Maintenance device for metal injection molding machine

Abstract

To positively remove in a brief time a metal material stuck to a screw, etc. used in a metal injection casting machine.SOLUTION: A maintenance apparatus 60 comprises a burner assembly 70 and a support table 80 that sustains the burner assembly 70, so as to dissolve and remove away a metal material stuck to a screw 50 used in a metal injection casting machine. The burner assembly 70 includes a plurality of gas burners 71 arranged around the screw 50 in positions mutually different in a circumferential direction of the screw 50 and a piping member 72 that connects the plurality of gas burners 71 into one body and forms a flow passage for supplying fuel to the respective gas burners 71.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a metal injection molding machine, and more particularly to the maintenance of a metal injection molding machine.

Background Art

[0002] A metal injection molding machine capable of molding a metal member having a desired shape is known. A general metal injection molding machine is composed of an injection device and a mold clamping device. The injection device supplies an alloy in a molten state or a semi-molten state, such as a magnesium alloy, an aluminum alloy, or a zinc alloy (hereinafter sometimes collectively referred to as "molten metal"), to the mold clamping device. More specifically, the injection device injects (fills) the molten metal into the cavity of the mold set in the mold clamping device.

[0003] The injection device includes a cylinder, a screw provided in the cylinder, and an injection nozzle attached to the tip of the cylinder. Pellet-shaped alloy (alloy chips) are supplied into the cylinder. The alloy chips supplied into the cylinder are heated and melted by the heat generated from a heater provided around the cylinder and the shear heat generated by the rotation of the screw. In other words, the solid-state alloy changes to a molten state or a semi-molten state in the cylinder. Thereafter, the molten metal is pushed by the screw moving in the axial direction and ejected from the tip of the injection nozzle.

[0004] The metal injection molding machine needs to be maintained regularly or as needed. For example, a part of the molten metal may adhere to the screw and solidify. That is, the metal material may adhere to the screw. Therefore, it is necessary to remove the screw from the cylinder regularly or as needed and remove the metal material adhering to the screw.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the maintenance of a metal injection molding machine, it is required to surely remove the metal material adhering to a screw or the like in a short time. Other problems and novel features will become apparent from the description of this specification and the attached drawings.

Means for Solving the Problems

[0007] The maintenance device of one embodiment includes a burner assembly and a support base for supporting the burner assembly. The burner assembly includes a plurality of gas burners arranged at positions different from each other in the circumferential direction around a screw or an injection nozzle used in a metal injection molding machine, and a piping member that connects and integrates the plurality of gas burners and forms a flow path for supplying fuel to each of the gas burners.

Effects of the Invention

[0008] According to one embodiment, the metal material adhering to a screw or the like used in a metal injection molding machine can be surely removed in a short time.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a maintenance device according to an embodiment will be described in detail with reference to the drawings. In all the drawings referred to for explaining the embodiment, members, devices, etc. having the same or substantially the same functions are denoted by the same reference numerals, and repeated explanations thereof are omitted.

[0011] <Metal injection molding machine> FIG. 1 is a cross-sectional view schematically showing an example of a metal injection molding machine. The illustrated metal injection molding machine 1 is composed of a mold clamping device 2 and an injection device 3. Molds 11 and 12 are set in the mold clamping device 2. The mold clamping device 2 opens and closes the set molds 11 and 12. The injection device 3 melts the supplied alloy chips to a molten state or a semi-molten state. In another view, the injection device 3 makes an alloy (molten metal) in a molten state or a semi-molten state. Further, the injection device 3 supplies the molten metal to the molds 11 and 12 set in the mold clamping device 2. More specifically, the injection device 3 injects the molten metal and injects (fills) it into the cavity 13 of the molds 11 and 12.

[0012] <Mold clamping device> The mold clamping device 2 includes an opposing fixed platen 14 and a movable platen 15. The mold 11 is set on the fixed platen 14, and the mold 12 is set on the movable platen 15. The movable platen 15 is movable in the opposing direction between the fixed platen 14 and the movable platen 15. In another view, the movable platen 15 is movable in a direction approaching the fixed platen 14 and is also movable in a direction away from the fixed platen 14.

[0013] When the movable platen 15 approaches the fixed platen 14, the mold 12 set on the movable platen 15 abuts against the mold 11 set on the fixed platen 14, and the molds 11 and 12 are closed. When the molds 11 and 12 are closed, a cavity 13 and a runner 16 are formed between the mold 11 and the mold 12. On the other hand, when the movable platen 15 separates from the fixed platen 14, the mold 12 set on the movable platen 15 separates from the mold 11 set on the fixed platen 14, and the molds 11 and 12 are opened.

