JP2010285690A - Method and apparatus for quenching metallic member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a cooling relaxing ability by adding a little quantity of water-soluble quenching agent before using, in comparison with the case of replacing the whole quantity of the water-soluble quenching agent. <P>SOLUTION: A first process in which a molecular weight polymer 24 (water-soluble polymer) having lower than the average molecular weight of a water-soluble polymer in the water-soluble quenching agent 26 before using, is separated from the water-soluble quenching agent 13b after using, that is, a separating removal device 22 (the separating device) is included. Further, a second process in which the water-soluble quenching agent 26 before using, is added into the water-soluble quenching agent 13c subjected to separation by the separating removal device 22, that is, an adjusting device 25 is included. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a quenching method and a quenching apparatus for a metal member, in which the metal member is immersed in a liquid and rapidly cooled, or a liquid is jetted onto the metal member to rapidly cool the metal member.

  Conventionally, for quenching of metal members, water-soluble quenching agents having features such as fire prevention ability and large cooling ability are used. Conventionally, it has been known that when the cooling rate of the metal member is too high, there are problems such as burning cracks, deformation (distortion) and residual stress. For example, in the case of quenching steel, particularly when the cooling rate is high at 400 ° C. or less, which is the martensite transformation start temperature of steel (the martensite transformation start temperature varies depending on the member and the cooling rate. The martensitic transformation is a transformation in which each atom of the crystal lattice is transformed into a new crystal by moving together without diffusion). In order to suppress this problem, for example, 20 to 30% by weight of a water-soluble polymer is added to the water-soluble quenching agent. This lowers the cooling rate of the metal member (hereinafter, the ability to suppress the cooling rate of the water-soluble quenching agent and water-soluble polymer is referred to as “cooling relaxation ability”).

FIG. 9 shows a conventional quenching apparatus 201. In this quenching apparatus 201, the quenching tank 212 for quenching the metal member 211, the water-soluble quenching agent 213, the cooling tower 214 for maintaining the quenching tank 212 at 30 to 50 ° C., and the water-soluble quenching agent 213 are melted. A circulation pump 215 for circulating the aqueous solution between the quenching tank 212 and the cooling tower 214 is provided.
In this quenching apparatus 201, by repeating quenching of the metal member heated to about 800 ° C. to 900 ° C., the water-soluble polymer in the water-soluble quenching agent 213 is, for example, thermally decomposed or oxidatively decomposed (constitutes the water-soluble polymer). The bonds between the carbons to break). This decomposition reduces the molecular weight of the water-soluble polymer. It is known that a water-soluble polymer having a small molecular weight has a low cooling relaxation ability. That is, the water-soluble quenching agent 213 is deteriorated by repeated use, and the cooling relaxation ability is lowered (hereinafter, the used aqueous solution in which the deteriorated water-soluble quenching agent is dissolved is referred to as “use liquid”).

  Therefore, there is the following technique for suppressing the problem of the cooling relaxation ability. For example, there is a technique of adding a non-degraded water-soluble quenching agent (hereinafter, an unused aqueous solution in which a non-degraded water-soluble quenching agent is dissolved is referred to as “new solution”) to the working solution. In addition, there is a technique for adding a new liquid having a high concentration of water-soluble polymer to the working liquid. In addition, there is a technique of adding a water-soluble quenching agent containing a water-soluble polymer having a molecular weight larger than that of a water-soluble polymer contained in a normal new solution to the working solution (for example, Patent Document 1).

Japanese Patent No. 3824695

  However, in these techniques, the water-soluble polymer whose cooling relaxation ability is reduced by thermal decomposition or oxidative decomposition remains dissolved in the aqueous solution. At present, the entire amount of the water-soluble quenching agent 213 is replaced from the quenching apparatus 201 in order to remove the deteriorated water-soluble polymer. In this case, the water-soluble polymer whose cooling relaxation ability is not lowered is also removed. Therefore, there is a problem that the cost for the water-soluble quenching agent increases.

  The object of the present invention is to provide a quenching method and quenching apparatus for metal members that can improve the cooling relaxation ability by adding a small amount of the water-soluble quenching agent before use compared to the case where the entire amount of the water-soluble quenching agent is replaced. It is to be.

  According to the first aspect of the present invention, there is provided a method for quenching a metal member, wherein a water-soluble polymer having a molecular weight lower than a weight average molecular weight of a water-soluble polymer in a water-soluble quenching agent before use is used. The 1st process to isolate | separate and the 2nd process of adding the water-soluble quenching agent before use to the water-soluble quenching agent which passed through the said 1st process are provided. “Before use” means that the product has never been used for quenching.

Many of the water-soluble polymers in the deteriorated water-soluble quenching agent have a lower molecular weight than the water-soluble polymer in the water-soluble quenching agent before use. In addition, a water-soluble polymer having a low molecular weight has a lower cooling relaxation ability than a water-soluble polymer having a high molecular weight. Therefore, in the first step, a water-soluble polymer having a low molecular weight (that is, a low cooling relaxation ability) is separated from the water-soluble quenching agent after use. In the first step, it is not necessary to separate a water-soluble polymer having a high molecular weight (high cooling relaxation ability). And in a 2nd process, the water-soluble quenching agent before use is added to the water-soluble quenching agent which passed through the 1st process.
Therefore, compared with the case where the whole amount of the deteriorated water-soluble quenching agent is replaced with the water-soluble quenching agent before use, the cooling relaxation ability can be improved by adding a small amount of the water-soluble quenching agent before use. Therefore, the cost concerning a water-soluble hardening agent can be reduced.

