JP2006009092A - Holder for heat-treating sintered parts and method for heat-treating annular sintered parts using this holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holder for efficiently heat-treating sintered parts, such as annular internal gear, and restraining the strain to low. <P>SOLUTION: The holder for heat treatment is constituted of two supporting bars 2, 3 parallel disposed for supporting a hole inner peripheral surfaces of the parts at the linear symmetrical position to the perpendicular line passing through the center of the sintered parts by passing through the holes of the annular sintered parts A and disposed on the line crossed with the crossing angle of θ=85-95° at the centers of the hung-down sintered parts while placing the plurality of sintered parts side by side to perform the heat treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat treatment jig for a sintered part that suspends and holds a heat treatment such as quenching for a ring-shaped sintered part such as an internal gear, and a ring that uses the heat treatment jig. The present invention relates to a heat treatment method for a shaped sintered part.

  For example, when quenching machine parts such as gears that are mass-produced, a method is generally employed in which the parts are placed on a refractory plate (laying plate) and heated, but this method requires efficient heat treatment. It ’s hard to hope.

In addition, although mechanical parts are stacked in multiple stages and heat-treated, it is difficult to expect uniform heating of the parts in this method. Further, when local support of a part is performed using a sintering jig as disclosed in Patent Document 1 below for uniform heating, most of the part floats in the air, and heat passes through each part of the part. However, this method tends to distort parts.
JP 2003-73728 A

  The present invention has been made in view of the above, and is a heat treatment jig that can efficiently heat-treat a ring-shaped sintered part by suspending the ring-shaped sintered part, and can suppress distortion caused by the heat treatment of the part. It is an object to provide a heat treatment method.

  In order to solve the above-mentioned problems, in the present invention, a perpendicular line passing through the center of the sintered part is arranged in a parallel arrangement to be suspended when heat-treating the part through a hole in the sintered part formed in a ring shape. On the other hand, it has two support rods that support the inner peripheral surface of the hole in a line-symmetrical position, and these two support rods are arranged on a line that intersects at the crossing angle of θ = 120 ° or less at the center of the suspended component A heat treatment jig for sintered parts is provided.

  In this heat treatment jig, the two support rods are arranged on a line intersecting at the crossing angle of θ = 85 ° to 95 ° at the center of the suspended part, or two support rods Those connected by a connecting rod are particularly preferable.

  When using the heat treatment jig of the present invention, a plurality of sintered parts having a horizontal axis are suspended and arranged so that they are supported at two points by two support rods, and efficiently heat treated. Can do.

  In addition, since the component is supported and suspended at two points, the heating is performed smoothly and uniformly, and distortion of the component due to non-uniform heating is suppressed to a small level.

  Furthermore, in the heat treatment jig of the present invention, two support rods are arranged on a line that intersects at an intersection angle of θ = 120 ° or less, more preferably θ = 85 ° to 95 ° at the center of the suspended part. Do point support. The strain can be reduced as compared with the case of hanging with a single support rod. Further, when the component is suspended on a jig in which the two support rods are arranged on the line where θ is 85 ° or more and 95 ° or less, distortion due to the weight of the heated component can be further reduced.

  In the heat treatment jig in which two support rods are connected by a plurality of joint rods, the deflection of the support rod due to the weight of the component is reduced, the adverse effect on the component is reduced, and the distortion of the component is further reduced. If the two support rods are connected by a connecting rod, the heat will not be disturbed and the parts will be heated uniformly. Therefore, the two support rods are connected via the connecting rod.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. The heat treatment jig 1 of FIG. 1 is used when quenching a ring-shaped iron-based sintered part A (hereinafter simply referred to as a sintered part A or a part A), 3 and a holder 4 that supports both ends of the support rods 2 and 3.

The support rods 2 and 3 are lines L that intersect at an angle θ (hereinafter referred to as a central angle) at the center O of the sintered part A in the state of FIG. 1 where the parts are suspended through the hole of the sintered part A. It is arranged on _1, L _2. At this time, the positions of the two support rods 2 and 3 are set so that the central angle θ is 120 ° or less, more preferably 85 ° to 95 °, and the height positions of the respective support rods are equal. Is stipulated. The holder 4 supports both ends of the support rods 2 and 3 and keeps the support rods 2 and 3 in a set position.

  At this time, the holder 4 may be provided with a protrusion 4 b that maintains the pitch P between the centers of the support bars 2 and 3 on the support surface 4 a that supports the support bars 2 and 3. Since the support rods 2 and 3 have a constant pitch P between the centers of the support rods 2 and 3 due to the protrusions 4b, the sintered parts A can be kept at a predetermined center angle θ in a suspended state.

  Furthermore, since the support surface 4a is flat, the pitch change block 4c shown in FIG. 2 can be attached to the protrusion 4b to change the center-to-center pitch P of the support rods 2 and 3, and sintered parts having different sizes. Even when A is suspended, it is possible to easily hang at an appropriate center angle θ by changing the mold.