[0014] Note that the mold clamping device 2 includes a plurality of ejector pins 17 for pushing out the molded product from the cavity 13. Further, the mold clamping device 2 includes a plug catcher 18 for receiving a lump (plug) of molten metal that may be formed at the tip of the injection nozzle 40.

[0015] <Injection Device> The injection device 3 is installed on a base (not shown). The injection device 3 is composed of a cylinder 30, an injection nozzle 40, a screw 50, etc. The injection device 3 is driven in a direction (forward) approaching the mold clamping device 2 and is also driven in a direction (backward) separating from the mold clamping device 2. That is, the injection device 3 moves forward and backward (recedes) with respect to the mold clamping device 2. When the injection device 3 moves forward to a predetermined position, the tip of the injection nozzle 40 contacts the sprue bush of the mold 11.

[0016] A hopper 31 is provided on the rear end side of the cylinder 30. The hopper 31 is a supply port for supplying alloy chips to the cylinder 30. The hopper 31 is fixed to the cylinder 30 via a hopper flange 32. Inside the hopper flange 32, a supply path communicating with the hopper 31 and the cylinder 30 is provided. The alloy chips put into the hopper 31 fall into the cylinder 30 through the supply path.

[0017] An injection nozzle 40 is attached to the tip of the cylinder 30. The injection nozzle 40 is pressed against the tip of the cylinder 30. More specifically, the rear end face of the injection nozzle 40 is pressed against the front end face of the cylinder 30 by an annular retainer 41 bolted to the cylinder 30. In other words, the flange portion of the injection nozzle 40 is sandwiched between the cylinder 30 and the retainer 41.

[0018] A screw 50 is provided inside the cylinder 30. The screw 50 is driven within the cylinder 30 by a drive mechanism 51. More specifically, the screw 50 is rotationally driven within the cylinder 30. Also, the screw 50 is driven straight forward within the cylinder 30.

[0019] A heater is provided around the cylinder 30. More specifically, a plurality of band heaters 33 are wound around the outer peripheral surface of the cylinder 30. The alloy chips supplied to the cylinder 30 are kneaded while being heated by the heat emitted from the band heaters 33 and the frictional heat generated as the screw 50 rotates. As a result, an alloy (molten metal) in a molten state or a semi-molten state is produced.

[0020] <Method for manufacturing a metal molded product> Next, an example of the procedure (process) for manufacturing a metal molded product using the metal injection molding machine 1 shown in FIG. 1 will be described. First, the molds 11 and 12 set in the mold clamping device 2 are opened, and the injection device 3 is retracted.

[0021] Then, alloy chips are put into the hopper 31 of the injection device 3. For example, magnesium alloy processed into pellets is put into the hopper 31. However, the alloy chips may be put into the hopper 31 in advance before retracting the injection device 3.

[0022] The alloy chips fed into the hopper 31 are supplied to the cylinder 30 via the supply path. The alloy chips supplied to the cylinder 30 are kneaded while being heated and melted. Viewed another way, the alloy chips undergo a phase change to a molten state or semi-molten state within the cylinder 30 and become molten metal.

[0023] The molten metal is further kneaded while being sent to the tip side of the cylinder 30 by the rotation of the screw 50. At this time, the screw 50 retreats while rotating. As a result, a storage chamber is formed in front of the screw 50, and the molten metal is stored in the storage chamber. This process of retreating the screw 50 while sending the molten metal forward is called "metering".

[0024] When a predetermined amount of molten metal has accumulated in the storage chamber, the rotation of the screw 50 is stopped. Then, the injection device 3 is advanced, and the tip of the injection nozzle 40 is brought into contact with the sprue bush of the mold 11 (the molds 11 and 12 are pre-closed).

[0025] Next, the screw 50 is advanced at high speed. Then, the molten metal stored in the storage chamber is injected from the tip of the injection nozzle 40 toward the molds 11 and 12. The injected molten metal passes through the runner 16 and flows into the cavity 13.

[0026] After that, the screw 50 is rotated again in preparation for the next injection. Specifically, the screw 50 is rotated and alloy chips are supplied into the cylinder 30. That is, the molten metal for the next injection is stored in the storage chamber.

[0027] After the molds 11 and 12 are cooled to a temperature below the temperature at which the molten metal in the cavity 13 solidifies, the molds 11 and 12 are opened and the metal molded product is taken out. For example, after the molds 11 and 12 are opened, the ejector pin 17 is driven to push out the metal molded product from the mold 12.

[0028] By repeating the above process, metal molded products of the same shape are continuously manufactured. That is, metal molded products of the desired shape are mass-produced.

[0029] As described above, the metal injection molding machine 1 for mass-producing metal molded products needs to be maintained regularly or as needed. For example, when the above process is repeated, molten metal may remain inside the injection nozzle 40 and solidify. Also, molten metal may adhere to the surface of the screw 50 and solidify. That is, the metal material may adhere to the inside of the injection nozzle 40 or the surface of the screw 50.