  In the method for quenching a metal member according to the second aspect of the invention, a water-soluble quenching agent containing the water-soluble polymer separated in the first step is sprayed onto the first injected portion of the metal member. Moreover, the water-soluble hardening agent which passed through the said 1st process or the 2nd process is injected to the 2nd to-be-injected part of the said metal member.

  In this metal member quenching method, a water-soluble quenching agent containing a water-soluble polymer having a low molecular weight (low cooling relaxation ability) is sprayed onto the first portion to be sprayed. Further, a water-soluble quenching agent containing a water-soluble polymer having a high molecular weight (high cooling relaxation ability) is sprayed onto the second spray target portion. That is, the cooling relaxation ability of the water-soluble quenchant injected between the first injected portion and the second injected portion is different. Therefore, a cooling rate can be adjusted for every to-be-injected part of a metal member.

  Moreover, in this invention, the water-soluble hardening agent containing the water-soluble polymer isolate | separated by the 1st process is injected to the 1st to-be-injected part of a metal member. That is, the water-soluble polymer in the deteriorated water-soluble quenching agent is reused. Therefore, the cost for the water-soluble quenching agent can be further reduced.

  In the quenching method for a metal member according to a third aspect of the invention, the metal member has a rod shape. The first injected part is an axially central part of the metal member. The second injected parts are both ends of the metal member in the axial direction. The bar shape is a shape in which the longitudinal direction of the member is the axial direction of the member.

In this metal member quenching method, the metal member is rod-shaped. Here, generally, when a rod-shaped metal member is quenched (without using the present invention), the cooling rate at both axial end portions is higher than that at the axial central portion.
Moreover, in this invention, the 1st to-be-injected part into which the water-soluble hardening agent containing a water-soluble polymer with a low molecular weight (low cooling relaxation ability) is injected is the axial direction center part of a metal member (generally cooling rate is low). Part). Moreover, the 2nd to-be-injected part by which the water-soluble hardening agent containing a water-soluble polymer with a high molecular weight (high cooling relaxation ability) is injected is the axial direction both ends (part with a generally high cooling rate) of a metal member. . Therefore, the difference in cooling rate between the first injected part and the second injected part can be reduced. Therefore, the metal member can be brought close to a uniform temperature distribution. As a result, it is possible to suppress problems such as burning cracks, deformation (distortion) and residual stress.

  In the method for quenching a metal member according to the fourth invention, the molecular weight of the water-soluble polymer separated in the first step is 10,000 or less.

  A water-soluble polymer having a molecular weight of 10,000 or less has a particularly low cooling relaxation ability compared to a water-soluble polymer having a molecular weight higher than 10,000. In the present invention, a water-soluble polymer having a molecular weight of 10,000 or less is separated in the first step. On the other hand, a water-soluble polymer having a molecular weight greater than 10,000 does not need to be separated in the first step. Therefore, compared with the case where a water-soluble polymer having a molecular weight higher than 10,000 is also separated, the cooling relaxation ability can be improved by adding a smaller amount of the water-soluble quenching agent before use. Therefore, the cost for the water-soluble quenching agent can be further reduced.

  According to a fifth aspect of the present invention, there is provided a metal member quenching apparatus comprising: a water-soluble polymer having a molecular weight lower than a weight-average molecular weight of a water-soluble polymer in a water-soluble quenching agent before use from a water-soluble quenching agent after use. A separation device for separation; and an adjustment device for adding a water-soluble quenching agent before use to the water-soluble quenching agent that has been separated. “Before use” means that the product has never been used for quenching.

  In this metal member quenching apparatus, as in the first aspect of the invention, a smaller amount of the water-soluble quenching agent before use is used in comparison with the case where the entire amount of the deteriorated water-soluble quenching agent is replaced with the water-soluble quenching agent before use. The cooling relaxation ability can be improved by adding. Therefore, the cost concerning a water-soluble hardening agent can be reduced.

  A metal member quenching apparatus according to a sixth aspect of the present invention includes a first injection unit that injects a water-soluble quenching agent containing a water-soluble polymer separated by the separation device onto a first injection target part of the metal member. In addition, the water-soluble quenching agent that has been separated or the water-soluble quenching agent to which the water-soluble quenching agent before use has been added by the adjusting device is injected into the second injected portion of the metal member. 2 injection parts are provided.

  In this metal member quenching apparatus, the cooling ability of the water-soluble quenchant injected between the first injected portion and the second injected portion is different as in the second invention. The cooling rate can be adjusted for each. Moreover, since the water-soluble polymer in the deteriorated water-soluble quenching agent is reused, the cost for the water-soluble quenching agent can be further reduced.

  In the metal member hardening apparatus according to a seventh aspect of the invention, the metal member has a rod shape. Moreover, the said 1st to-be-injected part is an axial direction center part of the said metal member. The second injected parts are both ends of the metal member in the axial direction.

