JP4214171B1 - Heat treatment system and heat treatment method - Google Patents

Abstract

The present invention provides a technique for realizing efficient processing in heat treatment for quenching and tempering a metal workpiece.
The present invention provides a heat treatment system for performing a heat treatment on a metal workpiece. This heat treatment system includes N units (N is an integer of 1 or more) for quenching and M units (M is from N) including a plurality of tempering furnaces having operation modes for performing tempering at mutually different temperatures. A large integer) tempering furnace and a transfer unit for transferring metal workpieces from N quenching furnaces to M tempering furnaces. The transfer unit has an operation mode in which the metal workpiece is selectively transferred from each of the N quenching furnaces to a plurality of tempering furnaces having different tempering temperatures.
[Selection] Figure 3

Description

  The present invention relates to a heat treatment for quenching and tempering.

  In the heat treatment of carbon steel, quenching is generally performed by heating the steel to change it to an austenite structure and then rapidly cooling to martensite structure, and tempering to give toughness to the steel hardened by quenching. Has been done. The quenching temperature may be any temperature that changes the state of the martensite structure, whereas the tempering temperature is set to various temperatures depending on the required metal properties (for example, toughness).

  However, in the past, efficient production management and production systems that take into account such differences in the characteristics of the heat treatment process have not been sufficiently studied. Furthermore, such a problem is not limited to carbon steel, but is a problem common to alloy steels and aluminum alloys.

JP 2001-335830 A JP-A-5-125436 JP-A-6-172849

  The present invention has been made to solve at least a part of the above-described conventional problems, and an object of the present invention is to provide a technique for realizing an efficient process in a heat treatment in which a metal workpiece is quenched and tempered. And

Means and effects for solving the problems

[Application Example 1]
A heat treatment system for heat treating a metal workpiece,
A quenching heating furnace, and a quenching heating conveyor for passing the metal workpiece in the quenching heating furnace, and quenching by N passes (N is an integer of 1 or more);
M units including a tempering furnace and a plurality of tempering furnaces having an operation mode in which tempering heating conveyors that pass the metal workpiece in the tempering heating furnace and tempering at different temperatures by the passage (M is an integer greater than N) tempering furnace;
A transfer unit for receiving the quenched metal workpiece from the N quenching furnaces and transferring the received metal workpiece to the M tempering furnaces;
With
The transfer section, a heat treatment system having a mode of operation for switching the transfer destination of said metal workpiece within the previous SL tempering furnace of the M stage from each of the N number of quenching furnace while continuing the transport.

  Since the heat treatment system of Application Example 1 has an operation mode in which a metal workpiece is selectively transferred from each of the N quenching furnaces to a plurality of tempering furnaces having different tempering temperatures, the operation of the quenching furnace is interrupted. The contents of the heat treatment can be switched to tempering without different tempering temperatures. As a result, it is possible to suppress the generation of carbon dioxide emitted during the interruption of the operation of the quenching furnace (while maintaining the temperature), and to operate the quenching furnace efficiently without the need to change the temperature inside the tempering furnace. Is possible.

  Note that the (MN) tempering furnace does not transfer the metal workpiece from the quenching furnace, but for at least one of the following reasons, the entire heat treatment system contributes to high efficiency. It has been found by the inventors. That is, firstly, such a tempering furnace can be used for heat treatment of metal workpieces in other lots where only tempering is required, and secondly, the in-furnace temperature of the quenching furnace is higher than that of the tempering furnace. Therefore, it is desirable to prioritize continuous operation of a quenching furnace that generates a large amount of carbon dioxide and requires atmospheric gas, and thirdly, a change in the furnace temperature of the tempering furnace and a change in the furnace This is because it is necessary to reduce the temperature inside the furnace as much as possible because it requires skilled craftsmen to check the state.

