WO2016190320A1

WO2016190320A1 - Heat treatment device and heat treatment method

Info

Publication number: WO2016190320A1
Application number: PCT/JP2016/065344
Authority: WO
Inventors: 恵里平山; 将大岩川; 慎太郎鈴木
Original assignee: Ntn株式会社
Priority date: 2015-05-25
Filing date: 2016-05-24
Publication date: 2016-12-01

Abstract

According to the present invention, a thin plate member in an unheated state is introduced into an upstream-side chamber having a low oxygen atmosphere with an oxygen concentration of 0.01% or less. Thereafter, inside a treatment chamber having a low oxygen atmosphere with a constant oxygen concentration of 0.01% or less, the thin plate member is loaded onto a heating plate heated to a predetermined heating temperature and the thin plate member is heated. Inside the treatment chamber, the thin plate member is loaded onto a cooling plate cooled to a predetermined cooling temperature and the thin plate member is cooled. Next, the thin plate member is left in the atmosphere.

Description

Heat treatment apparatus and heat treatment method

The present invention relates to a heat treatment apparatus and a heat treatment method, and more particularly, to a heat treatment apparatus and a heat treatment method for a thrust bearing component.

For example, as shown in FIG. 7, the thrust bearing includes a pair of race rings 1 and 2, rollers (needle rollers) 3 disposed between the pair of race rings 1 and 2, and adjacent needle rollers. And a cage 4 that holds the interval.

In such a thrust bearing, a large thrust load is applied to the races 1 and 2. For this reason, it is common to subject the raceway to a thermosetting treatment. For example, in the case of low carbon steel used for a thrust bearing race, dozens of μm is hardened from the surface by gas carburizing treatment or vacuum treatment. Then, in order to obtain the hardness according to a use application, the tempering process which makes a structure | tissue uniform is performed.

Conventionally, there is one in which a steel sheet is finished into a raceway shape by press working and then subjected to heat treatment including carbonitriding and high temperature tempering (Patent Document 1). In this case, the oxide film (scale) generated on the surface of the thrust bearing component (orbital ring) by heat treatment is removed.

FIG. 5 shows a case where gas carburizing and quenching is performed, and FIG. 6 shows a case where vacuum carburizing and quenching is performed. That is, in FIG. 5, gas carburizing and quenching is performed (step S1), and then a temper process (tempering process) (step S2) is performed, followed by a grinding process (scale removal process) (step S3). . In addition, after a grinding process, an inspection process (step S4) will be performed.

In FIG. 6, vacuum carburizing and quenching is performed (step S5), and then a temper process (tempering process) (step S6) is performed, followed by a grinding process (step S7). An inspection process (step S8) is performed.

JP 2008-82379 A

In gas carburizing and quenching, oxide scale adheres to the product surface in the quenching and tempering process, and therefore a process for removing this scale is required. In addition, when vacuum carburization is performed, adhesion of oxide scale is hardly observed, but in the next tempering process (tempering process), a temper color is adhered. Therefore, there is a case where the adhesion of oxide scale is suppressed by bright tempering in which the atmosphere in the furnace is adjusted. However, in this method, since a large amount of processing is performed in a large batch type furnace, a lot of time is required for adjusting the atmosphere, raising the temperature of the workpiece, and soaking.

Accordingly, the present invention is a heat treatment apparatus that can perform atmosphere adjustment and temperature raising / soaking of workpieces in a short time, and can process each workpiece inline without adhesion of oxide scale. And a heat treatment method.

The heat treatment apparatus of the present invention is a heat treatment apparatus for performing heat treatment on a thin plate member, and is set to an upstream chamber in which a low oxygen atmosphere having an oxygen concentration of a predetermined value or less and a low oxygen atmosphere having an oxygen concentration of the predetermined value or less. A processing plate, a heating plate as a heating means arranged in the processing chamber, a cooling plate as a cooling means arranged in the processing chamber, and a thin plate member from a low oxygen atmosphere below the predetermined value, A downstream chamber for placing in the atmosphere, and a non-heated thin plate member is introduced into the upstream chamber so that the oxygen concentration in the upstream chamber is a low oxygen atmosphere below the predetermined value, and this low oxygen atmosphere is set. In the processing chamber, the thin plate member is disposed on the heating plate and heated uniformly, and after the uniform heating, the thin plate member is disposed on the cooling plate in the processing chamber and cooled, After placement downstream side chamber of the following low-oxygen atmosphere value, taken out sheet member downstream side chamber is adjusted to the atmosphere.

