JPS6364497B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for hardening a leaf spring. When manufacturing arc-shaped leaf springs for use in vehicle suspension systems and the like, a quenching process is performed in which the arc-shaped high-temperature leaf spring material is immersed in oil and cooled. In this case, the so-called free quenching method in which the leaf spring material is immersed in oil in a free state causes quenching distortion and requires straightening work as a post-process, so the leaf spring material is held in a predetermined shape and quenched. A so-called press hardening method is used. In the conventional press hardening method, a holding mechanism consisting of an upper mold 2 and a lower mold 3 is provided on each side of an octagonal ring 1, as illustrated in FIGS. A plate spring material a is held between the plurality of pressing pieces 4 and the arcuate surface 5 formed on the lower die 3 at the insertion stage 6, and as the octagonal ring 1 rotates, the quenching oil in the tank 7 is released. After being sequentially immersed in 8, they were taken out at a take-out stage 9. Therefore, since the number of holding mechanisms used for cooling in the quenching oil 8 is only about 5, the usage efficiency is low and the takt time has to be slow, resulting in poor productivity and this tendency. In this case, the thickness of the leaf spring material a is almost significantly thick. In addition, each time the shape of the leaf spring material differs, it is necessary to adjust the push pieces 4 in the upper die 2 and change the lower die 3 for all the holding mechanisms, which requires a lot of time for setup work.
Furthermore, the leaf spring material is still at a fairly high temperature even after quenching, so it generates a lot of oily smoke when taken out.
Moreover, since the holding mechanism also generates oil smoke when it comes out of the oil 8, it is necessary to provide a large oil smoke removal device with a complicated structure. The present invention has been made under the above circumstances, and its purpose is to have a simple structure with a small number of holding mechanisms, high productivity, simple and easy setup work, and to An object of the present invention is to provide a method for hardening a leaf spring that generates a small amount of. Hereinafter, the present invention will be explained with reference to the drawings. In FIGS. 3 and 4, the quenching device 10
The apparatus includes a tank 12 containing a quenching liquid 11, and a conveyor 13 immersed in the liquid 11 is provided within the tank 12. The conveyor 13 includes a plurality of blocks 14 (some of which are not shown) arranged at predetermined pitches along its entire length, and each block 14 holds one leaf spring material a. It is configured to be moved intermittently so that it is stopped for a predetermined time every time it is moved one pitch in the direction of arrow A. The tank 12 is provided with cooling pipes 15 located on both sides of the conveyor 13. These pipes 15 are equipped with a large number of small holes 16 that face the movement path of the leaf spring material a and inject the quenching fluid 11, and are configured to cool and stir the quenching fluid in the vicinity of the leaf spring material a. has been done. The tank 12 is provided with a holding mechanism 20 capable of holding the leaf spring material a in a predetermined shape. This device 20 includes an upper mold part 21 and a lower mold part 22. The upper mold part 21 has a base part 23 and a plurality of horizontally extending parts (5 in the figure) that are detachably attached to the base part 23.
(in the case of one case), the plate-like body 24 is provided. These plate-shaped bodies 24... are blocks 1 of the conveyor 13.
4... are arranged at equal pitches, and the quenching liquid 1
1 and has an arcuate lower end edge 25 whose lateral center portion bulges downward. Further, the lower mold part 22 has a central pedestal 26 disposed at the center in the horizontal direction.
and a pair of side pedestals 2 placed on both sides of this.
7, 27. A central frame body 28 is attached to the central pedestal 26. Side pedestal 27,2
7 has side frames 30, 3 via pins 29, 29.
0 is supported so as to be swingable in the lateral direction. Each of the frame bodies 28 and 30, 30 supports a guide block 31 so as to be movable up and down, and is provided with a cylinder device 32 for driving each guide block 1 up and down.
Each guide block 31... supports push pieces 33, which are positioned opposite to the plate-shaped bodies 24, respectively, so as to be able to rise and fall, and spring members 34, which bias these push pieces 33 upward, are respectively provided. It is provided. The holding device 20 is configured to hold the leaf spring material a in a predetermined shape by sandwiching the plate spring material a between the push pieces 33 and the plate-shaped body 24 when the guide blocks 31 are in the raised position. Further, the frames 30, 30 arranged on both sides are connected to a cylinder device 37 via a link mechanism 36 including a link 5 that penetrates the tank 12 in a liquid-tight and reciprocating manner. By adjusting the amount of expansion and contraction, the horizontal position of the pusher piece 33 is variably set,
