JPH0647501B2 - Sintering method of long tubular molded body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for sintering a long tubular molded body such as a thin long tube.

(Prior art and its problems) For example, using oxide powder (Al ₂ O ₃ , ZrO ₂ etc.) and nitride powder (Si ₃ N ₄ etc.) granulated with a spray dryer, the outer diameter φ100 mm ~ 20mm, wall thickness 0.7 ~ 0.3mm, length 1000mm
The following method is used to produce a long cylindrical sintered product of a certain degree.

That is, the granulated powder is filled in the molding space inside the molding die and is molded by a wet rubber press to form a long cylindrical molded body. Next, the outer diameter of this molded body is white processed in advance by taking into account the amount of shrinkage during firing. Then, as shown in FIG. 7, at a position 30 to 50 mm from the upper end of the long cylindrical molded body 2,
A pair of through holes 11 are provided by drilling, the support rods 20 are inserted into the pair of through holes 11, both ends of the support rods 20 are placed on a support base 10 made of brick or the like, and the support rods 20 are set horizontally. Direction, and the long cylindrical molded body 2 is hung on this support rod 20, and this is sintered to form a long cylindrical sintered body,
Cut out the commercialized part of the sintered body. In FIG. 7, the portion of the molded body 2 below the fine line A corresponds to the commercialized portion 1.

However, when actually performing sintering, for example, when the length of the sintered body is 1000 mm, the distortion of the outer diameter and the inner diameter of the sintered body is large even at a position 200 mm downward from the support rod 20, and this influences the effect. The outer diameter and the inner diameter of the lowermost part of the sintered body also became large, and the roundness was lowered.

Further, when the through-hole 11 is provided in the molded body 2, it is necessary to provide the pair of through-holes 11 at positions that equally divide the elongated cylindrical molded body 2 into two, but in reality, a slight error occurs. ,
The molded body 2 tends to incline in the direction perpendicular to the paper surface in FIG. In addition, the support base 10 made of bricks etc. during sintering
Since it contracts unevenly, it is difficult to keep the supporting rod 20 strictly in the horizontal direction, and the supporting rod 20 is slightly inclined. Therefore, the molded body 2 tends to incline in the left-right direction in FIG. From these things, the way of applying gravity to each part of the molded body 2 becomes non-uniform when viewed in the radial direction, and the sintered body bends.

In order to deal with these problems, conventionally, the overall length of the molded body is made large in advance by taking into consideration the curvature of the entire cylindrical sintered body, and only the good portion with the small curvature of the sintered body is selected and cut out. In addition, in order to deal with the deterioration of the roundness, a polishing allowance is provided in advance on the outer and inner circumferences of the cylindrical molded body, and the outer and inner circumferences of the sintered body are ground to obtain a predetermined dimensional accuracy. Is giving. However, this method has a low yield of products and a very high manufacturing cost. Further, depending on the diameter of the cylindrical sintered body, the inner peripheral side may not be polished.

As shown in FIG. 8, there is a method of providing a thick portion 21 on the upper end portion of the long cylindrical molded body 2. In addition, as shown in FIG. 9, a thick portion 21 is provided at the upper end of the long cylindrical molded body 2, the thick portion 21 is placed on the annular Kochi-Tochi 22, and the Kochi-Tochi 22 is supported. There is also a way to support at 10. However, these methods cannot effectively prevent the bending of the long cylindrical molded body.

(Problems to be Solved by the Invention) An object of the present invention is to sinter a long tubular molded body so that bending of the long tubular molded body can be prevented when the long tubular molded body is suspended and sintered. Is to provide a method.

(Means for Solving the Problem) The present invention provides a long tubular molded body in which a pair of through holes are formed at positions facing each other; a main body, and a protruding portion protruding from the main body. And a block-shaped jig that is insertable into the internal space of the long tubular molded body; A through hole in the protruding portion is provided in the protruding portion in a direction perpendicular to the length direction of the long tubular molded body, and the long body for jig support is inserted into the through hole in the protruding portion. Place both ends of the lever-supporting elongated body on a support base, suspend the block jig by the jig-supporting elongated body, and move in a direction perpendicular to the length direction. By providing an in-body through-hole in the body in a direction intersecting with the through-hole in the protruding portion, the pair of the formed in the long tubular molded body And inserting the molded body supporting long body into a hole and the body in the through-hole hanging the elongated tubular shaped body, sintering the elongated tubular shaped body. The present invention relates to a method for sintering a long tubular molded body.