According to the heat treatment apparatus of the present invention, if a thin plate member as a workpiece is supplied to the upstream chamber, the thin plate member can be placed in a low oxygen atmosphere, and the heating process and the cooling process are always performed at a predetermined low oxygen content. The treatment can be performed in a treatment chamber maintained in an atmosphere, and the atmosphere adjustment can be facilitated. Further, since the heating means is constituted by a heating plate heated to a predetermined temperature, it can be simplified as the heating means, and the work can be soaked in a short time. The cooling means can be constituted by a cooling plate cooled to a predetermined temperature, can be a simple cooling means, and can cool the heated workpiece in a short time.

The tempering step can be performed on the thin plate member that has been subjected to non-oxidation quenching in a low oxygen atmosphere by the heat treatment apparatus.

The predetermined value of oxygen concentration is 0.01%. If the oxygen concentration is 0.01% or less, it is possible to effectively prevent the workpiece from being oxidized. The heating temperature of this heating plate is preferably 300 ° C. By heating the heating plate to 300 ° C. in this way, it can be heated to an optimum heating temperature at the time of tempering the workpiece. The cooling temperature of the cooling plate is preferably 10-30 ° C.

A thin plate member can be used as a component of a thrust bearing. Moreover, it can be set as a bearing ring as a component.

The heat treatment method of the present invention is a heat treatment method for performing heat treatment on a thin plate member, and after adjusting the non-heated thin plate member to an upstream chamber, the oxygen concentration is adjusted to a low oxygen atmosphere of 0.01% or less, and thereafter Then, after placing the thin plate member on a heating plate heated to a predetermined heating temperature in a processing chamber having a low oxygen atmosphere with an oxygen concentration of 0.01% or less at all times, The thin plate member is placed on a cooling plate cooled to a predetermined cooling temperature to cool the thin plate member. Next, the thin plate member is placed in a downstream chamber having a low oxygen atmosphere with an oxygen concentration of 0.01% or less. After the placement, the atmosphere in the downstream chamber is adjusted to the atmosphere.

According to the heat treatment method of the present invention, it is possible to prevent oxidation of a thin plate member that is a workpiece. Moreover, a workpiece | work can be mounted on the heating plate heated to predetermined temperature, and it can heat-treat to a workpiece | work in a short time. The workpiece can be placed on the cooling plate cooled to a predetermined temperature, and the heated workpiece can be cooled in a short time.

In the present invention, the atmosphere adjustment can be simplified and the temperature equalization for the workpiece can be achieved in a short time, and the productivity is excellent. In addition, the configuration of the heating means and the cooling means can be simplified, and the equipment of the heat treatment apparatus can be simplified and downsized. Moreover, since oxidation of the thin plate member, which is a workpiece, can be prevented, adhesion of oxide scale can be avoided, eliminating the need for scale removal work after heat treatment, and in-line processing in a short time without adhesion of oxide scale. Is possible.

The predetermined value of the oxygen concentration is 0.01%, and by making the oxygen concentration 0.01% or less of the upstream chamber, the downstream chamber, and the processing chamber, stable oxidation can be prevented. Further, when the heating plate is heated to 300 ° C., it can be heated to an optimum heating temperature at the time of tempering the workpiece.

1 is a simplified overall view of a heat treatment apparatus of the present invention. It is sectional drawing of the thrust bearing provided with the bearing ring to which heat processing is performed with the heat processing apparatus shown in the said FIG. It is a block diagram of the heat processing method of this invention. It is a flowchart figure which shows the heat processing method of this invention. It is a block diagram which shows a gas carburizing quenching process. It is a block diagram which shows a vacuum carburizing and quenching process. It is sectional drawing of a thrust bearing.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 2 is a thrust bearing provided with bearing components subjected to heat treatment by the heat treatment apparatus shown in FIG. 1 according to the present invention. That is, this thrust bearing holds a distance between a pair of

race rings

11, 12 and rollers (needle rollers) 13 disposed between the pair of

race rings

11, 12, and the adjacent needle rollers. And a container 14.

The bearing ring 11 has a bearing ring main body 11a made of a flat ring body and an inner flange portion 11b connected to the inner peripheral edge of the bearing ring main body 11a. The other bearing ring 11 has a flat ring body. The bearing ring main body 12a and the outer flange portion 12b connected to the outer peripheral edge of the bearing ring main body 12a.

