JPS6232995Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat treatment jig used in heat treatment of gear parts.

Automotive gear parts require high-precision heat treatment to give them superior strength and durability.

Conventionally, for heat treatment of large gear parts, there have been two methods: inserting the parts into the vertical rod of a vertical rod-type heat treatment jig and stacking them, setting the parts one by one into several tiers of holding frames of a holding frame-type heat treatment jig, There are other methods, such as hanging the parts horizontally on a horizontal bar type heat treatment jig, etc., but these methods can cause variations in the gear accuracy of the product after quenching, or the product may shake during transportation and cause damage to the product. This causes problems such as burns. Therefore, the problems of the above method will be discussed individually as follows.

In the first method of stacking parts continuously on a vertical rod type heat treatment jig, as shown in Fig. 2-1, vertical rods 3 are assembled on a tray 2, a spacer 4 is placed on the lowest level of the vertical rods 3, and parts 1 as shown in Fig. 1 are stacked on top of it in order. This method results in a large difference in hardening distortion due to the part load between the upper and lower levels of the parts, and in particular a large variation between the teeth of a single part. When stacking parts, attention must be paid to the flatness of the spacer 4, burrs on the overlapping surface of the parts, and the inclusion of foreign objects, and in particular the spacer 4.
The surface of the plate should be polished if necessary.

The method of setting the parts one by one in the second holding frame type heat treatment jig and stacking them in several tiers is to attach the collar 7 to the support 6 set up on the tray 2 in the third row as shown in Fig. 3-1. Assembling the holding frame 5 in multiple stages as shown in Figure 2,
In this method, the component 1 is set on the upper surface of each holding frame 5. In this method, there is a large difference in quenching strain between the upper and lower stages due to the time difference during quenching and cooling, and the variation is particularly large between the teeth of one part. The flatness of the holding frame 5 is important, and special attention must be paid to bending and deformation.

In addition, in the heat treatment of gear parts with a small width (thickness) and a large outer diameter such as those used in FF vehicles (see Fig. 1, tooth diameter D: 130 mm or more, thickness t: 20 to 30 mm), In the second method, the quenching position is 6th.
As shown in the figure, the jig moves in the direction of the arrow, and during quenching and cooling, the lower side A of the part to be processed is first cooled by the quenching oil C, and austenite transforms into martensite, expands, and the upper side It appears as a sled in a direction. After that, the upper b-plane is cooled and transforms into martensite, but since the lower side has already become hard, the warp does not return to its original state. This tendency is more pronounced for parts with thinner walls, and although the difference in cooling time is only small, it is a phenomenon that is clearly recognized.
Furthermore, it is thought that the variation in quenching strain of the teeth is largely influenced by the difference in cooling on both sides of the part to be processed.

Next, the method of hanging the parts on the third horizontal hanging bar type heat treatment jig is as shown in Figure 4-1.
In this method, the parts 1 are assembled and set by hanging the parts 1 on the horizontal hanging rods 8. This method improves the quenching distortion caused by vertical loads in the first and second methods, but since the inner diameter surface of the part 1 is supported at one place by the horizontal rod 8, the part becomes oval due to its own weight. This tendency is noticeable in thin parts. Furthermore, since the parts 1 are not restrained by the horizontal hanging rods 8, dents occur between the parts during transportation. In addition, even in the heat treatment furnace, the vibration caused by the movement of tray 2 can cause damage.
It causes quenching distortion.

An object of the present invention is to solve the above problems and provide a heat treatment jig that does not cause quenching distortion and can restrain parts to horizontal bars during heat treatment and during movement.

The inventor of this invention based on the conventional horizontal hanging bar type jig, and created a groove in the horizontal hanging bar that matches the inner diameter of the part to stabilize the part, prevent the parts from hitting each other, and devised the shape of the horizontal hanging bar. By supporting one component at two places, it was possible to alleviate the stress caused by the component's own weight and prevent it from becoming oval. In addition, in consideration of the life of the jig, the structure was designed to absorb thermal distortion and deformation of the jig, and the jig was an assembly type consisting of various parts such as the tray, support, collar, and horizontal beam bar.

That is, the heat treatment jig of the present invention includes a plurality of pillars set on a tray, a plurality of beams having collars inserted through the pillars and extending between the pillars.
It consists of horizontal rods that extend between these beams, and grooves are provided in the horizontal rods at appropriate intervals to match the shape of the receiving part of the workpiece. The apparatus is characterized in that fulcrums for supporting the object to be processed are provided at two locations with an interval of 120 degrees.