The "long tubular molded body" is preferably a material obtained by pressure-molding raw material powder with a cold isostatic press (rubber press) or a hot isostatic press. The raw material powder includes not only oxide-based and nitride-based ceramics-producing raw material powders but also metal raw material powders used in powder metallurgy.

When the long tubular molded body is sintered, it may be sintered in one step, or the molded body may be heated separately for calcination and main firing.

The “long support body” includes a long support rod, a support tube, and the like.
"Cylinder" includes a cylinder.

(Example) FIG. 1 is a schematic cross-sectional view showing a state where a long tubular molded body 2 is suspended and sintered using a universal joint 4 which is a lump jig, and FIG. First around
FIG. 3 is a cross-sectional view taken along a cross section perpendicular to the cross section of the figure, FIG. 3 is a plan view showing a state where the molded body 2 is suspended by using the joint 4, and FIG. It is a fragmentary sectional view shown.

A pair of circular through holes 11 are formed on the upper end portion side of the long cylindrical molded body 2 at positions facing each other and equally dividing the cylindrical molded body 2 into two. At the lower end, a thick portion 3 having a thickness larger than the thickness of the commercialized portion 1 (between the thin wires A and E) is provided.

The universal joint 4, which is a block jig, is composed of a substantially cylindrical main body 4a and a substantially cylindrical protruding portion 4b protruding from the upper end of the main body 4a, and the outer diameter of the protruding portion 4b is the main body 4a. It is smaller than the outer diameter of. Since the outer diameter of the main body 4a is smaller than the inner diameter of the molded body 1, the joint 4 can be inserted into the cylinder space of the molded body 2.

Then, with most of the main body 4a of the joint 4 inserted into the space inside the cylinder, the joint 4 is directed in a direction perpendicular to the lengthwise direction of the elongated cylindrical molded body 2 (shown by the chain line B). The projecting portion 4b is provided with a through hole 8 in the projecting portion having a circular cross section, and the jig supporting rod 9 is inserted into the through hole 8 so that both ends of the jig supporting rod 9 are placed on the support base 10. At this time, the jig support rod 9 is oriented in a substantially horizontal direction, and the levelness of the jig support rod 9 is measured with a level. The joint 4 is suspended vertically downward by the jig support rod 9.

Further, the body 4a is provided with an in-body through-hole 5 having a circular cross section in a direction perpendicular to the longitudinal direction of the molded body 2 and orthogonal to the through-hole 8 in the protruding portion. The hole 5 and the pair of through holes 11 are aligned with each other, and a single molded body supporting rod 6 is inserted into each of these through holes 5 and 11, and a long cylinder is formed vertically downward of the supporting rod 6. The shaped body 2 is suspended. The compact 1 is heated and sintered in this state to produce a long cylindrical sintered body, and the thick portion 3 of the obtained sintered body is used.
And a portion corresponding to the upper end is cut off to obtain a long cylindrical sintered product.

The joint 4 is preferably a reusable sintered body.

According to the present embodiment, since the jig support rod 9 and the molded body support rod 6 are orthogonal to each other, one support stand 10 is relatively raised during sintering, as indicated by arrow C, and jig support is performed. Even if the rod 9 is slightly inclined, the molded body 2 can rotate about the molded body supporting rod 6 as a center, so that the molded body 2 slightly rotates as indicated by an arrow D, and thus the molded body 2 itself moves in the vertical direction. It is held in a suspended state. Therefore, since the inclination of the jig support rod 9 can be absorbed without applying an unbalanced load to the molded body 2, it is possible to prevent the molded body 2 from bending.

In order to enhance this effect, it is preferable that the jig support rod 9 and the molded body support rod 6 are orthogonal to each other as in the present embodiment, but if both are intersecting at a predetermined angle, the jig support rod 9 is inclined. Has the effect of absorbing. From this, it is preferable that the jig support rod 9 and the molded body support rod 6 intersect at an angle of 60 to 120 degrees.

Further, since the thick portion 3 having a thickness larger than the thickness of the commercialized portion 1 is provided at the lower end of the molded body 2, it is possible to prevent cracks and breaks from occurring near the lower end, and It is possible to prevent deterioration of roundness due to distortion of the outer diameter.

