JP2021147626A - Quenching method and apparatus - Google Patents

Abstract

To obtain a metal member having a small amount of strain after being quenched.SOLUTION: A quenching treatment apparatus 30 includes an oil tank 34 in which a heat treatment oil 32 is stored, when quenching a metal member 10, the metal member is first lowered and immersed in the heat treatment oil 32 in the oil tank 34 to a predetermined depth, then, the metal member is raised at a predetermined rising speed and moving time so as not to be exposed from the heat treatment oil 32.SELECTED DRAWING: Figure 4

Description

The present invention relates to a quenching method and an apparatus thereof for cooling a heated metal member with heat treatment oil.

Various metal members can be obtained by forming a billet by forging or the like and then subjecting it to a heat treatment such as quenching. Quenching makes the metal member excellent in mechanical properties such as strength. Generally, quenching is performed by lowering the heated molded product toward the tank, and further immersing the molded product in water or heat treatment oil previously stored in the tank to quench the molded product.

When the shape of the metal member is large, cooling proceeds at the lowermost portion facing the heat treatment oil from the time when the portion is submerged to the time when the uppermost portion is submerged. Therefore, it is possible that cooling has progressed sufficiently in the lowermost part, even though the cooling of the uppermost part has just started. If the temperature difference between the two parts becomes excessively large due to this, the metal member will be distorted.

In order to avoid such a situation, as described in Patent Documents 1 and 2, when the metal member is immersed in the heat treatment oil, the steam film covering the surface of the metal member is uniformly formed. Attempts have been made to remove it. In this case, the cooling rate can be made as equal as possible regardless of the portion of the metal member. In Patent Document 1, it is proposed that the metal member is repeatedly raised and lowered (up and down reciprocating motion) in the heat treatment oil, and in Patent Document 2, the metal member is vibrated in addition to the up and down reciprocating motion. It is proposed to do.

JP-A-59-70715 Japanese Unexamined Patent Publication No. 2005-350756

When the moving distance (amplitude) of the vertical reciprocating motion is not sufficient, it is not easy to break the vapor film. In such a case, it becomes difficult to suppress the occurrence of distortion. Therefore, there is a demand for a quenching method capable of suppressing the occurrence of distortion in a metal member.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a quenching method and an apparatus thereof capable of preventing the metal member from being distorted as much as possible.

In order to achieve the above object, according to one embodiment of the present invention, in a quenching method in which a heated metal member is immersed in heat treatment oil and quenched.
Of the metal member descending toward the heat treatment oil, the portion first submerged in the heat treatment oil is referred to as the oil submersion start portion, and finally the portion submerged in the heat treatment oil is referred to as the oil submersion end portion. When the oil submersion end portion in the heat treatment oil is completed and the oil submersion start portion is in the steam film stage covered with a steam film, the oil in the heat treatment oil is used. A step of raising the metal member with the submerged end portion at the head so that the temperature difference between the oil submerged start portion and the oil submerged end portion is 60 ° C. or less.
A step of cooling the metal member with the heat treatment oil that has reached the boiling stage, and
A step of exposing the cooled metal member from the heat treatment oil, and
Quenching methods are provided.

Further, according to another embodiment of the present invention, in a quenching processing apparatus for quenching a metal member,
A holding member that holds the plurality of the metal members, and
An oil tank storing heat treatment oil for immersing a plurality of the metal members together with the holding member, and an oil tank.
An elevating actuator for moving the metal member into or out of the heat treatment oil by lowering or raising the holding member.
With
When the maximum separation distance between the adjacent metal members is L1, and the minimum separation distance between the side wall closest to the metal member and the metal member in the side wall of the oil tank or the holding member is L3. , A quenching processing apparatus having a value of L3 / L1 of less than 2 is provided.

According to the present invention, the metal member immersed in the heat treatment oil is raised in the heat treatment oil. As a result, a metal member having a small strain can be obtained. It is presumed that the reason for this is that the timing at which the vapor film covering the metal member is destroyed becomes substantially the same on the oil submersion start side and the oil submersion end side due to the above rise. That is, due to this destruction, the heat treatment oil in the vicinity of the oil submersion start portion that is first submerged in the heat treatment oil and the oil submergence end portion that is finally submerged in the heat treatment oil rapidly shifts to the boiling stage. As a result, it is presumed that the temperature difference between the two parts becomes smaller.