An embodiment of the present invention will be described below with reference to the drawings.

Embodiment FIG. 5-1 shows a part of the front side of the horizontal bar type jig of the present invention, which can be used for heat treatment of large gear parts (hereinafter referred to as parts). A plurality of beams 10 are inserted into the front and rear supports 6 that stand upright on the tray 2,
Each beam 10 is maintained at an appropriate distance by a collar 7. The cross-hanging rod 9 has an H-shaped cross section, and the component 1 is fixed in the groove 11 and further supported by fulcrums 11a and 11b as shown in FIG. 5-3, thereby relieving stress. Fulcrum 11a, 11b
It is preferable that the distance between the two points is such that the angle θ formed by the line connecting each point and the center of the component 1 is 60 to 120 degrees. If the distance between the two fulcrums is less than 60 degrees, the spacing is narrow and stress relaxation is insufficient, while increasing the angle to more than 120 degrees will not change the effect.

The overall shape of the horizontal hanging bar is shown in the plan view of Figure 5-4.
As shown in the elevational view of FIGS. 5-5 and the side view of FIGS. 5-6, it is convenient to provide the handheld portion 12 on the outside.

When the quenching strain was measured for all tooth parts of heat-treated parts using the jig of the present invention, tooth trace errors and variations were reduced by half. That is, in Fig. 7, the dotted lines , and , represent the tooth trace errors of the products processed by the conventional first, second, and third jigs, respectively, and the maximum error is 30 to 40μ, whereas the present invention's As shown in the figure, the error in products processed using a jig was around 10μ. Also, part end face runout (undulation)
Almost the same trend was obtained when evaluated by

As described above, when the heat treatment jig of the present invention is used, the quenching and cooling of both sides of the part becomes uniform, and the stress during quenching is relaxed, so the quenching distortion is halved and the dimensional accuracy of the gear is improved. Secondly, since the parts do not move during transportation, there is no contact between the parts, and there is no need for dents or the like. Therefore, the number of sets per tray can be increased.

In addition, since the entire jig is assembled with a tray, support, collar beam, horizontal hanging bar, etc., to absorb thermal strain, there is a place to escape even if thermal expansion occurs, reducing the lifespan of the jig by approximately 2. It has a doubling effect.

[Brief explanation of the drawing]

Figure 1 shows a cross-sectional view of the part to be processed, and Figure 2-
Figure 1 is a vertical cross-sectional view of the first example of a conventional jig, and Figure 2-
Figure 2 shows a cross-sectional view along the line A-A in Figure 2-1.
Figure 3-1 is a vertical cross-sectional view of a second example of a conventional jig;
Figure 3-2 shows a plan view of the holding frame of the same example;
Figure 4-1 is a vertical cross-sectional view of a third example of a conventional jig;
Fig. 4-2 shows a sectional view along the line B-B in Fig. 4-1, Fig. 5-1 is a longitudinal sectional view of the embodiment of the present invention, and Fig. 5-2 shows a sectional view taken along the line C-B in Fig. 5-1. C direction sectional view, 5th
-Figure 3 is a cross-sectional view when the parts are set, Figure 5-
Fig. 4 is a plan view of the horizontal hanging bar, Fig. 5-5 is an elevational view thereof, Fig. 5-6 is a sectional view taken in the direction D-D in Fig. 5-5, and Fig. 6 is a diagram showing the parts to be processed. Fig. 7 shows a graph of the quenching distortion of the tooth portion of the part to be processed. In the figure, 1... Parts, 2... Tray, 3... Vertical rod, 4... Spacer, 5... Holding frame, 6... Support, 7... Collar, 8, 9... Horizontal hanging bar, 10 ……
Beam, 11...groove portion, 11a, 11b...fulcrum, 12...handheld portion.

Claims (1)

[Scope of utility model registration request] It consists of a plurality of columns set up on a tray, a plurality of beams with collars narrowly inserted through the columns and spread between the columns, and horizontal bars that are spread between these beams, and are suitable for the horizontal bars. Grooves that match the shape of the receiving part of the workpiece are provided at equal intervals, and fulcrums that support the workpiece are provided in the grooves at two locations spaced apart from the center of the workpiece by 60 to 120 degrees. A heat treatment jig that is characterized by the ability to