In order to achieve the above effects well, the length l of the thick portion 3 is preferably 5 to 15 mm, and the ratio of the thickness of the thick portion 3 to the thickness of the commercialized portion 1 is 3: It is preferably 1 to 5: 1.

Further, a through hole 8 in the protruding portion is provided in the protruding portion 4b having an outer diameter that is considerably smaller than the outer diameter of the commercialized portion 1.
Since the jig support rod 9 is inserted into the through hole 8, the length of the portion of the support rod 9 spanning the through hole 8 in the projecting portion is small, and it becomes close to a state in which the molded body 2 is supported at one point. Therefore, the position of the pair of through holes 11 may be slightly displaced from the desired position, and
Even when the angle is slightly inclined, such a deviation or inclination can be easily absorbed by the clearance between the through hole 8 and the support rod 9. To further elaborate this point, in the case shown in FIG.
Since the distance between the pair of through holes 11 is long, the support rod 20 and the through holes are
If the clearance with respect to 11 is constant, the allowable inclination angle of the support rod 20 is very small, and an unbalanced load is inevitably applied to the molded body. On the other hand, in this embodiment, since the length of the through hole 8 is short, the allowable inclination angle of the jig support rod 9 is large, and the jig support rod 9 is not applied with an unbalanced load on the molded body 2.
Can absorb the inclination of. Therefore, it is possible to prevent the molded body 2 from being bent.

In order to enhance the effect described above, it is preferable that the ratio of the outer diameter of the protruding portion 4b and the outer diameter of the commercialized portion 1 is 1: 2 to 1: 3.

In the example of FIG. 5, the support mechanism of the universal joint 4 and the support mechanism of the elongated cylindrical molded body 12 are the same as those in FIG. However, in the present embodiment, the cylindrical support portion 20 having an outer diameter smaller than the outer diameter of the commercialized portion 1 of the molded body 12 is provided at the upper end portion of the molded body 12, and the cylindrical support portion 20 and the commercialized portion are provided. 1 and 1 are connected by a bent connecting portion 19. The supporting portion 20, the commercialized portion 1 and the connecting portion 19 are all integrally molded as a part of the elongated cylindrical molded body 12. The thick portion 3 shown in FIG. 1 is provided at the lower end of the elongated cylindrical molded body 12.

In the present embodiment, since the shape in which the front end side of the molded body 12 is narrowed is adopted, it is easier to downsize the joint 4 and the protruding portion 4b.

If the wall thickness of the cylindrical support portion 20 is 3 to 5 times the wall thickness of the commercialized portion 1, deterioration of the roundness can be prevented even in the upper portion of the commercialized portion 1, and the cylindrical support It is possible to effectively prevent the occurrence of cracks and the like due to the stress applied to the portion 20. By thus preventing the radial distortion over the entire commercialized portion 1, there is no need for polishing the inner peripheral surface and the outer peripheral surface of the long cylindrical sintered body.

Hereinafter, more specific examples will be described.

Using a high-purity alumina powder granulated by a spray dryer, a long cylindrical molded body was produced so that a long cylindrical sintered product having an outer diameter of 100 mm, a wall thickness of 0.7 mm and a total length of 1000 mm could be obtained after sintering. These molded products are shown in FIG. 1, FIG. 5, and FIG.
The compacts 2 and 12 were suspended by the methods shown in FIGS. 8, 8 and 9, and calcination and main calcination were performed sequentially. In the calcination step, the compacts 2 and 12 are held in the atmosphere and heated at 100 ° C / hour to
Hold at 0 ° C. for 3 hours. In the subsequent main firing step, in a hydrogen-nitrogen mixed gas, the temperature was raised from room temperature to 1000 ° C at 1000 ° C / hour, and from 1000 ° C to 1860 ° C at 100 ° C / hour.
Hold at 3 ° C for 3 hours.

In the molded body 2, a pair of through holes 11 are provided at a position 30 to 50 mm from the upper end, the thickness of the thick portion 3 is 1.5 mm larger than the thickness of the commercialized portion 1, and the dimension 1 is 5 to 5. It was set to 7 mm.
The inner diameter of the molded body 2 was 120 mm, the outer diameter of the main body 4a was 119.4 mm, and the outer diameter of the protruding portion 4b was 45 mm (example in FIG. 1). Also, the molded body
In No. 12, a pair of through holes was provided at a position 15 mm away from the upper end, and the wall thickness of the cylindrical support portion 20 was set to 3 to 5 times the wall thickness of the commercialized portion 1. In the molded bodies 2 and 12, the through holes 5, 8 and 11 had a diameter of 10 mm, and the support rods 6, 9 and 20 had an outer diameter of 5 to 7 mm.

