JP7156765B2 - Quenching method for steel parts - Google Patents

Description

TECHNICAL FIELD The present invention relates to a quenching method for quenching an object to be treated (steel parts) such as automobile parts in a quenching tank containing a refrigerant.

When quenching mechanical parts (steel parts) typically represented by automobile parts, the mechanical parts are immersed in a quenching bath filled with a coolant (oil or the like). At this time, from the viewpoint of processing efficiency, since a plurality of parts are loaded and immersed in the quenching bath, the oil flow in the quenching bath differs depending on the position of the loaded parts.

For example, there is naturally a difference in oil flow velocity between the parts positioned on the inner wall of the quenching bath and the parts positioned in the center of the stacked parts group. During quenching, if there is a difference in the flow speed of oil flowing near the parts, the cooling speed of the machine parts also differs. As a result, a difference in hardening effect occurs depending on the position of the stacked parts group.

Therefore, in the quenching treatment using oil, it is required to accurately grasp the flow velocity of the oil passing near the part to be quenched, and to eliminate the difference in the cooling rate among the parts as much as possible. As a method for making the cooling rate between such parts as uniform as possible, for example, in Patent Document 1, the bottom of the cooling tank is provided with a discharge port for discharging the cooling liquid in the quenching tank from the bottom to the top. Then, a quenching apparatus is disclosed in which the flow of cooling liquid from a discharge port is directed to the center of the workpiece.

In addition, in Patent Document 2, in order to equalize the cooling effect caused by the difference in the flow velocity of the quenching oil caused by whether the loading position in the quenching bath is upward or downward, the quenching bath A quenching apparatus is disclosed in which a rectifying plate having a wedge-shaped cross section is installed on the upper part of the plate.

JP 2010-7146 A JP 2016-211026 A

However, when the workpiece (steel part) is inserted into a basket or other workpiece moving means and quenched, if the amount of workpiece is too large, the workpiece placed at the bottom and the workpiece placed at the top A significant difference in flow velocity occurs between the oil flow and the oil flow in the object to be processed. In particular, since oil tends to stagnate near the center of the upper part of the basket, the flow velocity of the oil decreases, and as a result, the hardness of the material placed in the upper part is lower than that of the material placed in the lower part. descend.

This is because the hardness of the workpiece after quenching is greatly affected by the flow rate of the cooling liquid during quenching. can be stabilized. On the other hand, since the oil flow speed is higher around the object to be treated placed in the lower part of the basket than in the upper part of the basket, quench hardening spreads more than the hardness of the object to be treated placed in the upper part. was

Therefore, in the present invention, it is possible to supply a necessary and sufficient flow of oil to the vicinity of the center of the upper part of the basket even when the amount of the object to be treated (steel parts) is large, and to avoid the oil from entering the object to be treated. To provide a method for quenching a steel part, which can suppress an increase in the flow velocity around the object to be treated, and can uniformize the cooling speed of the object to be treated.

In order to solve the above-described problems, the present invention provides a quenching tank that stores oil, a stirring means that stirs the oil in the quenching tank, and a steel part (object to be treated) that moves within the quenching tank. In a quenching method using a quenching apparatus equipped with a steel part moving means, a steel part is quenched while covering the top of the steel part with a top plate having an opening. A quenching method was adopted. Also, this opening may be provided in the central portion of the top plate.

Furthermore, the distance h1 from the top plate to the oil surface of the quenching tank can be made shorter than the distance h2 from the steel part to the top plate. Further, the distance h2 from the steel part to the top plate is preferably in the range of 50 mm or more and less than 300 mm.

The steel part quenching method according to the present invention supplies a necessary and sufficient flow of oil to the vicinity of the center of the upper part of the cage even when the amount of the material to be treated is large, and the oil avoids the material to be treated. It is possible to suppress the increase in flow velocity around the object to be processed, and to make the cooling speed of the object to be processed uniform. Since the object to be treated is uniformly cooled regardless of the installation position in the quenching tank, it is possible to reduce the black scale removal (cutting allowance on the surface) of the object to be treated after quenching treatment.

1 is a schematic plan view of the interior of a quenching tank 1 used in the quenching method of the present invention; FIG. FIG. 2 is a sectional view taken along the line AA in the quenching tank 1 shown in FIG. 1; It is a schematic plan view in the quenching tank 1A which shows another form of this invention. 4 is a cross-sectional view taken along the line BB in the quenching tank 1A shown in FIG. 3. FIG. It is a schematic plan view in the quenching tank 1B which shows another form of this invention. 6 is a cross-sectional view taken along the line CC in the quenching tank 1B shown in FIG. 5. FIG.