These bearing

rings

11 and 12 are thin plate members which are bearing components subjected to heat treatment by the heat treatment apparatus shown in FIG. For this reason, the

races

11 and 12 are made of a material generally used for a thrust bearing race represented by a steel plate or the like.

As shown in FIG. 1, the heat treatment apparatus includes an upstream chamber 15 as a front chamber, a downstream chamber 16 as a rear chamber, and a processing chamber 17 disposed between the upstream chamber 15 and the downstream chamber 16. Prepare. Nitrogen gas (N 2) generated by a nitrogen gas generator (not shown) is supplied to the upstream chamber 15, the downstream chamber 16, and the processing chamber 17 to form a low oxygen atmosphere (nitrogen atmosphere). In this case, the processing chamber 17 is always set to a predetermined oxygen concentration (for example, 0.01% or less). As will be described later, the downstream chamber 16 is for placing the thin plate member in the atmosphere from a low oxygen atmosphere below the predetermined value.

That is, as the nitrogen gas, nitrogen generated by using a nitrogen gas generator such as a PSA (adsorption) type nitrogen gas generator, a membrane type nitrogen gas generator, or a cryogenic nitrogen gas generator is used.

Also, the upstream chamber 15 and the downstream chamber 16 are provided with mounting

surfaces

21 and 22 on which the bearing rings 11 and 12 that are bearing components, that is, the workpiece W that is a thin plate member is mounted. The upstream chamber 15 and the downstream chamber 16 can adjust the oxygen concentration from the atmosphere to a low oxygen atmosphere.

In the processing chamber 17, a heating plate 23 as a heating unit and a cooling plate 24 as a cooling unit are arranged. The heating plate 23 can be configured by a plate with a built-in heating coil, and the temperature of the workpiece placement surface 23a can be high-frequency heated to a predetermined high temperature. In this case, the heating temperature of the heating plate 23 can be controlled by control means (not shown). Further, the cooling plate 24 can be constituted by a plate with a built-in cooling pipe through which a cooling medium circulates, and the temperature of the work placement surface 24a can be cooled to a predetermined low temperature. Also in the cooling plate 24, the cooling temperature can be controlled by control means (not shown).

The heating temperature of the heating plate 23 can be controlled by adjusting the voltage applied to the heating coil, and the cooling temperature of the cooling plate 24 can be controlled by adjusting the temperature of the cooling medium circulating in the cooling pipe.

The cooling means of the heating plate 23 and the cooling plate 24 keeps the temperature constant by PID control.

In this heat treatment apparatus, the workpiece W is first put into the upstream chamber 15 and then transferred onto the mounting surface 23a of the heating plate 23 of the processing chamber 17, and then the mounting surface 24a of the cooling plate 24 of the processing chamber 17. It is arranged on the upper side and then conveyed to the downstream chamber 16. That is, as shown in FIG. 3, the heat treatment method according to the present invention includes a thin plate member supplying step 50 for supplying the workpiece W to the upstream chamber 15, and a low oxygen atmosphere forming step 51 for setting the upstream chamber 15 to a low oxygen atmosphere. The heating step 52 for heating the thin plate member as the workpiece W in the processing chamber 17 which is always in a low oxygen atmosphere, the cooling step 53 for cooling the thin plate member as the workpiece W in the processing chamber 17, and the thin plate as the workpiece W A thin plate member discharging step 54 is provided for supplying members to the downstream chamber 16 and adjusting the inside of the downstream chamber 16 from the low oxygen atmosphere to the atmosphere.

The work W is sequentially transferred from the upstream chamber 15 to the processing chamber 17 to the downstream chamber 16. In this heat treatment apparatus, a conveying means for conveying the workpiece W is provided, and the conveying means can be constituted by a conveying conveyor or the like.

By the way, the processed product after quenching is hard and excellent in wear resistance, but it is brittle, unstable, and has high internal stress. Therefore, it is preferable to perform tempering by heating to a temperature below the A1 transformation point. By this treatment, the structure becomes uniform, the internal stress is reduced, and the toughness is improved. The performance of the processed product is affected by the hardness, and the hardness is adjusted by the tempering temperature and time.

