JP3629441B2 - Electric heat processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for supplying a current to a workpiece made of a powder sintered material and performing a sintering process by energization heating, and particularly to an electrothermal processing apparatus suitable for commercial scale actual operation. Is.
[0002]
[Prior art]
Conventionally, a thermal processing apparatus as described in Japanese Patent No. 3132560 is known. This thermal processing apparatus includes a cylindrical mold for loading a workpiece made of a powder sintered material, a lower electrode as a lower mold that is slidably contacted with the mold from the lower part, and an inner fitting from the upper part. An upper electrode as an upper mold, a power supply device that supplies current to both electrodes, a pressurizing device that pressurizes a workpiece in the mold via both electrodes, and a control means that controls the current It has a basic configuration.
[0003]
After the workpiece is loaded into the mold of such an apparatus, the current from the power supply device is passed through the upper and lower electrodes while pressing the workpiece in the mold with a predetermined pressure through the upper and lower electrodes. By supplying the workpiece to the workpiece, the workpiece is heated to high temperature by energization heat generation and subjected to sintering treatment.
[0004]
[Problems to be solved by the invention]
By the way, the conventional thermal processing apparatus as described above is suitable for applying an electric current to a workpiece to experimentally perform a sintering process for the purpose of collecting various data. The volume of the mold may be about several ml. However, commercial operations cannot be performed using such a small device.
[0005]
Therefore, it is conceivable to scale up the experimental apparatus and enlarge it for actual operation, but when the mold becomes large, the heat dissipation area increases accordingly, so that the workpiece loaded in the mold and applied with current is The temperature gradient gradually decreases from the center position of the mold toward the outside in the radial direction.
[0006]
When the temperature distribution of the workpiece is not uniform during heat processing, a uniform sintering process cannot be performed, and a high-quality sintered product cannot be manufactured.
[0007]
The present invention has been made to solve the above-described problems, and eliminates non-uniform temperature distribution in the workpiece during the sintering process, thereby producing a homogeneous sintered product on an actual scale. It aims at providing the electrothermal-processing apparatus which can be obtained by this.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is an electrothermal processing apparatus for performing a sintering process on a workpiece by energization heat generation by supplying an electric current to the workpiece made of a powder sintered material, and the workpiece is loaded. A mold, a counter electrode that energizes the workpiece while sandwiching the workpiece in the mold, and auxiliary heating means disposed around the mold The auxiliary heating means includes a heat insulating member formed so as to surround the mold, and an energizing heating element provided on the heat insulating member, and the heat insulating member is detachably attached to the peripheral surface. It can be divided into a plurality of linings on the inner peripheral surface of a cylindrical container provided with a lid. It is characterized by that.
[0009]
According to the present invention, the workpiece made of the powder sintered material loaded in the mold is heated and sintered by supplying current from the counter electrode to be a sintered product. In this sintering process, the work piece receives heat from the auxiliary heating means provided around the mold in addition to its own energized heat generation, so heat radiation from the peripheral surface of the mold is reliably suppressed, High temperature is more uniformly and efficiently maintained by the combined use of internal heating and external heating.
[0010]
The energization thermal processing apparatus also includes a system that internally heats the workpiece in the mold by energizing heat generated by the current supplied from the counter electrode, and an auxiliary heating means disposed around the mold to move the workpiece in the mold. Since the workpieces are heat-treated by two systems, that is, the external heating system, the heat treatment of each system is first performed only by auxiliary heating means, for example, and the workpiece reaches a predetermined temperature. It is possible to perform various combinations in terms of time, for example, by applying a current from the counter electrode to the workpiece later, and the degree of freedom of the operation mode is improved.
[0011]
Therefore, even if the electrothermal processing device is large on a commercial scale, it is possible to make the obtained sintered product more homogeneous and of higher quality than before, and a sintered product with high commercial value Can be obtained.
[0012]
Also By using the energization heating element as the auxiliary heating means, it is possible to obtain a desired high temperature by adjusting the amount of supplied power after simplifying the structure of the auxiliary heating means, and the temperature control becomes easy. Further, since the energization heating element is provided on the heat insulating member, the workpiece in the mold is externally heated more efficiently by the heat insulating action.
[0013]
further The cylindrical container becomes a structurally strong furnace body by lining the heat insulating member. in addition Since the heat insulating member is divided into a plurality of linings on the inner peripheral surface of the cylindrical container provided with the lid, it is easy to apply the heat insulating member to the back side of the lid and the inner surface of the cylindrical container. Is called.
[0014]
Claim 2 The described invention is claimed. 1 In the invention described above, there is provided a pressing means for pressing the workpieces in the mold by pressing the counter electrodes in a direction approaching each other.
[0015]
According to the present invention, the workpiece in the mold is in a state in which the capacity is fixed by pressing by the pressurizing means. The movement of the particles trying to move away from each other is reliably prevented, which results in a good quality sintered product with the particles packed together.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 are partially cutaway perspective views showing an embodiment of an electrothermal processing apparatus according to the present invention, FIG. 1 is a state in which a lid is removed from a processing furnace body, and FIG. The state in which the lid is mounted on the processing furnace body is shown. 3 is a cross-sectional view taken along line AA in FIG.
[0017]
As shown in these drawings, the thermal processing apparatus 10 performs a sintering process on the sintered material M by energization heating by applying a pulse current to the sintered material (workpiece) M (FIG. 3). A vertically long rectangular parallelepiped frame 20, a thin plate-shaped cylindrical safety cover 30 provided in the frame 20, a thermal processing furnace 40 built in the safety cover 30, and this heat A counter electrode 50 that is inserted into the thermal processing furnace 40 in a sliding contact state from above and below the processing furnace 40, a cylinder device 70 that presses an electrode (upper electrode 51) above the counter electrode 50, and the counter electrode 50, each die side (soaking plates 51a, 52a and punch plates 51b, 52b, which will be described later) is fitted in a sliding contact state, and the counter electrode 50 and the die 60 are surrounded in the thermal processing furnace 40. And an auxiliary heating member 80 provided And it has a present configuration.
[0018]
The counter electrode 50 and the auxiliary heating member 80 are supplied with electric power from the power supply device 90. The power supply device 90 includes a pulse current supply unit 91 that supplies a predetermined pulse current obtained by modulating an alternating current from a commercial power source to the counter electrode 50, and three-phase 220V commercial power as it is to the auxiliary heating member 80. The auxiliary heating power supply unit 92 is supplied.
[0019]
Further, a vacuum pump 100 is provided in the vicinity of the frame body 20 to suck and remove the air in the thermal processing furnace 40 to make the inside of the thermal processing furnace 40 a vacuum environment. Is subjected to thermal processing on the sintered material M (FIG. 3) in a vacuum state.
[0020]
Further, in the vicinity of the frame body 20, a hydraulic unit 110 that supplies hydraulic pressure to the cylinder device 70 and raises and lowers the upper electrode 51 is provided. The sintered material M loaded in the mold 60 is compressed at a predetermined pressure by pressing the upper electrode 51 through the partition plate 24 by driving the hydraulic unit 110.
