CN108453233B

CN108453233B - Injection plunger device and lubricant supply method for injection plunger device

Info

Publication number: CN108453233B
Application number: CN201810151769.1A
Authority: CN
Inventors: 中田卓哉
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-02-17
Filing date: 2018-02-14
Publication date: 2021-02-02
Anticipated expiration: 2038-02-14
Also published as: JP6859737B2; JP2018130752A; CN108453233A

Abstract

The invention provides an injection plunger device and a lubricant supply method for the injection plunger device. The injection plunger device is used for supplying molten metal into a die of a die casting device, and comprises: a plunger sleeve; a plunger ram disposed within the plunger sleeve; the tail end of the plunger rod is connected with a plunger pressure head; and a lubricant supply unit for supplying lubricant between the plunger sleeve and the plunger ram. The plunger sleeve has: a molten metal passage to which molten metal is supplied; and an injection port opening into the interior space of the mold. The plunger ram is capable of reciprocating within the molten metal passageway between a forward limit and a rearward limit. The plunger rod has a plurality of lubricant flow paths therein. At least one of the plunger ram and the plunger rod has a plurality of lubricant discharge ports that are open at circumferentially different positions on the outer peripheral surface and are connected to the plurality of lubricant flow paths, respectively. The lubricant supply portion supplies lubricant to at least one of the plurality of lubricant flow paths according to an axial position of the plunger head when the plunger head moves from the forward limit to the backward limit.

Description

Injection plunger device and lubricant supply method for injection plunger device

Technical Field

The present invention relates to an injection plunger device and a lubricant supply method for the injection plunger device.

Background

Conventionally, there is known a die casting apparatus for molding a product having a predetermined shape in a mold by injecting a molten metal into the mold using an injection plunger apparatus. As an injection plunger device used in such a die casting device, for example, an air blowing device for a die casting machine disclosed in japanese patent application laid-open No. 7-164126 is known.

The air-blowing device for a die casting machine of japanese patent laid-open No. 7-164126 has a hollow cylindrical injection sleeve and a plunger ram capable of reciprocating in the injection sleeve. One end of the injection sleeve is connected with the mould. Inserting the plunger ram from the other end of the shot sleeve into the interior of the shot sleeve.

In the standby state, the plunger ram is located at a predetermined position (hereinafter, referred to as a retracted position) retracted with respect to the mold, and the plunger ram is moved to a predetermined position (hereinafter, referred to as an advanced position) close to the mold during injection of the molten metal. The plunger ram is returned to the retracted position again after the end of the injection. Further, the injection sleeve has a supply port for supplying molten metal between the advanced position and the retracted position.

The air blowing device for the die casting machine further has an air nozzle between the supply port of the injection sleeve and the retreated position. The air nozzle blows off burrs remaining on the inner wall of the injection sleeve by ejecting air into the injection sleeve, and spreads the lubricating oil injected into the injection sleeve from the supply port over the entire inner wall of the injection sleeve.

In detail, in the air blowing device for a die casting machine, after the plunger ram injects the molten metal supplied into the injection sleeve into the mold and returns to the retreated position, burrs remaining on the inner wall of the injection sleeve are blown off by ejecting air from the air nozzle. Then, the lubricant is supplied into the injection sleeve from the supply port, and the air is ejected from the air nozzle, so that the lubricant is scattered and spread over the entire inner wall of the injection sleeve.

Disclosure of Invention

In general, in an injection plunger device, if friction force is increased at a portion where an inner wall of a plunger sleeve contacts a plunger ram, a decrease or variation in injection speed, abrasion of the plunger sleeve, and the like occur. Therefore, it is preferable to apply an appropriate amount of lubricating oil (lubricant) to the contact portion. However, as disclosed in japanese patent application laid-open No. 7-164126, when lubricating oil (lubricant) is injected into an injection sleeve (plunger sleeve) from an air nozzle and is applied by diffusion with air, it is difficult to control the position and amount of application of the lubricating oil (lubricant) to the inner wall of the injection sleeve (plunger sleeve).

In contrast, it is conceivable to increase the amount of lubricant supplied into the plunger sleeve so as to widely apply the lubricant to the inner wall of the plunger sleeve. However, if the amount of the lubricant supplied into the plunger sleeve is increased, the lubricant is vaporized and enters the molten metal, and therefore, defects and the like may occur in the molded article molded by the mold.

Thus, it is difficult to suppress the influence of the lubricant on the molded article (generation of defects in the molded article, etc.) while securing lubricity between the plunger sleeve and the plunger ram.

The invention aims to provide an injection plunger device and a lubricant supply method of the injection plunger device, which can ensure the lubricity between a plunger sleeve and a plunger press head and simultaneously inhibit the influence of lubricant on a molded part.

An injection plunger device according to an embodiment of the present invention is an injection plunger device for supplying molten metal into a mold of a die casting device. The injection plunger device has: a cylindrical plunger sleeve; a cylindrical plunger ram disposed within the plunger sleeve; a shaft-shaped plunger rod, the tail end of which is connected with a plunger pressure head; and a lubricant supply portion that supplies lubricant between the plunger sleeve and the plunger ram. The plunger sleeve has: a molten metal passage to which molten metal is supplied; and an injection port located at one end side of the molten metal passage and opening toward the internal space of the mold. The plunger ram is capable of reciprocating within the molten metal passageway between an advancing limit on the injection port side and a retracting limit on the other end side of the molten metal passageway. The plunger rod has a plurality of lubricant flow paths extending axially therein. At least one of the plunger ram and the plunger rod has a plurality of lubricant discharge ports that are open at different positions in the circumferential direction of the outer circumferential surface and are connected to the plurality of lubricant flow paths, respectively. The lubricant supply portion supplies lubricant to at least one of the plurality of lubricant flow paths while the plunger head moves from the forward limit to the backward limit in the molten metal passage, in accordance with an axial position of the plunger head in the molten metal passage.

