CN113464510A - Hydraulic device and injection molding machine - Google Patents

Abstract

The invention provides a hydraulic device and an injection molding machine, which can effectively remove particles such as dust in a reciprocating flow path in which a working fluid reciprocates. The hydraulic device is used for an injection molding machine, and is provided with a hydraulic circuit through which an operating fluid flows, wherein the hydraulic circuit is provided with a reciprocating flow path (1) which generates one-direction flow (F1) and reverse flow (F2) of the operating fluid, the reciprocating flow path (1) comprises a plurality of branch flow path parts (2a) and (2b) which are branched into two or more parts and are mutually merged at the middle part of the reciprocating flow path, and are respectively responsible for the flow of either one of the one-direction flow (F1) and the reverse flow (F2) of the operating fluid, and a filter (5) is arranged in at least one of the branch flow path parts (2a) and (2 b).

Description

Hydraulic device and injection molding machine

Technical Field

The present application claims priority based on japanese patent application No. 2020 and 064794, filed on 31/3/2020. The entire contents of this Japanese application are incorporated by reference into this specification.

The present invention relates to a hydraulic device for an injection molding machine and an injection molding machine.

Background

Hydraulic devices are used for driving hydraulic cylinders or other hydraulic actuators. The hydraulic device generally operates a hydraulic actuator by causing a hydraulic fluid, typically hydraulic oil, to flow into a hydraulic circuit at a predetermined pressure by operation of a hydraulic pump or the like, to flow into the hydraulic actuator, and to flow out of the hydraulic actuator. This enables a large driving force to be obtained with a small hydraulic device.

In such a hydraulic apparatus, even if the hydraulic circuit is a closed circuit, dust entering from a minute gap of the hydraulic apparatus or the like, dust due to abrasion of metal parts in the hydraulic circuit or the like, sludge of the working fluid, and other fine particles may be mixed into the working fluid as the hydraulic apparatus is used. Filters are provided in the hydraulic circuit to remove such particulates from the working fluid to ensure long term proper operation of the hydraulic device.

The hydraulic device described above is sometimes used in combination with a hydraulic actuator in a mold clamping device, an ejector device, or the like of an injection molding machine to provide a mold clamping operation, a molded product removal operation, and other predetermined operations (for example, refer to patent document 1).

Patent document 1: japanese patent laid-open publication No. 2018-171904

However, in the hydraulic device described above, the hydraulic circuit may be provided with a reciprocating flow path that causes the hydraulic fluid to reciprocate by repeatedly generating one-way flow and a reverse flow of the hydraulic fluid. In this case, if a filter for removing particulates such as dust is provided in the reciprocating flow path, particulates in the working fluid trapped in the filter when flowing in one direction or the opposite direction are released from the filter and mixed again into the working fluid when flowing in the other direction. Therefore, a filter capable of effectively removing particulates cannot be provided in such a reciprocating flow path.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a hydraulic device and an injection molding machine capable of effectively removing fine particles such as dust in a reciprocating flow path through which a working fluid reciprocates.

A hydraulic apparatus which is used in an injection molding machine and which includes a hydraulic circuit in which a working fluid flows, the hydraulic circuit including a reciprocating flow path which generates a one-direction flow of the working fluid and a reverse flow of the working fluid, the reciprocating flow path including a plurality of branch flow path portions which branch into two or more streams midway, join with each other, and respectively take charge of either one of the one-direction flow of the working fluid or the reverse flow of the working fluid, wherein a filter is provided in at least one of the plurality of branch flow path portions.

Further, an injection molding machine for injecting a molding material into a mold device, which is provided with the hydraulic device, can solve the above problems.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the hydraulic device and the injection molding machine, fine particles such as dust can be effectively removed in the reciprocating flow path in which the working fluid reciprocates.

Drawings

Fig. 1 is a circuit diagram showing a reciprocating flow path of a hydraulic circuit provided in a hydraulic device according to an embodiment of the present invention.

Fig. 2 is a circuit diagram showing a reciprocating flow path of a hydraulic circuit provided in a hydraulic device according to another embodiment.

Fig. 3 is a cross-sectional view showing an example of an injection molding machine to which a hydraulic device according to an embodiment of the present invention can be applied.

Fig. 4 is a cross-sectional view of the mold clamping device and the mold apparatus and a circuit diagram of a hydraulic circuit of the hydraulic apparatus, which show the operation of the mold clamping device and the hydraulic apparatus provided in the injection molding machine of fig. 3 together with the mold apparatus.

Fig. 5 is a sectional view of the mold clamping device and the mold apparatus and a circuit diagram of a hydraulic circuit of the hydraulic device, which show operations subsequent to fig. 4.

Fig. 6 is a sectional view of the mold clamping device and the mold apparatus and a circuit diagram of a hydraulic circuit of the hydraulic device, which show operations subsequent to fig. 5.

Fig. 7 is a sectional view of the mold clamping device and the mold apparatus and a circuit diagram of a hydraulic circuit of the hydraulic device, which show operations subsequent to fig. 6.