[0021]
The frame body 20 includes a base plate 21 having a square shape in plan view, four columnar guide columns 22 erected at the four corners of the base plate 21, and bolted to the tops of the guide columns 22. And a square-shaped top plate 23 in a plan view fixed in a plan view, and a square-shaped partition plate 24 in a plan view in which the four corners are slidably contacted with the respective guide columns 22.
[0022]
Further, a cooling water channel 55 is provided inside the counter electrode 50 (the upper electrode 51 and the lower electrode 52), and cooling water from a cooling water source 120 such as clean water or industrial water is supplied to the cooling water channel 55 to thereby counter the counter electrode. 50 is cooled. By doing so, overheating of the counter electrode 50 is prevented.
[0023]
Further, an upper electrode control valve 121 is provided in the cooling water pipe from the cooling water source 120 to the upper electrode 51, and a lower electrode control valve 122 is provided in the cooling water pipe from the cooling water source 120 to the lower electrode 52. The temperature of the upper position of the upper electrode 51 and the lower position of the lower electrode 52 is controlled by adjusting the coolant flow rate by opening and closing these control valves 121 and 122.
[0024]
The upper electrode 51 and the lower electrode 52 are each provided with an inlet and an outlet for cooling water. However, if these are illustrated, the drawing becomes complicated and unsightly, and these are omitted.
[0025]
The cylinder device 70 is provided above the partition plate 24, while the safety cover 30, the thermal processing furnace 40, and the counter electrode 50 are provided below the partition plate 24. The applied pressure of the device 70 is transmitted to the upper electrode 51 through the partition plate 24, whereas the upper electrode 51 is in a state of being cut off from the cylinder device 70 when the cylinder device 70 does not perform a pressurizing operation. I have to.
[0026]
The safety cover 30 accommodates the thermal processing furnace 40, the counter electrode 50, and the mold 60 in a sealed state, a cylindrical container body 31, and a top plate 32 that closes the upper surface opening of the container body 31; An opening / closing door 33 is attached to the peripheral surface of the container body 31 so as to be freely opened and closed. An insertion hole 32a for inserting the upper electrode 51 in a sliding contact state is formed at the center position of the top plate 32.
[0027]
The opening / closing door 33 is attached to the container body 31 so as to be rotatable around a hinge (not shown) so as to close the peripheral opening 31a of the container body 31. The open / close door 33 is formed in an arc shape in a plan view in which the radius of curvature is set to be the same as the radius of the safety cover 30, and the center angle is set to approximately 120 °. Then, by closing the open / close door 33, the thermal processing furnace 40 is placed in the safety cover 30 to ensure safety.
[0028]
The thermal processing furnace 40 includes a processing furnace main body 41, a lid 42 that is detachably attached to the processing furnace main body 41, a bottom plate 44 that closes a bottom opening of the processing furnace main body 41, and an upper surface of the processing furnace main body 41. And a top plate 43 that closes the opening.
[0029]
The inner diameter of the processing furnace body 41 is set slightly larger than the dimension obtained by adding the thickness of the auxiliary heating member 80 to the outer diameter of the mold 60, whereby the sintered material M in the mold 60 is set to the auxiliary heating member 80. The heat from the auxiliary heating member 80 is received in a state of being very close.
[0030]
The thermal processing furnace 40 provided with such a processing furnace main body 41 is formed in a state in which a part of the peripheral surface of the cylindrical body is cut out, and the central angle in plan view is set to approximately 240 °, while the lid The body 42 is formed in an arc shape in plan view so as to correspond to the notched portion of the processing furnace main body 41, the radius of curvature is set to be the same as that of the processing furnace main body 41, and the central angle is substantially the same. The cylindrical body is formed with the processing furnace body 41 by being set to 120 ° and being fitted to the notched portion of the processing furnace body 41.
[0031]
Further, lower flanges 41a and 42a projecting by a predetermined amount toward the inside and the outside in the radial direction are respectively provided at the lower edge portion of the processing furnace body 41 and the processing furnace body 41, and the same upper edge portion. Are provided with upper flanges 41b and 42b similar to the lower flanges 41a and 42a, respectively. The bottom plate 44 is set to have the same diameter as the outer diameter of the lower flanges 41a and 42a with the lid 42 attached to the processing furnace body 41, and the top plate 43 has a diameter of The dimensions are set to be the same as the outer diameter dimensions of the upper flanges 41b and 42b.
[0032]
Therefore, by fixing the bottom plate 44 to the lower flanges 41a and 42a with bolts while the lid body 42 is mounted on the processing furnace main body 41, the top plate 43 is fixed to the upper flanges 41b and 42b with bolts. As shown in FIG. 2, the thermal processing furnace 40 in a state where the entrance / exit 45 of the processing furnace main body 41 is closed by the lid 42 is obtained. Then, by removing the bolts connecting the lower flange 42a and the bottom plate 44 of the lid 42 and the bolts connecting the upper flange 42b of the lid 42 and the top plate 43, the lid 42 is As shown in FIG. 1, it can be removed from the processing furnace body 41.
[0033]
Instead of fastening the lid body 42 to the processing furnace main body 41 with bolts as described above, the lid body 42 is attached to the processing furnace main body 41 through a hinge so that it can be opened and closed, and the lid body 42 is closed. You may make it lock a closed state with a predetermined | prescribed lock mechanism.
[0034]
The top plate 43 and the bottom plate 44 are provided with an upper cylindrical body 43a and a lower cylindrical body 44a for passing the lower electrode 52 and the upper electrode 51, concentrically with the top plate 43 and the bottom plate 44, respectively. An upper annular insulator 43b is interposed between the upper cylinder 43a and the upper electrode 51 in a sliding contact state, and a lower annular insulator 44b is interposed between the lower cylinder 44a and the lower electrode 52. Is installed. These annular insulators 43b and 44b make the counter electrode 50 and the thermal processing furnace 40 insulated from each other.
[0035]
The counter electrode 50 includes an upper electrode 51 provided on the upper part of the mold 60 and a lower electrode 52 provided on the lower part thereof. The sintered material M in the mold 60 is heated by its own heat generation and discharge heat upon application of pulse currents from the upper and lower electrodes 51 and 52, and the heat generation of punch plates 51b and 52b described later. The heat is transferred through the soaking plates 51a and 52a and heated, whereby the sintering process is performed.
[0036]
As shown in FIG. 3, the upper electrode 51 is laminated on the upper surface of the upper soaking plate 51a made of graphite and inserted into the cavity of the mold 60 in a sliding contact state from above. An upper punch plate 51b made of graphite, an upper pressure equalizing plate 51c stacked on the upper surface of the upper punch plate 51b, a first upper spacer 51d, a second upper spacer 51e, which are sequentially stacked on the upper surface of the upper pressure equalizing plate 51c, It consists of a third upper spacer 51f and a fourth upper spacer 51g.
[0037]
As shown in FIG. 3, the lower electrode 52 is laminated on the lower surface of the lower heat equalizing plate 52a and the lower heat equalizing plate 52a made of graphite inserted into the cavity of the mold 60 in a sliding contact state from below. A lower punch plate 52b made of graphite, a lower pressure equalizing plate 52c stacked on the lower surface of the lower punch plate 52b, a first lower spacer 52d and a second lower spacer 52e stacked sequentially on the lower surface of the lower pressure equalizing plate 52c. , A third lower spacer 52f and a fourth lower spacer 52g. The number of spacers can be appropriately increased or decreased according to the production scale and production status of the sintered product.