A lubricant supply method for an injection plunger device according to an embodiment of the present invention is a lubricant supply method for an injection plunger device including: a cylindrical plunger sleeve having a molten metal passage; a cylindrical plunger ram disposed within the plunger sleeve; a shaft-shaped plunger rod, the tail end of which is connected with a plunger pressure head; and a lubricant supply portion that supplies lubricant between the plunger sleeve and the plunger ram. The lubricant supplying method includes a lubricant discharging step of discharging lubricant a plurality of times from a plurality of lubricant discharge ports opened at different positions in a circumferential direction of an outer peripheral surface of at least one of the plunger head and the plunger rod by a lubricant supplying portion via a plurality of lubricant flow paths extending in an axial direction inside the plunger rod, in accordance with an axial position of the plunger head inside the molten metal passage, when the plunger head moves from an advance limit to a retreat limit on the injection port side inside the molten metal passage.

According to the injection plunger device of one embodiment of the present invention, the influence of the lubricant on the molded article can be suppressed while the lubricity of the plunger sleeve and the plunger ram is ensured. Further, according to the lubricant supplying method of the injection plunger device according to the embodiment of the present invention, friction and wear between the plunger sleeve and the plunger ram can be reduced.

The above and other features, elements, steps, features and advantages of the present invention will be more clearly understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

Drawings

Fig. 1 is a diagram schematically showing the configuration of a die-casting device having an injection plunger device of an embodiment.

Fig. 2 is a view schematically showing a state where molten metal is supplied into a molten metal passage of the injection plunger device.

Fig. 3 is a diagram schematically showing a state in which a plunger head of the injection plunger device moves in a molten metal passage.

Fig. 4 is a view schematically showing a state where molten metal is injected into a mold from an injection plunger device.

Fig. 5 is a diagram schematically showing a state where the plunger ram is discharged when it is in the 1 st position.

Fig. 6 is a diagram schematically showing a state where the plunger ram is discharged when it is in the 2 nd position.

Fig. 7 is a diagram schematically showing a state where the plunger ram is discharged when it is at the 3 rd position.

Fig. 8 is a flowchart illustrating an operation of the die-casting device.

Fig. 9 is a diagram schematically showing the relationship between the axial position of the plunger ram within the molten metal passage and the moving speed of the plunger ram, and the discharge of the lubricant at the axial position.

Fig. 10 is a flowchart illustrating the operation of the injection plunger device in the lubricant application step.

Fig. 11 is a view showing a schematic configuration of a plunger head of an injection plunger device according to another embodiment.

Fig. 12 is a graph comparing the amounts of gases contained in cast products in the respective methods of lubricant application.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated. The dimensions of the components in the drawings do not faithfully represent the actual dimensions of the components, the dimensional ratios of the components, and the like.

In the following description, the direction of gravity in a state where the die casting apparatus is installed is referred to as the "vertical direction". The direction in which the plunger rod 13 extends is referred to as "axial direction".

(die casting device)

Fig. 1 is a diagram schematically showing the configuration of a die-casting device 1 having an injection plunger device 10 according to an embodiment of the present invention. The die casting device 1 is a device for molding a metal molded product having a predetermined shape by injecting a molten metal from an injection plunger device 10 into a mold 2. The die casting device 1 includes a die 2, a movable platen 3, a fixed platen 4, a control section 8, and an injection plunger device 10.

The mold 2 has a movable mold 5 fixed to the movable platen 3 and a fixed mold 6 fixed to the fixed platen 4. Although not particularly shown, the movable platen 3 is movable in the die casting device 1 in the horizontal direction (left-right direction). The stationary platen 4 is fixed to a frame, not shown, of the die casting device 1. Therefore, by moving the movable platen 3 in a direction away from the fixed platen 4, the movable mold 5 of the mold 2 is moved in a direction away from the fixed mold 6. On the other hand, by moving the movable platen 3 in a direction to approach the fixed platen 4, the movable mold 5 of the mold 2 moves in a direction to approach the fixed mold 6.

The movable mold 5 and the fixed mold 6 have recessed portions 5a and 6a corresponding to the shape of the molded article on the opposing surfaces, respectively. Thereby, in a state where the movable mold 5 is closest to the fixed mold 6, the cavity 7 (the inner space of the mold) is formed between the movable mold 5 and the fixed mold 6. A molten metal is injected into the cavity 7 from an injection plunger device 10 described later, whereby a molded article having a predetermined shape is molded. After the molded article having a predetermined shape is molded by the mold 2, the molded article can be taken out from the mold 2 by separating the movable mold 5 from the fixed mold 6.

The control unit 8 controls driving of the die casting device 1. Specifically, the control unit 8 controls the movement of the movable mold 5, the injection of the molten metal by the injection plunger device 10, and the like. The control unit 8 controls the driving of the die casting device 1 based on a detection signal output from a position detection unit 16 (detecting an axial position of a plunger rod 13 of an injection plunger device 10 described later), that is, based on an axial position of a plunger ram 12. The detailed operation of the die casting device 1, including also the injection plunger device 10, will be described later.

(injection plunger device)

The injection plunger device 10 is a device for supplying molten metal into the cavity 7 of the mold 2. The injection plunger device 10 includes a plunger sleeve 11, a plunger ram 12, a plunger rod 13, a lubricant supply unit 15, and a position detection unit 16.

The plunger sleeve 11 is a cylindrical metal member having a molten metal passage 11a therein. One end side in the axial direction of the plunger sleeve 11 penetrates the movable die 5. That is, the one end side of the plunger sleeve 11 is connected to the cavity 7 between the movable mold 5 and the fixed mold 6.

The plunger sleeve 11 has a molten metal passage 11a, an injection port 11b, and a supply port 11 c. The molten metal passage 11a is a passage having a circular cross section and extending in the axial direction in the cylindrical plunger sleeve 11. The injection port 11b is located on one end side of the plunger sleeve 11, i.e., one end side of the molten metal passage 11a, and is open in the axial direction toward the cavity 7 of the mold 2. That is, the injection port 11b is an opening portion for injecting the molten metal in the molten metal passage 11a into the cavity 7 of the mold 2. The supply port 11c is located at the end of the side wall of the plunger sleeve 11 opposite to the injection port 11b and opens upward. The supply port 11c is an opening portion for supplying the molten metal into the molten metal passage 11 a.