Description of the symbols

1. 1a to 1 c-reciprocating flow path, 2a, 42 a-first branch flow path portion, 2b, 42 b-second branch flow path portion, 3a, 43 a-first flow path connecting portion, 3b, 43 b-second flow path connecting portion, 4a, 4b, 44a, 44 b-check valve, 5, 45-filter, 6 a-first main flow path portion, 6 b-second main flow path portion, 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7 h-flow path portion, 8-tank, 10-injection molding machine, 11-injection device, 12-screw, 13-heating device, 14-cylinder, 14 a-supply port, 14 b-nozzle, 14 c-water-cooling cylinder, 15-motor box, 21-moving device, 22-hydraulic pump, 23-pump-work motor, 24-hydraulic cylinder, 25-slide base, 26-guide, 31-clamp, 32-platen, 32 a-fixed platen, 32 b-movable platen, 32C-connecting rod, 33-platen running mechanism, 34-cylinder body portion, 34 a-flange, 34 b-step, 35-piston portion, 36-rod portion, 37-cylinder closing portion, 37 a-small diameter end portion, 41-hydraulic circuit, 101-mold device, 102-fixed mold, 103-movable mold, 104-movable member, F1-one-direction flow of working fluid, F2-reverse flow of working fluid, C1-first hydraulic chamber, C2-second hydraulic chamber, C3-third hydraulic chamber, P1-first hydraulic port, p2-second hydraulic port, P3-third hydraulic port, HP-hydraulic pump, SM-servomotor, L1-first supply and discharge flow path, L2-second supply and discharge flow path, L3-third supply and discharge flow path, CL-flow path connection, SV 1-SV 3-stop valve, RT-reservoir tank, PV-charging valve, Lc-common flow path, La-regulation flow path, Ls-auxiliary flow path, Fr-frame.

Detailed Description

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

(Hydraulic circuit)

A hydraulic apparatus according to an embodiment of the present invention is an apparatus for causing a hydraulic fluid to flow through a hydraulic circuit and driving a hydraulic cylinder such as a hydraulic cylinder, a hydraulic motor, and various other hydraulic actuators provided in an injection molding machine, which will be described later, by a pressure generated in the hydraulic circuit.

The hydraulic device has a reciprocating flow path 1 as shown in fig. 1, for example, in a part thereof. In the reciprocating flow path 1 illustrated in fig. 1, at a certain timing when the hydraulic apparatus is used, the hydraulic fluid such as the hydraulic oil flows in the one-directional flow F1 indicated by an arrow in fig. 1. And, at a timing different from the timing, the working fluid flows along a reverse flow F2 for the reverse arrow in fig. 1. That is, in the reciprocating flow path 1, the one-direction flow F1 of the working fluid and the reverse flow F2 of the working fluid are repeatedly generated, and the working fluid reciprocates in one direction and the reverse direction.

In this way, even if a filter including filter paper or the like is simply disposed in the reciprocating flow path in which the working fluid reciprocates, the function of trapping fine particles such as dust by the filter does not effectively function. This is because, even if the particulates contained in the working fluid are trapped in the filter when the working fluid flows in one direction or the reverse direction, the particulates are released from the filter and mixed again into the working fluid when the working fluid flows in the other direction by reciprocating the working fluid.

In contrast, in this embodiment, the reciprocating flow path 1 includes a plurality of branch flow path portions 2a and 2b that branch into two or more streams and join each other in the middle. More specifically, the reciprocating flow channel 1 includes 2 first branch flow channel parts 2a and 2b that branch into two and join with each other, and the first flow channel connecting part 3a and the second flow channel connecting part 3b are provided at the branching point or the joining point thereof. In addition, when the working fluid flows in one direction F1, the first channel connecting part 3a becomes a branch point and the second channel connecting part 3b becomes a confluence point, and when the working fluid flows in the reverse direction F2, the second channel connecting part 3b becomes a branch point and the first channel connecting part 3a becomes a confluence point.

Further, in each of the first branch passage portion 2a and the second branch passage portion 2b, a check valve 4a and a check valve 4b are disposed midway therebetween. As a result, the first branch passage part 2a and the second branch passage part 2b are caused to flow in only one direction of the working fluid, i.e., either the one direction F1 or the reverse direction F2. Here, as an example, the check valves 4a and 4b are arranged such that the first branch flow path portion 2a takes charge of one-directional flow F1 of the working fluid and the second branch flow path portion 2b takes charge of a reverse flow F2 of the working fluid.

At least one of the first branch flow path part 2a and the second branch flow path part 2b is provided with the filter 5 only in the first branch flow path part 2a in the embodiment shown in fig. 1. Accordingly, since the working fluid always passes through the filter only in one of the one-direction flow F1 and the reverse flow F2, the particulate matter trapped in the filter 5 in the one direction can be prevented from being separated from the filter 5 in the other-direction flow. As a result, particulates can be effectively removed from the working fluid by the filter 5, and the working fluid is kept clean while the hydraulic device is in use.

In the first branch flow path portion 2a provided with the filter 5, the check valve 4a is preferably disposed on the upstream side of the filter 5 in the flow direction of the working fluid (the direction in which the working fluid flows in one direction F1). In the example shown in fig. 1, a check valve 4a is disposed between the first channel connecting portion 3a and the filter 5 in the first branch channel portion 2 a. In this case, when the working fluid cleaned by the filter 5 in the one-direction flow F1 is sucked through the second branch flow path portion 2b in the reverse flow F2 by switching the flow direction, the uncleaned working fluid that may remain between the filter 5 and the check valve 4a is prevented from being sucked by the check valve 4 a.

In the detailed description of the reciprocating flow path 1 illustrated in fig. 1, the working fluid flowing in the first main flow path portion 6a along the one-directional flow F1 flows into the first branch flow path portion 2a from the first flow path connecting portion 3a because it cannot flow through the check valve 4b and the second branch flow path portion 2 b. In the first branch flow path part 2a, the working fluid passes through the flow path portion 7a between the first flow path connecting part 3a and the check valve 4a, the flow path portion 7b between the check valve 4a and the filter 5, and the flow path portion 7c between the filter 5 and the second flow path connecting part 3b in this order, and reaches the second main flow path part 6 b. On the other hand, when the working fluid flows in the reverse direction F2, the working fluid flows from the second main channel portion 6b into the second branch channel portion 2b at the second channel connecting portion 3b, flows into the first branch channel portion 2a where the check valve 4a is present, and flows into the first main channel portion 6a through the channel portion 7d between the second channel connecting portion 3b and the check valve 4b, and the channel portion 7e between the check valve 4b and the first channel connecting portion 3a in this order.