[0038]
The sintered material M loaded in the mold 60 is applied with a pulse current from the pulse current supply unit 91 while being pressed and clamped between the soaking plates 51a and 52a. Is heated and sintered by the heat generated by the electric current and the discharge heat generated by the arc discharge generated between the particles of the sintered material M.
[0039]
FIG. 4 is a perspective view showing an embodiment of the punch plates 51b and 52b. (A) shows the upper punch plate 51b and (B) shows the lower punch plate 52b. The upper punch plate 51b and the lower punch plate 52b have the same specifications except that the outer diameter is set slightly larger on the lower punch plate 52b than on the upper punch plate 51b. The upper punch plate 51b is used with the punch surface facing downward, while the lower punch plate 52b is used with the punch surface facing upward.
[0040]
As shown in FIG. 4, the punch plates 51 b and 52 b include a punch plate main body 53 having an outer diameter slightly smaller than the inner diameter of the die 60 and a circular protrusion formed on one surface of the punch plate main body 53. Part 54.
[0041]
The circular protrusion 54 is set to be slightly smaller in diameter than the punch plate main body 53 and is concentrically provided from the punch plate main body 53. In the circular protrusion 54, a plurality of punch slits 54a parallel to each other are recessed at an equal pitch so as to cross the circular protrusion 54, and punch protrusions are respectively provided between adjacent punch slits 54a. 54b is formed. An annular flat portion 53 a is formed between the outer peripheral edge of the circular protrusion 54 and the outer peripheral edge of the punch plate body 53.
[0042]
As shown in FIG. 3, the punch plates 51b and 52b sandwich the sintered material M through the soaking plates 51a and 52a. Such punch plates 51b and 52b are used for the following reason. That is, the punch plates 51b and 52b are provided with the punch protrusions 54b, so that only the surface of the punch protrusions 54b comes into contact with the soaking plates 51a and 52a. Since the current density per contact area increases, the amount of heat generated at the contact position between the punch ridge 54b and the heat equalizing plates 51a and 52a is increased. This is much higher than in the case of contact.
[0043]
Therefore, when the same electric power is supplied, the punch plates 51b and 52b generate a larger amount of heat than those without the punch protrusions 54b and are heated to a higher temperature. Then, the heat of the punch plates 51b and 52b heated to a higher temperature is transmitted to the sintered material M in a state of being evenly uniformed through the soaking plates 51a and 52a. In addition, the sintered material M is heated by energization heat generation by the pulse current applied from the soaking plates 51a and 52a, and is also heated by the arc discharge generated between the particles of the sintered material M to be sintered. Will be given. If the punch plates 51b and 52b are not provided with punch protrusions 54b described later and the opposing surfaces of the punch plates 51b and 52b are flush with each other, the soaking plates 51a and 52a are omitted. Can do.
[0044]
The pressure equalizing plates 51c and 52c (FIG. 3) are interposed between the punch plates 51b and 52b and the first spacers 51d and 52d, and equalize the pressurizing force from the first spacers 51d and 52d. 52b. By providing the pressure equalizing plates 51c and 52c between the punch plates 51b and 52b and the first spacers 51d and 52d, there is no uneven distribution of the press position on the punch plates 51b and 52b, and the punch plates 51b and 52b are protected. Is done.
[0045]
The first to third upper spacers 51d, 51e, 51f (FIG. 3) are all housed in the thermal processing furnace 40. Of the first to fourth upper spacers 51d, 51e, 51f, 51g, the first to third upper spacers 51d, 51e, 51f are formed of an annular body. These inner diameter dimensions are set so that the first upper spacer 51d is maximized and gradually decreases toward the third upper spacer 51f. By doing so, the first to third upper spacers 51 d, 51 e, 51 f are configured to decrease as the axial sectional area is separated from the mold 60.
[0046]
On the other hand, the fourth upper spacer 51g (which plays a role of a substantial electrode) is provided with a cooling water channel 55 inside, and the cooling water from the cooling water source 120 is supplied to the cooling water channel 55. The upper part of the upper electrode 51 is cooled.
[0047]
The first upper spacer 51d has a maximum current density as a result of the inner diameter dimension being maximized compared to other spacers (that is, the sectional area is minimized). In the meantime, the maximum energized heat generation amount can be obtained, while the cross-sectional area sequentially decreases toward the second to third upper spacers 51e and 51f, so that the energized heat generation amount decreases gradually, and the upper electrode is caused by the thermal gradient due to this The cooling process 51 (cooling process of the upper electrode 51 by supplying cooling water to the cooling water channel 55 of the fourth upper spacer 51g) is not adversely affected.
[0048]
The first to third lower spacers 52d, 52e, 52f are dimensioned exactly the same as the first to third upper spacers 51d, 51e, 51f.
[0049]
On the other hand, an insulating ring 56 made of an insulating material is interposed between the lower cylindrical body 44a of the thermal processing furnace 40 and the fourth lower spacer 52g, and thereby the electrical connection between the thermal processing furnace 40 and the fourth lower spacer 52g is made. In an isolated state.
[0050]
The mold 60 is a sintered material that is sandwiched between the thickness dimensions of the upper and lower soaking plates 51a and 52a, the upper and lower punch plates 51b and 52b, and the upper and lower soaking plates 51a and 52a. The dimension is set slightly shorter than the dimension obtained by adding the thickness dimension of M. Such a mold 60 has an inner diameter dimension slightly larger than the diameter dimension of the soaking plates 51a, 52a, and an annular angle formed by cutting a corner portion of the lower inner peripheral surface over the entire circumference. A groove 61 is provided.
[0051]
The annular square groove 61 has an inner diameter dimension slightly larger than that of the punch plate body 53 of the lower punch plate 52b, whereby the annular square groove 61 is externally fitted to the punch plate body 53 as shown in FIG. In this state, the upper surface of the annular square groove 61 comes into close contact with the annular flat portion 53a of the lower punch plate 52b.
[0052]
As shown in FIGS. 1 to 3, the cylinder device 70 includes a hydraulic cylinder 71 that is vertically placed and fixed to the center of the top surface of the top plate 23 of the frame 20 by bolting, and is directed downward from the hydraulic cylinder 71. And a press ram 73 concentrically fixed to the lower end of the piston rod 72.
[0053]
A through hole 23a for inserting the piston rod 72 is formed in the center of the top plate 23 of the frame body 20, and the piston rod 72 protruding downward from the hydraulic cylinder 71 passes through the through hole 23a. And hangs downward from the top plate 23. The lower end of the piston rod 72 is formed with a male screw portion 72a in which a male screw is screwed, while a screw hole 73a corresponding to the male screw portion 72a is screwed in the center of the upper surface of the press ram 73, and the male screw portion 72a. Is screwed into the screw hole 73 a so that the press ram 73 is connected to the piston rod 72.