It is an overall schematic perspective view of a helical gear which is a metal member to be hardened. It is a schematic front view of the quenching processing apparatus which carries out the quenching method. It is a schematic front view which shows the state which the uppermost part (oil submerged end part) of a helical gear is submerged in oil. It is a schematic front view which shows the state which reached the maximum stroke point of a helical gear. It is a schematic front view which shows the state which the helical gear is raised from the maximum stroke point. It is a graph which showed the time from the time when the helical gear reached the maximum stroke point to the start of ascending, and the temperature difference between the oil submerged start portion and the oil submerged end portion. It is a graph which showed the moving time from the start of ascending of the helical gear set to various ascending speeds to reaching a predetermined ascending position, and the temperature difference between the oil submerged start portion and the oil submerged end portion. It is a graph which showed the relationship between the temperature difference of the oil submersion start part and the oil submergence end part, and the strain amount of a helical gear. It is a schematic front view of the quenching processing apparatus for mass production.

Hereinafter, preferred embodiments of the quenching method and the apparatus thereof according to the present invention will be described, and will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall schematic perspective view of a helical gear 10 which is a metal member to be hardened. As is well known, the helical gear 10 has an annular portion 16 in which a through hole 12 is formed and an inclined tooth 18 provided on a side peripheral wall of the annular portion 16, for example, forging a material. It is an annulus shape obtained by the above.

The helical gear 10 is in a so-called standing posture in which the radial direction is along the gravity direction (vertical direction) and the thickness direction is substantially orthogonal to the gravity direction, and in this state, the helical gear 10 is stored in the oil tank 34 described later. It is submerged in the heat treatment oil 32. Therefore, the lowermost portion 20 of the helical gear 10 at the lowermost end in the gravity direction is submerged in the heat treatment oil 32 earliest, while the uppermost portion 22 at the uppermost end is submerged in the heat treatment oil 32 at the latest. In other words, the oil submersion of the helical gear 10 starts at the lowest portion 20 and ends at the uppermost portion 22. Therefore, in the following, the lowermost portion 20 is also referred to as the “oil submerged start portion 20”, and the uppermost portion 22 is also referred to as the “oil submerged end portion 22”.

FIG. 2 is a schematic front view of a quenching processing device 30 for quenching one helical gear 10. The quenching processing apparatus 30 includes an oil tank 34 for storing the heat treatment oil 32, a holding member 36 for holding the helical gear 10, and an elevating actuator for raising or lowering the holding member 36.

The oil tank 34 is set to be long in the direction of gravity, so-called vertically long, and its height direction dimension H is set to about 4 to 6 times the diameter D of the helical gear 10 in the standing posture. A sufficient amount of the heat treatment oil 32 is stored in the oil tank 34, and the height dimension (depth) h thereof is set to about 3 to 5.5 times the diameter D of the helical gear 10. Here, the diameter D is the diameter of the tip circle circumscribing the tip of each inclined tooth 18.

The holding member 36 has, for example, a cylindrical shape and is passed through a through hole 12 of the helical gear 10. When the holding member 36 comes into contact with the inner wall above the through hole 12, the helical gear 10 is held by the holding member 36. The holding member 36 may have a hook shape having a raised claw portion.

The elevating actuator in this case comprises a high speed servo 38. The holding member 36 is attached to the tip of the elevating rod 40 constituting the servo 38, and as the elevating rod 40 performs the elevating operation (advancing / retreating operation), the holding member 36 moves up and down integrally with the elevating rod 40. Of course, at this time, the helical gear 10 held by the holding member 36 moves up and down.

The descending speed, ascending speed, and stroke amounts ST1 and ST2 (see FIGS. 4 and 5) of the ascending / descending rod 40 at the time of descending and ascending can be input as set values to a control unit (not shown). That is, the control unit controls the ascending speed, the descending speed, and the stroke amounts ST1 and ST2 at the time of ascending and descending the elevating rod 40 so as to be the input set value. When the diameter D of the helical gear 10 is 200 mm, in the ascending step S2 described later, the ascending speed is set to 25 to 100 mm / sec, and the moving time from the start of ascending the helical gear 10 to reaching the ascending position is 4 seconds. It is preferable to adjust the stroke amount ST1 so as to be as described above. A specific example of the stroke amount ST1 is 100 to 700 mm, typically 400 to 600 mm.

The height dimension H of the oil tank 34 is such that the helical gear 10 is exposed from the heat treatment oil 32 even when the ascending speed of the helical gear 10 in the ascending step S2 is 25 to 100 mm / sec and the moving time is 4 seconds or more. Is set to a length that does not. Since a specific example of the stroke amount ST1 is 100 to 700 mm, the height dimension H may be set to a value close to this.