Although not shown in the drawings, three or more flow path branching portions may be provided in the reciprocating flow path. In this case, by providing a check valve or the like, at least one of the three or more flow path branching portions causes the working fluid to flow only in one direction, and the other at least one flow path branching portion causes the working fluid to flow only in the opposite direction. Then, by providing a filter in at least one of these flow path branching portions, the above-described function of trapping fine particles by the filter can be effectively exhibited.

As the filter 5, various filters usable in hydraulic devices such as hydraulic devices can be used. Specifically, for example, there are an intake line filter, an inline filter, a return line filter, and other line filters. As an example, a filter in which a cylindrical filter element such as a cylinder is disposed inside a frame body can be cited. In this filter, the working fluid flows into the space on the outer peripheral side of the filter element inside the frame, passes through the cylindrical filter element from the outer peripheral side toward the inner peripheral side, and is then discharged from the space on the inner peripheral side of the filter element to the outside of the frame. The filter element can be made of filter paper, metal mesh or punched metal or the like. When the working fluid passes through the filter element, particulates such as dust in the working fluid are trapped in the filter element.

The flow path portion other than the filter 5 and various valves in the reciprocating flow path 1 can be formed of a steel pipe or other piping such as a metal pipe and/or a rubber hose.

As in the embodiment shown in fig. 2 (a), the filters 5a and 5b may be provided in 2 or more of the plurality of branch flow path portions 2a and 2 b. The reciprocating flow path 1a in fig. 2 (a) has substantially the same configuration as the embodiment shown in fig. 1 except that the filter 5b is disposed downstream of the check valve 4b in the flow direction of the working fluid (the direction of the backward flow F2) in the second branch flow path portion 2b, and the flow path portion 7F is provided between the check valve 4b and the filter 5 b. In this case, even in the second branch flow path portion 2b where only the reverse flow F2 of the working fluid is generated, the fine particles in the working fluid can be effectively removed by the filter 5 b. However, since the arrangement of the filters 5a and 5b causes a pressure loss here, depending on the configuration of the hydraulic device and the hydraulic circuit thereof, it may be preferable to arrange the filter 5 only in the first branch flow path portion 2a as shown in fig. 1.

As shown in fig. 2 (b), at least one branch flow path portion 2a may be provided with 2 or more check valves 4a and 4c, as shown in the reciprocating flow path 1 b. In the reciprocating flow path 1b, as an example, in the first branch flow path portion 2a, 2 check valves 4a and 4c are disposed on both sides in the flow direction of the working fluid with the filter 5 interposed therebetween. The first branch flow path portion 2a is constituted by a flow path portion 7a, a check valve 4a, a flow path portion 7h, a filter 5, a flow path portion 7g, a check valve 4c, and a flow path portion 7c, which are provided in this order in the direction in which the working fluid flows F1 in one direction. The other structure is substantially the same as that of the reciprocating flow path 1 shown in fig. 1. In the reciprocating flow path 1b of fig. 2 (b), when the working fluid flows in the reverse flow F2, the working fluid is prevented from reaching the filter 5 of the first branch flow path portion 2a and further reaching the flow path portion 7h ahead thereof by the check valve 4c of the first branch flow path portion 2a, and therefore contamination of the working fluid by the particulates once trapped in the filter 5 can be further effectively prevented.

The embodiment shown in fig. 2c further includes a tank 8 capable of storing the working fluid, and one end portion on the most downstream side (left end portion in fig. 2 c) of the one-directional flow F1 of the working fluid in the reciprocating flow path 1c is connected to the tank 8. The embodiment of fig. 2 (c) is the same as the embodiment shown in fig. 1 except that the tank 8 is provided. In this case, as shown in the drawing, the filter 5 is preferably provided in the first branch flow path portion 2a that takes charge of the flow of the working fluid to the tank 8 (the flow F1 in one direction of the working fluid). Thus, for example, when the working fluid mixed with particulates used in other parts of the hydraulic circuit, not shown, flows toward the tank 8 along the one direction flow F1 of the working fluid, the working fluid can be cleaned by the filter 5. Then, here, the working fluid that has been cleaned by the filter 5 enters the tank 8, and the cleaned working fluid is stored in the tank 8. Therefore, at this time, the always clean working fluid can be sent out from the tank 8 in the reverse flow F2 of the working fluid.

The reciprocating flow path 1c shown in fig. 2 (c) may be used as an unillustrated adjustment flow path for allowing excess or deficiency of the working fluid to flow in a main circuit portion including the first supply/discharge flow path L1, the second supply/discharge flow path L2, the third supply/discharge flow path L3, and the common flow path Lc in the hydraulic circuit 41 as described later. At this time, the tank 8 is supplied with the excess working fluid in the main circuit portion and stores the working fluid.

In the reciprocating flow path 1c shown in fig. 2 (c), a filter may be further provided on the second branch flow path part 2b side. However, for example, when the working fluid is sucked by a pump (not shown) provided on the other end portion (the right end portion in fig. 2 (c)) side of the reciprocating flow path 1c to generate the backward flow F2 of the working fluid, the suction force may be reduced due to a pressure loss caused by the filter provided in the second branch flow path portion 2 b. For this reason, as shown in fig. 2 (c), it may be preferable to provide the filter 5 only in the first branch flow path portion 2a that is responsible for the flow of the working fluid to the tank 8.