[0054]
The press ram 73 is formed by a concentric two-stage cylinder, and the diameter of the lower large-diameter portion is set to be substantially the same as the diameter of the upper electrode 51. The press ram 73 is opposed to the fourth upper spacer 51 g of the upper electrode 51 through the partition plate 24 of the frame body 20. Therefore, when the hydraulic pressure from the hydraulic unit 110 is supplied to the hydraulic cylinder 71 in the forward direction and the piston rod 72 is lowered, the upper electrode 51 is pressed downward through the partition plate 24, thereby The sintered material M is pressed by the upper and lower soaking plates 51a and 52a.
[0055]
According to the cylinder device 70 configured as described above, the pressure force of the cylinder device 70 is transmitted to the sintered material M in the mold 60 via the counter electrode 50 via the piston rod 72, the press ram 73 and the partition plate 24. Moreover, since the press ram 73 is separable from the partition plate 24, the press ram 73 is applied to the sintered material M for applying pressure energy, and for the energizing heating to the sintered material M. It becomes possible to perform the sintering process on the sintered material M in a state where the application of electric energy for discharge heating is made independent of each other.
[0056]
On the other hand, in the case where the conventional upper electrode 51 is integrated with the press ram 73, the pressing operation by the cylinder device 70 for the sintered material M and the pulse from the pulse current supply unit 91 for the sintered material M are performed. Since the current application operation is inseparably performed, the pressurization operation and the pulse current application operation cannot be performed independently of each other, and the degree of freedom in setting the sintering conditions is narrow. In the pressurization structure of the embodiment, since the pressurization operation and the current application operation can be performed independently of each other, the degree of freedom in setting the sintering conditions is greatly increased, and appropriate sintering conditions are set. By selecting, a good quality sintered product having a wide range of characteristics can be obtained.
[0057]
FIG. 5 is a perspective view showing an embodiment of the auxiliary heating member 80, where (a) is a partially cutaway exploded perspective view, and (b) is an assembled perspective view. As shown in FIG. 5, the auxiliary heating member 80 includes a heat insulating member 81 formed in an arc shape made of a heat insulating material such as brick or mortar, and a rod-shaped energization heating element 82 provided on the heat insulating member 81. It has a basic configuration. Examples of the energization heating element 82 include a metal heater such as nichrome wire, a graphite heater, and the like.
[0058]
The heat insulating member 81 has a central angle set to 120 °. Therefore, by aligning both side edges of the three heat insulating members 81 with each other, as shown in FIG. . The heat insulating member 81 has a thickness dimension set slightly thinner than the distance between the inner surface of the processing furnace main body 41 (lid 42) (FIG. 1) and the outer peripheral surface of the mold 60, and has a vertical dimension of The dimension is set substantially the same as the distance between the lower flange 41a and the upper flange 41b. Therefore, as shown in FIG. 1, the two heat insulating members 81 can be mounted in a press-fitted state between the lower flange 41 a and the upper flange 41 b in the processing furnace body 41 through the entrance / exit 45. The remaining integral heat insulating member 81 is mounted between the lower flange 42a and the upper flange 42b of the lid 42 in a press-fitted state.
[0059]
Instead of press-fitting the auxiliary heating member 80 between the upper and lower flanges, a predetermined locking means is provided, and the auxiliary heating member 80 is locked by the locking means, whereby the auxiliary heating member 80 is locked to the processing furnace body 41 and the lid body 42. You may make it mount on. By doing so, it becomes possible to attach the auxiliary heating member 80 having a size corresponding to the scale of the sintered material M to be sintered at any time, and versatility is improved.
[0060]
The heat insulating member 81 has a plurality of insertion grooves 81a for inserting the energization heating elements 82 on the inner surface thereof, and the insertion grooves 81a are curved so as to have the same radius of curvature. An energization heating element 82 is attached. Further, between the end portions of the adjacent insertion insertion grooves 81a, insertion grooves 81b extending in the vertical direction for fitting connection wires 82a connecting the respective heating elements 82 in series are recessed in a zigzag state. ing.
[0061]
Further, on the upper and lower sides of one side end surface of the heat insulating member 81, lead holes 81 c for drawing out the lead wires 82 b from the uppermost and lowermost energization heating elements 82 are respectively drilled and drawn out from these lead holes 81 c. The lead wire 82b is connected to a power line from the auxiliary heating power supply unit 92 of the power supply device 90, so that the power from the auxiliary heating power supply unit 92 can be supplied to each energizing heating element 82. It has become.
[0062]
The energization heating element 82 is preferably mounted in the fitting insertion groove 81a with a predetermined gap between the energization heating element 82 and the inner wall surface. This is because the energization heating element 82 may reach a high temperature of approximately 2000 ° C., and the inner wall surface may be melted when the high-temperature energization heating element 82 is in contact with the inner wall surface of the fitting groove 81a. Because there is.
[0063]
The auxiliary heating member 80 has a curvature outer diameter dimension set to be substantially the same as the inner diameter dimension of the central portion of the processing furnace main body 41, and the curvature inner diameter dimension is slightly larger than the outer diameter dimension of the mold 60. Accordingly, the sintered material M in the mold 60 is auxiliary heated by receiving heat rays irradiated from the energization heating element 82 by heat radiation.
[0064]
Therefore, for example, when the heat processing furnace 40 excluding the auxiliary heating member 80 is inserted into a conventionally known ordinary heating furnace, the heat source for auxiliary heating exists at a position far from the sintered material M. Therefore, the sintered material M in the mold 60 cannot be heated by the radiant heat from the heat source, and eventually the sintered material M is thermally conductive through an inert gas such as nitrogen or argon enclosed in the heating furnace. Therefore, not only does it take a long time for the sintered material M to reach a predetermined high temperature, but a large amount of expensive inert gas is supplied into the heating furnace each time the sintering process is performed. This has been a bottleneck in speeding up the sintering process and reducing the cost.
[0065]
On the other hand, in this embodiment, the energization heating element 82 is provided at a very close distance to the sintered material M, and the sintering material M is instantaneously heated by the radiant heat of the energization heating element 82. The sintered material M is not only rapidly heated, but it is not necessary to use an expensive inert gas necessary for heat conduction, which is extremely effective in reducing the cost of the sintering process.
[0066]
According to the auxiliary heating member 80 configured in this manner, first, the auxiliary heating member 80 is formed by combining the three heat insulating members 81 and can be divided into three parts. It can be attached to the processing furnace main body 41 via the other, and the remaining integral part can be attached to the lid body 42, and the construction of the auxiliary heating member 80 for the thermal processing furnace 40 is facilitated. The sintered material M and the sintered product can be easily put in and out of the thermal processing furnace 40 without being moved.
[0067]
Further, the sintered material M in the mold 60 is being sintered by energization heat generation and discharge heat generation by applying a pulse current from the pulse current supply unit 91 of the power supply device 90 through the counter electrode 50, That is, in the state where internal heating is being performed, the sintered material M in the mold 60 is generated by the heat generation of the energization heating element 82 by supplying the power from the auxiliary heating power supply unit 92 to the energization heating element 82 of the auxiliary heating member 80. Heat dissipation from the outside in the radial direction is prevented. Therefore, the sintered material M in the mold 60 can be obtained because the heat distribution through the outer peripheral surface of the mold 60 is surely prevented, the temperature distribution inside becomes uniform, and uniform sintering treatment is performed. The resulting sintered product is of high homogeneous commercial value.
