power support units (44, 45) comprises a fluid pressure cylinder (S1, S2, S3, S4) which is either a pneumatic cylinder or a hydraulic cylinder, and a piston rod (53) with a tip, the tip of the piston rod comprising an engaging part configured to engage detachably with the tractor unit (48, 49); and the towing unit (48, 49) is provided with a pair of engagement grooves (48a, b; 49a,b) which are open to the front and rear in the direction of transport.

Description

BackgroundField of Expertise

[0001] The present invention relates to a mold changing device provided together with an injection molding machine, which loads and unloads a mold into and from the injection molding machine. State of the art

[0002] Due to diversified needs in recent years, there has been a growing demand for low-volume, high-variation injection molding production. Therefore, the frequency of changing molds used in injection molding machines is increasing.

[0003] It is necessary to shorten the time required for the mold change described above in order to increase productivity.

[0004] To address this need, JP 2018-1738 A discloses a method for accelerating and decelerating a mold by up and down movements of a weight. In JP 2018-1738 A, an electric drive is used as the main component for moving a mold, and the weight is connected to the mold.

[0005] Patent Document 1: JP 2018-1738 A

[0006] According to the method disclosed in JP 2018-1738 A, the weight at the uppermost position is set to a reference position where the mold completes its movement in a mold changer or an injection molding machine. Then, the weight is lowered in synchronization with the movement of the mold by half a stroke or less, reaching the lowest position. The weight begins to rise and stops at the target position as the mold approaches the target position.

[0007] As a result, as the mold accelerates, the weight is pulled and lowered by gravity, accelerating the mold. Therefore, it is possible to achieve high acceleration compared to a configuration using a drive unit, such as an electric motor, alone.

[0008] Furthermore, the weight increases during deceleration of the mold, exerting such a force on the mold that it decelerates. This makes it possible to achieve greater deceleration compared to a configuration where a drive unit, such as an electric drive, is used alone.

[0009] DE 10 2017 114 967 A1 relates to a method for producing an injection-molded part by a single injection-molding machine while switching between two molds, the method comprising: a first step in which a mold closure, injection, and pressure holding take place in the injection-molding machine; a second step in which, after the first step, the mold is transported outside the injection-molding machine and cooled outside the injection-molding machine;and a third step in which, after the second step, the mold is transported into the injection molding machine, the mold is opened, and an injection-molded part is demolded in the injection molding machine, wherein the first to third steps are repeatedly carried out, while the second step is carried out for a first mold, the third step and the next first step are carried out for a second mold, the first mold is transported by a first transport device arranged on one lateral side of the injection molding machine, and the second mold is transported by a second transport device arranged on the other lateral side of the injection molding machine and driven independently of the first transport device;

[0010] WO 82 / 01506 A1 discloses a mold sorting table for operation with an injection molding machine, defining a transfer position for a mold half and left and right loading positions, together with means for moving a mold half to and from the transfer position from or to any of the molding positions of the machine and two loading positions.

[0011] US 2018 / 0 056 558 A1 describes a rotational molding injection molding machine comprising: a fixed platen; a movable platen which is opened and dosed in a horizontal direction with respect to the fixed platen; and a turntable to which a plurality of molds are attached and which is rotatable on the fixed platen or the movable platen, the rotational molding injection molding machine further comprising: a mold member configured from the plurality of molds, and a mold mounting plate to which the plurality of molds are mounted; and a mounting portion provided on the turntable of the fixed platen or the movable platen, and on which the mold mounting plate is mounted when the mold member is mounted. Short description

[0012] However, according to the method disclosed in JP 2018-1738 A, since the weight is at a high position with the mold at a movement start position, it is necessary to perform work such as fixing the position of the mold in order to fix or detach the mold on the mold changing device.

[0013] There is also a method for connecting the weight to the drive unit, such as an electric drive. Generally, the mold changer is turned off for safety when the mold is attached to or removed from the mold changer. However, due to the weight of the weight, it may cause the drive unit, such as an electric drive, to move.