[Application Example 2]
A heat treatment system of Application Example 1,
The said transfer part is a conveyor which transfers the said metal workpiece | work from the said quenching furnace to the said tempering furnace, Comprising: The heat processing system which has a turning conveyor which changes the said tempering furnace of the said transfer destination by turning while continuing the said transfer.

  In the heat treatment system of the application example 2, since the rotating conveyor that changes the tempering furnace of the transfer destination by rotating is provided, the tempering furnace can be reliably changed while visually confirming the switching of the metal workpiece on the rotating conveyor. . Furthermore, since a certain amount of time is required for the transfer of the metal workpiece on the turn conveyor, it is possible to turn the work while continuing the operation of the entire heat treatment system including the transfer on the turn conveyor.

[Application Example 3]
A heat treatment system of application example 2 ,
The transfer unit has a transfer unit that receives the metal workpiece from the rolling conveyor and transfers the metal workpiece to the tempering heating conveyor,
The said delivery part is a heat processing system which has a horizontal swing function for putting the said metal workpiece uniformly on the said tempering heating conveyor .

Heat treatment system of the application example 3, since includes a transfer unit having a horizontal swing function for uniformly placing a metal workpiece on tempering heating conveyor, and turning conveyor and tempering heating conveyor not be parallel to However, the metal workpiece can be uniformly placed on the tempering heating conveyor.

[Application Example 4]
A heat treatment method for heat treating a metal workpiece,
A quenching process for quenching;
A switching step of switching the transfer destination of the metal workpiece among a plurality of tempering furnaces that perform tempering at mutually different temperatures ;
And said metal workpiece feed moves you transferring step tempering furnace became the transfer destination of the metallic workpiece,
Tempering in the transferred tempering furnace;
With
The switching process is a heat treatment method in which the switching is performed while continuing the processes of the quenching process, the tempering process, and the transfer process .

  The present invention can be realized in various forms other than those described above, and can be realized in various forms such as a heat treatment apparatus and a production management method.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Conventional heat treatment system configuration:
B. Configuration and processing content of the heat treatment system of the first embodiment:
C. Configuration of the heat treatment system of the second embodiment:
D. Variations:

A. Conventional heat treatment system configuration:
FIG. 1 is an explanatory diagram showing the configuration of a conventional heat treatment system. The conventional heat treatment system includes a quenching furnace 100 and a tempering furnace 200. In this heat treatment system, the quenching furnace 100 performs “quenching” on the metal workpiece Wrk. The quenched metal workpiece Wrk is transferred to the tempering furnace 200 via the transfer unit 300, where tempering is performed. Prior art heat treatment systems have been proposed in, for example, Patent Documents 1 to 3.

  FIG. 2 is a cross-sectional view showing a configuration of a conventional heat treatment system. The quenching furnace 100 includes a quenching heating furnace 120 for quenching and heating the metal workpiece Wrk, a quenching heating conveyor 111 for transferring the metal workpiece Wrk through the quenching heating furnace 120 at a constant speed, and quenching oil for rapid cooling. The cooling oil tank 112b, the drawer conveyor 112 for passing the metal work Wrk through the cooling oil tank 112b and taking out the metal work Wrk from the cooling oil tank 112b, and the metal work Wrk taken out from the cooling oil tank 112b are discharged from the quenching furnace 100. And a discharge conveyor 113. In addition, you may make it add the apparatus which performs the process which performs washing | cleaning and drying as needed.

  The tempering furnace 200 includes a tempering heating furnace 220 that heats the metal work Wrk for tempering, a tempering heating conveyor 210 that transfers the metal work Wrk through the tempering heating furnace 220 at a constant speed, and a product (a metal that has undergone heat treatment). And a storage box 230 for storing the workpiece Wrk).