[0068]
Hereinafter, the operation control of the thermal processing apparatus 10 will be described with reference to FIG. FIG. 6 is a block diagram illustrating an embodiment of operation control of the thermal processing apparatus 10 executed by the control device 130.
[0069]
As shown in this figure, the control device 130 is for performing overall operation control of the thermal processing apparatus 10 and is constituted by a so-called microcomputer, and has a built-in CPU 131 as an arithmetic processing unit. The input / output device 132 that inputs predetermined data to the control device 130 or outputs the calculation result of the CPU 131, the RAM 133 that is a readable / writable external storage device that temporarily stores data, and the control program are stored. A ROM 134 that is a read-only external storage device is provided.
[0070]
The control device 130 is configured to execute the control program read from the ROM 134 based on a predetermined command signal input from the input / output device 132 and detection signals from various sensors to be described later. A predetermined control signal is output to the auxiliary heating power supply unit 92), the vacuum pump 100, the hydraulic unit 110, and the upper and lower electrode control valves 121 and 122, and the vacuum pump 100 is driven thereby to cause the thermal processing furnace 40 to operate. The inside is in a reduced pressure state, and a pulse current is applied to the sintered material M in the mold 60 via the counter electrode 50 by the output of the drive signal (pulse current) from the pulse current supply unit 91, and the auxiliary heating power supply unit The commercial AC power is supplied to the auxiliary heating member 80 by the output of the drive signal (commercial AC current) from 92, and the sintered material M is When the cylinder device 70 is driven by the output of a drive signal (hydraulic pressure) from the hydraulic unit 110, the pressing force of the press ram 73 against the upper electrode 51 is adjusted, and the opening of the electrode control valves 121 and 122 is adjusted to provide a cooling water source. The flow rate of 120 is controlled.
[0071]
In order to execute the control as described above by the control device 130, the thermal processing device 10 is provided with various sensors 140 for detecting the processing status at various places. The sensor 140 includes a plurality of first temperature sensors 141 (equipped in the lower heat equalizing plate 52a in the example shown in FIG. 6) that are internally provided at predetermined pitches in the radial direction on the heat equalizing plates 51a and 52a. A second temperature sensor 142 housed in the fourth upper spacer 51g, a third temperature sensor 143 housed in the fourth lower spacer 52g, and a pressure sensitive sensor 144 provided on the partition plate 24 immediately below the press ram 73 are employed. ing.
[0072]
The first temperature sensor 141 is internally heated by being applied with a pulse current by the counter electrode 50 in the mold 60, and the diameter of the sintered material M being externally heated by obtaining heat from the auxiliary heating member 80. This is for detecting the temperature distribution in the direction. While the detection signal of the first temperature sensor 141 is input to the CPU 131, the set temperature distribution of the sintered material M is input to the CPU 131 from the input / output device 132 in advance, and the detection signal from the first temperature sensor 141 is The corresponding detected temperature and the set temperature are compared one by one by the CPU 131, and when the difference between the detected temperature and the set temperature exceeds the allowable limit, the CPU 131 supplies the pulse current supply unit 91 and the auxiliary heating power supply. A control signal is output toward the unit 92 so that the difference falls within an allowable range.
[0073]
Specifically, for example, when the temperature of the center position of the sintered material M is within the allowable range, but the temperature of the peripheral portion is lower than the allowable range, the CPU 131 supplies the auxiliary heating power supply unit. A control signal for increasing the amount of power supplied to the auxiliary heating member 80 is output toward 92, and the auxiliary heating power supply unit 92 that receives the control signal increases the amount of power supplied to the auxiliary heating member 80. As a result, an increase in the amount of heat generated by the energization heating element 82 raises the temperature of the peripheral portion of the sintered material M, and the temperature distribution is restored to an allowable range.
[0074]
On the other hand, for example, when the temperature of the peripheral portion of the sintered material M is within the allowable range, but the temperature of the central portion exceeds the allowable range, the pulse current Supply of pulse current from the supply unit 91 to the counter electrode 50 is temporarily interrupted. As a result, the sintered material M is not subjected to internal heating due to energization heat generation and discharge heat generation, so only the external heating by the auxiliary heating member 80 is performed and the temperature of the central portion of the sintering material M is lowered until it falls within an allowable range. Will be allowed to.
[0075]
If necessary, the temperature distribution of the sintered material M is uniform from the pulse current supply unit 91 and the auxiliary heating power supply unit 92 to the counter electrode 50 and the auxiliary heating member 80 based on the temperature detection result of the third temperature sensor 143. Since the predetermined drive signal is output, the sintered material M maintains a predetermined temperature distribution set in advance by the cooperation of the counter electrode 50 and the auxiliary heating member 80.
[0076]
Further, in the present embodiment, at the initial stage of the sintering process of the sintered material M, the auxiliary heating member 80 is heated by the AC power from the auxiliary heating power supply unit 92 and the surface temperature thereof is increased to about 1000 ° C. After being warmed (heated to this temperature in about 15 minutes) and confirmed to be about 1000 ° C. by the detection signal of the third temperature sensor 143, a drive signal (pulse current) from the pulse current supply unit 91 Is supplied to the counter electrode 50. By carrying out like this, it can sinter to the sintering material M quickly and appropriately, restraining electric power cost.
[0077]
In other words, if sintering is performed only by external heating by the auxiliary heating member 80, it takes 3 to 4 hours to bring the sintering temperature to 1000 ° C. with a volume of about “490 mm × 460 mm × 380 mm”. In the embodiment, since the counter electrode 50 and the auxiliary heating member 80 are used in combination, the temperature raising time can be greatly shortened, and the sintering treatment of the sintered material M at a uniform temperature can be achieved. Can do.
[0078]
In the present embodiment, since the mold 60 is made of graphite that can be energized, the pulse current applied to the counter electrode 50 is also energized to the mold 60 to generate heat, and the mold 60 itself. Since this serves as a carbon heater, the mold 60 contributes to a homogeneous sintering process for the sintered material M in this respect.
[0079]
The second temperature sensor 142 and the third temperature sensor 143 are for detecting the temperatures of the fourth upper spacer 51g and the fourth lower spacer 52g, and these detection signals are inputted to the control device 130 one by one, The CPU 131 compares the stored set temperature and the control signal is output from the control device 130 to the upper and lower electrode control valves 121 and 122 based on the comparison result, and so-called feedback control is performed. The temperature control of the fourth spacers 51g and 52g is performed by adjusting the amount of cooling water from 120.
[0080]
The pressure sensor 144 is for detecting the pressing force of the cylinder device 70 against the sintered material M, and the control device 130 has a set pressure value set in advance according to the type of the sintered material M, The detected pressure value indicated by the detection signal from the pressure-sensitive sensor 144 is compared, and when this difference exceeds the allowable limit, a control signal is output to the hydraulic unit 110, and the hydraulic pressure from the hydraulic unit 110 is thereby output. The adjustment is such that the pressing force applied to the sintered material M by the cylinder device 70 becomes a set pressure value.
[0081]
By such pressure control, the sintered material M is subjected to a sintering process in a state where an optimum pressure is always applied according to the type, and the quality of the sintered product depends on the type of the sintered material M. Inconveniences that vary are avoided.