Although the hydraulic circuit having the reciprocating flow path 1c in fig. 2 (c) may be an open circuit, the tank 8 may be a sealed tank to form a closed circuit.

(Hydraulic device for injection molding machine)

The hydraulic device provided with the hydraulic circuit as described above can be used for the injection molding machine 10 as illustrated in fig. 3. As will be described in detail later, the injection molding machine 10 is provided with: an injection device 11 that melts the molding material and injects the molding material into the mold device 101 by rotation and forward movement of a screw 12 disposed inside and heating of a heating device 13 disposed around; a moving device 21 that moves the injection device 11 forward/backward relative to the mold device 101; and a mold clamping device 31 that opens and closes the mold device 101 between a mold clamping state and a mold opening state. In many cases, the injection molding machine 10 further includes an ejection device, not shown, that takes out a molded article from the mold device 101 in the mold opened state. In the illustrated example, the mold apparatus 101 includes a fixed mold 102 and a movable mold 103 defining a cavity therein in a clamped state, and a movable member 104 such as an ejector pin that is displaced by the ejector to extrude and take out a molded product. The mold apparatus 101 is attached to the injection molding machine 10 as appropriate in accordance with the shape of a molded article to be manufactured, and the like, and is replaceable, and the mold apparatus 101 is not regarded as a part of the injection molding machine 10.

In each of the above-described respective apparatuses constituting the injection molding machine 10, the hydraulic apparatus according to the embodiment of the present invention is used for the mold clamping apparatus 31. The mold clamping device 31 moves the movable mold 103 relative to the fixed mold 102 of the mold device 101 to open or close the mold device 101, and brings the mold device 101 into a mold clamping state, a mold closing state, or a mold opening state. The mold clamping device 31 shown in the figure mainly includes a platen 32 disposed so as to sandwich the mold device 101 from both sides, and a platen operating mechanism 33 for moving the platen 32. In the mold clamping device 31, the platen operating mechanism 33 is hydraulically driven, and is driven by a hydraulic device.

Further, here, the platen 32 includes: a fixed platen 32a located between the injection device 11 and the mold device 101 and fixed with respect to the frame Fr; and a movable platen 32b that is positioned between the fixed platen 32a and the die device 101 and is displaceable toward and away from the fixed platen 32 a. The fixed mold 102 of the mold apparatus 101 located between the fixed platen 32a and the movable platen 32b is attached to the fixed platen 32a side, and the movable mold 103 is attached to the movable platen 32b side. The mold clamping device 31 is provided with one or more tie bars 32c extending from the fixed platen 32a toward a cylinder body 34 described later and connecting the fixed platen 32a and the cylinder body 34. In this embodiment, the displacement of the movable platen 32b toward or away from the fixed platen 32a is guided by the connecting rods 32c, but may not be guided by the connecting rods 32 c.

At a position where the movable platen 32b is separated from the fixed platen 32a, the movable mold 103 of the mold apparatus 101 is in an open state in which it is opened from the fixed mold 102, and by bringing the movable platen 32b from the separated position toward the fixed platen 32a, the movable mold 103 is in a closed state in which it is closed with respect to the fixed mold 102, and by bringing the movable platen 32b further toward the fixed platen 32a, the movable mold 103 is in a clamped state in which it is pressed against the fixed mold 102. Here, the direction of the fixed platen 32a of the clamping unit 31 to which the fixed mold 102 is attached, which is closer to the mold apparatus 101, is set to the front side, and the direction of separation from the fixed platen 32a is set to the rear side. In most parts of the mold clamping device 31 other than the fixed platen 32a, the part closer to the fixed platen 32a is the forward side in the right direction, and the part farther from the fixed platen 32a is the backward side in the left direction.

The platen operation mechanism 33 includes: a cylindrical cylinder body 34 attached to the other end side of a connecting rod 32c extending through the movable platen 32 b; a cylindrical piston portion 35 fixed to the movable platen 32b and reciprocating inside the cylinder body portion 34 to move the movable platen 32 b; a cylindrical rod portion 36 provided inside the cylinder body portion 34 and inserted inside the piston portion 35; and an annular cylinder block 37 provided around the piston 35 and closing the opening end of the cylinder body 34.

The cylinder body 34, the piston 35, and the rod 36 each have a substantially closed-end cylindrical shape having a closed end portion closed at one end and an open end portion open at the other end. The piston portion 35 is inserted into the cylinder body portion 34 in a direction in which the opening end portions thereof face each other. Further, the outer peripheral surface of the piston portion 35 except for the vicinity of the opening end thereof is formed with a slightly smaller diameter than the inner peripheral surface of the cylinder body portion 34, and a gap is present between the outer peripheral surface of the piston portion 35 and the inner peripheral surface of the cylinder body portion 34. The rod portion 36 is attached such that a closed end thereof is fixed to the closed end of the cylinder body portion 34 in the cylinder body portion 34, and the rod portion 36 is inserted into the piston portion 35 in a direction in which the open ends thereof face each other.