Next, the quenching method according to the present embodiment will be described. In this case, the quenching method is performed on the helical gear 10 obtained through forging or the like, and includes a dipping step S1, an ascending step S2, a position maintaining step S3, and an exposure step S4.

In the dipping step S1, the entire heated helical gear 10 is immersed in the heat treatment oil 32. For this purpose, first, the servo 38 is operated and the elevating rod 40 is lowered. Along with this, the holding member 36 and the helical gear 10 are integrally lowered toward the oil tank 34. At this time, the lowering speed of the elevating rod 40 is preferably in the range of 500 to 1000 mm / sec as described later.

In the descending helical gear 10, first, the oil submersion start portion 20 comes into contact with the heat treatment oil 32 (see FIG. 2). As the helical gear 10 continues to descend, the oil submersion start portion 20 is submerged in the heat treatment oil 32. Immediately after the oil submersion start portion 20, the oil submersion start portion 20 is covered with the steam of the heat treatment oil 32. That is, the heat treatment oil 32 in the vicinity of the oil submersion start portion 20 is in the vapor film stage.

When the helical gear 10 continues to be lowered, the portion between the oil submersion start portion 20 and the oil submersion end portion 22 is sequentially submerged in the heat treatment oil 32. Of course, in the vicinity of the oil-submerged portion, the heat treatment oil 32 sequentially forms a steam film and covers the oil-submerged portion. In this way, as the oil submersion of the helical gear 10 progresses, the portion covered with the vapor film gradually expands. Then, as shown in FIG. 3, the oil submerged end portion 22 is finally submerged in oil and covered with a vapor film. After that, the helical gear 10 continues to descend, and as shown in FIG. 4, the elevating rod 40 descends to the maximum stroke point.

In the present embodiment, when the elevating rod 40 descends to the maximum stroke point, the descending speed of the elevating rod 40 and the descending speed of the elevating rod 40 so that the heat treatment oil 32 in the vicinity of the oil submersion start portion 20 still maintains the steam film stage. The stroke amount ST1 is set. If the descending speed is excessively small, the heat treatment oil 32 in the vicinity of the oil submersion start portion 20 shifts to the boiling stage, and the oil submersion start portion 20 is sufficiently cooled. In this case, the temperature difference between the oil submersion start portion 20 and the oil submersion end portion 22 becomes large, which contributes to the occurrence of distortion in the inclined teeth 18 and the like. On the other hand, even if an excessively large descent speed is set, it is not possible to obtain a descent speed higher than the capability of the servo 38. From the above viewpoint, it is preferable that the elevating speed of the elevating rod 40 is within the range of 500 to 1000 mm / sec.

Further, if the stroke amount ST1 at the time of descending is excessively short, the helical gear 10 is exposed from the heat treatment oil 32 at the time of the ascending step S2. On the other hand, if it is excessively long, the moving distance in the ascending step S2 becomes large, and the heat treatment oil 32 in the vicinity of the oil submersion start portion 20 tends to shift to the boiling stage by this amount. Therefore, similarly to the above, while the helical gear 10 ascends in the heat treatment oil 32 in the ascending step S2, the temperature difference between the oil submersion start portion 20 and the oil submersion end portion 22 becomes large. In order to avoid the above, it is preferable that the stroke amount ST1 is 100 to 700 m.

Next, immediately after the helical gear 10 reaches the maximum stroke point, the helical gear 10 is immediately raised to start the ascending step S2. That is, the lifting rod 40 is raised, and the holding member 36 and the helical gear 10 are integrally raised. At this time, the helical gear 10 rises with the oil submerged end portion 22 at the head. Therefore, since the heat treatment oil 32 comes into contact with the oil submerged end portion 22 while flowing relatively, the oil submerged end portion 22 can be cooled preferentially.

The moving distance of the helical gear 10 in the ascending step S2 is set so that the helical gear 10 is not exposed from the heat treatment oil 32. That is, at the time when the ascending step S2 is completed, the entire helical gear 10 is still immersed in the heat treatment oil 32 as shown in FIG. The helical gear 10 is maintained in this position until a predetermined time elapses. That is, the position maintenance step S3 is performed.