[0030] If the metal material adheres to the inside of the injection nozzle 40, the flow path (nozzle hole) may be narrowed or blocked. Also, if the metal material adheres to the surface of the screw 50, the conveying ability may decrease. Clogging of the injection nozzle 40 and a decrease in the conveying ability of the screw 50 are contributing factors to insufficient injection volume (short shot).

[0031] Also, when replacing consumable parts such as piston rings, it is necessary to disassemble the screw 50. More specifically, it is necessary to remove the screw head from the screw body. At this time, the metal material adhering to the surface of the screw 50 may hinder disassembly.

[0032] For the above reasons, it is necessary to dissolve and remove the metal material adhering to the inside of the injection nozzle or the surface of the screw.

[0033] <Maintenance Device> Figures 2 and 3 are perspective views of a maintenance device used for the maintenance of the metal injection molding machine 1. The maintenance device 60 is used for the removal operation of the metal material, which is one of the maintenance operations of the metal injection molding machine 1. More specifically, the maintenance device 60 is used for the operation of dissolving and removing the metal material adhering to the inside of the injection nozzle 40, the surface of the screw 50, etc.

[0034] The maintenance device 60 is composed of a burner assembly 70, a support base 80, etc. The burner assembly 70 is supported by the support base 80 so as to be displaceable with respect to the injection nozzle 40 and the screw 50. More specifically, the burner assembly 70 is supported at least so as to be vertically movable and rotatable. For example, the burner assembly 70 is rotatable between the state shown in FIG. 2 (vertical state) and the state shown in FIG. 3 (horizontal state). Further, the burner assembly 70 is vertically movable (ascendable and descendable) in the vertical state and is also vertically movable (ascendable and descendable) in the horizontal state.

[0035] Viewed from another perspective, the state shown in FIG. 2 is the vertical state of the burner assembly 70, and the state shown in FIG. 3 is the horizontal state of the burner assembly 70. Further, the vertical state is a state rotated 90° or approximately 90° with respect to the horizontal state (standing state). In other words, the horizontal state is a state rotated 90° or approximately 90° with respect to the vertical state (lying state).

[0036] The burner assembly 70 in the vertical state (FIG. 2) is suitable for the maintenance work (metal material removal work) of the screw 50, and the burner assembly 70 in the horizontal state (FIG. 3) is suitable for the maintenance work (metal material removal work) of the injection nozzle 40. Details of each work will be described later.

[0037] <Burner assembly> The burner assembly 70 includes a plurality of gas burners 71. More specifically, the burner assembly 70 includes four gas burners 71a, 71b, 71c, and 71d. Those gas burners 71a, 71b, 71c, and 71d are connected to each other by a piping member 72 and integrated.

[0038] The piping member 72 includes an annular pipe 73 that can be arranged to surround the screw 50 or the injection nozzle 40, and a straight pipe 74 connected to the annular pipe 73. The annular pipe 73 and the straight pipe 74 communicate with each other and form a flow path for supplying fuel to each gas burner 71. Fuel flows from a supply source (e.g., a gas cylinder) through the straight pipe 74 into the annular pipe 73 and is supplied to each gas burner 71 via the annular pipe 73.

[0039] That is, the piping member 72 is a frame member (support member) that integrates the plurality of gas burners 71 and at the same time is a flow path forming member that forms a flow path for supplying fuel to the plurality of gas burners 71.

[0040] Note that the fuel (gas) supplied to the gas burner 71 is not limited to a specific gas. Examples of gases that can be supplied to the gas burner 71 include acetylene gas and propane gas. Also, a mixed gas in which oxygen is mixed with acetylene gas or propane gas is also an example of a gas that can be supplied to the gas burner 71.

[0041] The annular pipe 73 has a polygonal outer shape. More specifically, the annular pipe 73 has a generally octagonal outer shape as a whole. The straight pipe 74 is orthogonal to one side of the annular pipe 73 and is connected to that side.

[0042] In the following description, the side of the annular pipe 73 to which the straight pipe 74 is connected may be referred to as "connection portion 73a" to distinguish it from other parts. Also, the side of the annular pipe 73 that is parallel to the connection portion 73a and opposite to the connection portion 73a may be referred to as "holding portion 73b" to distinguish it from other parts. However, such a distinction is only for convenience of explanation.

[0043] The gas burners 71a, 71b, 71c, 71d are evenly arranged along the annular pipe 73. In other words, the gas burners 71a, 71b, 71c, 71d are provided at equal intervals (90° intervals) on the annular pipe 73.