  In FIG. 3, two support rods 2 and 3 are connected via a plurality of connecting rods 5 having a constant length. The joint rod 5 is installed at an appropriate interval in the longitudinal direction of the support rods 2 and 3. The heat treatment jig 11 of FIG. 3 is different from the heat treatment jig of FIG. 1 in that the joint rod 5 is provided, but the other configuration is the same as that of the heat treatment jig 1 of FIG. Omitted.

  FIG. 4 shows a state in which the sintered part A is suspended from the heat treatment jig 1 (or 11) of the present invention. In this way, a plurality of sintered parts A are suspended in a horizontal row. If the total weight of the parts at this time is large, the support rods 2 and 3 will bend, and if they are used repeatedly, the support rods 2 and 3 will bend and will not be restored. Is considered to be reduced. In the heat treatment jig 11 of FIG. 3, the support rods 2 and 3 are reinforced by the joint rods 5, so that the problem hardly occurs.

  The support rods 2 and 3 are equal in height to each other, and the part A is a line symmetrical position with respect to a perpendicular passing through the center of the part as shown in FIG. 3 is supported. In the heat treatment jig of the present invention, since the support point at this time is appropriately set, when one point is supported by one support rod, or two supports with the central angle θ outside the range of the present invention The distortion of the component A due to heat is less likely to occur than when two points are supported by a rod.

  The results of confirming the effect of the present invention will be described below. In the test, two shafts having a diameter of 8 mm were prepared, and the shafts were arranged in parallel as support rods 2 and 3 as shown in FIG. 5, and the two support rods 2 and 3 had an outer diameter of φ68.85 mm and an inner diameter. The sintered part A having a height of 55.75 mm and a weight of 100 g is suspended, and the central angle θ of the line on which the support rod is arranged is changed as shown in Table 1, and before and after the heat treatment (quenching) of the sintered part A The amount of inner diameter change (distance between points a and b) was examined. Table 1 and FIG. 6 show the measurement results of the amount of change in the inner diameter before and after the heat treatment with an average of 10 sintered parts A. The amount of change in the inner diameter of the component before and after the heat treatment when the sintered component A was suspended by one support rod was 0.088 mm.

  As can be seen from the test results, Sample Nos. 6 to 10 having a center angle θ of 85 ° to 95 ° have extremely small changes in the inner diameter before and after the heat treatment. In addition, since the amount of change in the inner diameter before and after the heat treatment of the sintered part A is suspended by one support rod is 0.088 mm, if the center angle θ is 120 ° or less, it is more accurate than the case of single suspension. It can be seen that a sintered part with good quality can be obtained.

  If the strain at the time of heat treatment increases, the defective rate of the product increases, which is not preferable. Heat treatment jig (invention product) having support bars 2 and 3 arranged at a center angle θ = 90 ° and heat treatment jig (comparative product 1) having support bars 2 and 3 arranged at a center angle θ = 60 ° ) And a heat treatment jig (comparative product 2) supported at one point with one support rod, a heat treatment comparison test was conducted. The defect occurrence rate at the time of use 2 was about 10%, whereas the defect occurrence rate was reduced to about 2% at the time of using the invention product.

  Moreover, the heat treatment jig of FIG. 1 and the heat treatment jig of FIG. 3 obtained almost no difference, but the heat treatment jig of FIG. 3 is more durable and maintains the effect of strain suppression over a long period of time. It is clear that it will be done.

  As can be seen from the test results, by using the heat treatment jig of the present invention, it becomes possible to greatly reduce the defect occurrence rate of sintered parts made by heat treatment after sintering.

(A) Sectional view showing the heat treatment jig of the embodiment in use, (b) Perspective view showing the main part of the holder (A) Cross-sectional view showing another embodiment of heat treatment jig, (b) Perspective view showing main part of holder (A) Perspective view showing still another embodiment of heat treatment jig, (b) End view of the jig Side view sectional drawing which shows the state which suspended the sintered component in the heat processing jig | tool of FIG. 1 or FIG. Diagram showing the inner diameter change measurement point in the effect confirmation test The figure which shows the relation between the center angle and the inside diameter change amount in the two suspensions in the test result

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Heat processing jig | tool 2, 3 Support rod 4 Holder 4a Support surface 4b Protrusion 4c Pitch change block 5 Joint rod A Sintered part

Claims (4)

  The inner circumferential surface of the hole of the part is supported in a line-symmetrical position with respect to a perpendicular line passing through the center of the sintered part, which is suspended when the part is heat-treated through the hole of the sintered part formed in a ring shape. A heat treatment jig for a sintered part having two support bars and arranged on a line where the two support bars intersect at an intersection angle of θ = 120 ° or less at the center of the suspended part.   2. The heat treatment jig for sintered parts according to claim 1, wherein the two support rods are arranged on a line intersecting at an intersection angle of θ = 85 ° to 95 ° at the center of the suspended part.   The heat treatment jig for sintered parts according to claim 1 or 2, wherein the two support bars are connected by a plurality of joint bars.   A heat treatment method for a ring-shaped sintered part, wherein the heat treatment is performed by suspending the part with the heat treatment jig according to any one of claims 1 to 3.

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