The above rise destroys the vapor film covering the helical gear 10. That is, the timing at which the vapor film is destroyed is substantially simultaneous on the oil submersion start side and the oil submersion end side. The heat treatment oil 32 in contact with the portion of the helical gear 10 where the steam film is broken causes nucleate boiling in a relatively short time. That is, in the position maintenance step S3, the heat treatment oil 32 in the vicinity of the helical gear 10 transitions to the boiling stage substantially at the same time over the entire helical gear 10. As a result, the helical gear 10 is cooled and hardened.

Finally, in the exposure step S4, the elevating rod 40, the holding member 36, and the helical gear 10 are raised under the action of the elevating actuator, and the helical gear 10 is exposed (retracted) from the heat treatment oil 32. This completes the quenching.

After all, according to the present embodiment, the number of times of the ascending step S2, in other words, the number of ascending steps can be set to only once. Therefore, the time from when the helical gear 10 is submerged in the heat treatment oil 32 until it is exposed to the outside of the heat treatment oil 32 can be shortened as much as possible. As will be described later, even if the number of rises is only once, the helical gear 10 having a sufficiently small amount of strain can be obtained.

FIG. 6 is a graph showing the time from when the helical gear 10 reaches the maximum stroke point to the start of ascending (that is, ascending step S2) and the temperature difference between the oil submerged start portion 20 and the oil submerged end portion 22. Yes, the horizontal axis is the ascending speed of the elevating rod 40. In this case, the vapor film stage is "0S", which indicates that the helical gear 10 started ascending immediately after reaching the maximum stroke point. Further, "2S" in which only the lower part of the helical gear 10 is in the boiling stage and "5S" in which the entire helical gear 10 is in the boiling stage indicate that the ascending is started after stopping for 2 seconds or 5 seconds at the maximum stroke point. Further, "only submerged in oil" means that the helical gear 10 was stopped at the maximum stroke point and the ascending step S2 was not performed.

From FIG. 6, it can be seen that the temperature difference between the oil submersion start portion 20 and the oil submersion end portion 22 can be set to 60 ° C. or less by immediately starting the ascending step S2 following the immersion step S1. It is presumed that the reason for this is that when the timing of starting the ascending step S2 is delayed as described above, the heat treatment oil 32 in the vicinity of the oil submersion start portion shifts to the boiling stage.

In FIG. 7, when the ascending speed of the helical gear 10 (or the elevating rod 40) is set variously, the moving time from when the helical gear 10 starts ascending to when it reaches a predetermined ascending position is shown on the horizontal axis and is submerged in oil. It is a graph which makes the temperature difference between the start part 20 and the oil submerged end part 22 the vertical axis. The stroke amount ST2 is calculated by multiplying the ascending speed by the moving time, and in this case, the maximum stroke amount is set to 400 mm. From FIG. 7, by setting the ascending speed of the helical gear 10 to 25 mm / sec or more and the moving time to 4 seconds or more, the temperature difference between the oil submersion start portion 20 and the oil submersion end portion 22 can be reduced to 60 ° C. or less. I understand.

Further, FIG. 8 shows a graph in which the temperature difference between the oil submersion start portion 20 and the oil submersion end portion 22 is on the horizontal axis and the strain amount of the helical gear 10 is on the vertical axis. The temperature difference in this graph is obtained as a value obtained by subtracting the temperature of the oil submersion end portion 22 from the temperature of the oil submersion start portion 20. Therefore, a negative value means that the oil submersion start site 20 has a lower temperature than the oil submersion end site 22. With reference to FIG. 8, it is clear that the helical gear 10 having a small amount of strain can be obtained by performing the ascending step S2 described above.

When it is desired to quench a large number of helical gears 10 at the same time, the mass-produced quenching processing apparatus 50 shown in FIG. 9 may be used. In this case, the holding plate 52 as a holding member is housed in the oil tank 34. A plurality of (for example, 12) cylindrical holding bars 54 to be passed through the through holes 12 are provided on one end surface of the holding plate 52 so as to extend in the same direction. The holding plate 52 rises or falls with respect to the oil tank 34 under the action of the lifting actuator configured in the same manner as in FIG. Along with this, the holding plate 52 is evacuated from the heat treatment oil 32 stored in the oil tank 34, or enters the heat treatment oil 32.

A plurality of helical gears 10 are held in one holding bar 54 in a direction orthogonal to the paper surface. If a hooking recess is formed on the upper surface of the holding bar 54 and the helical gear 10 is hooked on the hooking recess to hook the helical gear 10, the helical gears 10 are held in the holding bar 54 in a state of being separated from each other. Is easy. Further, the helical gears 10 held by the two holding bars 54 that are in close contact with each other on the left and right or up and down are separated by the separation distances L1 and L2. In addition, L1 and L2 may be equal or different.