For each of the long cylindrical sintered products thus obtained, the presence or absence of cracks on the upper end side and the lower end side, the strain between the outer diameter and the inner diameter, and the presence or absence of bending were measured.

As can be seen from the table, the samples of FIGS. 1 and 5 produced according to the examples of the present invention gave good results with respect to bending, distortion and cracking.

Measuring method For distortion of outer diameter and inner diameter, first measure 50 from the upper end of each sample.
Cut the sample at the position of mm, measure the maximum and minimum values of the outer and inner diameters of the upper and lower ends of the sample with a digital caliper, and use the deviation between the maximum and minimum values as the distortion. It was calculated.

Regarding the curve, each sample 14 was placed on the surface plate 16 as shown in FIG. 6, and the maximum value q of the gap between the sample 14 and the surface of the surface plate was measured by the dial gauge 15.

(Effect of the Invention) According to the present invention, the elongated body for supporting the formed body is inserted through the pair of through holes formed in the elongated cylindrical formed body and the through hole in the main body of the massive jig to form the elongated tube. Since the shaped body is suspended, the elongated tubular shaped body can be rotated around the shaped body-supporting elongated body.

Then, the jig supporting elongated body is inserted into the projecting portion through hole of the massive jig, and both ends of the jig supporting elongated body are placed on the support base. Since the through-holes in the main body are provided in the intersecting direction, even if the jig supporting elongated body is slightly inclined, the molded body supporting elongated body intersecting with the jig supporting elongated body can be provided. As a center, the long tubular molded body slightly rotates in the direction in which the inclination is canceled. Therefore, since the molded body itself can be held in a state of being hung substantially vertically, it is possible to prevent bending due to an eccentric load applied to the molded body.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a long cylindrical molded body is suspended by using a universal joint, and FIG. 2 is a cross-sectional view of the periphery of the universal joint taken along a cross section orthogonal to the cross section of FIG. FIG. 3 is a plan view showing a state in which a long cylindrical molded body is suspended by using a universal joint, and FIG. 4 is a cross-sectional view showing a state in which a jig support rod is slightly inclined. FIG. 5 is a cross-sectional view of an essential part showing a state in which a long cylindrical molded body having a squeezed upper end side is suspended using a universal joint, and FIG. 6 is a curve of a long cylindrical sintered product. FIG. 7, FIG. 8, FIG. 9, and FIG. 9 are schematic cross-sectional views showing a conventional method for suspending a long cylindrical molded body. 1 ... Commercialized part 2, 12 ... Long cylindrical molded body 3 ... Thick part 4 ... Universal joint (an example of a block jig) 4a ... Main body, 4b ... Projection part 5 ... Through hole in main body, 6 ... Molding Body support rod 8 ... Through hole in protruding portion, 9 ... Jig support rod 10 ... Support base 11 ... A pair of through holes 14 facing each other ... Long cylindrical sintered product, 19 ... Connection portion 20 ... Thick wall Cylindrical support portion B ... Virtual line indicating the length direction of the long cylindrical molded body C ... Arrow indicating the relative elevation of one support base D ... Arrow indicating the rotation direction of the long cylindrical molded body

Claims (1)

[Claims] 1. A long jig formed with a pair of through holes formed at positions facing each other; a block-shaped jig comprising a main body and a projecting portion projecting from the main body. To prepare a massive jig that can be inserted into the space inside the cylinder of the long cylindrical molded body; and a length of the long cylindrical molded body with a part of the massive jig inserted into the space inside the cylinder. A through hole in the protruding portion is provided in the protruding portion in a direction perpendicular to the vertical direction, and a long member for supporting a jig is inserted into the through hole in the protruding portion to insert the long hole for supporting the jig. Both ends of the body are placed on a support base, the massive jig is suspended by the jig supporting elongated body, and the through hole in the protruding portion is formed in a direction perpendicular to the length direction. An in-body through-hole is provided in the body in a direction intersecting with each other, and the pair of through-holes and the in-body through-hole formed in the elongated tubular molded body. And inserting the molded body supporting long body hanging the elongated tubular shaped body, sintering the elongated tubular shaped body, sintering method of the long cylindrical molded body.