A columnar plunger ram 12 is disposed in the molten metal passage 11a of the plunger sleeve 11 so as to be capable of reciprocating. That is, the plunger ram 12 can reciprocate in the molten metal passage 11 a. When the plunger ram 12 reciprocates in the molten metal passage 11a, a position of the plunger ram 12 closest to the injection port 11b is an advance limit, and a position of the plunger ram 12 closest to an end portion on the opposite side to the injection port 11b (the other end side of the molten metal passage 11 a) is a retreat limit. The plunger ram 12 reciprocates between an advancing limit and a retreating limit in the molten metal passage 11 a. In fig. 2, the forward limit of the plunger ram 12 is indicated by a broken line, and the backward limit of the plunger ram 12 is indicated by a solid line.

The plunger rod 13 is a shaft-like member to which the plunger ram 12 is connected at a distal end side. The plunger rod 13 is moved in the axial direction relative to the plunger sleeve 11 by a drive device not shown. Thereby, the plunger ram 12 reciprocates in the molten metal passage 11a of the plunger sleeve 11.

The plunger rod 13 has 2

lubricant flow paths

13a and 13b extending in the axial direction inside thereof. Lubricant (e.g., lubricating oil) is supplied from a lubricant supply unit 15 described later to the

lubricant flow paths

13a and 13 b. The plunger rod 13 has an upper lubricant outlet 13c and a lower lubricant outlet 13d (a plurality of lubricant outlets) connected to the 2

lubricant passages

13a and 13b, respectively, at predetermined axial positions and at different positions in the circumferential direction on the outer peripheral surface. The upper lubricant discharge port 13c opens upward (upward in the direction of gravity). The lower lubricant discharge port 13d opens downward (downward in the direction of gravity).

Thus, the lubricant supplied from the lubricant supply portion 15 described later to one of the 2

lubricant passages

13a and 13b is discharged from the upper lubricant outlet 13c or the lower lubricant outlet 13d toward the outside of the plunger rod 13.

The position detection unit 16 detects the position (axial position) of the plunger rod 13 in the axial direction. That is, the position detecting unit 16 can detect the axial position of the plunger tip 12 in the molten metal passage 11 a. The detection signal output from the position detection unit 16 is input to the control unit 8 of the die casting device 1. The control section 8 controls the driving of the die casting device 1 based on the detection signal, that is, based on the axial position of the plunger ram 12. The control unit 8 outputs the input detection signal to a lubricant supply control unit 50, which will be described later.

The lubricant supply portion 15 supplies lubricant between the inner surface of the plunger sleeve 11 and the plunger ram 12. Specifically, the lubricant supply unit 15 supplies lubricant to any one of the 2

lubricant passages

13a and 13b of the plunger rod 13.

The lubricant supply unit 15 includes a lubricant supply control unit 50, a pump 61, a switching unit 62, and a lubricant tank 63. In the present embodiment, the lubricant supply unit 15 includes 3 pumps 61. The 3 pumps 61 supply lubricant from the lubricant tank 63 storing lubricant to any one of the 2

lubricant passages

13a and 13b in the plunger rod 13. The switching unit 62 is constituted by, for example, a switching valve, and switches the connection between 3 pumps 61 and 2

lubricant flow paths

13a and 13b in the plunger rod 13. Specifically, in the present embodiment, 1 of the 3 pumps 61 is connected to one of the 2

lubricant flow paths

13a and 13b by the switching unit 62. The pump 61 and the switching unit 62 have the same configuration as a conventional pump and a conventional switching valve, respectively, and therefore, detailed descriptions of the pump 61 and the switching unit 62 are omitted.

The lubricant supply control unit 50 includes a pump control unit 51 that controls driving of the pump 61 and a switching control unit 52 that controls driving of the switching unit 62. The switching control unit 52 drives the switching unit 62 in accordance with the axial position of the plunger rod 13, and connects 1 of the 3 pumps 61 to one of the 2

lubricant flow paths

13a and 13 b. The pump control unit 51 drives the pump 61 connected to one of the 2

lubricant flow paths

13a and 13b by the switching unit 62, and supplies lubricant into the one lubricant flow path.

In the present embodiment, the lubricant is discharged 3 times when the plunger ram 12 moves from the forward limit to the backward limit in the molten metal passage 11a as described later. The switching unit 62 connects a different pump 61 to any one of the 2

lubricant flow paths

13a and 13b every time discharge is performed. That is, in the present embodiment, 3 pumps 61 are used as dedicated pumps for respective discharges. This makes it possible to discharge the lubricant in an amount suitable for each discharge at an appropriate timing.

A signal relating to the axial position of the plunger ram 12 is input from the control portion 8 of the die-casting device 1 to the lubricant supply control portion 50. While the plunger ram 12 moves from the forward limit to the backward limit in the molten metal passage 11a, the lubricant supply control portion 50 determines whether or not the plunger ram 12 has reached any of 3 positions from the 1 st position to the 3 rd position, which will be described later, based on the signal. When the plunger ram 12 reaches any one of 3 positions, which will be described later, from the 1 st position to the 3 rd position, the lubricant supply control unit 50 drives the switching unit 62 by the switching control unit 52 and drives the pump 61 by the pump control unit 51.

The 3 rd position is a position (contact position) where the plunger ram 12 contacts the upper side of the inner surface of the plunger sleeve 11 when the plunger ram 12 moves from the retreat limit to the advance limit within the molten metal passage 11 a. The 3 rd position is the position of the plunger ram 12 shown, for example, in fig. 7.

Since the high-temperature molten metal is supplied into the molten metal passage 11a, the plunger sleeve 11 is deformed by the heat of the molten metal. In this case, since the molten metal is located below the molten metal passage 11a, the lower side of the plunger sleeve 11 is more likely to expand than the upper side in a cross section perpendicular to the axial direction of the plunger sleeve 11. As a result, the central portion in the longitudinal direction of the plunger sleeve 11 is curved convexly downward.

Therefore, when the plunger ram 12 moves from the retreat limit to the advance limit within the molten metal passage 11a, the plunger ram 12 comes into contact with the upper side of the inner surface of the plunger sleeve 11.

The 2 nd position is a position (speed switching position) at which the moving speed of the plunger ram 12 is switched to a speed equal to or greater than a predetermined value when the plunger ram 12 moves from the retreat limit to the advancement limit. The 2 nd position is the position of the plunger ram 12 shown, for example, in fig. 6.