Therefore, this heat treatment apparatus is used for tempering the components of a thrust bearing that has been previously quenched (for example, vacuum carburized and quenched), for example, the race ring (inner ring) 11. In the vacuum carburizing and quenching, carbon is infiltrated into the surface layer of steel and the carbon concentration is increased before quenching to obtain a hard surface and wear resistance. Moreover, since the inside has low hardness, high toughness can be obtained. Furthermore, since the treatment is performed in a vacuum furnace, there is little grain boundary oxidation or decarburization in the surface layer portion.

Next, a method of tempering the workpiece W, which is the

races

11 and 12, using this heat treatment apparatus will be described with reference to FIGS. First, the workpiece W is arranged in the upstream chamber 15. And the inside of this upstream chamber 15 is made into a low oxygen atmosphere (step S10). In this case, nitrogen gas is supplied from a nitrogen gas generator (not shown) to make the nitrogen atmosphere a low oxygen atmosphere having an oxygen concentration of 0.01% or less. In addition, the workpiece | work W as the bearing rings 11 and 12 used the outer diameter dimension D which was 100 mm or less, plate | board thickness T was 1 mm or less, and the collar height H was 6 mm or less (refer FIG. 2).

Thereafter, the workpiece W is placed on the placement surface 23a of the heating plate 23 of the processing chamber 17 in a low oxygen atmosphere (oxygen concentration is 0.01% or less). In the processing chamber 17, a low oxygen atmosphere having an oxygen concentration of 0.01% or less is constantly maintained. For this reason, by placing the workpiece W on the heating plate 23, the workpiece W is placed under the low oxygen atmosphere. Heated. In this case, the heating temperature of the heating plate 23 is about 300 ° C.

Thereby, the workpiece W is uniformly heated to about 300 ° C. in a short time (step S11). In this case, the entire workpiece is within 300 ° C. ± 10 ° C. in 30 seconds. Thereafter, it is placed on the mounting surface 24a of the cooling plate 24 that is cooled to about 10 to 30 ° C. in the processing chamber 17, for example. As a result, the workpiece W is cooled in a short time in a low oxygen atmosphere (step S12).

That is, tempering after heating to a relatively high temperature below the transformation point and then cooling at an appropriate rate can be performed in a low oxygen atmosphere in a short time. Thereafter, the workpiece W is disposed on the placement surface 22 of the downstream chamber 16. Then, the atmosphere is adjusted to the atmosphere after being introduced into the downstream chamber 16 in a low oxygen atmosphere having an oxygen concentration of 0.01% or less. As a result, the workpiece W is placed in the atmosphere (step S13). Thereby, the tempering process using the heat treatment apparatus shown in FIG. 1 is completed.

If the thin plate member which is the work W is supplied to the upstream chamber 15, the thin plate member can be placed in a low oxygen atmosphere, and the heating process and the cooling process are always maintained in a predetermined low oxygen atmosphere. It can be performed in the processing chamber 17, and the atmosphere adjustment can be facilitated. Further, since the heating means is constituted by the heating plate 23 heated to a predetermined temperature, the heating means can be simplified, and the workpiece W can be subjected to soaking in a short time. The cooling means can be constituted by the cooling plate 24 cooled to a predetermined temperature, can be a simple cooling means, and can cool the heated workpiece W in a short time.

That is, according to the present invention, the atmosphere adjustment can be simplified and the temperature uniformity for the workpiece W can be achieved in a short time, and the productivity is excellent. In addition, the configuration of the heating means and the cooling means can be simplified, and the equipment of the heat treatment apparatus can be simplified and downsized. In particular, since the oxidation of the thin plate member that is the workpiece W can be prevented, adhesion of oxide scale can be avoided, and after heat treatment, there is no need for scale removal work, and in-line can be achieved in a short time without adhesion of oxide scale. Processing is possible.

The predetermined value of the oxygen concentration is 0.01%, and by setting the oxygen concentration to 0.01% or less of the oxygen concentration in the upstream chamber 15 and the processing chamber 17, stable oxidation can be prevented. Further, when the heating plate is heated to 300 ° C., the workpiece W can be heated to an optimum heating temperature during tempering.

As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made. The atmosphere is not limited to a nitrogen atmosphere, and may be an atmosphere of an inert gas such as argon other than nitrogen or a reduced pressure atmosphere. Moreover, although the oxygen concentration in the low oxygen atmosphere was set to 0.01% or less, the oxygen concentration range can be variously set within 0.01% or less. That is, the lower limit can be set according to the capacity of the nitrogen gas generator to be used.