[0082]
Next, the pulse current output from the pulse current supply unit 91 will be described. A pulse power supply circuit (not shown) is provided in the pulse current supply unit 91, and various pulse characteristic adjustments are performed by transmitting an input signal from the input / output device 132 to the power supply circuit via the control device 130. The element can be changed. Specifically, the pulse frequency can be changed within the range of 1 Hz to 500 Hz, and the pulse period, the pulse interval, and the pulse width can be changed, and the current energy of the pulse can be within the range of 50 to 5000 A.
[0083]
As a function particularly suitable for performing discharge sintering, the pulse power supply circuit has a power supply voltage in the range of 2 to 24 V, and is 0.01 to 0 at the beginning of pulse application for dielectric breakdown that causes arc discharge. Only for an instant of 1 second, the same unit system is configured to generate a high-frequency high voltage whose voltage value is 50 to 5000 times the value of the specific electric resistance of the sintered material M.
[0084]
By using such a pulse power supply circuit and generating electric discharge when performing discharge sintering, by changing the pulse current and increasing the energy, a voltage much higher than the steady-state discharge voltage is rapidly increased. It has already been experimentally confirmed that when it is applied in a short time range of 1 second or less, arc discharge is effectively generated. Note that the critical voltage at which discharge occurs depends on the specific resistance of the sintered material as the sample, and the discharge start voltage must be several times higher than the steady state. Discharge continues.
[0085]
And by applying a high voltage only for a short time in this way, arc discharge can be induced at once, and powder particles can be melted instantaneously to perform sintering effectively. Specifically, it is extremely effective to apply a high-frequency high voltage of 100 V to 10000 V only for an instant of 0.01 seconds to 0.1 seconds at the rising edge of the pulse.
[0086]
As described above, the thermal processing apparatus 10 according to the present embodiment can effectively perform the sintering or the burning using the discharge energy by combining various pulses or applying a high voltage at the rising edge of the pulse. it can.
[0087]
In other words, according to the thermal processing apparatus 10 of the present embodiment, the arc discharge can be appropriately controlled so that the discharge energy itself by the arc discharge can be used effectively, and the temperature of the arc discharge is tens of thousands of degrees microscopically ( It is theoretically analyzed at the atomic level, and by effectively using arc discharge, it is possible to reduce the temperature of the material macroscopically and prevent thermal adverse effects while achieving sintering at a microscopically high temperature. In addition, the sintered material M is heated to a certain temperature by the auxiliary heating member 80 before the arc discharge heat processing, so that the sintered material M can be quickly and surely sintered while suppressing the power cost. Processing can be performed.
[0088]
Furthermore, in the thermal processing apparatus 10 of the present embodiment, the discharge pulse and the pulse pressure generated thereby can be used effectively. That is, when pulse energy is periodically applied to the sintered material M filled in the mold 60, when the pulse energy is applied, the surface of the sintered material M is compressed and the pressure applied to the powder increases, and the pulse The pressure applied to the powder fluctuates at a cycle corresponding to the current cycle. And it becomes a high temperature by the pressure energy when the powder surface is compressed, and it will be in the state which powder particles can couple | bond together.
[0089]
At this time, since the entire pressure of the sintered material M is fixed by the cylinder device 70, the pressure energy acts microscopically between the powder particles, and the powder is sintered without impairing the characteristics of the powder. Can promote ligation.
[0090]
For example, when a pulse current is applied to the sintered material M in the mold 60 with an overall pressure of 1000 kg, a pulse energy of 1000 A, and a frequency of 1 Hz, pressure fluctuations of 1300 kg on the pressurization side and 700 kg on the decompression side corresponding to the pulse period ( By controlling such pressure fluctuation, it is possible to promote the binding of the powder particles on the pressure side while preventing the material from melting on the pressure reduction side.
[0091]
This discharge effect of the pulse current is effective in the early stage of sintering of the powdery sintered material M, and the conductivity increases as the sintering progresses and the gap between the particles decreases. Move to Joule heating due to specific resistance. From this point of time, the heat generated by the punch protrusions 54b of the punch plates 51b and 52b and the heat generated by the auxiliary heating member 80 effectively act on the sintered material M.
[0092]
As described in detail above, the thermal processing apparatus 10 according to the present embodiment performs a sintering process on the sintered material M by energization heat generation by supplying a pulsed current to the sintered material M in a powder state. The die 60 is configured to include a die 60 loaded with the binding material M, a counter electrode 50 to which a pulse current is applied while the die 60 is sandwiched, and an auxiliary heating member 80 disposed around the die 60. Therefore, the sintered material M loaded in the mold 60 generates heat by being supplied with the pulse current from the counter electrode 50 and is sintered to become a sintered product. In this sintering process, the sintered material M receives heat from the auxiliary heating member 80 provided around the die 60 in addition to its own energized heat generation, so that heat radiation from the peripheral surface of the die 60 is ensured. Furthermore, the high temperature of the sintered material M can be maintained more uniformly and efficiently by the combined use of internal heating and external heating.
[0093]
The thermal processing apparatus 10 includes a system for internally heating the sintered material M in the mold 60 by energization and discharge heat generation by applying a pulse current from the counter electrode 50, and an auxiliary heating member 80 disposed around the mold 60. Since the sintered material M is heat-treated by two systems including a system for externally heating the sintered material M in the mold 60, the heat treatment of each system is performed by, for example, only the auxiliary heating member 80 at first. Thus, after the sintered material M reaches a predetermined temperature, a pulse current from the counter electrode 50 can be applied to the sintered material M, for example, in various combinations in terms of time, and the degree of freedom of operation mode Can be improved.
[0094]
Therefore, even if the thermal processing apparatus 10 is a large-scale one on a commercial scale, it is possible to make the obtained sintered product more homogeneous and of higher quality than before, and a sintered product with a high commercial value. Can be obtained.
[0095]
Since the auxiliary heating member 80 includes the heat insulating member 81 formed so as to surround the mold 60 and the energization heating element 82 provided on the heat insulating member 81, the structure of the auxiliary heating member 80 is simplified. In addition, a desired high temperature can be obtained by adjusting the amount of power supplied, and the temperature of the sintered material M can be easily controlled. Further, since the heating element 82 is provided on the heat insulating member 81, heat dissipation can be prevented by the heat insulating action of the heat insulating member 81, and the sintered material M in the mold 60 can be more efficiently transferred to the outside. Can be heated.
[0096]
In addition, since the processing furnace main body 41 provided with the auxiliary heating member 80 and the lid 42 that is detachably attached to a part of the peripheral surface thereof, the inner peripheral surface of the thermal processing furnace 40 is divided into a plurality of lines so as to be lined. The auxiliary heating member 80 can be easily attached to the back side of the processing furnace main body 41 and the lid body 42.
[0097]
Furthermore, since the thermal processing apparatus 10 is provided with a cylinder device 70 that presses the sintered material M in the mold 60 by pressing the counter electrodes 50 in a direction approaching each other, the sintered material in the mold 60 is provided. M is in a state where its capacity is fixed by being pressed by the cylinder device 70, and each particle of the sintered material tends to be separated from each other by the impact of arc discharge caused by application of a pulse current. It is possible to obtain a high-quality sintered product in which the movement is surely prevented and each particle is packed.