In the present embodiment, when the injection plunger device 10 injects molten metal into the cavity 7 of the mold 2, the moving speed of the plunger ram 12 in the molten metal passage 11a is initially low, and is switched to a high speed (a speed equal to or greater than a predetermined value) from the middle. This prevents the molten metal in the molten metal passage 11a from containing air and the like, and thus prevents the quality of the molded article molded by the mold 2 from being degraded.

At the speed switching position of the plunger ram 12 described above, the plunger ram 12 is closer to the forward limit than the backward limit. Therefore, the length of the plunger rod 13 in the molten metal passage 11a becomes longer than that in the case where the plunger ram 12 is at the retreat limit. Thus, the plunger rod 13 is easily inclined downward, and the plunger pressure head 12 is easily brought into contact with the lower side of the inner surface of the plunger sleeve 11.

The 1 st position is a position between the speed switching position and the forward limit. The 1 st position is the position of the plunger ram 12 shown, for example, in fig. 5. In this position, the plunger ram 12 is closer to the advance limit than the speed switching position, and therefore, the plunger rod 13 is more likely to tilt downward. Therefore, the plunger pressure head 12 is more easily brought into contact with the lower side of the inner surface of the plunger sleeve 11.

(operation of die casting device)

Next, the operation of the die casting device 1 having the above-described configuration will be described with reference to fig. 2 to 4 and 8. Fig. 2 to 4 are views showing the action of the injection plunger device. Fig. 8 is a flowchart illustrating an outline of the operation of the die casting device 1.

After the flow shown in fig. 8 is started (started), in step SA1, the control unit 8 moves the movable platen 3 to bring the movable mold 5 closer to the fixed mold 6.

In step SA2, the control unit 8 of the die casting device 1 causes a molten metal supply unit, not shown, to supply the molten metal M into the injection plunger device 10. At this time, the molten metal M is supplied from the supply port 11b of the plunger sleeve 11 into the molten metal passage 11a (see the blank arrow in fig. 2). The operations at step SA1 and step SA2 may be performed simultaneously, or the operation at step SA1 may be performed after the operation at step SA 2.

Thereafter, in step SA3, the controller 8 causes the injection plunger device 10 to inject the molten metal into the cavity 7 of the mold 2. Specifically, the control unit 8 drives the plunger rod 13 of the injection plunger device 10 to move the plunger ram 12 from the retreat limit (the position of the plunger ram 12 shown in fig. 2) to the advance limit (the position of the plunger ram 12 shown by the broken line in fig. 2) in the molten metal passage 11 a. At this time, the moving speed of the plunger ram 12 is switched from a low speed to a high speed at a position closer to the forward limit than the backward limit in the molten metal passage 11a (see fig. 3). Then, by moving the plunger ram 12 to the forward limit of the molten metal passage 11, the molten metal M in the molten metal passage 11 can be injected into the cavity 7 of the mold 2 (see fig. 4). In addition, the plunger ram 12 that has moved to the advance limit stops at the advance limit.

Fig. 9 shows a change in the moving speed of the plunger ram 12 when the plunger ram 12 moves from the retreat limit to the advance limit in the molten metal passage 11. In fig. 9, the solid line indicates the moving speed of the plunger ram 12, and the broken line indicates a value obtained by converting the speed of the signal output from the control unit 8 when the plunger rod 13 is driven.

As shown in fig. 9, when the plunger ram 12 starts moving from the retreat limit to the advance limit in the molten metal passage 11, the moving speed of the plunger ram 12 increases to a constant speed. As described above, the central portion of the plunger sleeve 11 in the axial direction is curved convexly downward by the heat of the molten metal M. Therefore, the plunger ram 12 moving in the molten metal passage 11 of the plunger sleeve 11 is in contact with the upper side of the inner surface of the plunger sleeve 11. The contact position is a position (position III in fig. 9) at which the moving speed of the plunger ram 12 reaches a constant speed.

When the plunger ram 12 moves forward from the retreat limit to the advance limit of the molten metal pathway 11, the plunger ram moves at a constant speed of a low speed (for example, 0.2m/s) within a predetermined range (a section between III and II in fig. 9), and then the moving speed is switched to a high speed (for example, 2m/s) (a section between II and I in fig. 9). The position (position II in fig. 9) at which the moving speed of the plunger ram 12 is switched from a constant speed, which is a low speed, to a speed equal to or greater than a predetermined value is a speed switching position.

Further, between the speed switching position and the advance limit, the plunger ram 12 is in contact with the inner surface of the plunger sleeve 11, and therefore, the frictional force generated between the plunger ram 12 and the inner surface of the plunger sleeve 11 increases. The position where the plunger ram 12 contacts the inner surface of the plunger sleeve 11 between the speed switching position and the advance limit is the position I in fig. 9.

In step SA4 shown in fig. 8, after the molten metal injected into the mold 2 is cooled and solidified (after cooling for a predetermined time), the control unit 8 moves the movable platen 3 in a direction to separate the movable mold 5 from the fixed mold 6. Thereafter, the molded article molded in the mold 2 is taken out.

In the next step SA5, a mold release agent is applied to the surfaces of the recesses 5a and 6a of the movable mold 5 and the fixed mold 6 by a mold release agent application device, not shown.

In step SA6, the control unit 8 drives the plunger rod 13 to start the movement of the plunger head 12 from the forward limit to the backward limit.

In step SA7, when the plunger ram 12 moves from the forward limit to the backward limit, the lubricant is discharged together with air from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d of the plunger rod 13 by the lubricant supply unit 15. That is, in step SA7, a lubricant application step of applying a lubricant between the plunger ram 12 and the inner surface of the plunger sleeve 11 is performed. The lubricant application process in this step SA7 is described later.

After step SA7, the flow ends (end). When the molding of the next molded article is continued, the die casting device 1 returns to step SA1 to repeat the operation of the flow shown in fig. 8.

(Lubricant application step)

Next, the lubricant application step performed in step SA7 shown in fig. 8 will be described with reference to fig. 5 to 7 and 10. Fig. 5 to 7 are diagrams schematically showing the state of lubricant application in the injection plunger device 10. Fig. 10 is a diagram illustrating a flow of the lubricant application process.