[0014] When the mold is near the reference position, such as in a mold changer or injection molding machine, a force to move the mold is constantly applied to the mold, requiring the drive unit to generate force to hold the mold in place. Therefore, a power supply is required even while the mold is stopped.

[0015] Furthermore, if the power supply to the drive unit, such as the electric drive, is cut off due to an emergency stop or power failure, the weight of the weight can cause the mold to move and come into contact with another mold.

[0016] As a method to prevent the mold from moving when the power is turned off, there is a method using a motor with a brake mechanism in the drive unit. However, the holding force exerted by the brake mechanism is generated by frictional force caused by brake pads and the like, and therefore, it is not desirable to use the brake mechanism daily because the brake mechanism only has a certain service life.

[0017] To increase the acceleration and deceleration of the mold, a larger weight must be installed within an area where the drive unit can easily take control.

[0018] However, up and down movements of such a large weight can cause vibrations in the mold changing device or the injection molding machine.

[0019] When the weight's motion changes rapidly from rising to falling, a strong jerk continues to be exerted on wire elements, such as chains and wires, and rotating elements, such as pulleys and pinions. Therefore, elements with sufficiently high strength must be used and the elements replaced regularly.

[0020] Since it is still necessary to provide space for moving the weight up and down in the mold changing device, it may be necessary to increase the size of the mold changing device.

[0021] In light of the above problems of the above-mentioned conventional art, an object of the present invention is to provide a mold changing device having excellent operability, safety, energy saving and space efficiency while achieving high acceleration and deceleration of a mold at the time of changing the mold.

[0022] A mold changing device according to the present invention, which is provided together with an injection molding machine, comprises a main conveyor unit configured to load and unload a mold into and from the injection molding machine, the conveyor unit capable of generating a driving force for positioning the mold, and a force assisting unit configured to assist the conveyor unit in accelerating and decelerating the mold.

[0023] Such a configuration makes it possible to move the mold between a removal position, where the mold is released from the injection molding machine, and a loading position, where the mold is attached to the injection molding machine, by the driving force exerted by the conveyor unit.

[0024] A compressive force directed forward in a transport direction is exerted on the mold by the force assist unit when the transport of the mold begins.

[0025] This pressure force acts as an auxiliary drive force to the drive force exerted by the conveyor unit.

[0026] As described above, at the start of the mold transportation, a transportation force applied to the mold can be amplified by adding the auxiliary driving force, which is the pressing force applied by the force assisting unit, to a transportation force, which is the driving force applied by the conveying unit.

[0027] This makes it possible to increase a change in the transport speed of the mold compared to a configuration where the main conveyor unit is used alone.

[0028] On the other hand, when the mold approaches a predetermined transport position, the transport speed of the mold is reduced by the driving force exerted by the conveying unit.

[0029] The force support unit interacts with the conveyor unit during a deceleration process and exerts a compressive force in a direction opposite to the transport direction, thus supporting the deceleration of the mold.

[0030] Accordingly, when decelerating the mold, the deceleration force exerted on the mold can be amplified by adding the auxiliary deceleration force, which is the pressing force exerted by the force assisting unit, to the deceleration force exerted by the conveying unit.

[0031] This makes it possible to increase a change in transport speed when decelerating the mold.

[0032] Such a larger change in the transport speed during acceleration or deceleration of the mold makes it possible to increase the loading and unloading speed of the mold and thereby shorten the time required for mold change.

[0033] For example, a fluid pressure cylinder using pneumatic pressure or hydraulic pressure is expediently used as a power assist unit that increases the driving force exerted by the conveyor unit for loading and unloading.

[0034] The fluid pressure cylinder has a simple structure consisting of a cylinder body and a piston rod and is therefore cost-effective.

[0035] Controlling the opening and closing of valves connected to the fluid pressure cylinders allows the fluid pressure cylinders to produce an effect only when necessary.

[0036] Since the effect can still be easily adjusted by adjusting the pressure in each of the fluid pressure cylinders, the scale reduction is easy.

[0037] Therefore, it is possible to ensure that the mold changing device has excellent manageability, safety, energy saving and space efficiency while achieving high acceleration and deceleration.