  In this metal member quenching apparatus, the difference in cooling rate between the first injected portion and the second injected portion can be reduced as in the third aspect of the invention. Therefore, the metal member can be brought close to a uniform temperature distribution.

  In the quenching apparatus for metal members according to the eighth invention, the molecular weight of the water-soluble polymer separated by the separating apparatus is 10,000 or less.

  In this metal member quenching apparatus, as in the case of the fourth invention, the cooling relaxation ability is improved by adding a smaller amount of a water-soluble quenching agent before use than when separating a water-soluble polymer having a molecular weight higher than 10,000. it can. Therefore, the cost for the water-soluble quenching agent can be further reduced.

It is the distribution of the molecular weight of the water-soluble polymer for each of the new solution and the used solution. It is the cooling rate of each of the new liquid and the used liquid. It is a cooling rate of a quenching agent containing a water-soluble polymer having a predetermined molecular weight. It is the hardening apparatus using the hardening method of the metal member which concerns on this invention. It is molecular weight distribution of the water-soluble polymer used for the quenching test. It is a cooling rate distribution in the end surface part of a metal member. It is a cooling rate distribution in the center part of a metal member. FIG. 5 is a diagram corresponding to FIG. 4 of the second embodiment. It is a conventional quenching device.

  Hereinafter, an embodiment of a quenching method of a metal member according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows the molecular weight distribution of the water-soluble polymer in each of the new solution and the used solution. FIG. 2 shows the cooling rates of the new liquid and the used liquid. FIG. 3 shows the cooling rate of a quenching agent containing a water-soluble polymer having a predetermined molecular weight. FIG. 4 shows a quenching apparatus using the metal member quenching method according to the present invention. Hereinafter, with reference to FIGS. 1-4, the hardening apparatus using the hardening method of the metallic member which concerns on this invention is demonstrated in detail.

  First, the water-soluble polymer in the water-soluble quenching agent has a lower molecular weight by use, the used liquid has a faster cooling rate than the new liquid, and the water-soluble polymer having a lower molecular weight than the higher molecular weight has a lower cooling rate. Explain that is large. Then, the hardening apparatus 1 using the hardening method of the metal member which concerns on this invention is demonstrated.

(Relationship between molecular weight of water-soluble polymer and cooling rate)
First, it shows that the water-soluble polymer in the water-soluble quenching agent is reduced in molecular weight by use. Fig. 1 shows the water solubility of each of the new liquid (an unused aqueous solution in which a non-degraded water-soluble quenching agent is dissolved) and the working liquid (an aqueous solution after use in which a degraded water-soluble quenching agent is dissolved). It is a graph which shows the molecular weight distribution of a polymer. The vertical axis represents the ratio, and the horizontal axis represents the molecular weight. A solid line indicates a new solution, and a broken line indicates a working solution. The water-soluble polymer of the water-soluble quenching agent is polyalkylene glycol, and the main components are polyethylene glycol and polypropylene glycol.
The distribution of the molecular weight of the water-soluble polymer contained in the new solution and the working solution was as follows. As shown in FIG. 1, the new solution had a relatively sharp distribution with a peak at a molecular weight of about 20,000. On the other hand, the peak value of the distribution of the used solution was slightly lower than that of the new solution. In the use solution, the proportion of the water-soluble polymer having a molecular weight of 20000 or less was higher than that of the water-soluble polymer having a molecular weight of more than about 20000. Thus, it can be seen that the water-soluble polymer in the water-soluble quenching agent has a low molecular weight as a result of use. This is due to the thermal decomposition and oxidative decomposition of the water-soluble polymer.

(Relationship between used liquid and new liquid and cooling rate)
Next, it is shown that the used liquid has a faster cooling rate (lower cooling relaxation ability) than the new liquid. FIG. 2 is a graph showing the cooling rate of each of the new liquid and the used liquid. This cooling rate is a cooling rate in a 350 ° C. to 150 ° C. region where martensitic transformation of steel occurs. That is, the faster the cooling rate in this region, the more likely problems such as burn cracking, deformation (strain), and residual stress of the metal member occur. In addition, the result shown here is not the result in the large quenching tank used in the operation, but the test result on the laboratory scale. The cooling rate is calculated from the center temperature of the metal member.
The cooling rates of the new solution and the used solution were as follows. As shown in FIG. 2, it was about 10 K / second in the working solution. With the new solution, it was about 7 K / sec. Therefore, it can be seen that the cooling rate of the used solution is faster (cooling relaxation ability is lower) than the new solution.