When the flow shown in fig. 10 is started (started), the lubricant supply control unit 50 determines whether or not the plunger ram 12 has reached the 1 st position of the molten metal passage 11a based on the detection signal of the position detection unit 16 input via the control unit 8 at step SB 1. The 1 st position is a position between the forward limit and a position (speed switching position) at which the moving speed of the plunger ram 12 is switched to a speed equal to or greater than a predetermined value when the plunger ram 12 moves from the backward limit to the forward limit in the molten metal passage 11a (see fig. 5).

In the 1 st position, the plunger ram 12 is closer to the advance limit than the speed switching position, and therefore, the plunger rod 13 is liable to tilt downward. Therefore, the plunger ram 12 is easily brought into contact with the lower side of the inner surface of the plunger sleeve 11. In addition, the 1 st position is the position of I in fig. 9.

If it is determined at step SB1 that the plunger ram 12 has reached the 1 st position (yes), the routine proceeds to step SB 2. In this step SB2, one pump 61 of the 3 pumps 61 is connected to the lubricant flow path 13b connected to the lower lubricant discharge port 13d by the switching portion 62. Then, the pump control unit 51 drives one pump 61 to discharge the lubricant together with air from the lower lubricant discharge port 13d to the outside of the plunger rod 13 (see the arrow in fig. 5). Thereby, the lubricant is applied to the inner surface of the plunger sleeve 11, and therefore, the lubricant is supplied between the inner surface of the plunger sleeve 11 and the plunger ram 12 that moves toward the retreat limit within the molten metal passage 11 a.

If it is determined at step SB1 that the plunger ram 12 has not reached the 1 st position (no), the determination at step SB1 is repeated until it is determined that the plunger ram 12 has reached the 1 st position.

At step SB3, which is entered after the lubricant is discharged from the lower lubricant discharge port 13d at step SB2, the lubricant supply control portion 50 determines whether or not the plunger ram 12 has reached the 2 nd position of the molten metal passage 11 based on the detection signal of the position detection portion 16 inputted via the control portion 8. This 2 nd position is a speed switching position (see fig. 6).

In the speed switching position (2 nd position) of the plunger ram 12, as described above, the plunger rod 13 is liable to tilt downward, and the plunger ram 12 is liable to contact the lower side of the inner surface of the plunger sleeve 11. In addition, the 2 nd position is the position of II in fig. 9.

If it is determined at step SB3 that the plunger ram 12 has reached the 2 nd position (yes), the routine proceeds to step SB 4. In this step SB4, the switching portion 62 connects one pump 61 other than the pump used in step SB2 of the 3 pumps 61 to the lubricant flow path 13b connected to the lower lubricant discharge port 13 d. Then, the pump control unit 51 drives one pump 61 to discharge the lubricant together with air from the lower lubricant discharge port 13d to the outside of the plunger rod 13 (see the arrow in fig. 6). Thereby, the lubricant is applied to the inner surface of the plunger sleeve 11, and therefore, the lubricant is supplied between the inner surface of the plunger sleeve 11 and the plunger ram 12 that moves toward the retreat limit within the molten metal passage 11 a.

If it is determined at step SB3 that the plunger ram 12 has not reached the 2 nd position (no), the determination at step SB3 is repeated until it is determined that the plunger ram 12 has reached the 2 nd position.

At step SB5, which is entered after the lubricant is discharged from the lower lubricant discharge port 13d at step SB4, the lubricant supply control portion 50 determines whether or not the plunger tip 12 has reached the 3 rd position of the molten metal passage 11 based on the detection signal of the position detection portion 16 inputted via the control portion 8. The 3 rd position is a position where the plunger ram 12 contacts the upper side of the inner surface of the plunger sleeve 11 when the plunger ram 12 moves from the retreat limit to the advance limit. That is, the 3 rd position is a position between the speed switching position and the retreat limit (see fig. 7).

As described above, the central portion in the longitudinal direction of the plunger sleeve 11 is curved convexly downward by the heat of the molten metal. Thus, when the plunger ram 12 moves from the retreat limit to the advance limit within the molten metal passage 11a, the plunger ram 12 comes into contact with the upper side of the inner surface of the plunger sleeve 11. The 3 rd position as the contact position is the position of III in fig. 9.

If it is determined at step SB5 that the plunger ram 12 has reached the 3 rd position (yes), the routine proceeds to step SB 6. In step SB6, the pumps 61 other than the pumps used in steps SB2 and SB4 among the 3 pumps 61 are connected to the lubricant flow path 13a connected to the upper lubricant discharge port 13c by the switching portion 62. Then, the pump control unit 51 drives one pump 61 to discharge the lubricant together with air from the upper lubricant discharge port 13c to the outside of the plunger rod 13 (see the arrow in fig. 7). Thereby, the lubricant is applied to the inner surface of the plunger sleeve 11, and therefore, the lubricant is supplied between the inner surface of the plunger sleeve 11 and the plunger ram 12 that moves toward the retreat limit within the molten metal passage 11 a.

If it is determined at step SB5 that the plunger ram 12 has not reached the 3 rd position (no), the determination at step SB5 is repeated until it is determined that the plunger ram 12 has reached the 3 rd position.

After the lubricant is discharged from the upper lubricant discharge port 13c in step SB6, the flow ends (end).

Here, steps SB2, SB4, SB6 of discharging the lubricant from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d according to the axial position of the plunger ram 12 in the molten metal passage 11a correspond to the lubricant discharging process. The step SB2 of discharging the lubricant from the lower lubricant discharge port 13d between the advance limit and the speed switching position corresponds to the discharge 1 st process. The step SB4 of discharging the lubricant from the lower lubricant discharge port 13d at the speed switching position corresponds to the discharge 2 nd process. Step SB6 of discharging the lubricant from the upper lubricant discharge port 13c between the speed switching position and the retreat limit corresponds to the discharge 3 rd process.

As described above, by discharging the lubricant from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d of the plunger rod 13 through the plurality of

lubricant flow paths

13a and 13b in the plunger rod 13, the lubricant can be more efficiently supplied between the inner surface of the plunger sleeve 11 and the plunger ram 12. Thereby, friction and wear of the plunger sleeve 11 and the plunger ram 12 can be reduced.