Further, the side wall 56 of the oil tank 34 and the helical gear 10 which is in close contact with the side wall 56 are separated by the minimum separation distance L3. The minimum separation distance L3 is set to be smaller than twice the larger value in the separation distances L1 and L2. For example, when L1 is larger than L2 (when L1 is the maximum separation distance), the following relational expression holds between L1 and L3.
2 x L1> L3
By transforming this equation, the following relational expression can be obtained.
(L3 / L1) <2

When the above relational expression is established between the separation distances L1 to L3, the heat treatment oil 32 that flows the clearance between the side wall 56 and the helical gear 10 that is in close contact with the side wall 56 when the holding plate 52 is raised. And the flow rate of the heat treatment oil 32 flowing between the adjacent helical gears 10 are substantially in equilibrium. Therefore, by raising the holding plate 52 under the above-mentioned conditions, the steam film can be broken and the boiling stage can be changed in the same manner as described above.

Although the holding plate 52 having no side wall is illustrated in FIG. 9, when the oil tank 34 is wide, a holding plate provided with a side wall may be used instead of the holding plate 52. In this case, the separation distance between the side wall of the holding plate and the helical gear 10 that is in close contact with the side wall may be set to L3 so as to satisfy the above relational expression.

In any case, similarly to the quenching processing apparatus 30, in the ascending step S2, it is preferable that the ascending speed is 25 mm / sec or more and the ascending time is 4 seconds or more. It goes without saying that all the helical gears 10 are not exposed from the heat treatment oil 32 at the end of the ascending step S2.

The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, the elevating actuator may be a linear actuator incorporating a servomotor or a cylinder.

10 ... Helical gear 18 ... Inclined teeth 20 ... Oil submersion start part (bottom part) 22 ... Oil submersion end part (top part)
30 ... Quenching processing device 32 ... Heat treatment oil 34 ... Oil tank 36 ... Holding member 38 ... Servo 40 ... Elevating rod 50 ... Quenching processing device for mass production 52 ... Holding plate 54 ... Holding bar 56 ... Side wall

Claims (8)

In the quenching method in which a heated metal member is immersed in heat treatment oil and quenched.
The portion of the metal member that descends toward the heat treatment oil is first the portion that is submerged in the heat treatment oil as the oil submersion start portion, and finally the portion that is submerged in the heat treatment oil as the oil submersion end portion. When the oil submersion end portion in the heat treatment oil is completed and the oil submersion start portion is in the steam film stage covered with a steam film, the heat treatment oil is used. A step of raising the metal member with the oil submerged end portion at the head so that the temperature difference between the oil submerged start portion and the oil submerged end portion is 60 ° C. or less.
A step of cooling the metal member with the heat treatment oil that has reached the boiling stage, and
A step of exposing the cooled metal member from the heat treatment oil, and
Quenching method with. The quenching method according to claim 1, wherein the metal member is raised once, and the metal member is held in the raised position for cooling. The quenching method according to claim 1 or 2, wherein the depth of the heat treatment oil is at least twice the height of the metal member. The quenching method according to any one of claims 1 to 3, wherein the ascending speed of the metal member is 25 mm / sec or more and the ascending time is 4 seconds or more. In the quenching method according to any one of claims 1 to 4, the metal member is used for heat treatment in an upright posture in which the metal member is formed of an annular shape and the thickness direction is substantially orthogonal to the gravity direction. Quenching method of immersing in oil. The quenching method according to claim 5, wherein a gear is used as the metal member. In a quenching processing device for quenching metal members
A holding member that holds the plurality of the metal members, and
An oil tank storing heat treatment oil for immersing a plurality of the metal members together with the holding member, and an oil tank.
An elevating actuator for moving the metal member into or out of the heat treatment oil by lowering or raising the holding member.
With
When the maximum separation distance between the adjacent metal members is L1, and the minimum separation distance between the side wall closest to the metal member and the metal member in the side wall of the oil tank or the holding member is L3. , L3 / L1 value is less than 2. Quenching processing apparatus. In the processing apparatus according to claim 7, when the height of the oil tank raises the metal member with an ascending speed of 25 mm / sec or more and an ascending time of 4 seconds or more, all the metal members are raised. A quenching treatment device set to a size that is not exposed from the heat treatment oil.

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