[0098]
Furthermore, since this sintering process is performed in a vacuum environment, the heat generated by the auxiliary heating member 80 is not transmitted to the sintered material M due to heat conduction. Therefore, in the present embodiment, the auxiliary heating member 80 is provided at a position as close as possible to the sintered material M in the thermal processing furnace 40. By doing so, the heat generation energy of the energization heating element 82 can be efficiently transmitted to the sintered material M by heat radiation.
[0099]
On the other hand, in the conventional method in which the thermal processing furnace 40 is mounted in a normal heating furnace, the thermal energy of the heat source cannot be transmitted to the sintered material M by thermal radiation, and therefore, the thermal processing furnace 40 is expensive. Insufficient inert gas must be injected to heat the sintered material M by heat conduction through the inert gas, and not only can the sintering process be performed quickly, but also there is a disadvantage of increased running costs. To do.
[0100]
Incidentally, when the auxiliary heating member 80 of the present invention is adopted, it has been found from the results of various demonstration tests that the sintering process can be performed with approximately 1/50 of the power consumption when the conventional heating furnace is adopted. ing.
[0101]
The present invention is not limited to the above embodiment, and includes the following contents.
[0102]
(1) In the above embodiment, the mold 60 is made of graphite, and the heat generated by energizing the graphite mold 60 is also used as a heating source of the sintered material M. Since it is configured so that the sintered material M can be externally heated by the auxiliary heating member 80 without using the mold 60 as a heating source, it is not necessary to make the mold 60 particularly made of graphite.
[0103]
(2) In the above embodiment, the cylinder device 70 that is operated by the hydraulic pressure from the hydraulic unit 110 is employed as the pressurizing means for the sintered material M. However, in the present invention, the pressurizing means is the cylinder device 70. For example, the structure may be such that a predetermined pressing rod is actuated by driving an electric motor to press the sintered material M.
[0104]
(3) In the above embodiment, the pulse current is supplied from the pulse current supply unit 91 of the power supply device 90 to the counter electrode 50. However, in the present invention, the current supplied to the counter electrode 50 is a pulse. The current is not limited to a current, and may be a normal direct current or an alternating current that is not in a pulse state.
[0105]
(4) In the above embodiment, the large plate-like partition plate 24 that moves up and down while being guided by the guide column 22 is provided between the press ram 73 of the cylinder device 70 and the fourth upper spacer 51 g of the upper electrode 51. However, the present invention is not limited to the large partition plate 24 interposed between the press ram 73 and the fourth upper spacer 51g, and may have substantially the same dimensions as the fourth upper spacer 51g. Alternatively, the press ram 73 may be directly brought into contact with the fourth upper spacer 51g without providing the partition plate 24 in particular.
[0106]
(5) In the above embodiment, the safety cover 30 is provided so as to surround the thermal processing furnace 40. However, in the present invention, it is not essential to provide the safety cover 30 surrounding the thermal processing furnace 40. In particular, the safety cover 30 may not be provided. However, in this case, since the inside of the thermal processing furnace 40 needs to be in a reduced pressure environment, the thermal processing furnace 40 itself needs to have a sealed structure.
[0107]
(6) In the above embodiment, the outer diameter of the fourth lower spacer 52g is slightly larger than the inner diameter of the mold 60 so that they interfere with each other. However, instead of this, the mold 60 may be fixed in the thermal processing furnace 40 through a support member provided separately.
[0108]
(7) In the above embodiment, the first to third upper spacers 51d, 51e, 51f and the first to third lower spacers 52d, 52e, 52f are all formed of an annular body. The first to third upper spacers 51d, 51e, 51f and the first to third lower spacers 52d, 52e, 52f are not limited to being annular, and the cross-sectional area gradually increases as the distance from the mold 60 increases. Any shape can be used as long as it does. For example, it may be rod-shaped or a star-shaped cross section.
[0109]
【Example】
Example 1
When the auxiliary heating member 80 is used (Example), the radial temperature distribution in the thermal processing furnace 40 including the sintered material M is larger than when the auxiliary heating member 80 is not used (Comparative Example). The following comparative test was conducted to confirm how much improvement was achieved.
[0110]
First, the thermal processing apparatus 10 having the thermal processing furnace 40 having an inner diameter (diameter) dimension of 360 mm is used, and the mold 60 having an inner diameter dimension of 100 mm is externally fitted to the lower electrode 52 in the thermal processing furnace 40. In 60, the sintering material M which consists of nickel powder was loaded so that the thickness dimension might be set to 10 mm.
[0111]
Subsequently, the upper electrode 51 is lowered by driving the cylinder device 70, and the upper soaking plate 51a and the upper punch plate 51b (FIG. 3) of the upper electrode 51 are inserted into the mold 60, and a predetermined pressure (500 kg / cm 2) is obtained. Then, the sintered material M was pressed. Thereafter, the lid 45 closes the entrance / exit 45 of the processing furnace main body 41 so that the heat processing furnace 40 is sealed, and the vacuum pump 100 is driven to reduce the pressure to a predetermined degree of vacuum (10 Pa to 50 Pa). Completed.
[0112]
And in the Example, the electric power (220V commercial electric power) from the auxiliary heating power supply unit 92 was supplied to the auxiliary heating member 80, and the temperature in the thermal processing furnace 40 was first raised to 850 ° C. This temperature increase took approximately 15 minutes. Next, a pulse current (pulse frequency 150 Hz, pulse content 70%, pulse energy 3000 A) from the pulse current supply unit 91 is applied to the sintered material M through the counter electrode 50, and the sintered material M is energized and heated and discharged. Heated internally for 5 minutes with exotherm.
[0113]
Immediately after the end of the internal heating, the temperature (the temperature of the sintered material M and the temperature in the furnace) detected by the plurality of first temperature sensors 141 (FIG. 6) provided was output to the input / output device 132. For this test, a predetermined number of temperature sensors are arranged at appropriate locations outside the mold 60 in the thermal processing furnace 40, and as a result of this temperature detection, the inner wall of the thermal processing furnace 40 starts from the center position of the thermal processing furnace 40. The temperature distribution up to the position could be obtained.
[0114]
On the other hand, in the comparative example, a pulse current is supplied to the sintered material M from the beginning without supplying power to the auxiliary heating member 80, and the central portion of the sintered material M reaches 850 ° C. At that time, the supply of pulse current was stopped. Other test conditions were the same as in the examples.
[0115]
The temperature distribution in the thermal processing furnace 40 of the example and the comparative example is as shown in the graph of FIG. In FIG. 7, black circles are examples, and white circles are comparative examples. As shown in this graph, in the case of the example, not only the sintered material M but also the target temperature of 850 ° C. is maintained, and the temperature is maintained up to the position of the wall material of the thermal processing furnace 40. I understand. And it reaches the space part of the thermal processing furnace 40, and the temperature falls rapidly.
[0116]
On the other hand, in the case of the comparative example, the temperature of the sintered material M itself decreases with a predetermined temperature gradient as it moves away from the center position in the radial direction, and 750 ° C. on the outer peripheral surface of the sintered material M. The temperature is lowered by 100 ° C. with respect to the center position. In this case, since the temperature distribution in the sintered material M is not uniform, a homogeneous sintered body as a product cannot be obtained.