[0038] The conveyor unit may be a drive comprising a towing unit to which the mold is coupled and forming a linear transport path.

[0039] This drive can, for example, be an electric drive consisting of a combination of a servo motor, a ball screw, and a linear guide. The drive can also be any drive capable of generating a driving force to move the mold linearly.

[0040] For example, the electric actuator can stop at a suitable position on the linear guide, which has a linear shape, with a nut serving as a drag unit that moves along an axis of the ball screw and holds the nut in the stop position. Therefore, the electric actuator enables the mold connected to the nut to move or stop with high precision.

[0041] Furthermore, the power assist unit can be arranged along the electric drive since the electric drive has a linear external shape.

[0042] This allows the components of the conveyor unit to be arranged compactly, thus keeping the installation space small.

[0043] The tip of the piston rod of the fluid pressure cylinder is provided with an engaging part that releasably engages the nut part.

[0044] Such a configuration makes it possible to couple the force support unit and the mold with the nut part.

[0045] This makes it possible to simplify the structure of transmission of the driving force exerted by the force assist unit to the mold.

[0046] A single-acting retractable cylinder or a double-acting cylinder is used as a fluid pressure cylinder. Pneumatic pressure or hydraulic pressure is used as the fluid that drives the fluid pressure cylinder.

[0047] According to the mold changing device of the present invention, it is possible to provide a mold changing device with excellent manageability, safety, energy saving and space efficiency while achieving high acceleration and deceleration of the mold at the time of mold changing. Brief description of the drawings Fig. 1 is a plan view of an injection molding machine to which an embodiment of a mold changing device according to the present invention is applied; Fig. 2 shows the injection molding machine to which the embodiment of the mold changing device according to the present invention is applied, viewed from the direction of a mold mounting surface of a fixed mold; Fig. 3 is an enlarged perspective view of a drive unit of the embodiment of the mold changing device according to the present invention; Fig. 4 is a schematic view of the embodiment of the mold changing device according to the present invention, showing the mold changing process; Fig. 5 is a schematic view of the embodiment of the mold changing device according to the present invention, showing the mold changing process; Fig. 6 is a schematic view of the embodiment of the mold changing device according to the present invention, showing the mold changing process; Fig. 7 is a schematic view of the embodiment of the mold changing device according to the present invention, showing the mold changing process; Fig. 8 is a schematic view of the embodiment of the mold changing device according to the present invention, showing the mold changing process. Detailed description

[0048] An embodiment of the present invention will be described with reference to the drawings.

[0049] First, descriptions will be given of a configuration of an injection molding machine to which the embodiment of the present invention is applied and a procedure for changing the mold in the injection molding machine with reference to Fig. 1.

[0050] In these drawings, reference numeral 1 denotes the injection molding machine.

[0051] The injection molding machine 1 comprises: a base 2; two parallel fixed platens 3 and 4 fixed to the base 2 at a distance from each other and bonded thereto; four tie rods 5 integrally installed between the fixed platens 3 and 4 (only the two tie rods arranged at the top are shown in the drawings); a movable platen 6 slidably mounted between the two fixed platens 3 and 4 on the tie rods 5; an injection cylinder 7 provided on the side of one fixed platen 3 for injecting a molding resin; and a clamping device 8 attached to the other fixed platen 4 for urging the movable platen 6 toward the one fixed platen 3.

[0052] A fixed mold 9 is detachably attached by clamps 10 to the surface of one fixed mold clamping plate 3 opposite the movable mold clamping plate 6 (mold mounting surface). A movable mold 11 is detachably attached by clamps to the surface of the movable mold clamping plate 6 opposite the fixed mold clamping plate 3 (mold mounting surface).

[0053] Mold changing devices 20 and 21 are provided on both sides of the injection molding machine 1, facing positions between the one fixed mold platen 3 and the movable mold platen 6 to perform a mold change between the fixed mold 9 and the movable mold 11.