Next, the water-soluble quenching agent shows that the cooling rate of the water-soluble polymer having a low molecular weight is higher than that of the high-molecular weight. FIG. 3 shows the cooling rates of two types of samples in which a water-soluble polymer having a predetermined molecular weight is mixed in the new solution. The cooling rate here is the cooling rate in the 350 ° C. to 150 ° C. region as in the above test.
One sample was prepared as follows. Polyethylene glycol having a weight average molecular weight of 20,000 (hereinafter referred to as PEG) was added to the new solution. The volume ratio of fresh solution and PEG is 50:50. Hereinafter, this water-soluble quenching agent is referred to as “molecular weight 20000”.
The other sample was prepared as follows. PEG having a weight average molecular weight of 2000 (referred to as “PEG2000”) and PEG having a weight average molecular weight of 7500 (referred to as PEG7500) were added to the new solution. The volume ratio of the new solution, PEG2000, and PEG7500 is 50:25:25. Hereinafter, this water-soluble quenching agent is referred to as “molecular weight 2000 + 7500”. The “molecular weight 20000” and “molecular weight 2000 + 7500” were adjusted so that the number of molecules of the water-soluble polymer was almost the same.
The cooling rates of “molecular weight 20000” and “molecular weight 2000 + 7500” were as follows. As shown in FIG. 3, at “molecular weight 20000”, the cooling rate was about 7.5 K / sec. That is, the rate of cooling is only slightly increased as compared with the cooling rate of the new liquid (about 7 K / second, see FIG. 2). With “molecular weight 2000 + 7500”, the cooling rate was about 9.6 K / sec. That is, the cooling rate is comparable to the cooling rate of the used liquid (about 10 K / second, see FIG. 2).
From this, it can be seen that when the proportion of the water-soluble polymer having a molecular weight of 10,000 or less is large (50% by volume), the cooling rate is increased.

(Hardening equipment)
Based on the above experimental results, a quenching apparatus 1 using the metal member quenching method according to the present invention will be described with reference to FIG.

  The quenching device 1 is a device that quenches the metal member 11. The outline of the quenching apparatus 1 is as follows. The metal member 11 is put into the quenching tank 12 and quenched. This quenching tank 12 is filled with a water-soluble quenching agent 13a (note that what is actually put into the quenching tank 12 is an aqueous solution containing the water-soluble quenching agent 13a. However, in the present invention, the water-soluble quenching agent is used. For example, an aqueous solution containing the water-soluble quenching agent 13 is also referred to as “water-soluble quenching agent 13”). The water-soluble quenching agent 13 a is supplied from the cooling tower 14 to the quenching tank 12. The water-soluble quenching agent 13 b deteriorated by quenching in the quenching tank 12 is sent to the quenching agent improving unit 20 via the circulation pump 15. The water-soluble quenching agent 13 d whose cooling relaxation ability has been improved by the quenching agent improving unit 20 is sent to the cooling tower 14. In this way, the water-soluble quenching agent 13 circulates in the quenching apparatus 1.

  The quenching tank 12 is provided for rapidly cooling the metal member 11. This quenching tank 12 functions as follows. The water-soluble quenching agent 13 a adjusted to a predetermined temperature (30 to 50 ° C.) by the cooling tower 14 is put into the quenching tank 12. The metal member 11 is immersed in the water-soluble quenching agent 13a, and the metal member 11 is rapidly cooled (that is, quenched). By repeating this rapid cooling, the water-soluble quenching agent 13a deteriorates. The deteriorated water-soluble quenching agent 13b is discharged to the circulation pump 15.

  The water-soluble quenching agent 13 is dissolved or dissolved in an aqueous solution used for quenching. The water-soluble quenching agent 13 contains a water-soluble polymer in order to slow down the cooling rate of the metal member 11. This water-soluble polymer is polyalkylene glycol, and the main components are polyethylene glycol and polypropylene glycol.

  The cooling tower 14 is provided in order to maintain the quenching tank 12 and the water-soluble quenching agent 13 at 30 ° C to 50 ° C. After being heated by quenching, the water-soluble quenching agent 13d that has passed through the circulation pump 15 and the quenching agent improving unit 20 is placed in the cooling tower 14 and cooled. Then, the cooled water-soluble quenching agent 13 a is supplied to the quenching tank 12.

  The circulation pump 15 is provided to circulate the water-soluble quenching agent 13 in the quenching apparatus 1. The circulation pump 15 takes in the water-soluble quenching agent 13 b from the quenching tank 12 and delivers it to the quenching agent improving unit 20.

  The quenching agent improving unit 20 is provided to improve the cooling relaxation ability of the quenching agent. The quenching agent improving unit 20 includes an analyzer 21, a separation / removal device 22 (separation device), an analyzer 23, and an adjustment device 25.

  The analyzer 21 is provided for measuring the molecular weight of the deteriorated water-soluble quenching agent 13b. The analyzer 21 is as follows. For example, one or a plurality of methods such as a chromatography method (GPC method), a thermal conductivity measurement method, and a viscosity measurement method are used. Thereby, the molecular weight distribution of the water-soluble quenching agent 13b is measured. Then, how much this molecular weight distribution differs from the molecular weight distribution of the new liquid is determined. In addition, a water-soluble quenching agent 13 b is put from the circulation pump 15 and discharged to the separation / removal device 22.