[0117]
From the above, it has been proved that the present invention in which the auxiliary heating member 80 is provided around the mold 60 is excellent in performing the sintering process ensuring the uniform temperature distribution of the sintered material M. .
[0118]
Example 2
After the measurement of the temperature distribution in Example 1 is completed, both the Example in which dual-system heating is performed on the sintered material M that has already been heated to 850 ° C. and the Comparative Example in which only pulse current application is performed. About 1100 degreeC of the target temperature which can perform a sintering process was heated up. It was confirmed that the heating rate of the sintered material M at this time was about 30% faster than that of the comparative example in the case of the example. In addition, it was confirmed that the amount of electric power required from the start to the end of sintering was about 1/3 of the comparative example in the case of the example.
[0119]
Example 3
In the initial stage of raising the temperature of the sintered material M, the temperature of the sintered material M is raised to a predetermined temperature (for example, 1000 ° C.) only by applying a pulse current without performing auxiliary heating, and then applying a pulse current. It was confirmed that the sintering material M may be sintered only by auxiliary heating.
[0120]
【The invention's effect】
According to the first aspect of the present invention, the energizing thermal processing apparatus includes a mold in which a workpiece is loaded, a counter electrode that supplies current while sandwiching the mold, and an auxiliary that is disposed around the mold. Since the heating means is configured, a workpiece made of a powder sintered material is loaded into a mold, and a current from the counter electrode is supplied to the workpiece, so that the workpiece is sintered by energization heat generation. Can be made into sintered products. In this sintering process, the work piece receives heat from the auxiliary heating means provided around the mold in addition to its own energized heat generation, so heat radiation from the peripheral surface of the mold is reliably suppressed, The combined use of internal heating and external heating can maintain the high temperature of the workpiece more uniformly and efficiently.
[0121]
In addition, the energization thermal processing apparatus is a system that internally heats the workpiece in the mold by energization heat generation by supplying current from the counter electrode, and the auxiliary heating means arranged around the mold to externally remove the workpiece in the mold. Since the workpieces are heat-treated by two systems, that is, the system to be heated, the heat treatment of each system is first performed by, for example, only the auxiliary heating means, and the workpiece reaches a predetermined temperature. Thus, the current from the counter electrode can be supplied to the work piece in various combinations in terms of time, and the degree of freedom of the operation mode can be improved.
[0122]
Therefore, even if the electrothermal processing device is large on a commercial scale, it is possible to make the obtained sintered product more homogeneous and of higher quality than before, and a sintered product with high commercial value Can be obtained.
[0123]
Also The auxiliary heating means is provided with a heat insulating member formed so as to surround the mold, and an energization heating element provided on the heat insulating member, so that the structure of the auxiliary heating means is simplified and supplied. A desired high temperature can be obtained by adjusting the amount of electric power, and the temperature of the workpiece can be easily controlled.
[0124]
Also Since the heat insulating member can be divided into a plurality of linings on the inner peripheral surface of the cylindrical container having a lid that is detachably mounted on the peripheral surface, the heat insulating member is provided on the back side of the lid and the inner surface of the cylindrical container. On the other hand, the heat insulating member can be easily attached.
[0125]
Claim 2 According to the described invention, the workpiece in the mold is in a state in which its capacity is fixed by pressing by the pressurizing means, so that the sintered material is subjected to arc discharge impact by applying a pulse current. Thus, the movement of the particles to be separated from each other is surely prevented, whereby a high-quality sintered product in which the particles are packed together can be obtained.
[Brief description of the drawings]
FIG. 1 is a partially cutaway perspective view showing an embodiment of an electrothermal processing apparatus according to the present invention, showing a state in which a lid is removed from a processing furnace body.
2 is a perspective view showing a state where a lid is attached to a processing furnace main body of the energization heat processing apparatus shown in FIG. 1; FIG.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
FIGS. 4A and 4B are perspective views showing an embodiment of a punch plate, where FIG. 4A shows an upper punch plate and FIG. 4B shows a lower punch plate.
5A and 5B are perspective views showing an embodiment of an auxiliary heating member, in which FIG. 5A is a partially cutaway exploded perspective view, and FIG. 5B is an assembled perspective view.
FIG. 6 is a block diagram showing an embodiment of operation control of the thermal processing apparatus executed by the control device.
FIG. 7 is a graph showing the temperature distribution in the thermal processing furnace of Examples and Comparative Examples.
[Explanation of symbols]
10 Thermal processing equipment 20 Frame
21 Foundation plate 22 Guide support
23 Top plate 23a Through hole
24 Partition plate 30 Safety cover
31 Container body 31a Circumferential opening
32 Top plate 32a Insertion hole
33 Opening / closing door 40 Thermal processing furnace
41 Processing furnace body 41a Lower flange
41b Upper flange 42 Lid
42a Lower flange 42b Upper flange
43 Top plate 43a Upper cylinder
44b Lower annular insulator 44 Bottom plate
44a Lower cylinder 45 Entrance / exit
50 Counter electrode 51 Upper electrode
51a Upper soaking plate 51b Upper punch plate
51c Upper pressure equalizing plate
51d First upper spacer
51e Second upper spacer
51f Third upper spacer
51g Fourth upper spacer
52 Lower electrode 52a Lower soaking plate
52b Lower punch plate 52c Lower pressure equalizing plate
52e Second lower spacer
52d first lower spacer
52f Third lower spacer
52g Fourth lower spacer
53 Punch plate body 53a Annular flat part
54 Circular protrusion 54a Punch slit
54b Punch ridge
55 Cooling channel 56 Insulation ring
60 type 61 annular square groove
70 Cylinder device 71 Hydraulic cylinder
72 Piston rod 72a Male thread
73 Press ram 73a Screw hole
80 Auxiliary heating member 81 Heat insulation member
81a Insertion groove 81b Groove
81c Drawer hole 82 Electric heating element
82a Connecting wire 82b Lead wire
90 Power supply 91 Pulse current supply unit
92 Power supply unit for auxiliary heating
100 Vacuum pump 110 Hydraulic unit
120 Cooling water source 121 Control valve for upper electrode
122 Control valve for lower electrode 130 Control device
131 CPU 132 I / O device
133 RAM 134 ROM
140 sensor 141 first temperature sensor
142 Second temperature sensor 143 Third temperature sensor
144 Pressure-sensitive sensor

Claims (2)

An electrothermal processing apparatus for performing a sintering process on a workpiece by energization heat generation by supplying an electric current to the workpiece made of a powder sintered material, and a mold in which the workpiece is loaded, A counter electrode for energizing the workpiece while sandwiching the workpiece, and auxiliary heating means disposed around the mold , wherein the auxiliary heating means is formed so as to surround the mold. The heat insulating member and an energization heating element provided on the heat insulating member are configured, and the heat insulating member is lined on the inner peripheral surface of the cylindrical container having a lid body that is detachably attached to the peripheral surface. capable energized thermal processing apparatus according to claim der Rukoto which may be divided into a plurality. Claim 1 Symbol placement of energized thermal processing apparatus, characterized in that pressurizing means for pressurizing the workpiece is provided in the mold by pressing in a direction toward the counter electrode to each other.

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