[0054] The mold changing devices 20 and 21 include bases 22 and 23 that are nearly orthogonal to the base 2 of the injection molding machine 1. A large number of rollers 30 are arranged on the top surfaces of the bases 22 and 23 to support the fixed mold 9 and the movable mold 11 (hereinafter referred to as mold (9, 11)).

[0055] These rollers 30 are arranged so that the transport direction is orthogonal to the pull rods 5 in two rows on the bases 22 and 23 with distances therebetween in the longitudinal direction of the pull rods 5.

[0056] Furthermore, the rollers 30 are installed on the mold mounting surfaces of the fixed mold clamping plate 3 and the movable mold clamping plate 6, as shown in Fig. 2 (note that Fig. 2 shows a state in which the rollers 30 are installed only on the fixed mold clamping plate 3).

[0057] Furthermore, the mold changing devices 20 and 21 according to the present embodiment are located on the bases 22 and 23.

[0058] As in Fig. 1, the mold changing devices 20 and 21 comprise electric drives 42 and 43 arranged between the rows of rollers 30 on the bases 22 and 23 and parallel to the row direction, and a pair of power assist units 44 and 45 arranged along the electric drives 42 and 43.

[0059] The pair of mold changing devices 20 and 21 according to the present embodiment have the same configuration and are arranged symmetrically with the injection molding machine 1 therebetween. A description will be given below of one mold changing device 21, and reference numerals in parentheses indicating components of the other mold changing device 20 are appended to the reference numerals for the one mold changing device 21.

[0060] In particular, the electric drive 43 (42) comprises a linear guide 47 (46) located linearly between the rows of rollers 30 and a drag unit 49 (48) movably mounted on the linear bearing and coupled to the mold.

[0061] As in Fig. 2, the fixed mold 9 is integrally coupled to the drag unit 49 (48) by a coupling arm 51 (50), which enables the fixed mold 9 to move synchronously with the drag unit 49 (48) along the linear guide 47 (46).

[0062] First, a description will be given of a configuration of the towing unit 49 (48) with reference to Fig. 3.

[0063] On both sides of the towing unit 49 (48), engagement grooves 49a and 49b (48a and 48b) are formed, which are open forward and backward in the transport direction.

[0064] According to the present embodiment, the power assist unit 45 uses a pair of fluid pressure cylinders S1 and S2 (S3 and S4) actuated by compressed air. The fluid pressure cylinders S1 and S2 (S3 and S4) are single-acting, retraction-type cylinders.

[0065] As in Fig. As shown in Figure 2, the fluid pressure cylinders S1 and S2 (S3 and S4) are arranged opposite each other. A locking pin 53 (52), which is releasably engaged in the drag unit 49 (48) via the openings of the engagement grooves 49a and 49b, is provided at the tip of each piston rod of the fluid pressure cylinders S1 and S2 (S3 and S4).

[0066] According to the present embodiment, the locking pin 53 (52) serves as an engagement part between the drag unit 49 (48) and a corresponding one of the fluid pressure cylinders S1 and S2 (S3 and S4).

[0067] Next, a description will be given of a drive system of the fluid pressure cylinders S1 and S2 (S3 and S4) with reference to Fig. 4.

[0068] The compressed air supply pipes P1 and P2 for supplying the compressed air to retract the piston rods are each connected to a corresponding piston chamber of each of the fluid pressure cylinders S1 and S2 (S3 and S4).

[0069] An air compressor A, which supplies the compressed air, is connected to the compressed air supply pipes P1 and P2, and the solenoid valves V1 and V5 are located in the middle of the air supply pipes P1 and P2, respectively.

[0070] Furthermore, the solenoid valves V2 and V6 and the pressure relief valves V3 and V7 are connected between the fluid pressure cylinders S1 and S2 and the solenoid valves V1 and V5 in the compressed air supply pipes P1 and P2.

[0071] The solenoid valves V2 and V5 each cause a corresponding one of the compressed air supply pipes P1 and P2 to communicate with the atmosphere or to be shut off from it.

[0072] The pressure relief valves V3 and V7 each prevent pressure in a corresponding piston chamber from rising to or above a predetermined value.