B. Configuration and processing content of the heat treatment system of the first embodiment:
3-6 is explanatory drawing which shows the structure of the heat processing system 10 of 1st Example. 3 and 4 show the operation mode when performing high temperature tempering. The heat treatment system 10 according to the first embodiment is selectively made of metal in either the tempering furnace 200 that is in a state of executing high-temperature tempering or the tempering furnace 200a that is in a state of executing low-temperature tempering via a turn conveyor 310. It differs from the heat treatment system 10 of the prior art in that the workpiece Wrk can be transferred.

  The turn conveyor 310 rotates around the rotation axis P, and when the turn conveyor 310 is at the position shown in FIG. 3 (the position shown by the solid line), the metal workpiece Wrk discharged from the discharge conveyor 113 enters the tempering furnace 200. It is transferred and high temperature tempering is performed. In this transfer, as shown in FIG. 4, the metal work Wrk discharged from the discharge conveyor 113 is placed on the turning conveyor 310, and further moved on the turning conveyor 310 and then placed on the tempering heating conveyor 210. Is done by.

  5 and 6 show the operation mode when performing low temperature tempering. When the turning conveyor 310 is at the position shown in FIG. 5, the metal workpiece Wrk discharged from the discharge conveyor 113 is transferred to the tempering furnace 200a, and low temperature tempering is executed. As shown in FIG. 6, the metal work Wrk discharged from the discharge conveyor 113 is placed on the turn conveyor 310 and further moved on the turn conveyor 310 and then tempered and heated via the transfer unit 400. This is done by being placed on the conveyor 210a. The delivery unit 400 has a swinging function (turning in the horizontal direction) in order to uniformly place the metal workpiece Wrk on the tempering heating conveyor 210a.

  In the first embodiment, the tempering furnace 200 in a state where high-temperature tempering is executed has the same configuration as the tempering furnace 200a in a state where low-temperature tempering is executed, and only the set temperature is different. Alternatively, it may be a separate configuration. The configuration of the present embodiment has the same configuration, and it is possible to perform high temperature tempering in the tempering furnace 200 and low temperature tempering in the tempering furnace 200a. Furthermore, it is possible to stop one of them. When the tempering furnace on the stopped side is changed, the tempering temperature is changed while the operation of the quenching furnace 100 is continued by setting the tempering temperature after the change before the treatment. Can be used.

  FIG. 7 is a flowchart showing the contents of the heat treatment of the first embodiment. In this heat treatment, quenching and tempering of the metal workpiece Wrk, which is an annealed carbon steel, are performed. In step S100, a quenching process is executed. In this embodiment, the quenching process is a process in which the metal workpiece Wrk, which is carbon steel, is heated to a high temperature region above the transformation point to form a structure called austenite and then rapidly cooled to change to a martensite structure.

  The heating to the quenching temperature is performed by being transferred at a constant speed by the quenching heating conveyor 111 inside the quenching heating furnace 120 (FIGS. 4 and 6) set to the quenching temperature. The quenching temperature varies depending on the carbon content, but is generally set within a range of 800 ° C to 900 ° C. The rapid cooling is performed by putting the metal work Wrk from the quenching heating conveyor 111 into the cooling oil tank 112b in which the quenching oil is put. The metal workpiece Wrk charged into the cooling oil tank 112b is placed on the discharge conveyor 113 by the drawer conveyor 112.

  In step S200, it is determined whether the tempering furnace needs to be switched. This determination is made every time the metal workpiece Wrk is switched, that is, every lot of the metal workpiece Wrk. For example, when a lot to be subjected to low-temperature tempering is scheduled to be discharged from the discharge conveyor 113 after passing a lot to be subjected to high-temperature tempering, tempering that performs low-temperature tempering from the tempering furnace 200 in which the metal workpiece Wrk is transferred is performed. Changed to furnace 200a.

  The operator can determine whether or not to switch the tempering furnace based on the process management table while the metal workpieces Wrk of each lot are flowing. As a result of this determination, when it is determined that switching is not necessary, the process proceeds to step S400, and when it is determined that switching is necessary, the process proceeds to step S300.