(First step)
The separation / removal device 22 (separation device) is provided to separate or separate and remove the low molecular weight polymer from the use liquid (hereinafter, separation or separation / removal is simply referred to as “separation / removal” or the like). The separation / removal device 22 is as follows. Water-soluble quenching agent 13b is put from the analyzer 21 side. The low molecular weight polymer 24 is separated and removed from the water-soluble polymer contained in the water-soluble quenching agent 13b. The molecular weight of the low molecular weight polymer 24 to be separated and removed is desirably 10,000 or less. This molecular weight is lower than the weight average molecular weight (about 20000) of the water-soluble polymer in the unused water-soluble quenching agent 13.
The separation / removal device 22 is, for example, a column. This column is a cylindrical container filled with, for example, silica gel or polymer gel. By putting the water-soluble quenching agent 13b in this container, the low molecular weight polymer 24 having a molecular weight of 10,000 or less can be separated and removed. The separation / removal device 22 may be a device that separates and removes the low molecular weight polymer 24 by, for example, thermally decomposing the water-soluble quenching agent 13b.
Then, after the low molecular weight polymer 24 is separated and removed, the remaining water-soluble quenching agent 13c (including a water-soluble polymer having a molecular weight greater than 10,000) is discharged to the analyzer 23 side. If it is determined from the analysis result in the analyzer 21 that this separation / removal is unnecessary, the water-soluble quenching agent 13b is put out to the analyzer 23 side without separation / removal.

  The analyzer 23 is provided for measuring the concentration of the water-soluble quenching agent 13b. The water-soluble quenching agent 13 c is put in from the separation / removal device 22 and taken out to the adjustment device 25.

(Second step)
The adjusting device 25 is provided for adding a new liquid. The adjusting device 25 functions as follows. The water-soluble quenching agent 13c is put from the analyzer 23. A new liquid is added to this water-soluble quenching agent 13c. This new solution is obtained by dissolving an unused (before use) water-soluble quenching agent 26 in water 27. The molecular weight of the water-soluble polymer of the water-soluble quenching agent 26 is desirably 20000 or more. The concentration of the water-soluble polymer in the new liquid is adjusted according to the concentration of the water-soluble quenching agent 13c measured by the analyzer 23. And the water-soluble hardening agent 13d which added the new liquid is discharged | emitted to the cooling tower 14 side.
Specifically, the adjustment device 25 is, for example, an automatic liquid preparation device. This automatic liquid preparation device includes, for example, a container containing unused water-soluble quenching agent 26, a container containing water 27, a container containing water-soluble quenching agent 13c from which low molecular weight polymer 24 has been separated and removed, and It has a stirring part which stirs what mixed these liquids. The amount of each liquid is adjusted from each of these containers. These liquids are mixed and stirred in the stirring section. Thereby, the water-soluble quenching agent 13d containing the high molecular weight polymer 28 is prepared.

(Features of quenching method and apparatus for metal member according to first embodiment)
The metal member quenching method and metal member quenching apparatus 1 of the present embodiment have the following characteristics.

As shown in FIG. 1, the water-soluble polymer in the deteriorated water-soluble quenching agent has a lower molecular weight than the water-soluble polymer in the water-soluble quenching agent before use. As shown in FIGS. 2 and 3, the water-soluble polymer having a low molecular weight has a faster cooling rate (lower cooling relaxation ability) than the water-soluble polymer having a high molecular weight.
Therefore, as shown in FIG. 4, the separation / removal device 22 separates and removes the low molecular weight polymer 24 (low cooling relaxation ability) from the water-soluble quenching agent 13 b after use (first step). The low molecular weight polymer 24 has a molecular weight lower than the weight average molecular weight of the water-soluble polymer in the water-soluble quenching agent 26 before use. Further, the separation / removal device 22 does not separate and remove a water-soluble polymer having a high molecular weight (high cooling relaxation ability).
And in the adjustment apparatus 25, the unused water-soluble hardening agent 26 and the water 27 (namely, new liquid) are added to the water-soluble hardening agent 13c which passed through the separation / removal device 22 (2nd process). That is, the water-soluble quenching agent 13c containing the high molecular weight polymer 28 (high cooling relaxation ability) is prepared.
Therefore, compared with the case where the entire amount of the deteriorated water-soluble quenching agent 13b is replaced with the water-soluble quenching agent 26 before use, the cooling relaxation ability can be improved by adding a small amount of the water-soluble quenching agent 26 before use. . Therefore, the cost concerning the water-soluble quenching agent 13 can be reduced.

  A water-soluble polymer having a molecular weight of 10,000 or less has a particularly low cooling relaxation ability compared to a water-soluble polymer having a molecular weight higher than 10,000. Therefore, the separation / removal device 22 separates and removes the water-soluble polymer having a molecular weight of 10,000 or less from the water-soluble quenching agent 13b (first step). On the other hand, a water-soluble polymer having a molecular weight greater than 10,000 is not separated by the separation / removal device 22 (first step). Therefore, compared with the case where the water-soluble polymer having a molecular weight higher than 10,000 is separated and removed, the cooling relaxation ability can be improved by adding a smaller amount of the water-soluble quenching agent 26 before use. Therefore, the cost for the water-soluble quenching agent can be further reduced.

(Second Embodiment)
FIG. 5 is a graph showing the molecular weight distribution of the water-soluble polymer used in the quenching test. FIG. 6 is a distribution of the cooling rate of each water-soluble quenching agent in the end surface portion of the rod-shaped metal member. FIG. 7 is a distribution of the cooling rate of each water-soluble quenching agent in the central portion of the rod-shaped metal member. FIG. 8 shows a quenching apparatus using the quenching method for metal members according to the second embodiment (corresponding to FIG. 4). First, a quenching test of a rod-shaped metal member will be described. Thereafter, the quenching apparatus 101 will be described.