[0044] Viewed another way, the gas burner 71a is connected to an inclined portion extending from one end of the connecting portion 73a, and the gas burner 71b is connected to an inclined portion extending from the other end of the connecting portion 73a. Further, the gas burner 71c is connected to an inclined portion extending from one end of the holding portion 73b, and the gas burner 71d is connected to an inclined portion extending from the other end of the holding portion 73b.

[0045] Each gas burner 71 faces the center or substantially the center of the annular pipe 73. As a result, the gas burner 71a and the gas burner 71c face each other or substantially face each other. Also, the gas burner 71b and the gas burner 71d face each other or substantially face each other.

[0046] When the screw 50 or the injection nozzle 40 is inserted into the center or substantially the center of the annular pipe 73, a plurality of gas burners 71 are arranged around the screw 50 or the injection nozzle 40 at positions different from each other in the circumferential direction. More specifically, four gas burners 71a, 71b, 71c, and 71d are evenly arranged around the screw 50 or the injection nozzle 40 in the circumferential direction.

[0047] <Support base> The support base 80 has a bottom portion 81 and a pair of side wall portions 82 and 83 provided on both sides of the bottom portion 81. The side wall portion 82 and the side wall portion 83 face each other with the burner assembly 70 interposed therebetween. Wheels 84 are provided at the four corners of the bottom portion 81, respectively. Thus, an operator can easily move the support base 80 that supports the burner assembly 70. That is, the operator can easily move the maintenance device 60.

[0048] Viewed another way, the operator can displace the burner assembly 70 with respect to the screw 50 or the injection nozzle 40 by moving the support base 80 that supports the burner assembly 70.

[0049] <Support mechanism> The support base 80 is provided with support mechanisms 91 and 92 that displaceably support the burner assembly 70 with respect to the screw 50 and the injection nozzle 40. More specifically, the support mechanisms 91 and 92 support the burner assembly 70 so as to be vertically movable and rotatable. In the following description, the support mechanism 91 may be referred to as the "right support mechanism 91", and the support mechanism 92 may be referred to as the "left support mechanism 92".

[0050] FIG. 4 is a partially enlarged view showing the left support mechanism 92. FIG. 5(A) is a front view schematically showing the structure of the left support mechanism 92. FIG. 5(B) is a cross-sectional view schematically showing the structure of the left support mechanism 92. Note that FIG. 5(B) shows a cross-section along the line X-X in FIG. 5(A).

[0051] The right support mechanism 91 is provided inside a slit 82a formed in the side wall portion 82. On the other hand, the left support mechanism 92 is provided inside a slit 83a formed in the side wall portion 83. However, the right support mechanism 91 and the left support mechanism 92 have a common basic structure. Specifically, the right support mechanism 91 and the left support mechanism 92 have a double structure composed of a square outer pipe 93 and an inner pipe 94.

[0052] As shown in FIGS. 2 and 3, the outer pipe 93 of the right support mechanism 91 is disposed inside the slit 82a of the side wall portion 82 and is fixed to the bottom portion 81 and the side wall portion 82. Further, the inner pipe 94 is inserted into the outer pipe 93 and is movable in the longitudinal direction (vertical direction).

[0053] As shown in FIG. 4, the outer pipe 93 of the left support mechanism 92 is disposed inside the slit 83a of the side wall portion 83 and is fixed to the bottom portion 81 and the side wall portion 83. Also, the inner pipe 94 is inserted into the outer pipe 93 and is movable in the longitudinal direction (vertical direction).

[0054] At the upper end of each inner pipe 94, a receiving groove 94a is provided. And the straight pipe 74 of the piping member 72 is loosely fitted and supported in the receiving groove 94a provided in the inner pipe 94 of the right support mechanism 91.

[0055] On the other hand, in the receiving groove 94a provided in the inner pipe 94 of the left support mechanism 92, the rod 75a of the holding member 75 attached to the burner assembly 70 is loosely fitted and supported. The holding member 75 is attached at a position on the holding portion 73b of the piping member 72 (annular pipe 73) where the rod 75a is coaxial with the straight pipe 74.

[0056] Viewed in another way, on both sides of the burner assembly 70, support shafts supported by the support mechanisms 91 and 92 are respectively provided. More specifically, on one side of the burner assembly 70, a support shaft (the straight pipe 74 of the piping member 72) supported from below by the inner pipe 94 of the right support mechanism 91 is provided. Also, on the other side of the burner assembly 70, a support shaft (the rod 75a of the holding member 75) supported from below by the inner pipe 94 of the left support mechanism 92 is provided.

[0057] Therefore, when the protruding length of the inner pipe 94 with respect to the outer pipe 93 changes, the height of the burner assembly 70 changes. Specifically, when the protruding length of the inner pipe 94 with respect to the outer pipe 93 increases, the burner assembly 70 rises. On the other hand, when the protruding length of the inner pipe 94 with respect to the outer pipe 93 decreases, the burner assembly 70 descends. That is, the burner assembly 70 moves up and down.