An example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic plan view of the interior of the quenching tank 1 used in the quenching method of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. As shown in FIGS. 1 and 2, a large number of steel parts W are orderly immersed in a quenching tank 1 constituting a quenching apparatus used in the quenching method of the present invention. A top plate T is installed at a predetermined interval above.

An opening 2 having a diameter φd is provided in the center of the top plate T. As shown in FIG. The oil pressure-fed from the stirring means (agitator) of the quenching device (not shown) is directed upward from the lower side of the steel parts W immersed in the quenching tank by the steel part moving means (not shown). flow. At this time, the pumped oil weaves through the steel parts W and also flows into the central portion of the quenching tank 1 shown in FIG. A part of the oil flowing through the central portion passes through the opening 2 of the top plate T and flows into the oil surface.

Furthermore, the installation position of the top plate T in the quenching tank 1 can be freely adjusted in the depth direction of the quenching tank 1 . In the embodiment shown in FIG. 1, the distance (depth) from the steel part W closest to the oil surface to the oil surface is as shown in FIG. The sum of the distance h1 from T to the oil level in the quenching tank 1 and the distance h2 from the steel part W closest to the oil level to the top plate T (the shortest distance from the steel part W to the top plate T) (h1+h2).

In this case, the distance h1 from the top plate T to the oil surface of the quenching tank 1 is made shorter than the distance h2 from the steel part W closest to the oil surface to the top plate T (h1<h2). This is because, as described above, the oil flowing through the central portion of the oil tank 1 in the form shown in FIG.

3 and 5 show schematic plan views of the interior of quenching tanks 1A and 1B showing another embodiment of the present invention in addition to the embodiment shown in FIGS. FIG. 4 shows a cross-sectional view of the interior of the quenching tank 1A shown in FIG. 3 taken along line BB, and FIG. 6 shows a cross-sectional view of the inside of the quenching tank 1B shown in FIG. 5 taken along line CC. 3 to 6, illustration of the steel component W is omitted.

A top plate T1 in the quenching tank 1A shown in FIGS. 3 and 4 is provided with four rectangular openings 2A to 2D each having a width w1. Compared to the form of the top plate T shown in FIGS. 1 and 2, since more openings are provided, the air bubbles generated from the steel parts during quenching can be led to the oil surface side more quickly. It is valid.

Further, the top plate T2 in the quenching tank 1B shown in FIGS. 5 and 6 is provided with three rectangular openings 2E to 2G each having a width w2. Both sides of the top plate T2 (the outer side of the openings 2E and 2G) are inclined toward the oil surface direction, and the edge portion of the top plate T2 is on the side opposite to the oil surface (the bottom of the quenching tank 1B). side).

5 and 6 in the quenching bath, air bubbles generated from the steel parts during quenching are more likely to occur on the lower surface of the top plate than in the top plate configuration shown in FIGS. , so it is effective in guiding the air bubbles as far as possible from the axis of the stirrer (not shown) and suppressing entrainment of the air bubbles.

Considering the distance (depth) that the oil flowing from the bottom of the oil tank 1 can reach the oil surface while maintaining the flow velocity, the distance h2 from the steel part W to the top plate T is 50 mm or more and less than 300 mm. It is desirable to

In addition, in the present embodiment, the shape of the opening 2 of the top plate T is circular as shown in FIG. 1 and square as shown in FIGS. Other shapes such as . Furthermore, the top plate may optionally be provided with a plurality of openings according to the shape and/or packaging of the steel parts W.

1, 1A, 1B Quenching tanks 2, 2A to 2G Openings T, T1, T2 Top plate W Steel parts (workpieces)
h1 Distance from the top plate to the oil level in the quenching tank h2 Distance from the steel part to the top plate φd Diameter of the opening w1, w2 Size of the opening

Claims (3)

A quenching apparatus comprising a quenching tank for storing oil, a stirring means for stirring the oil in the quenching tank, and a steel part moving means for moving the steel parts within the quenching tank is used. A steel part quenching method, wherein a large number of the steel parts are immersed in the quenching tank, a top plate is installed above the many steel parts and below the oil level, and the top plate is A method of quenching steel parts, characterized in that an opening is provided in the central part and the oil flows from the lower side to the upper side of the many steel parts . 2. The steel part quenching method according to claim 1 , wherein a distance h1 from the top plate to the oil surface of the quenching tank is shorter than a distance h2 from the steel part to the top plate. . 3. The method of quenching steel parts according to claim 2, wherein a distance h2 from said steel parts to said top plate is 50 mm or more and less than 300 mm.

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