With the above configuration, the platen operation mechanism 33 is provided with: a first hydraulic chamber C1 defined by the inner peripheral surface of the cylinder body 34, the outer peripheral surface of the rod 36, and the end surface of the opening end of the piston 35; a second hydraulic chamber C2 defined by the interior of the piston portion 35 and the interior of the rod portion 36; and a third hydraulic chamber C3 defined by the outer peripheral surface of the piston portion 35, the inner peripheral surface of the cylinder body portion 34, and the cylinder closing portion 37. The first hydraulic chamber C1, the second hydraulic chamber C2, and the third hydraulic chamber C3 are provided with a first hydraulic port P1, a second hydraulic port P2, and a third hydraulic port P3, respectively, for supplying the working fluid from the hydraulic circuit 41 of the hydraulic device to the respective hydraulic chambers. The platen operating mechanism 33 including the first hydraulic chamber C1, the second hydraulic chamber C2, and the third hydraulic chamber C3 has a double-acting cylinder structure having a difference in area with respect to each pressure receiving surface of the working fluid.

The hydraulic apparatus of this embodiment is provided with a hydraulic circuit 41 as shown in fig. 4 to 7, which supplies the working fluid to the first hydraulic chamber C1, the second hydraulic chamber C2, and the third hydraulic chamber C3 via the first hydraulic port P1, the second hydraulic port P2, and the third hydraulic port P3. The illustrated hydraulic circuit 41 mainly includes a hydraulic pump HP operated by a servo motor SM, a first supply/discharge passage L1 connected to a first hydraulic port P1 of a first hydraulic chamber C1, a second supply/discharge passage L2 connected to a second hydraulic port P2 of a second hydraulic chamber C2, and a third supply/discharge passage L3 connected to a third hydraulic port P3 of a third hydraulic chamber C3. The hydraulic pump HP can switch the direction of sending the working fluid between the first supply/discharge passage L1 and the second supply/discharge passage L2 side and the third supply/discharge passage L3 side by the servo motor SM. The hydraulic fluid sent to the first supply/discharge passage L1 and the second supply/discharge passage L2 by the hydraulic pump HP flows through the common passage Lc, and then flows through the first supply/discharge passage L1 or the second supply/discharge passage L2 branched at the passage connection portion CL.

Here, the first supply/discharge passage L1, the second supply/discharge passage L2, and the third supply/discharge passage L3 are provided with, for example, shut-off valves SV1, SV2, and SV3 that can be switched between open and closed by being electrically driven under the control of an unillustrated control unit or the like. Accordingly, the working fluid can be supplied to or discharged from the first hydraulic chamber C1, the second hydraulic chamber C2, and/or the third hydraulic chamber C3 using a predetermined supply/discharge passage, if necessary.

Here, the hydraulic circuit 41 is provided with: a reservoir tank RT for storing excess working fluid in the hydraulic circuit 41 and discharging the working fluid when the working fluid in the hydraulic circuit 41 is insufficient; and a control passage La for connecting the hydraulic pump HP to the reservoir RT and flowing an excess or deficiency of the hydraulic fluid. The reserve tank RT is connected to a first hydraulic port P1 of the first hydraulic chamber C1 through an auxiliary flow path Ls via a charging valve PV. The charging valve PV is connected to a pilot conduit, not shown, that communicates with the third supply/discharge conduit L3, and is configured to open in response to a pilot pressure from the pilot conduit. In this embodiment, the first supply/discharge flow path L1 and the auxiliary flow path Ls are connected to the first hydraulic chamber C1 at the common first hydraulic port P1, but although not shown, the auxiliary flow path may be connected to the first hydraulic chamber by a port separate from the first hydraulic port of the first supply/discharge flow path.

The illustrated hydraulic circuit 41 may be an open circuit, but is preferably a closed circuit. In the case of a closed circuit, a temperature controller or the like required for an open circuit is not required, and simplification and miniaturization of the hydraulic device can be achieved. The closed circuit also has an advantage that oil as the working fluid is less likely to be thermally degraded than the open circuit.

According to the mold clamping device 31 having the platen operating mechanism 33 and the hydraulic device having the hydraulic circuit 41 as described above, the mold device 101 can be opened and closed including the mold closing step, the pressure raising step, the mold clamping step, the pressure reducing step, and the mold opening step as described below.

In the mold closing process, the hydraulic pump HP is operated by the servo motor SM in a state where the cutoff valve SV1 is closed and the cutoff valves SV2 and SV3 are open, and the hydraulic fluid introduced into the third hydraulic chamber C3 is sucked through the third supply and discharge passage L3 as indicated by an arrow in fig. 4. At this time, the hydraulic fluid is sent to the second hydraulic chamber C2 through the common flow path Lc and the second supply/discharge flow path L2 by the operation of the hydraulic pump HP. Thus, the piston portion 35 moves forward in the cylinder body portion 34 due to the pressure increase in the second hydraulic chamber C2 accompanying the inflow of the hydraulic fluid, and the second hydraulic chamber C2 expands accordingly. By this movement of the piston portion 35, the movable platen 32b fixed to the closed end portion of the piston portion 35 and the movable mold 103 attached to the movable platen 32b approach the fixed mold 102 on the fixed platen 32a side, and the mold apparatus 101 is closed.

Next, in the pressure increasing step and the mold clamping step, the stop valve SV1 is opened and the stop valves SV2 and SV3 are closed, and the hydraulic fluid is sent from the common flow path Lc and the first supply/discharge flow path L1 to the first hydraulic chamber C1 by the hydraulic pump HP as shown in fig. 5. In the mold closing step, the charge valve PV is opened because the first hydraulic chamber C1 becomes a negative pressure as the piston portion 35 moves forward. Thereby, as shown by arrows in fig. 5, the working fluid is supplied from the reserve tank RT to the first hydraulic chamber C1 through the auxiliary flow path Ls.