(Hardening test of rod-shaped metal parts)
First, a quenching test of a rod-shaped metal member will be described. In this quenching test, the relationship between the molecular weight of the water-soluble polymer and the cooling rate in the quenching of the rod-shaped metal member was examined. In addition, the following test result was not obtained using the large-sized quenching tank used for operation, but is a result of a laboratory-scale test.

  First, the sample used for the quenching test will be described. A round bar-shaped test piece was used as the metal member. Further, three types of water-soluble quenching agents having different molecular weights of the water-soluble polymers (hereinafter also referred to as “each water-soluble quenching agent”) were used. FIG. 5 shows a graph showing the molecular weight distribution (relationship between molecular weight (horizontal axis) and ratio (vertical axis)) of each water-soluble quenching agent. Each water-soluble quenching agent is the following (1) to (3). (1) A water-soluble quenching agent to which PEG having a weight average molecular weight of about 20000 is added (hereinafter referred to as “molecular weight 20000”, see solid line in the graph). (2) A water-soluble quenching agent to which PEG having a weight average molecular weight of about 8000 is added (hereinafter referred to as “molecular weight 8000”, see broken line in the graph). (3) A water-soluble quenching agent to which PEG having a weight average molecular weight of about 4000 is added (hereinafter referred to as “molecular weight 4000”; see the two-dot chain line in the graph). The molecular weight distribution of “molecular weight 8000” has a range of molecular weights. The ratio of about 10,000 molecular weight is almost the same as the ratio of about 8,000 molecular weight. Therefore, by examining a sample having a molecular weight of 8000, a water-soluble polymer having a molecular weight of 10,000 (or less) can be examined.

  Next, the relationship between the molecular weight of the water-soluble polymer and the cooling rate will be described. 6 and 7 are graphs showing the cooling rate distribution (relationship between temperature (horizontal axis) and cooling rate (vertical axis)) for each water-soluble quenching agent. The results of “molecular weight 4000”, “molecular weight 8000”, and “molecular weight 20000” are indicated by squares, triangles, and circles in the graph. In FIG. 6, the cooling rate distribution in the end surface part (part corresponding to the both ends 132 of the metal member 11 shown in FIG. 8) of a metal member is shown. FIG. 7 shows the cooling rate distribution at the center of the metal member (the part corresponding to the center 131 of the metal member 11 shown in FIG. 8). These cooling rates were calculated from changes over time in the temperature of the metal member.

  6 and 7 that the cooling rate of the end face portion is higher than that of the center portion. Therefore, compared with the center part and the inside of a metal member, a temperature difference tends to occur between the end surface part and the inside of the metal member. Therefore, as is conventionally known, the cracks and deformation (distortion) are likely to occur at the end face portion.

  6 and 7 that the cooling rate is higher as the molecular weight of the water-soluble polymer in the water-soluble quenching agent is smaller. As described above, troubles such as burning cracks are likely to occur particularly when the cooling rate in the martensitic transformation region of 400 ° C. or lower is high. This problem is particularly problematic at the end face portion (see FIG. 6) where the cooling rate is high.

  On the other hand, it can be seen that in the central part where the cooling rate is low (see FIG. 7), the above-described problem hardly occurs even if the water-soluble polymer has a low molecular weight. That is, the case where “molecular weight 20000” is used for the end surface portion (see reference symbol A1 in FIG. 6) and the case where molecular weights of 10,000 or less (“molecular weight 4000” and “molecular weight 8000”) are used in the central portion (reference symbol A2 in FIG. 7). And A3)), the cooling rate is almost the same value. Specifically, all of A1 to A3 are, for example, about 30 K / sec at 400 ° C., for example, about 20 K / sec at 350 ° C.

  It can also be seen that the temperature distribution on the surface of the metal member can be made uniform. That is, even in a temperature range other than 350 ° C. to 400 ° C., A1 to A3 have similar cooling rate distributions. Therefore, if “molecular weight 20000” is used for the end face portion and molecular weights of 10,000 or less (“molecular weight 4000” and “molecular weight 8000”) are used for the center portion, the cooling speed is almost the same between the end face portion and the center portion. Therefore, the temperature distribution on the surface of the metal member can be made uniform.

(Hardening equipment)
FIG. 8 shows a quenching apparatus 101 using the metal member quenching method according to the second embodiment. The difference from the first embodiment is that (1) the low molecular weight polymer 24 separated by the separation / removal device 22 (first step) is reused, and (2) the low molecular weight polymer 24 (water-soluble quenching agent). 113) and the high molecular weight polymer 28 (water-soluble quenching agent 13a) are separately injected onto the metal member 11.

  The metal member 11 is a member having a different cooling rate at the time of quenching depending on the part. Specifically, the metal member 11 has a rod shape (that is, a shape in which the longitudinal direction is the axial direction). That is, the cooling rate of the axial both ends 132 (second injected portion) is higher than the cooling rate of the axial center portion 131 (first injected portion) (see FIGS. 6 and 7). The metal member 11 is, for example, a crankshaft.

  The quenching tub 12 includes a pool-like (basket-shaped) quenching tub main body 12a and an injection unit 140 attached to the quenching tub main body 12a.