Further, the heating temperature of the heating plate 23 is not limited to 300 ° C. When performing low temperature tempering at a tempering temperature of about 150 ° C. to 200 ° C. or the like, the tempering temperature can be set to about 550. In the case of performing high temperature tempering at a temperature of 650 ° C to 650 ° C, this tempering temperature can be set. The cooling temperature of the cooling plate 24 can be variously changed according to the heating temperature of the heating plate 23 or the like.

Using the heat treatment apparatus shown in FIG. 1, the tempering process is performed in a low oxygen atmosphere (nitrogen atmosphere) with an oxygen concentration of 0.01% or less (the present invention system), and the conventional tempering process (the present system). Table 1 below shows the result of comparison with the case of performing tempering treatment in the atmosphere.

That is, in the conventional method, the heating temperature was 200 ° C., and the heating temperature was 60 minutes. In the method of the present invention, the heating temperature was 300 ° C., and the heating temperature was 0.5 minutes (30 seconds). The cooling temperature was 10-30 ° C., and the cooling temperature was 10-30 seconds. As the workpiece, a thrust bearing race and an inner race were used, and the race 11 shown in FIG. 2 was used. In this case, the outer diameter D was 100 mm, the plate thickness T was 1 mm, and the heel height H was 6 mm. In addition, the workpiece W is previously subjected to vacuum carburizing and quenching. As can be seen from Table 1, the scale adheres in the conventional method, but the scale does not adhere in the method of the present invention.

The thin plate member constituting the workpiece W may be a bearing ring (inner ring) or a bearing ring (outer ring) which is a thrust bearing component. Moreover, the members other than the thrust bearing components, for example, various thin plate members used in various machines such as a transport machine, a construction machine, and a machine tool may be used.

W Thin plate (work)
15 Upstream chamber 16 Downstream chamber 17 Processing chamber 23 Heating plate 24 Cooling plate

Claims

A heat treatment apparatus for performing heat treatment on a thin plate member,
An upstream chamber in which the oxygen concentration is a low oxygen atmosphere having a predetermined value or less, a processing chamber in which the oxygen concentration is set to a low oxygen atmosphere having the predetermined value or less, and a heating plate as a heating means disposed in the processing chamber; A cooling plate disposed in the processing chamber as a cooling means, and a downstream chamber for placing the thin plate member in the atmosphere from a low oxygen atmosphere below the predetermined value, and the upstream chamber is a non-heated thin plate member The oxygen concentration in the upstream chamber is set to a low oxygen atmosphere below the predetermined value, and the thin plate member is heated evenly by the heating plate in the processing chamber set to the low oxygen atmosphere. A heat treatment apparatus, wherein the thin plate member is placed in the downstream chamber after being heated and cooled by a cooling plate in the treatment chamber.
The heat treatment apparatus according to claim 1, wherein a tempering step is performed on the thin plate member that has been subjected to non-oxidation quenching.
The heat treatment apparatus according to claim 1 or 2, wherein the predetermined value is 0.01%.
The heat treatment apparatus according to any one of claims 1 to 3, wherein the heating temperature of the heating plate is 300 ° C.
5. The heat treatment apparatus according to claim 1, wherein the cooling temperature of the cooling plate is 10 to 30 ° C.
The heat treatment apparatus according to any one of claims 1 to 5, wherein the thin plate member is a component part of a thrust bearing.
A heat treatment method for performing heat treatment on a thin plate member,
After putting the non-heated thin plate member into the upstream chamber, the oxygen concentration is adjusted to a low oxygen atmosphere of 0.01% or less, and thereafter, in a processing chamber in which the oxygen concentration is always a low oxygen atmosphere of 0.01% or less. After placing the thin plate member on the heating plate heated to a predetermined heating temperature and heating the thin plate member, the thin plate member is placed on the cooling plate cooled to the predetermined cooling temperature in the processing chamber. A heat treatment method characterized by cooling and then adjusting the atmosphere to the atmosphere after being introduced into a downstream chamber of a low oxygen atmosphere having an oxygen concentration of 0.01% or less and discharging the thin plate member.
A heat treatment method comprising performing a tempering step on the thin plate member subjected to non-oxidation quenching using the heat treatment method according to claim 7.