[0058] <Height adjustment mechanism> The left support mechanism 92 includes a height adjustment mechanism 95 that enables adjustment of the height of the burner assembly 70. Refer to FIGS. 4 and 5. The height adjustment mechanism 95 is composed of a long hole 95a formed in the outer pipe 93, a screw shaft 95b screw-coupled to the inner pipe 94 through the long hole 95a, and a height adjustment lever 95c attached to the base end (root) of the screw shaft 95b.

[0059] The base end side of the screw shaft 95b protruding from the long hole 95a protrudes outside the side wall portion 83 through the slit 83a. On the other hand, the height adjustment lever 95c attached to the base end of the screw shaft 95b has dimensions and a shape that cannot pass through the long hole 95a.

[0060] Therefore, when the screw shaft 95b is rotated clockwise using the height adjustment lever 95c, the outer surface of the inner pipe 94 is pressed against the inner surface of the outer pipe 93, and the inner pipe 94 is temporarily fixed to the outer pipe 93. On the other hand, when the screw shaft 95b is rotated counterclockwise using the height adjustment lever 95c, the pressing of the inner pipe 94 against the outer pipe 93 is released, and the fixing of the inner pipe 94 to the outer pipe 93 is also released.

[0061] As a result, when the screw shaft 95b is rotated in a predetermined direction to release the fixing of the inner pipe 94 to the outer pipe 93, the protruding length of the inner pipe 94 with respect to the outer pipe 93 can be changed. That is, the burner assembly 70 can be moved up and down. Then, when the screw shaft 95b is rotated in the reverse direction to fix the inner pipe 94 to the outer pipe 93 again, the changed protruding length is maintained. That is, the burner assembly 70 is held at an arbitrary height.

[0062] <Angle adjustment mechanism> The left support mechanism 92 further includes an angle adjustment mechanism 96 that enables adjustment of the angle of the burner assembly 70. The angle adjustment mechanism 96 includes a bracket 96a fixed to the upper part of the inner pipe 94, a clamp (pipe clamp) 96b fixed to the bracket 96a, and an angle adjustment lever 96d attached to the tightening bolt 96c of the clamp 96b.

[0063] The end of the rod 75a of the holding member 75 loosely fitted in the receiving groove 94a of the inner pipe 94 is inserted into the clamp 96b. The clamp 96b has an inner diameter that decreases when the tightening bolt 96c is tightened and increases when the tightening bolt 96c is loosened.

[0064] As a result, when the tightening bolt 96c is tightened using the angle adjustment lever 96d, the clamp 96b closes and the rotation of the rod 75a is restricted. On the other hand, when the tightening bolt 96c is loosened using the angle adjustment lever 96d, the clamp 96b opens and the rotation restriction of the rod 75a is released.

[0065] Here, as described above, the rod 75a and the straight pipe 74 are coaxial support shafts provided on both sides of the burner assembly 70. Also, as described above, each support shaft is loosely fitted in the receiving groove 94a. Therefore, when the rotation restriction of the rod 75a is released, the burner assembly 70 can be rotated about the rod 75a and the straight pipe 74 as the rotation axes. After that, when the rotation of the rod 75a is restricted again, the changed rotation angle is maintained.

[0066] Note that it is preferable that the rod 75a and the straight pipe 74 are coaxial. On the other hand, even if the rod 75a and the straight pipe 74 are not completely coaxial, it is possible to rotatably support the burner assembly 70 using these as support shafts. Also, even if the rod 75a and the straight pipe 74 are not completely coaxial, it is possible to rotate the burner assembly 70 using these as rotation axes. That is, the coaxiality of the rod 75a and the straight pipe 74 is not an essential condition for rotatably supporting or rotating the burner assembly 70.

[0067] That is, the angle adjustment mechanism 96 holds the burner assembly 70 at an arbitrary rotation angle. As a result, the burner assembly 70 in the horizontal state can be changed to and maintained in the vertical state. Also, the burner assembly 70 in the vertical state can be changed to and maintained in the horizontal state. Of course, the state of the burner assembly 70 can also be changed to and maintained in a state (rotation angle) other than the vertical state or the horizontal state.

[0068] <Example of Use of Maintenance Device 1> As shown in FIG. 2, the maintenance device 60 is used for the removal operation of the metal material fixed to the screw 50. For example, the maintenance device 60 is used for the removal operation of the metal material fixed to the screw head and its periphery (tip portion) of the screw 50. A procedure for removing the metal material fixed to the tip portion of the screw 50 using the maintenance device 60 will be described.

[0069] First, place and fix the screw 50 taken out from the cylinder 30 on the workbench 100. At this time, project the tip portion of the screw 50 forward of the workbench 100.