  In step S300, the tempering furnace is switched. Switching of the tempering furnace is performed by turning the turning conveyor 310 as described above in accordance with the end of the lot of the metal workpiece Wrk. The end of the lot of the metal workpieces Wrk can be determined in the end and process management when, for example, all the metal workpieces Wrk are placed on the tempering heating conveyors 210 and 210a.

  In the present embodiment, whether or not all the metal workpieces Wrk have been placed on the tempering heating conveyors 210 and 210a can be confirmed by visual inspection of the dummy workpieces indicating the end of each lot. The dummy workpiece is a dummy workpiece placed after the last metal workpiece Wrk in order to prevent foreign matter from entering when the lot of metal workpieces Wrk is placed on the quenching heating conveyor 111. In the present embodiment, the dummy workpiece also has a role of forcibly discharging the metal workpiece Wrk staying in the cooling oil tank 112b.

  The tempering furnace switching operation is performed by turning the turning conveyor 310. The turning work can be performed in about 10 seconds in the configuration of the present embodiment. On the other hand, since the time for the metal workpiece Wrk to flow on the turn conveyor 310 is sufficiently long (generally several tens of minutes), after the break appears on the turn conveyor 310 using the cut of each lot. However, the switching operation can be performed while continuing all operations.

  In step S400, a tempering process is executed. The tempering process is performed by restarting the operation of the drawer conveyor 112, the discharge conveyor 113, and the turn conveyor 310 in response to the completion of the turn of the turn conveyor 310. Heating to the tempering temperature is performed by transferring the inside of the tempering heating furnace 220 (FIG. 4) set to the tempering temperature at a constant speed by the tempering heating conveyor 210.

  Tempering is a heat treatment for increasing the toughness by changing the structure of the metal workpiece Wrk, which has been changed to a martensite structure by quenching, to another structure such as a sorbite structure. The tempering temperature varies in various ways depending on the required toughness and other metallic properties, and is set to various temperatures within a range of 150 ° C to 600 ° C. Specifically, for example, a high tempering temperature of 550 to 650 ° C. is used for materials of bolts, nuts, and shafts that generate a sorbite structure and require toughness and high tension. On the other hand, a low tempering temperature of, for example, 150 to 200 ° C. is used for various gears and automobile parts materials that require high hardness (for example, Vickers hardness) and wear resistance.

  As described above, the heat treatment system 10 according to the first embodiment can selectively transfer the metal workpiece Wrk from the single quenching furnace 100 to the two tempering furnaces 200 and 200a having different tempering temperatures. The contents of the heat treatment can be switched to tempering with different tempering temperatures without interrupting the operation of the quenching furnace. As a result, it is possible to suppress the generation of carbon dioxide emitted during the interruption of the operation of the quenching furnace (while maintaining the temperature), and to operate the quenching furnace efficiently without the need to change the temperature inside the tempering furnace. Is possible.

  In conventional heat treatment systems, it has been common technical knowledge that a quenching furnace and a tempering furnace correspond one-on-one. For this reason, in order to change the tempering temperature, the temperature in the furnace of the tempering furnace had to be changed, and the quenching furnace had to be stopped during that time. On the other hand, changing the in-furnace temperature in the tempering furnace takes time in units of several hours especially when the temperature is lowered. Had to perform verification work.

  The verification and management of the furnace temperature is extremely important because the heat treatment is a process having a unique property called a special process. The special process is a process specified in, for example, ISO 9001 clause 7.5.3, and the quality of the process (process) cannot be confirmed by product inspection. This is a process in which the quality of the product must be guaranteed.

  In this way, changing the temperature of the heat treatment furnace is a heavy burden due to the need for thorough verification and management by skilled technicians, and even when changing the tempering temperature, the quenching furnace is wasted because it maintains the furnace temperature. Was forced to consume a lot of fuel. However, conventionally, since tempering is generally performed immediately after quenching, the quenching furnace and the tempering furnace are practically considered as an integrated heat treatment apparatus, and it is common knowledge of those skilled in the art that they are always equipped with one-to-one. Met. This is because if left for a long time after quenching, cracks may occur.