Here, since the cutoff valve SV2 is closed, the working fluid sent to the second hydraulic chamber C2 is directly held there in the mold closing process. In this state, as described above, the working fluid fed into the first hydraulic chamber C1 presses the piston portion 35 from the end surface on the opening end portion side thereof, and therefore the piston portion 35, the movable platen 32b, and the movable die 103 are slightly moved further forward, and a required mold clamping force is applied to the mold apparatus 101.

In the subsequent pressure reducing process, the working fluid is sucked from the first hydraulic chamber C1 through the first supply/discharge passage L1 and the common passage Lc by the operation of the hydraulic pump HP while maintaining the closed states of the cutoff valves SV2 and SV3, as shown in fig. 6. At this time, the hydraulic pump HP discharges an excessive amount of the hydraulic fluid to the reservoir RT. Thus, the extra working fluid is stored in the reservoir RT through the adjustment passage La. By the operation of the hydraulic device, as the working fluid is discharged from the first hydraulic chamber C1, the mold clamping force acting on the mold device 101 gradually decreases, and the piston portion 35 slightly moves to the rear side.

Thereafter, as a mold opening step, the cutoff valve SV1 is closed, the cutoff valves SV2 and SV3 are opened, and as shown in fig. 7, the hydraulic fluid is sent from the third supply/discharge passage L3 to the third hydraulic chamber C3 by the hydraulic pump HP, and the hydraulic fluid in the second hydraulic chamber C2 is sucked through the second supply/discharge passage L2 and the common passage Lc. As a result, the piston portion 35 is largely retracted rearward and dropped into the cylinder body portion 34, and the movable platen 32b and the movable mold 103 are separated from the fixed mold 102 on the fixed platen 32a side, and the mold device 101 is opened.

When the internal pressure of the third supply/discharge passage L3 becomes equal to or greater than the predetermined value due to the hydraulic fluid in the third hydraulic chamber C3 being filled (C5), the pilot pressure rises through the pilot line, and the charging valve PV opens. At the same time, the working fluid remaining in the first hydraulic chamber C1 flows from the auxiliary flow path Ls into the reserve tank RT due to the contraction of the first hydraulic chamber C1 caused by the retraction of the piston portion 35.

The embodiment of the present invention can be applied to various flow paths in the hydraulic circuit 41 of the hydraulic device described above, in which the hydraulic fluid can reciprocate. Among these, in the adjustment flow path La, since a pressure loss due to the arrangement of the filter 45 described later is less likely to be a large problem, it is particularly preferable to apply the embodiment of the present invention to the adjustment flow path La as described below.

More specifically, in the adjustment passage La, as described above, the working fluid flows in one direction from the hydraulic pump HP to the reservoir RT in the pressure reducing step or the like. In the opening step or the like, the hydraulic fluid flows in a reverse direction from the reservoir tank RT to the hydraulic pump HP. Therefore, the adjustment flow path La corresponds to a reciprocating flow path in which one-direction flow of the working fluid and a reverse-direction flow of the working fluid are generated.

As described above, in the reciprocating flow path in which the working fluid reciprocates, even if a filter is simply provided in the middle of the pipe line of one flow path, the particulate matter cannot be efficiently removed by the filter, and therefore, the first branch flow path section 42a and the second branch flow path section 42b that are branched into two or more streams and merge with each other are provided in the adjustment flow path La of the present embodiment. The first branch passage portion 42a and the second branch passage portion 42b branch or merge with each other at the first flow passage connecting portion 43a and the second flow passage connecting portion 43 b. In addition, the number of the branch flow path portions may be 3 or more. Then, for example, since the first branch flow path portion 42a is responsible for one-direction flow of the working fluid and the second branch flow path portion 42b is responsible for the reverse flow of the working fluid, in the illustrated example, the check valves 44a and 44b are provided in the first branch flow path portion 42a and the second branch flow path portion 42b, respectively.

In addition to providing the first branch flow path part 42a and the second branch flow path part 42b, a filter 45 is disposed in at least a part of these branch flow path parts. In this embodiment, by providing the filter in the first branch flow path portion 42a, when the hydraulic fluid flows in one direction from the hydraulic pump HP to the reserve tank RT, the hydraulic fluid passes through the first branch flow path portion 42a by the check valves 44a and 44b, and at this time, particulates are removed by the filter 45. Thereby, the clean working fluid is accumulated in the reservoir tank RT.

On the other hand, when the hydraulic fluid flows in the reverse direction from the reserve tank RT to the hydraulic pump HP, the hydraulic fluid passes through the second branch flow path portion 42b without passing through the first branch flow path portion 42a by the check valves 44a and 44b provided in the first branch flow path portion 42a and the second branch flow path portion 42b, respectively. Therefore, the particulate matter trapped by the filter 45 of the first branch flow path portion 42a when flowing in one direction can be prevented from being mixed again into the working fluid when flowing in the reverse direction.

As described above, in the first branch flow path portion 42a provided with the filter 45, the check valve 44a is preferably disposed on the upstream side in the flow direction of the working fluid with respect to the filter 45. At this time, when the hydraulic pump HP sucks the hydraulic fluid from the reservoir tank RT to generate the reverse flow of the hydraulic fluid, the check valve 44a prevents the unclean hydraulic fluid remaining between the filter 45 and the check valve 44a from being sucked when the hydraulic fluid flows in one direction, and therefore contamination of the clean hydraulic fluid from the reservoir tank RT can be suppressed.