Further, according to the above configuration, the lubricant can be supplied to the portion between the plunger sleeve 11 and the plunger ram 12, which is necessary at a necessary timing. This can suppress the supply of an excessive lubricant between the plunger sleeve 11 and the plunger ram 12, and thus can suppress the occurrence of a defect in the molded article due to the lubricant.

The plunger rod 13 has an upper lubricant outlet 13c and a lower lubricant outlet 13d, so that lubricant can be efficiently supplied between the inner surface of the plunger sleeve 11 and the plunger ram 12. Therefore, friction and wear of the plunger sleeve 11 and the plunger ram 12 can be further reduced.

In the die casting device 1, when the plunger ram 12 moves in the molten metal passage 11a, the plunger ram 12 is likely to come into contact with the inner surface of the plunger sleeve 11 at a position in the vertical direction. Therefore, as described above, by providing the plunger rod 13 with the upper lubricant discharge port 13c opened upward and the lower lubricant discharge port 13d opened downward, the lubricant can be supplied more reliably to the contact portion where the plunger sleeve 11 and the plunger ram 12 are in contact with each other. Therefore, friction and wear of the plunger sleeve 11 and the plunger ram 12 can be further reduced.

Further, in the above configuration, when the plunger ram 12 moves from the forward limit to the backward limit in the molten metal passage 11a, the lubricant supply portion 15 discharges the lubricant from the lubricant discharge port near the contact portion of the plunger ram 12 with the plunger sleeve 11 out of the upper lubricant discharge port 13c and the lower lubricant discharge port 13d at the position where the plunger ram 12 contacts the inner surface of the plunger sleeve 11 when the plunger ram 12 moves from the backward limit to the forward limit in the molten metal passage 11 a.

This makes it possible to more reliably supply lubricant to the contact portion where the plunger ram 12 contacts the plunger sleeve 11, at the position where the plunger ram 12 contacts the inner surface of the plunger sleeve 11. Therefore, the lubricant can be efficiently supplied between the plunger ram 12 and the plunger sleeve 11, and therefore, the friction and wear between the plunger sleeve 11 and the plunger ram 12 can be further reduced while further suppressing the occurrence of defects in the molded product due to the lubricant.

In the above configuration, the lubricant supply unit 15 includes: a plurality of pumps 61; a switching unit 62 that switches the connection between the plurality of pumps 61 and the plurality of

lubricant flow paths

13a and 13 b; and a lubricant supply control unit 50 that controls driving of the plurality of pumps 61 and the switching unit 62.

This enables the lubricant to be supplied to each of the plurality of

lubricant flow paths

13a and 13 b. Therefore, the lubricant can be supplied from the upper lubricant discharge port 13c and the lower lubricant discharge port 13d through one of the plurality of

lubricant flow paths

13a, 13b at different timings.

Further, when the lubricant is discharged a plurality of times using the same pump, the discharge pressure of the pump may decrease and the lubricant may not be discharged from the lubricant discharge port in a required amount. However, as described above, by switching the connection between the plurality of pumps 61 and the plurality of

lubricant flow paths

13a and 13b by the switching portion 62, a decrease in the discharge pressure of the pumps can be suppressed, and therefore, a necessary amount of lubricant can be supplied between the plunger ram 12 and the plunger sleeve 11.

In the above configuration, the number of pumps included in the plurality of pumps 61 is equal to the number of times that the lubricant is discharged from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d when the plunger head 12 moves from the forward limit to the backward limit in the molten metal passage 11 a. The lubricant supply control unit 50 includes a switching control unit 52 that controls driving of the switching unit 62 and a pump control unit 51 that controls driving of the pump 61. The switching control portion 52 connects a different one of the plurality of pumps 61 to one of the

lubricant flow paths

13a, 13b via the switching portion 62 every time the plunger head 12 is discharged from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d when moving from the forward limit to the backward limit within the molten metal passage 11 a. The pump control portion 51 discharges the lubricant from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d connected to one lubricant flow path through the one lubricant flow path by the pump 61 connected to the one lubricant flow path.

Thus, each time the lubricant is discharged from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d, the lubricant can be supplied from a different pump 61 of the plurality of pumps 61 to one of the

lubricant flow paths

13a and 13 b. Therefore, the lubricant can be discharged from the upper lubricant outlet 13c or the lower lubricant outlet 13d through one of the

lubricant passages

13a and 13b at predetermined timings.

(other embodiments)

In summary, the embodiments of the present invention have been described, but the above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments without departing from the scope of the present invention.

In the embodiment, when the plunger ram 12 moves from the forward limit to the backward limit, the lubricant supply unit 15 discharges the lubricant from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d when the axial position of the plunger ram 12 is the 1 st position to the 3 rd position. However, the lubricant supply portion 15 may discharge the lubricant from the upper lubricant discharge port 13c or the lower lubricant discharge port 13d only when the axial position of the plunger ram 12 is at the 2 nd position and the 3 rd position.

That is, the lubricant supply unit 15 may not discharge the lubricant from the lower lubricant discharge port 13d when the plunger ram 12 is located at a position (1 st position) between the forward limit of the molten metal passage 11a and a speed switching position at which the moving speed of the plunger ram 12 is switched when the plunger ram 12 moves from the backward limit to the forward limit.

The position at which the plunger ram 12 contacts the inner surface of the plunger sleeve 11 is not limited to the position (1 st position to 3 rd position) of the embodiment. Further, as long as the lubricant can be discharged to the portion where the plunger ram 12 contacts the inner surface of the plunger sleeve 11, the lubricant may be discharged from either one of the upper lubricant discharge port 13c and the lower lubricant discharge port 13 d.

When discharging the lubricant to the inner surface of the plunger sleeve 11, the lubricant may be discharged from both the upper lubricant discharge port 13c and the lower lubricant discharge port 13d, instead of discharging the lubricant from only one of the upper lubricant discharge port 13c and the lower lubricant discharge port 13 d. That is, when there are a plurality of lubricant discharge ports, the lubricant may be discharged simultaneously from all or a part of the lubricant discharge ports.