[0070] Next, install the maintenance device 60 in front of the workbench 100, and insert the tip portion of the screw 50 inside the burner assembly 70 (annular pipe 73) in a vertical state. In other words, surround the tip portion of the screw 50 with the annular pipe 73.

[0071] After that, displace the burner assembly 70 with respect to the screw 50 so that the tip portion of the screw 50 is disposed at the center or substantially the center of the annular pipe 73. That is, adjust the position of the burner assembly 70. More specifically, move the support base 80 back and forth and left and right, or move the burner assembly 70 up and down. However, the height of the burner assembly 70 may be adjusted in advance before installing the maintenance device 60 in front of the workbench 100.

[0072] Then, ignite the four gas burners 71 and heat the metal material fixed to the tip portion of the screw 50. More specifically, heat the metal material fixed to the surface of the tip portion of the screw 50 to its melting point or a temperature around the melting point. For example, heat the metal material for a predetermined time with a predetermined heating power based on experimental results, experience, etc.

[0073] Note that the surface temperature of the tip portion of the screw 50 and the metal material may be measured by a temperature sensor, and the heating power, combustion time (heating time), etc. of the gas burner 71 may be adjusted based on the measurement results. By using a temperature sensor, the heating temperature and heating time can be managed with higher accuracy.

[0074] On the bottom 81 of the support table 80, a tray 85 filled with digestion sand is installed. The metal material melted by heating with the gas burner 71 drips from the screw 50 due to its own weight. The metal material dripping from the screw 50 falls into the tray 85 and is collected.

[0075] When the tip of the screw 50 is arranged at the center or substantially at the center of the annular pipe 73, the four gas burners 71 are arranged evenly around the tip of the screw 50 in the circumferential direction of the screw 50. Therefore, the tip of the screw 50 is heated simultaneously from four different directions.

[0076] Viewed in another way, even if the screw 50 is not rotated or the gas burner 71 is not moved, the entire circumference of the screw 50 can be heated evenly. As a result, the metal material fixed to the tip of the screw 50 can be surely melted in a short time.

[0077] Note that a part of the melted metal material may scatter during operation. However, on both sides of the burner assembly 70, there are side wall portions 82, 83 of the support table 80. Therefore, the scattered metal material is received by the side wall portions 82, 83 and does not scatter outside the side wall portions 82, 83 (around the maintenance device 60). Viewed in another way, the side wall portions 82, 83 of the support table 80 serve as a cover (scattering prevention cover) for preventing the scattering of the metal material to the surroundings.

[0078] There are no walls, covers, etc. for receiving the scattered metal material in front of or above the burner assembly 70. However, walls, covers, etc. for receiving the scattered metal material may be provided in front of or above the burner assembly 70.

[0079] However, the amount of metal material scattered during operation is small and its momentum is not strong. On the other hand, if walls, covers, etc. are provided in front of or above the burner assembly 70, the workability may deteriorate. For example, walls, covers, etc. provided in front of or above the burner assembly 70 may prevent the height adjustment of the burner assembly 70. Therefore, in the present embodiment, priority is given to workability, and no walls, covers, etc. are provided in front of or above the burner assembly 70.

[0080] <Example of Use of Maintenance Device 2> As shown in FIG. 3, the maintenance device 60 is also used for the removal work of the metal material fixed to the injection nozzle 40. For example, the maintenance device 60 is also used for the removal work of the metal material fixed inside the injection nozzle 40 (inside the nozzle hole). The procedure for removing the metal material fixed inside the injection nozzle 40 using the maintenance device 60 will be described.

[0081] First, install the maintenance device 60 at an arbitrary location. Then, place the injection nozzle 40 removed from the cylinder 30 upright at the center or substantially the center of the tray 85. More specifically, place the injection nozzle 40 on top of a plurality of refractory bricks 86 stacked at the center or substantially the center of the tray 85. However, the refractory bricks 86 are only used for height adjustment and clearance securing. Therefore, if height adjustment and clearance securing are not required, the refractory bricks 86 may be omitted. Also, height adjustment and clearance securing may be achieved by a member different from the refractory bricks 86.

[0082] Next, insert the injection nozzle 40 inside the horizontally positioned burner assembly 70 (annular pipe 73). Specifically, lower the horizontally positioned burner assembly 70 around the injection nozzle 40 to a height that does not interfere with the placement work of the injection nozzle 40, and surround the injection nozzle 40 with the annular pipe 73. Of course, the height adjustment mechanism 95 is used to hold the burner assembly 70 at the retracted position and to lower it from the retracted position.

[0083] Subsequently, the four gas burners 71 are ignited to heat the injection nozzle 40. Then, the metal material inside the injection nozzle 40 melts. The melted metal material flows out from inside the injection nozzle 40 due to its own weight and drops into the tray 85.