When the excess hydraulic fluid flows in one direction from the hydraulic pump HP to the reservoir tank RT, the hydraulic fluid can flow at a high pressure due to the pressure received by the hydraulic fluid from the platen operating mechanism 33. Therefore, the pressure loss when the working fluid passes through the filter 45 of the first branch flow path portion 42a does not normally become a significant problem. In contrast, in the reverse flow of the hydraulic fluid from the reservoir tank RT to the hydraulic pump HP, the hydraulic fluid is sucked from the reservoir tank RT by the hydraulic pump HP, and therefore, it is preferable that the pressure loss is small. For this reason, as shown in this embodiment, the filter 45 is preferably provided only in the first branch flow path portion 42a that takes charge of the flow of the working fluid from the hydraulic pump HP to the reserve tank RT (one-directional flow of the working fluid).

The filter and the branch flow path unit described above are more preferably provided in the adjustment flow path La for adjusting excess and deficiency of the working fluid described herein than in the first supply/discharge flow path L1, the second supply/discharge flow path L2, the third supply/discharge flow path L3, and the common flow path Lc for causing the working fluid to flow between the hydraulic pump HP and the first hydraulic chamber C1, the second hydraulic chamber C2, and the third hydraulic chamber C3. This is because the filter does not need to be set to that high pressure specification.

In the platen operating mechanism 33 driven by the hydraulic device, in this example, as shown in fig. 3, the cylindrical cylinder body portion 34 has a flange 34a extending outward around the opening end portion located on the front side. The connecting rod 32c is disposed through the flange 34a, and is connected to the cylinder body 34 by the flange 34a with a screw.

Further, inside the opening end of the cylinder body 34, the inside diameter is made larger than the inside of the cylinder body 34, and a step 34b is formed there. The third hydraulic port P3 is provided near the step 34 b. On the other hand, the annular cylinder block 37 has a small-diameter end 37a having a smaller outer diameter than the central portion at each end in the axial direction. The annular cylinder block sealing portion 37 is attached to the cylinder body 34 by bringing the rear side surface of the central portion thereof into contact with the front side surface of the flange 34a of the cylinder body 34 and fitting the small-diameter end portion 37a into the step 34b of the cylinder body 34.

The mold clamping device 31 shown in the figure is a horizontal type mold clamping device in which the moving direction of the movable platen 32b is parallel to the horizontal direction, but a vertical type mold clamping device in which the moving direction is the vertical direction may be used.

In the mold clamping device 31, the fixed platen 32a is fixed to the frame Fr in the cylinder body 34 and the fixed platen 32a of the platen operating mechanism 33, but conversely, the cylinder body can be fixed to the frame.

Here, the mold clamping device 31 driven by a hydraulic device is described as an example, but such a hydraulic device can be applied to a hydraulic actuator included in an ejector device provided in the injection molding machine 10, the injection device 11, and various other devices.

(injection molding machine)

As described above, the injection molding machine 10 includes the injection device 11, the moving device 21, the mold clamping device 31, and the ejector device. The illustrated mold apparatus 101 may be referred to as a 2-plate mold divided mainly into two, i.e., a fixed mold 102 and a movable mold 103, but may be a three-plate mold divided into 3 parts by further including a slide mold, a slide core, or a stripper plate.

In order to manufacture a molded product using the injection molding machine 10, a pressure raising step and a mold clamping step are performed in which the mold apparatus 101 is closed by the mold clamping apparatus 31 to be in a mold clamping state in a state where the molding material is already disposed in the injection apparatus 11 by a predetermined amount in the second half of the previous molding.

Next, a filling step of injecting the molding material into the mold apparatus 101 by advancing the screw 12 and filling the molding material into the cavity in the mold apparatus 101, and a pressure holding step of further advancing the screw 12 and holding the molding material in the tip portion of the injection apparatus 11 at a predetermined pressure are sequentially performed.

Then, a cooling step of cooling and solidifying the molding material filled in the cavity of the mold apparatus 101 to obtain a molded product is performed. In this case, the following measurement steps are performed: the molding material separately charged into the injection device 11 is transported toward the tip end portion of the injection device 11 by the rotation of the screw 12 and melted under the heating by the heating device 13, and a predetermined amount of the molding material is disposed at the tip end portion.

Then, through a decompression step of reducing the clamping force to the mold apparatus 101 by operating the clamping apparatus 31 and a mold opening step of opening the mold apparatus 101, a removal step of removing the molded product from the mold apparatus 101 by moving the movable member 104 by the ejector is performed.

The details of each device of the injection molding machine 10 are as follows. Since the mold clamping device 31 is as described above, the description thereof will be omitted here.

The injection device 11 mainly includes: a cylinder 14 such as a cylinder extending toward the die apparatus 101; a screw 12 disposed inside the cylinder 14 so as to be parallel to the central axis and having fins provided around the screw; a belt-like heating device 13 disposed around the cylinder 14 so as to surround the circumference thereof; and a motor case 15 disposed on the rear side of the cylinder 14 and the screw 12. Although not shown, the motor case 15 includes: a metering motor for rotating the screw 12 about the center axis to store a predetermined amount of molding material in the front end portion of the cylinder 14; an injection motor that performs forward and backward displacements of the screw 12 in respective directions of a direction approaching the mold apparatus 101 and a direction away from the mold apparatus 101; and a pressure detection sensor or the like that detects the pressure that the screw 12 receives from the molding material.

Here, the direction of the fixed platen 32a of the clamping unit 31 to which the fixed mold 102 is attached, which is closer to the mold apparatus 101, is set to the front side, and the direction of the fixed platen 32a is set to the rear side. Therefore, when the injection device 11 is viewed on the right side of the fixed platen 32a in fig. 3, the left direction closer to the fixed platen 32a is the forward side, and the right direction farther from the fixed platen 32a is the rearward side.