In the embodiment, the lubricant discharge ports are an upper lubricant discharge port 13c opening upward and a lower lubricant discharge port 13d opening downward. However, the discharge port of the lubricant may be opened in any direction as long as the lubricant can be discharged to the portion where the plunger ram 12 contacts the inner surface of the plunger sleeve 11. The number of lubricant discharge ports is not limited to 2, and may be 1 or more than 2. Even in this case, it is preferable that each lubricant discharge port is opened at a different position in the circumferential direction of the outer circumferential surface of the plunger sleeve 11.

In the embodiment, the plunger rod 13 has an upper lubricant drain 13c and a lower lubricant drain 13 d. However, the plunger presser may be provided with a lubricant discharge port. For example, as shown in fig. 11, a lubricant discharge port 101c may be provided in the plunger ram 101 connected to the plunger rod 13 via the ram head 102.

Specifically, as shown in fig. 11, the plunger ram 101 includes a ram portion 101a on the distal end side and a lubricant discharge portion 101 b. The lubricant discharge portion 101b has a plurality of lubricant discharge ports 101c arranged in the circumferential direction. The ram joint 102 has a plurality of

lubricant passages

102a and 102b connected to a plurality of lubricant discharge ports 101c inside. The plurality of

lubricant passages

102a and 102b are connected to the

lubricant passages

13a and 13b in the plunger rod 13, respectively.

Thus, the lubricant supplied to one of the

lubricant passages

13a and 13b in the plunger rod 13 flows through one of the

lubricant passages

102a and 102b in the ram head 102 and is discharged from the lubricant discharge port 101c of the lubricant discharge portion 101b of the plunger ram 101.

As described above, by providing the lubricant discharge port 101c in the lubricant discharge portion 101b of the plunger ram 101, even when the ram portion 101a of the plunger ram 101 is worn or the like, a proper amount of lubricant can be discharged from the lubricant discharge port 101c at a proper timing without being affected by the wear or the like of the head portion 101 a.

Further, both the plunger rod and the plunger pressure head may be provided with a lubricant discharge port. That is, the configuration shown in fig. 11 may be combined with the configuration of the embodiment.

In the embodiment, the plunger rod 13 has 2

lubricant passages

13a and 13b inside. However, more than 2 lubricant flow paths may be provided inside the plunger rod 13.

In the embodiment, as an example of the lubricant discharged from the upper lubricant discharge port 13c and the lower lubricant discharge port 13d of the plunger rod 13, a lubricant is used. However, the lubricant may be a lubricant other than the lubricating oil as long as the lubricant functions as the lubricant.

In the embodiment, the lubricant supply unit 15 includes 3 pumps 61. However, there may be less than 3 pumps, and there may be more than 3 pumps. In the embodiment, the 3 pumps 61 are dedicated pumps for discharging the lubricant for each discharge, but the present invention is not limited to this, and the lubricant may be discharged a plurality of times by 1 pump. Preferably, the number of pumps is the number corresponding to the number of times the plunger ram is discharged from the lubricant discharge port when moving from the forward limit to the backward limit in the molten metal passage.

[ examples ] A method for producing a compound

In order to confirm the effects of the configuration of the present embodiment described above, the state of application of the lubricant to the inner surface of the plunger sleeve 11 was confirmed. The following methods were used as comparative examples 1 and 2, in addition to the method of the present embodiment.

Comparative example 1

When the plunger ram is located at the retreat limit of the molten metal passage, the lubricant is discharged into the plunger sleeve 11 together with air, and oil is dropped to the plunger ram.

Comparative example 2

When the plunger ram moves from the forward limit to the backward limit in the molten metal passage (when the plunger ram returns to the backward limit after injection molding), the lubricant is discharged once into the plunger sleeve 11 together with air from the lubricant discharge port of the plunger rod.

The amounts of lubricant discharged in the respective methods are shown in table 1. In each method, the discharge amount of the lubricant was set to the discharge amounts of the coating conditions 1 to 3 shown in table 1.

[ TABLE 1 ]

The length of the plunger sleeve used for the evaluation was 1160mm, and the inner diameter of the plunger sleeve was 140 mm. Thus, the area of the inner surface of the plunger sleeve is 510000mm². In either method, the pressure of the air injected together with the lubricant is 10 MPa. In either method, the diameter of the discharge port for discharging the lubricant and the air is 2.5 mm.

Under the above conditions, after discharging the lubricant into the plunger sleeve by each method, the range (lubricant-applied area) into which the lubricant penetrates on the standard japanese paper was measured by abutting the standard japanese paper against the inner surface of the plunger sleeve. The measurement results are shown in table 2.

[ TABLE 2 ]

	Comparative example 1	Comparative example 2	The present embodiment
				Coating conditions
1	331.500mm²	357.000mm²	438.600mm²
				Coating conditions 2	260.100mm²	265.200mm²	372.300mm²
Coating conditions 3	198.900mm²	249.900mm²	346.800mm²

According to table 2, the lubricant application area is maximized under any one of the application conditions by the method of the present embodiment. Therefore, it is found that the method of the present embodiment is the most effective method among 3 coating methods as a method of applying the lubricant to the inner surface of the plunger sleeve.

Further, as is clear from table 2, the lubricant application area under the application condition 3 of the present embodiment is equal to the lubricant application area under the application condition 1 of the comparative examples 1 and 2. Therefore, according to the coating method of the present embodiment, the discharge amount of the lubricant into the plunger sleeve can be reduced as compared with the case of the methods of comparative examples 1 and 2.

Next, in the above 3 coating methods, the lubricant was applied to the inner surface of the plunger sleeve under the condition that the lubricant application area became the same (under the condition that the underlined area in table 2 was obtained in each coating method), and a cast product (molded product) was obtained by a die casting apparatus. Then, the amount of gas contained in the cast product was measured. In addition, a gas chromatography type gas analyzer manufactured by NINZINGER corporation was used for measuring the amount of gas.

Fig. 12 shows the measurement results of the amount of gas contained in the cast product. As shown in fig. 12, when the lubricant is applied to the inner surface of the plunger sleeve by the method of the present embodiment, the amount of gas contained in the cast product (particularly, the amount of gas due to the lubricant) is smaller than in the methods of comparative examples 1 and 2. This is considered to be because, when the method of the present embodiment is used, the amount of lubricant discharged can be reduced as compared with the methods of comparative examples 1 and 2.