  The injection part 140 (the 1st injection part 141 and the 2nd injection part 142) is an apparatus which injects the water-soluble hardening agents 13a and 113 to the inner side of the hardening tank main body 12a. The injection unit 140 is attached to, for example, the side surface (or the bottom surface) of the quenching tank body 12a. The injection unit 140 includes a plurality of injection nozzles 140n, and the water-soluble quenching agents 13a and 113 are injected from the injection nozzles 140n (in order to avoid complexity, only one of the plurality of injection nozzles is indicated in FIG. 8). Is attached).

  The first injection unit 141 applies the water-soluble quenching agent 113 including the low molecular weight polymer 24 separated by the separation / removal device 22 (by the first step) to the axial center portion 131 (first injection target portion) of the metal member 11. ). That is, the water-soluble quenching agent 113 having a low cooling relaxation ability is sprayed to the central portion 131 having a low cooling rate. The first injection unit 141 is connected to the separation / removal device 22 via the cooling tower 114. Moreover, in order to inject the water-soluble quenching agent 113 to the center part 131 of the metal member 11, it attaches to the longitudinal direction center part vicinity of the hardening tank main body 12a. The cooling tower 114 has the same function as the cooling tower 14. The cooling tower 114 may be integrated with the cooling tower 14.

  Various devices can be provided in the flow path 151 between the first injection unit 141 and the separation / removal device 22. For example, the analyzer 21 and the separation / removal device 22 may be added to the flow channel 151 to remove a water-soluble polymer having a molecular weight equal to or lower than a predetermined value and then discharged to the flow channel 152. Further, the adjusting device 25 may be provided in the flow channel 151, and the concentration may be adjusted by adding water to the water-soluble quenching agent 113.

  The second injection unit 142 is configured so that the water-soluble quenching agent 13a (13d) to which the water-soluble quenching agent 26 before use is added by the adjusting device 25 (the second step) is added to both ends of the metal member 11 in the axial direction. This is a portion that is ejected to 132 (second ejected portion). That is, the water-soluble quenching agent 13a having a high cooling relaxation ability is sprayed to both end portions 132 having a high cooling rate. The second injection unit 142 is connected to the adjustment device 25 via the cooling tower 14. Moreover, in order to inject the water-soluble hardening agent 13a to the both ends 132 of the metal member 11, a total of two are attached near the longitudinal direction both ends of the quenching tank main body 12a.

  Note that a flow path 153 (indicated by a two-dot chain line in FIG. 8) connecting the analyzer 23 and the cooling tower 14 may be provided. That is, the water-soluble quenching agent 13c that has been separated and removed by the separation / removal device 22 (through the first step) is passed through both ends of the metal member 11 without going through the adjustment device 25 (without going through the second step). You may make it inject to 132 (2nd to-be-injected part). The flow path 153 is used when adjustment by the adjusting device 25 is not necessary as a result of analyzing the water-soluble quenching agent 13c by the analyzer 23.

(Characteristics of quenching method and apparatus for metal member according to second embodiment)
The metal member quenching method and metal member quenching apparatus 101 of the present embodiment have the following characteristics.

In the metal member quenching apparatus 1, as shown in FIG. 8, the water-soluble quenching agent 113 containing the low molecular weight polymer 24 separated by the separation / removal apparatus 22 (first step) is removed from the central portion 131 of the metal member 11. It injects with the 1st injection part 141 to (1st to-be-injected part). That is, the low molecular weight polymer 24 having a low cooling relaxation ability is jetted to the central portion 131.
Further, the water-soluble quenching agent 13c separated by the separation / removal device 22 (after the first step) or the water-soluble quenching agent 26 before use was added by the adjusting device 25 (the second step was passed). ) The water-soluble quenching agent 13a is sprayed to the both end portions 132 of the metal member 11 by the second spraying portion 142. That is, the high molecular weight polymer 28 having a high cooling relaxation ability is sprayed to both end portions 132.
That is, the cooling relaxation ability of the water-soluble quenching agents 113 and 13a (or 13c) injected between the central portion 131 and the both end portions 132 is different. Therefore, the cooling rate can be adjusted for each portion to be ejected of the metal member 11 (separately between the central portion 131 and both end portions 132).

  Further, the water-soluble quenching agent 113 containing the low molecular weight polymer 24 separated by the separation / removal device 22 (by the first step) is sprayed to the central portion 131 of the metal member 11. That is, the low molecular weight polymer 24 in the deteriorated water-soluble quenching agent 13b is reused. Therefore, the cost for the water-soluble quenching agent can be further reduced.

The metal member 11 quenched by the metal member quenching apparatus 101 has a rod shape. As described above, generally, when the rod-shaped metal member 11 is quenched (without using the present invention), the cooling rate of the both end portions 132 is higher than that of the central portion 131 (see FIGS. 6 and 7).
Moreover, the water-soluble quenching agent 113 containing the low molecular weight polymer 24 with low cooling relaxation ability is injected to the center part 131 (generally a part with a low cooling rate). Moreover, the water-soluble quenching agent 13a containing the high molecular weight polymer 28 with a high cooling relaxation ability is sprayed to both ends 132 (generally a part with a high cooling rate). Therefore, the difference in cooling rate between the central portion 131 and both end portions 132 of the metal member 11 can be reduced. Therefore, the metal member 11 can be brought close to a uniform temperature distribution. As a result, it is possible to suppress problems such as burning cracks, deformation (distortion) and residual stress.