[0073] On the other hand, the intake and discharge pipes P3 and P4 are each connected to the other piston chamber of a corresponding one of the fluid pressure cylinders S1 and S2 (S3 and S4). Solenoid valves V4 and V8, which each open and close a corresponding one of the intake and discharge pipes P3 and P4, are connected to the intake and discharge pipes P3 and P4.

[0074] The respective drive units of the solenoid valves V1, V2, V4, V5, V6, and V8 are electrically connected to a control unit C. The solenoid valves V1, V2, V4, V5, V6, and V8 are individually opened and closed according to a control signal from the control unit C.

[0075] Although the pressure relief valves V3 and V7, like the other solenoid valves, can be individually opened and closed according to a control signal from the control unit C, it is more reliable to use mechanical pressure relief valves that do not require such control.

[0076] Furthermore, the electric drive 43 (42) is electrically connected to the control unit C, and information such as position information, speed information and thrust information about the carriage 49 are sent from the electric drive to the control unit C.

[0077] As in Fig. 4, the mold changing device 21 (20) according to the present embodiment moves the mold (9, 11) between a removal position on the mold changing device 21 (20) and a loading position in the injection molding machine 1.

[0078] The following is a description of a step of charging the mold (9, 11).

[0079] The towing unit 49 (48), to which the fixed mold 9 is connected, is stopped in a waiting position by the electric drive 43 (42), whereby the mold (9, 11) is held in the removal position.

[0080] Furthermore, as in Fig. 4, the engagement groove 49a, which opens rearwardly in the transport direction relative to the towing unit 49 (48), extends to the fluid pressure cylinder S1, which is located downstream in the transport direction. A locking pin 53 (52) located in the fluid pressure cylinder S1 (S3) engages.

[0081] Each of the solenoid valves is controlled, for example under the following condition 1. Condition 1:

[0082] Solenoid valve V1 closed and solenoid valves V2 and V4 open.

[0083] This condition can keep the fluid pressure cylinder S1 (S3) in a stopped state.

[0084] The mold (9, 11) in the waiting position is moved by a driving force exerted by the electric drive 43 (42) synchronously with the towing unit 49 to the mold changing device 20, as is done by a Fig. 5 is displayed.

[0085] At the start of the operation of the electric drive 43 (42), each of the solenoid valves is controlled under the following condition 2. Condition 2:

[0086] Solenoid valves V1 and V4 open and solenoid valve V2 closed.

[0087] Condition 2 ensures that the compressed air is supplied to one cylinder chamber of the fluid pressure cylinder S1 (S3) via the compressed air supply pipe P1.

[0088] Under this control, the fluid pressure cylinder S1 (S3) is actuated to retract, and the locking pin 53 (52) located on the fluid pressure cylinder S1 (S3) pushes the drag unit 49 (48) in the locked state toward the injection molding machine 1, as required by the Fig. 5 is displayed to increase the driving force.

[0089] Therefore, in addition to a transport force exerted by the electric drive 43 (42), a pressure force exerted by the fluid pressure cylinder S1 (S3) also acts on the mold (9, 11).

[0090] This increases the transport force acting on the shape (9, 11), which increases the translation speed of the shape (9, 11) (ie the transport speed).

[0091] Note that the control of each of the transport assist solenoid valves described above can also be performed before the mold is loaded.

[0092] This is effective to prevent a time delay during which the pressure force builds up, since it takes a certain time to supply factory air, i.e. compressed air, to the fluid pressure cylinder S1 (S3) to increase the pressure to a sufficient value.

[0093] Although the mold (9, 11) is transported in an accelerated state, during the transport, the fluid pressure cylinder S1 (S3) fully retracts, or the solenoid valve is controlled under the following condition 3 or condition 4, so that the operation of the fluid pressure cylinder S1 (S3) is interrupted. Condition 3:

[0094] Solenoid valve V1 closed. Condition 4:

[0095] Solenoid valves V1 and V4 closed.

[0096] This interrupts the supply of compressed air to the fluid pressure cylinder S1 (S3) and then releases the locking pin 53 (52) from the towing unit 49 (48), as shown in Fig. 6 is shown.