The cylinder 14 is provided with a supply port 14a to which a hopper for feeding the molding material into the cylinder 14 is attached on the rear side and in front of the motor case 15, and a nozzle 14b having a reduced cross-sectional area is provided on the front side near the front end of the die apparatus 101. A water cooling cylinder 14c for water cooling or the like may be provided near the supply port 14 a.

For example, as shown in the drawing, the heating device 13 disposed around the cylinder 14 including around the nozzle 14b is divided into a plurality of portions in the axial direction (the left-right direction in fig. 3), and the inside of the cylinder 14 inside each heating device portion can be heated at different temperatures.

According to the injection device 11 having such a configuration, the molding material charged into the cylinder 14 from the supply port 14a is heated by the heating device 13 on the outer peripheral side of the cylinder 14 in the metering step, and is conveyed forward inside the cylinder 14 while being melted by the rotation of the screw 12 driven by the metering motor, and is filled into the front end portion of the cylinder 14. At this time, the screw 12 is moved backward by the injection motor to form a space filled with the molding material at the front end of the cylinder 14. As described above, the metering step can be performed in a cooling step or the like in the previous molding.

Then, in the filling step, the screw 12 is advanced and displaced, whereby the molding material at the distal end portion of the cylinder 14 is injected toward the mold apparatus 101 through the nozzle 14 b. In the subsequent pressure holding step, the pressure is applied to the molding material filled in the cavity of the mold device 101 by the molding material remaining at the distal end portion of the cylinder 14. In this case, the molding material that becomes insufficient in the cavity of the mold apparatus 101 due to cooling shrinkage of the molding material can be replenished.

The injection molding machine 10 is an inline screw type, but may be a pre-molding type injection molding machine that is structurally and functionally separated into a plasticizing cylinder and a plasticizing screw, and an injection cylinder and an injection plunger.

The moving device 21 is, for example, an advancing/retreating drive mechanism provided at a lower portion of the motor case 15 of the injection device 11 and configured to advance and retreat the injection device 11 with respect to the fixed platen 32 a. Various mechanisms can be used as the forward/backward driving mechanism constituting the traveling device 21, but the illustrated traveling device 21 includes a hydraulic pump 22 such as a hydraulic pressure, a motor 23 for pump operation such as an electric motor for operating the hydraulic pump 22, and a double-acting hydraulic cylinder 24 for supplying a hydraulic fluid from the hydraulic pump 22 to push out/pull in a piston rod whose tip is fixed to the fixed platen 32 a. The transfer device 21 further includes the hydraulic pump 22, a pump working motor 23, a slide base 25 to which a hydraulic cylinder 24 is attached, and a guide 26 laid on the frame Fr and guiding the linear movement of the slide base 25, thereby realizing the forward and backward displacement of the injection device 11 placed on the upper portion of the slide base 25.

The injection device 11 can be separated from the mold device 101 by the moving device 21, or the injection device 11 can be brought close to the mold device 101 to press the nozzle 14b of the cylinder 14 of the injection device 11 to the so-called nozzle contact of the mold device 101 with a predetermined pressure.

Although not shown, the ejector device provided in the movable platen 32b includes an ejector rod extending through the movable platen 32b and driven to advance and retreat so as to press the movable member 104 such as the ejector pin of the die apparatus 101 from the rear side, and a rod driving source including a motion conversion mechanism such as a motor and a ball screw for operating the ejector rod.

In the molded product taking-out step, the ejector rod driven by the rod driving source is advanced by the ejector device, the movable member 104 is protruded inside the mold device 101, and the molded product can be taken out from the mold device 101. Further, after the movable member 104 is projected, the ejector lever can be retracted by the lever drive source and returned to the original position.

Claims (10)

1. A hydraulic device for an injection molding machine, comprising a hydraulic circuit for flowing a working fluid, wherein,

the hydraulic circuit has a reciprocating flow path that generates one-directional flow of the working fluid and a reverse flow of the working fluid,

the reciprocating flow path includes a plurality of branch flow path portions that branch into two or more streams midway and join with each other, and each of which takes charge of one of the flow of the working fluid in one direction and the reverse flow of the working fluid in the reverse direction,

a filter is provided in at least one of the plurality of branch flow path portions.

2. The hydraulic apparatus of claim 1,

also comprises a tank capable of storing the working fluid,

one end of the reciprocating flow path is connected to the tank.

3. The hydraulic apparatus of claim 2,

the filter is provided in the branch flow path portion for causing the working fluid to flow to the tank.

4. The hydraulic apparatus of claim 2 or 3,

the tank connected to one end portion of the reciprocating flow path is a storage tank that stores excess working fluid in the hydraulic circuit and discharges an insufficient amount of working fluid in the hydraulic circuit,

the hydraulic device further includes a hydraulic pump provided on the other end portion side of the reciprocating flow path.

5. The hydraulic device according to any one of claims 1 to 4,

each of the plurality of branch flow path portions includes a check valve.

6. The hydraulic apparatus of claim 5,

the check valve is disposed on the branch flow path portion where the filter is provided, and on an upstream side in a flow direction of the working fluid with respect to the filter.

7. The hydraulic device according to any one of claims 1 to 6,

the hydraulic circuit is a closed circuit.

8. The hydraulic device according to any one of claims 1 to 7,

for the operation of the hydraulic cylinder.

9. An injection molding machine injects a molding material into a mold device, wherein,

the injection molding machine is provided with the hydraulic device according to any one of claims 1 to 8.

10. The injection molding machine according to claim 9,

the mold clamping device is also provided with a mold clamping device which opens or closes the mold device through hydraulic driving by using the hydraulic device.

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