(Modification)
In the said embodiment, as shown in FIG.4 and FIG.8, the water-soluble quenching agent 13 was continuously processed from the circulation pump 15 to the quenching agent improvement part 20 and the cooling tower 14. FIG. However, the present invention can be applied even if the quenching agent improving unit 20 is installed in a bypass line and implemented in a batch manner.

  Moreover, in the said embodiment, as shown in FIG. 4, the new liquid (The water-soluble hardening agent 26 before use and the water 27) was added with the adjustment apparatus 25. As shown in FIG. However, for example, the low molecular weight polymer 24 separated and removed by the separation / removal device 22 may be subjected to a process of recovering the cooling relaxation ability, and the water-soluble quenching agent having recovered the cooling relaxation ability may be added by the adjustment device 25. In this case, the cost for the water-soluble quenching agent can be further reduced.

  In the embodiment, the water-soluble polymer having a molecular weight of 10,000 or less is separated and removed by the separation / removal device 22. However, the molecular weight of the water-soluble polymer to be separated and removed can be changed according to the required cooling relaxation ability and cost, for example, the molecular weight of the water-soluble polymer to be separated and removed is 7500 or less.

  Moreover, the rod-shaped metal member 11 shown in FIG. 8 can be deformed into various shapes. In the case of deformation, the distribution of the cooling rate of the metal member is examined in advance. Then, the high molecular weight polymer 28 is sprayed to the portion where the cooling rate is high, and the low molecular weight polymer 24 is sprayed to the portion where the cooling rate is low. The injection position of the metal member is preferably a position where the temperature distribution of the metal member is uniform.

  Moreover, in the said embodiment, as shown in FIG. 8, it divided into two types, the low molecular weight polymer 24 and the high molecular weight polymer 28, and injected the water-soluble quenching agents 113 and 13a to the metal member 11. FIG. However, the molecular weight of the water-soluble polymer may be divided into three or more types, and these may be divided and injected into three or more types of positions where the cooling rate of the metal member 11 is different. In this case, the temperature distribution of the metal member 11 can be made more uniform. As a result, fire cracking and deformation can be further suppressed.

(Reference example)
In addition, it is also possible to prepare the low molecular weight polymer 24 and the high molecular weight polymer 28 separately from the quenching apparatus 1 (FIG. 4) or 101 (FIG. 8), and inject them separately at different positions on the metal member 11. .

DESCRIPTION OF SYMBOLS 1,101 Quenching apparatus for metal members 11, 211 Metal members 13, 113 Water-soluble quenching agent 13a Water-soluble quenching agent before use 13b Water-soluble quenching agent after use 13c The first step (separated) ) Water-soluble quenching agent 13d Water-soluble quenching agent passed through the second step (added water-soluble quenching agent before use) 22 Separation and removal device (separation device)
24 Low molecular weight polymer (separated water-soluble polymer)
25 Adjustment device 26 Water-soluble quenching agent before use added in the second step 131 Central portion (first injected portion)
132 Both ends (second injected part)
141 1st injection part 142 2nd injection part

Claims (8)

A first step of separating a water-soluble polymer having a molecular weight lower than the weight average molecular weight of the water-soluble polymer in the water-soluble quenching agent before use from the water-soluble quenching agent after use;
A second step of adding a water-soluble quenching agent before use to the water-soluble quenching agent that has undergone the first step. Spraying a water-soluble quenching agent containing the water-soluble polymer separated in the first step onto the first injected portion of the metal member;
The hardening method of the metal member of Claim 1 which injects the water-soluble hardening agent which passed through the said 1st process or the 2nd process to the 2nd to-be-injected part of the said metal member. The metal member is rod-shaped,
The first injected portion is a central portion in the axial direction of the metal member,
The method for quenching a metal member according to claim 2, wherein the second injected parts are both axial ends of the metal member.   The method for quenching a metal member according to any one of claims 1 to 3, wherein the molecular weight of the water-soluble polymer separated in the first step is 10,000 or less. A separation device for separating a water-soluble polymer having a molecular weight lower than the weight average molecular weight of the water-soluble polymer in the water-soluble quenching agent before use from the water-soluble quenching agent after use;
A metal member quenching apparatus comprising: an adjustment device that adds a water-soluble quenching agent before use to the water-soluble quenching agent that has been separated. A first injection unit that injects a water-soluble quenching agent containing the water-soluble polymer separated by the separation device onto the first injected part of the metal member;
The second injection that injects the water-soluble quenching agent that has been separated or the water-soluble quenching agent to which the water-soluble quenching agent before use has been added by the adjusting device to the second injected portion of the metal member. A metal member quenching apparatus according to claim 5, further comprising a portion. The metal member is rod-shaped,
The first injected portion is a central portion in the axial direction of the metal member,
The said 2nd to-be-injected part is a quenching apparatus of the metal member of Claim 6 which is the axial direction both ends of the said metal member.   The metal member quenching apparatus according to any one of claims 5 to 7, wherein the molecular weight of the water-soluble polymer separated by the separation apparatus is 10,000 or less.

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