[0097] Even after the fluid pressure cylinder S1 (S3) is released from the towing unit 49 (48), the transport of the mold (9, 11) is continued by the electric drive 43 (42).

[0098] Then, when the transport position reaches half of the transport distance, the transport speed of the mold (9, 11) is reduced by a deceleration force generated by the electric drive 43 (42).

[0099] Before and after the time when the mold (9, 11) is decelerated by the electric drive 43 (42), the engagement groove 49b of the drag unit 49 (48), which is opened forward in the transport direction, is engaged by the locking pin 53 of the other fluid pressure cylinder S2 (S4) which is kept retracted, as shown in Fig. 7 is shown.

[0100] Before the towing unit 49 (48) and the locking pin 53 (52) engage with each other, each of the solenoid valves is controlled, for example under the following condition 5. Condition 5:

[0101] Solenoid valve V5 and V8 open and solenoid valve V6 closed.

[0102] This control brings the locking pin 53 (52) and the drag unit 49 (48) into contact with each other before the mold (9, 11) reaches a reference position in the injection molding machine.

[0103] As described above, when the locking pin 53 (52) comes into contact with the drag unit 49 (48), the fluid pressure cylinder S2 (S4) and the mold (9, 11) are coupled together. An inertial force of the mold (9, 11) acts on the fluid pressure cylinder S2 (S4) so ​​that the fluid pressure cylinder S2 (S4) extends.

[0104] However, since the fluid pressure cylinder S2 (S4) is actuated to retract, a pull is created against an external force that would like to extend the fluid pressure cylinder S2 (S4).

[0105] This tension on the fluid pressure cylinder S2 (S4) acts to assist the deceleration action of the electric drive 43 (42), which in turn increases the change in speed of the mold (9, 11) during deceleration.

[0106] Under condition 5, the deceleration effect can be obtained by closing the solenoid valve V5 or V8, but the deceleration force can be made constant by opening the solenoid valves V5 and V8.

[0107] Such a deceleration effect makes it possible to quickly stop the mold (9, 11) at the reference position in the injection molding machine 1, as shown in Fig. 8 is shown.

[0108] For example, after the mold (9, 11) is stopped at the reference position, each of the solenoid valves is controlled under the following condition 6. Condition 6:

[0109] Solenoid valve V5 closed and solenoid valves V6 and V8 open.

[0110] This control eliminates thrust applied to the fluid pressure cylinder S2 (S4) so ​​that the mold (9, 11) is kept in the stopped state.

[0111] However, if the mold (9, 11) is fixed, for example, by a mold clamping device so that it can receive the thrust applied to the fluid pressure cylinder S2 (S4), the control can be continued under the condition B described above.

[0112] In particular, when the mold (9, 11) is in the injection molding machine 1, it is desirable not to release the compressed air, since the mold (9, 11) is held by the clamps.

[0113] When the mold (9, 11) is held by the clamps, it is possible to make the thrust exerted by the electric actuator 43 (42) disappear independently of the thrust exerted on the fluid pressure cylinder S2 (S4) because the mold (9, 11) is held by the clamps.

[0114] Further, when the control is performed under the above-described condition 5, the compressed air is enclosed between the fluid pressure cylinders S1 and S2 (S3 and S4) and the air compressor A. Thus, compressed air hardly leaks, which makes it possible to repeatedly use the compressed air for the acceleration and deceleration of the mold.

[0115] This in turn makes it possible to reduce the energy required to generate the compressed air.

[0116] On the other hand, in the case where the mold is on the mold changing device 21 (20) and no clamp is prepared on the mold changing device 21 (20), it is desirable that the compressed air in the fluid pressure cylinder S1 (S3) is released when the mold (9, 11) is stopped.

[0117] The reason for this is that in a case where the thrust applied to the fluid pressure cylinder S1 (S3) is maintained, the electric actuator 43 (42) must be caused to generate a thrust against the thrust applied to the fluid pressure cylinder S1 (S3) in order to stop the mold (9, 11).