  In contrast to such technical common sense, the present inventor does not dare to change the in-furnace temperature of the tempering furnace, but by reversing the idea of switching between tempering furnaces having different in-furnace temperatures. I created it. In particular, according to the common general knowledge at the time of filing of the present application, there is a concern that switching of the tempering furnace leads to generation of a tempering furnace in which the metal workpiece Wrk does not flow from the quenching furnace. However, in reality, there is a processing request that requires only the tempering process, and therefore it is possible to cause the tempering furnace in which the metal workpiece Wrk does not flow from the quenching furnace to execute the tempering process independently. It was found by analysis of process control by a worker. Furthermore, the present inventor succeeded in solving such a problem by a method described later.

C. Configuration of the heat treatment system of the second embodiment:
FIG. 8 is an explanatory diagram showing the configuration of the heat treatment system 10a of the second embodiment. The heat treatment system 10a of the second embodiment is different from the heat treatment system 10 of the first embodiment in that a quenching furnace 100b, a tempering furnace 200b, and a turning conveyor 310b are added. In the present embodiment, the tempering furnace 200b performs medium temperature tempering at about 400 ° C. Medium temperature tempering is a heat treatment that changes the bainite structure to be more elastic than the sorbite structure.

  In the heat treatment system 10a of the second embodiment, the tempering furnace 200 can selectively transfer the metal workpiece Wrk to the two tempering furnaces 200 and 200a via the turning conveyor 310 and the transfer unit 400. On the other hand, the tempering furnace 200b can selectively transfer the metal workpiece Wrk to the two tempering furnaces 200a and 200b via the turning conveyor 310b and the transfer unit 400. The tempering furnace 200a is shared by the two quenching furnaces 100 and 100b.

  With such a configuration change, in the heat treatment system 10 of the first embodiment, two tempering furnaces 200 and 200a correspond to one quenching furnace 100, but the heat treatment system 10a of the second embodiment. Then, the three tempering furnaces 200, 200a, and 200b correspond to the two quenching furnaces 100 and 100b. Thus, in the heat treatment system 10 of the first embodiment, one tempering furnace in which the metal workpiece Wrk does not flow from the quenching furnace is generated for one quenching furnace, whereas the heat treatment of the second embodiment. In the system 10a, only one 0.5 tempering furnace is required for one quenching furnace.

  In particular, for heat treatment specialists who perform heat treatment including a small variety of heat treatment processes, there is a high demand for ensuring the flexibility of heat treatment processes and reducing the burden on skilled technicians. The convenience of the heat treatment systems 10 and 10a of the above-described embodiments that achieve both is extremely high.

  Also in the second embodiment, the tempering furnace 200 in a state of executing high temperature tempering, the tempering furnace 200a in a state of executing low temperature tempering, and the tempering furnace 200b in a state of executing intermediate temperature tempering are all the same. It may be configured so that only the set temperature is different, or may be different.

  Further, it is not necessary for the three tempering furnaces 200, 200a, 200b to always perform heat treatment at mutually different temperatures. For example, the two tempering furnaces 200, 200b have an operation mode in which they operate at the same temperature. Alternatively, all three units may have an operation mode that operates at the same temperature.

  As described above, it may be configured to have an operation mode including a plurality of tempering furnaces that perform heat treatment at different temperatures in response to a request in process management. This also applies to the first embodiment and other modifications described later. This is because the present invention provides flexibility in the operation of the quenching furnace and the tempering furnace, and does not always require operation in such an operation mode.