From the above results, by using the injection plunger device and the lubricant supplying method of the present embodiment, it is possible to suppress the influence of the lubricant on the molded article while securing the lubricity of the plunger sleeve and the plunger ram.

The present invention can be used for an injection plunger device that injects molten metal into a mold of a die casting device, for example.

Claims

1. An injection plunger device for supplying molten metal into a die of a die casting device, comprising:

a cylindrical plunger sleeve;

a cylindrical plunger ram disposed within the plunger sleeve;

a shaft-like plunger rod having the plunger pressure head connected to a distal end thereof; and

a lubricant supply portion that supplies lubricant between the plunger sleeve and the plunger ram,

the plunger sleeve has:

a molten metal passage to which the molten metal is supplied; and

an injection port located at one end side of the molten metal passage, opening toward an inner space of the mold,

the plunger ram being capable of reciprocating within the molten metal passage between an advancing limit on the injection port side and a retracting limit on the other end side of the molten metal passage,

the plunger rod has a plurality of lubricant flow paths extending axially within the plunger rod,

the injection plunger device is characterized in that,

at least one of the plunger ram and the plunger rod has a plurality of lubricant discharge ports that are open at different positions in the circumferential direction of the outer peripheral surface and are connected to the plurality of lubricant flow paths, respectively,

the lubricant supply unit supplies lubricant to at least one of the plurality of lubricant flow paths based on a detection signal output from a position detection unit that detects an axial position of the plunger head in the molten metal passage when the plunger head moves from the forward limit to the backward limit in the molten metal passage,

the plunger rod has the plurality of lubricant discharge ports on an outer circumferential surface,

the lubricant supply unit includes:

a plurality of pumps;

a switching unit that switches connection between the plurality of pumps and the plurality of lubricant flow paths; and

a lubricant supply control unit that controls driving of the plurality of pumps and the switching unit,

the number of pumps included in the plurality of pumps is equal to the number of times the plunger ram is discharged from the plurality of lubricant discharge ports when moving from the forward limit to the backward limit in the molten metal passage,

the lubricant supply control unit includes:

a switching control unit that controls driving of the switching unit; and

a pump control unit that controls driving of the pump,

the switching control portion connects a different one of the plurality of pumps to one of the plurality of lubricant flow paths via the switching portion each time the plunger head discharges lubricant from the plurality of lubricant discharge ports while moving from the forward limit to the backward limit within the molten metal passage,

the pump control portion causes the lubricant to be discharged from the lubricant discharge port connected to the one lubricant flow path through the one lubricant flow path by the pump connected to the one lubricant flow path.

2. The injection plunger device of claim 1,

the plurality of lubricant drain ports includes:

an upper lubricant discharge port that opens upward in the direction of gravity; and

and a lower lubricant outlet opening downward in the direction of gravity.

3. The injection plunger device of claim 1,

the lubricant supply portion discharges the lubricant from a lubricant discharge port that is close to a contact portion where the plunger ram contacts the inner surface of the plunger sleeve, among the plurality of lubricant discharge ports, at a position where the plunger ram contacts the inner surface of the plunger sleeve when the plunger ram moves from the forward limit to the backward limit within the molten metal passage.

4. The injection plunger device of claim 2,

5. A method of supplying lubricant to an injection plunger device, the injection plunger device comprising:

a cylindrical plunger sleeve having a molten metal passage;

a columnar plunger ram disposed in the molten metal passage;

the lubricant supplying method is characterized by comprising a lubricant discharging step,

in the lubricant discharging step, when the plunger ram moves from the advancing limit to the retreating limit on the injection port side in the molten metal passage, lubricant is discharged a plurality of times from a plurality of lubricant discharge ports, which are open at different positions in the circumferential direction of the outer peripheral surface of at least one of the plunger ram and the plunger rod, by the lubricant supplying section via a plurality of lubricant flow paths extending in the axial direction inside the plunger rod, based on a detection signal output from a position detecting section that detects the axial position of the plunger ram in the molten metal passage,

in the lubricant discharging step, the lubricant is discharged,

discharging lubricant from a lubricant discharge port, which is close to a contact portion where the plunger ram contacts the inner surface of the plunger sleeve, among the plurality of lubricant discharge ports, by the lubricant supply portion, at a plurality of positions where the plunger ram contacts the inner surface of the plunger sleeve when moving from the retreat limit to the advance limit within the molten metal passage,

the plurality of locations includes:

a speed switching position at which a moving speed of the plunger ram is switched to a speed equal to or greater than a predetermined value when the plunger ram moves from the retreat limit to the advance limit within the molten metal passage; and

a contact position where the plunger head is in contact with an inner surface of the plunger sleeve deformed by heat of the molten metal when the plunger head moves from the retreat limit to the advancement limit within the molten metal passage,

the plurality of lubricant drain ports includes:

an upper lubricant outlet opening upward in the direction of gravity; and

a lower lubricant outlet opening downward in the direction of gravity,

at the speed switching position, the lubricant discharge port near the contact portion is the lower side lubricant discharge port,

at the contact position, the lubricant discharge port near the contact portion is the upper side lubricant discharge port.

6. The lubricant supplying method of an injection plunger device according to claim 5,

the plurality of positions includes a position between the speed switch position and the forward limit,

the lubricant discharge port that is close to the contact portion is a lower lubricant discharge port that is open downward in the direction of gravity among the plurality of lubricant discharge ports at a position between the speed switching position and the advance limit.

7. The lubricant supplying method of an injection plunger device according to claim 5,

the lubricant discharging step includes the steps of:

a discharge step 1 of discharging the lubricant from the lower lubricant discharge port among the plurality of lubricant discharge ports when the plunger ram is located at a1 st position between the forward limit and a speed switching position at which a moving speed of the plunger ram is switched to a predetermined value or more when the plunger ram moves from the backward limit to the forward limit in the molten metal passage;

a discharge 2 nd step of discharging the lubricant from the lower lubricant discharge port of the plurality of lubricant discharge ports when the plunger ram is located at a2 nd position as the speed switching position in the discharge 2 nd step; and

and a discharge 3 rd step of discharging the lubricant from the upper lubricant discharge port among the plurality of lubricant discharge ports when the plunger ram is located at a3 rd position between the speed switching position and the retraction limit in the discharge 3 rd step.