It is configured to be adaptable to various leaf spring materials of different lengths. In the hardening device 10, the leaf spring material a is heated to a predetermined temperature in a heating furnace (not shown) and subjected to forming processes such as perforation and curving, and is transferred into the tank 12 via the insertion device 17. and,
By lowering the insertion device 17, the conveyor 13
When the conveyor 13 stops, the conveyor 13 moves the conveyor 13 intermittently as described above. Then, when passing through the holding device 20, the plate-shaped bodies 24...
By raising the pusher pieces 33 through the cylinder device 32 each time the pusher pieces 33 are positioned and stopped at mutually opposing parts, the leaf spring material a is moved to the plate-like body 24.
... and the push piece 33..., and the plate-shaped body 24...
It is held in a predetermined arc shape formed on the lower end edge 25 of. The longitudinal position of the holding device 20 with respect to the conveyor 13 is set so that the leaf spring material a is held in a predetermined shape only while it is in and near the transformation region from austenite to martensite. Further, the conveyor 13 has a length sufficient to substantially completely cool the leaf spring material a. A pulling device 18 is provided on the downstream side of the conveyor 13, and when this lifting device moves up, the almost completely cooled leaf spring material a is taken out from the conveyor 13 and transferred to a tempering furnace (not shown). It is configured so that it can be done. According to the above configuration, since the leaf spring material a is held in a predetermined shape by the holding device 20 only while it is in the transformation region from austenite to martensite and its vicinity (it is left unattended while the conveyor 13 is moving). However, as shown in Tables 1 and 2, the amount of deformation due to quenching is substantially the same as in conventional press quenching. 1st
In Table and Table 2, A is an example of the present invention, and B and C are cases of conventional press quenching and free quenching, respectively. Table 1 shows the case where the leaf spring material is 20 mm thick, 90 mm wide, and 850 mm long, and the camber of the lower edge 25 of the plate body 24 is 13.5 mm. 8mm, width 60
mm, length 850mm, camber of plate 24 50.5mm
In both cases, the number of samples is 10. Further, since the leaf spring material a is moved in the quenching liquid 11 until it is almost completely cooled, and the holding device 20 is not moved in or out of the quenching liquid 11, the quenching liquid 11
Even if ordinary quenching oil is used, no oil smoke is generated, so there is no need to provide oil smoke removal means as in conventional devices. moreover,
Even when the plate spring material is thick, the residence time in the quenching fluid 11 is long enough, so there is no need to slow down the takt time, and productivity can be improved. Moreover, since the holding device 2 is held in a predetermined shape only while in the transformation region and its vicinity,
0, the number of plate-shaped bodies 24... and push pieces 33... etc. may be small, and the holding device 20 can be replaced by a plate spring material a.
Since there is no need to move the hardening device 10 along with the hardening device 10, the overall structure of the hardening device 10 is simplified. In addition, since the pusher pieces 33 placed on the sides are swingably provided and the plate-like bodies 24 are provided above, setup work is easy and the time required is short. 1
2, after passing through the holding device 20, the plate-like bodies 24 can be replaced and the positions of the push pieces 33 on the sides can be adjusted freely, which contributes to improving the operating rate. I can do it. Note that the present invention is not limited to the above-mentioned embodiment, and for example, the push piece 33 disposed on the side
... may be of non-swinging type, or the holding device 2
The orientation of 0 may be reversed vertically. others,
Various modifications and applications are possible within the scope of the gist of the present invention. In the present invention, when a high-temperature leaf spring material formed as described above is cooled in a liquid, the leaf spring material is moved intermittently in the liquid to create a transformation region from austenite to martensite and its transformation region. This feature is characterized in that it is maintained in a predetermined shape when it is in a nearby space and in a stopped state. Therefore, the amount of deformation due to quenching can be sufficiently reduced, and the generation of oil smoke can be effectively prevented. Moreover, the structure of the device can be simplified, productivity is excellent, and setup work is easy. It can have many excellent practical effects.

【table】 <

Claims (1)

[Claims] 1. When cooling a molded high-temperature leaf spring material in a liquid, while intermittently moving the leaf spring material in the liquid, only while in and near the transformation region from austenite to martensite,
A method for quenching a leaf spring, characterized in that the leaf spring is held in a predetermined shape when it is in a stopped state.