[0084] Here, when the burner assembly 70 is in a horizontal state, the center of the annular pipe 73 is located directly above or substantially directly above the center of the tray 85. Therefore, when the horizontal burner assembly 70 is lowered from the retracted position to the periphery of the injection nozzle 40, the injection nozzle 40 is disposed at the center or substantially at the center of the annular pipe 73. As a result, the four gas burners 71 are evenly arranged in the circumferential direction around the injection nozzle 40. Accordingly, the injection nozzle 40 is heated simultaneously from four different directions.

[0085] Viewed from another perspective, even if the injection nozzle 40 is not rotated or the gas burner 71 is not moved, the entire circumference of the injection nozzle 40 can be uniformly heated. As a result, the metal material adhering to the inside of the injection nozzle 40 can be surely melted in a short time.

[0086] As described above, the maintenance device 60 of the present embodiment includes a plurality of gas burners 71 arranged at different positions in the circumferential direction around the screw 50 or the injection nozzle 40. Therefore, the screw 50 and the injection nozzle 40 can be heated simultaneously from two or more different directions. As a result, the metal material adhering to the screw surface and inside the injection nozzle can be surely removed in a short time.

[0087] Furthermore, the maintenance device 60 of the present embodiment includes a burner assembly 70 that is rotatable between a vertical state suitable for heating the screw 50 and a horizontal state suitable for heating the injection nozzle 40. That is, the maintenance device 60 can handle both the removal operation of the metal material on the screw surface and the removal operation of the metal material inside the injection nozzle with a single unit.

[0088] However, it is not impossible to heat the screw 50 without setting the burner assembly 70 in a vertical state. Also, it is not impossible to heat the injection nozzle 40 without setting the burner assembly 70 in a horizontal state. For example, the injection nozzle 40 may be placed on the workbench 100 shown in FIG. 2 and arranged in the same manner as the screw 50 shown simultaneously, and heated by the vertically positioned burner assembly 70. In this case, it is preferable to tilt the injection nozzle 40 slightly so that the molten metal material flows out smoothly from the injection nozzle 40.

[0089] FIG. 6 is a block diagram showing a modified example of the maintenance device 60. The maintenance device 60 may be added with a temperature sensor 97 capable of measuring the temperature of a heating target (such as the screw 50, the injection nozzle 40, and the metal material adhering thereto) heated by the gas burner 71, and a control unit 98 capable of controlling the gas burner 71 based on the measurement result of the temperature sensor 97. The control unit 98 automatically controls at least one of the heating power and the combustion time (heating time) of the gas burner 71 based on the measurement result of the temperature sensor 97, for example. More specifically, the control unit 98 weakens or strengthens the heating power of the gas burner 71 based on the measurement result of the temperature sensor 97. Further, the control unit 98 shuts off the fuel supply to the gas burner 71 based on the measurement result of the temperature sensor 97. The adjustment of the heating power of the gas burner 71 is realized, for example, by increasing or decreasing the supply pressure of the fuel.

[0090] The maintenance device 60 may also be provided with a notification unit 99a that issues warnings such as sound, light, and messages. The notification unit 99a issues a warning when the measurement result of the temperature sensor 97 exceeds a threshold value, for example. The threshold value is set to a temperature that can prevent deterioration of the screw 50 and the injection nozzle 40 due to overheating, for example. The illustrated notification unit 99a operates according to the control of the control unit 98, but may be made independent of the control unit 98. In this case, the output of the temperature sensor 97 is directly input to the notification unit 99a.

[0091] Furthermore, the maintenance device 60 may be provided with a display unit 99b for displaying the measurement results of the temperature sensor 97. By providing the display unit 99b, it is possible to check the heating state (such as temperature and temperature change) at any time while heating is being performed under automatic control by the control unit 98. Also, it is possible to manually adjust the firing power and combustion time of the gas burner 71 while checking the measurement results of the temperature sensor 97.

[0092] As described above, the invention made by the present inventor has been specifically described based on the embodiments. However, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof.

[0093] For example, the gas burner assembly may be provided with the number of gas burners necessary for heating the screw or injection nozzle simultaneously from two or more different directions. In other words, the gas burner assembly may be provided with at least two gas burners, and the number of gas burners is not limited to four.

[0094] Also, all or part of the plurality of gas burners provided in the gas burner assembly may be unevenly arranged in the circumferential direction of the screw or injection nozzle. However, it is desirable that the position of the gas burner is a position where the metal material dripping from the screw or the like does not hit.

[0095] The outer shape of the annular pipe may be circular or elliptical, or may be a polygon other than an octagon such as a triangle, a quadrilateral, or a hexagon.