[0118] When the thrust is continuously generated by the electric drive 43 (42), the load on the electric drive 43 (42) increases and the power consumption also increases.

[0119] However, when the compressed air in the fluid pressure cylinder S1 (S3) is released, compressed air must be newly generated to compensate for the thus released compressed air, which increases the power consumption of the air compressor A.

[0120] Therefore, if the stopping time of the mold (9, 11) is short, a method in which the compressed air is not released is also an effective option.

[0121] Such an acceleration function and deceleration function can be carried out in the same way by operating the pair of fluid pressure cylinders S1 and S2 (S3 and S4) in a reverse order to the operations described above to take out the mold (9, 11).

[0122] It is extremely important how quickly the mold can be stopped in an emergency because the mold is heavy.

[0123] The fluid pressure cylinders S1 and S2 (S3 and S4) usually support both the acceleration and deceleration performed by the electric drive 43 (42) with a constant force. However, a high deceleration force can be achieved by closing the solenoid valves V5, V6, and V8 in an emergency stop during loading or closing the solenoid valves V1, V2, and V4 in an emergency stop during unloading, increasing the pressure to the limit.

[0124] However, the maximum allowable pressure of the fluid pressure cylinders S1 and S2 (S3 and S4) is predetermined, so that when the internal pressure reaches the maximum allowable pressure, the pressure relief valves V3 and V7 are actuated, thereby releasing the compressed air in the fluid pressure cylinders S1 and S2 (S3 and S4) so ​​that the internal pressure becomes less than or equal to the maximum allowable pressure.

[0125] This makes it possible to prevent damage to the fluid pressure cylinders S1 and S2 (S3 and S4).

[0126] After the emergency stop, closing the solenoid valves V1 and V5 and opening all other solenoid valves can prevent the compressed air from remaining in the fluid pressure cylinders S1 and S2 (S3 and S4) and thus prevent unintentional movement of the mold (9, 11).

[0127] Note that the type, shape, and the like of each of the components shown in the above-described embodiment are merely examples, and various changes may be made depending on the requirements of construction and the like.

[0128] For example, although the description has been made of the example in which the pneumatic type fluid pressure cylinders S1, S2, S3 and S4 are used, hydraulic type fluid pressure cylinders may be used instead.

[0129] Furthermore, the single-acting retraction-type cylinder can be replaced by a single-acting push-type cylinder, or a double-acting cylinder can be used.

[0130] Various motors, such as stepper motors, can be used as the main conveyor unit instead of servo motors. A rack and pinion drive can also be used instead of a ball screw.

[0131] Furthermore, the main conveying unit may be a linear motor or the like or alternately a hydraulic cylinder or pneumatic cylinder with a positioning function.

Claims

[1] A mold changing device provided together with an injection molding machine (1), comprising: a first mold changing device (20) which is designed to generate a driving force for loading a mold (9) into the injection molding machine (1) and a second mold changing device (21) which is designed to generate a driving force for removing the mold (9) from the injection molding machine (1); wherein the first mold changing device (20) and the second mold changing device (21) each comprise: a conveyor unit forming a linear transport path and a drag unit (48, 49) configured to move the mold (9) along the transport path and a linear guide (47) configured to movably mount the drag unit (48, 49) a pair of power assist units (44, 45) arranged along the electric drives (42, 43) and opposite each other wherein each of the power assist units (44, 45) comprises a fluid pressure cylinder (S1, S2, S3, S4), which is either a pneumatic cylinder or a hydraulic cylinder, and a piston rod (53) having a tip, the tip of the piston rod comprising an engaging portion configured to releasably engage the tractor unit (48, 49); and the towing unit (48, 49) is provided with a pair of engagement grooves (48a, b; 49a, b) which are open forward and backward in the transport direction. [2] A mold changing device according to claim 1, wherein each of the fluid pressure cylinders (S1, S2, S3, S4) is a single-acting retraction type cylinder. [3] A mold changing device according to claim 1, wherein each of the fluid pressure cylinders (S1, S2, S3, S4) is a double-acting cylinder.

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