[0096] In the above embodiment, the straight pipe also serves as one of the support shafts of the gas burner assembly. However, a support shaft may be provided separately from the straight pipe. In this case, the straight pipe can be replaced with a flexible pipe member such as a tube or a hose. Also, the annular pipe and the straight pipe that also serves as the support shaft may be connected by a rotary joint.

[0097] The height adjustment mechanism can also be replaced with a suspension type or a rack and pinion type. For example, the burner assembly may be suspended by a wire so as to be movable up and down. In this case, when the wire is wound around or taken off from a reel or a pulley, the burner assembly rises. On the other hand, when the wire is paid out from the reel or the pulley, the burner assembly descends.

[0098] The alloy processed by the metal injection molding machine to be maintained using the maintenance device is not limited to a magnesium alloy. That is, the maintenance device can also be used for removing the metal material adhering to the screw and the injection nozzle used in the metal injection molding machine for processing other alloys.

Explanation of Signs

[0099] 1 Metal injection molding machine 2 Mold clamping device 3 Injection device 11, 12 Mold 13 Cavity 14 Fixed platen 15 Movable platen 16 Runner 17 Ejector pin 18 Plug catcher 30 Cylinder 31 Hopper 32 Hopper flange 33 Band heater 40 Injection nozzle 41 Pressing metal 50 Screw 51 Driving mechanism 60 Maintenance device 70 Burner assembly 71, 71a, 71b, 71c, 71d Gas burner 72 Pipe member 73 Annular pipe 73a Connection part 73b Holding part 74 Straight pipe 75 Holding member 75a Rod 80 Support stand 81 Bottom 82, 83 Side wall parts 82a, 83a Slits 84 Wheel 85 Tray 86 Firebrick 91 Support mechanism (right support mechanism) 92 Support mechanism (left support mechanism) 93 Outer pipe 94 Inner pipe 94a Receiving groove 95 Height adjustment mechanism 95a Long hole 95b Screw shaft 95c Height adjustment lever 96 Angle adjustment mechanism 96a Bracket 96b Clamp 96c Tightening bolt 96d Angle adjustment lever 97 Temperature sensor 98 Control unit 99a Notification unit 99b Display unit 100 Workbench

Claims

1. A maintenance device for melting and removing a metal material fixed to a screw or an injection nozzle used in a metal injection molding machine, comprising: a burner assembly and a support base for supporting the burner assembly; The burner assembly includes: a plurality of gas burners arranged at positions different from each other in the circumferential direction around the screw or the injection nozzle; a piping member that connects and integrates the plurality of gas burners and forms a flow path for supplying fuel to each of the gas burners.

2. The maintenance device according to claim 1, wherein the burner assembly is displaceable relative to the screw or the injection nozzle.

3. The maintenance device according to claim 2, wherein the burner assembly is supported by the support base so as to be vertically movable.

4. The maintenance device according to claim 3, further comprising a height adjustment mechanism for adjusting the height of the burner assembly.

5. The maintenance device according to any one of claims 1 to 4, wherein the burner assembly is supported by the support base so as to be rotatable.

6. The maintenance device according to claim 5, wherein the burner assembly is rotatable between a horizontal state and a vertical state rotated 90° with respect to the horizontal state.

7. The maintenance device according to claim 5 or 6, further comprising an angle adjustment mechanism for adjusting the rotation angle of the burner assembly.

8. The piping member includes an annular pipe that can be arranged to surround the screw or the injection nozzle, and a straight pipe connected to the annular pipe. The maintenance device according to any one of claims 5 to 7, wherein the burner assembly is rotatable about the straight pipe as a rotation axis.

9. The maintenance device according to any one of claims 1 to 8, wherein the plurality of gas burners are evenly arranged in the circumferential direction of the screw or the injection nozzle.

10. The maintenance device according to any one of claims 1 to 9, wherein the support base has a bottom portion and a pair of side wall portions provided on both sides of the bottom portion and facing each other with the burner assembly interposed therebetween.

11. The maintenance device according to any one of claims 1 to 10, wherein the support base has a tray for collecting the metal material removed from the screw or the injection nozzle.

12. The support stand is the maintenance device according to any one of claims 1 to 11, having wheels.

13. A temperature sensor capable of measuring the temperature of an object to be heated heated by the gas burner, and a control unit capable of controlling the gas burner based on the measurement result of the temperature sensor, and the control unit controls at least one of the heating power and the combustion time of the gas burner based on the measurement result of the temperature sensor. The maintenance device according to any one of claims 1 to 12.

14. The maintenance device according to claim 13, having a notification unit that issues an alarm when the measurement result of the temperature sensor exceeds a threshold value.

15. The maintenance device according to claim 13 or 14, having a display unit that displays the measurement result of the temperature sensor.

Images