D. Variations:
As mentioned above, although several embodiment of this invention was described, this invention is not limited to such embodiment at all, and implementation in various aspects is possible within the range which does not deviate from the summary. is there. In particular, elements other than the elements described in the independent claims in the constituent elements in each of the embodiments described above are additional elements and can be omitted as appropriate.

D-1. First Modification: In the above-described embodiment, a combination of one quenching furnace and two tempering furnaces and a combination of two quenching furnaces and three tempering furnaces are illustrated. Various combinations such as a combination of a quenching furnace and four tempering furnaces, a combination of three quenching furnaces and five tempering furnaces, and a combination of four quenching furnaces and six tempering furnaces are possible. Furthermore, since other combinations are possible by devising the conveyor, it is possible to combine at least one quenching furnace and more tempering furnaces than the number of quenching furnaces.

D-2. Second Modification: In the above embodiment, the metal workpiece is exemplified by carbon steel, but the present invention can be applied to other metal materials. The present invention can also be applied to heat treatment of other metals that perform quenching and tempering, such as alloy steel and aluminum alloy.

D-3. Third Modification: In the above-described embodiments, not all of the above-described advantages and effects lead to the essential constituent elements of the present invention, and the present invention makes it possible to easily realize each of the above-described advantages and effects. It is sufficient to provide design freedom and realize at least one advantage or effect.

Explanatory drawing which shows the structure of the heat processing system of a prior art. Sectional drawing which shows the structure of the heat processing system of a prior art. Explanatory drawing which shows the structure of the heat processing system 10 of 1st Example. Sectional drawing which shows the structure of the heat processing system 10 of 1st Example. Explanatory drawing which shows the structure of the heat processing system 10 of 1st Example. Sectional drawing which shows the structure of the heat processing system 10 of 1st Example. The flowchart which shows the content of the heat processing of 1st Example. Explanatory drawing which shows the structure of the heat processing system 10a of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a ... Heat processing system 100, 100b ... Quenching furnace 111 ... Quenching heating conveyor 112 ... Cooling conveyor 112b ... Cooling oil tank 113 ... Discharge conveyor 120 ... Quenching heating furnace 200, 200a, 200b ... Tempering furnace 210 ... Tempering heating conveyor 220 ... Tempering Heating furnace 230 ... Container box 300, 400 ... Transfer section 310, 310b ... Turning conveyor

Claims (4)

A heat treatment system for heat treating a metal workpiece,
A quenching heating furnace, and a quenching heating conveyor for passing the metal workpiece in the quenching heating furnace, and quenching by N passes (N is an integer of 1 or more);
M units including a tempering furnace and a plurality of tempering furnaces having an operation mode in which tempering heating conveyors that pass the metal workpiece in the tempering heating furnace and tempering at different temperatures by the passage (M is an integer greater than N) tempering furnace;
A transfer unit for receiving the quenched metal workpiece from the N quenching furnaces and transferring the received metal workpiece to the M tempering furnaces;
With
The transfer section, a heat treatment system having a mode of operation for switching the transfer destination of said metal workpiece within the previous SL tempering furnace of the M stage from each of the N number of quenching furnace while continuing the transport. The heat treatment system according to claim 1,
The said transfer part is a conveyor which transfers the said metal workpiece | work from the said quenching furnace to the said tempering furnace, Comprising: The heat processing system which has a turning conveyor which changes the said tempering furnace of the said transfer destination by turning while continuing the said transfer. The heat treatment system according to claim 2,
The transfer unit has a transfer unit that receives the metal workpiece from the rolling conveyor and transfers the metal workpiece to the tempering heating conveyor,
The said delivery part is a heat processing system which has a horizontal swing function for putting the said metal workpiece uniformly on the said tempering heating conveyor. A heat treatment method for heat treating a metal workpiece,
A quenching process for quenching;
A switching step of switching the transfer destination of the metal workpiece among a plurality of tempering furnaces that perform tempering at mutually different temperatures;
A transfer step of transferring the metal workpiece to a tempering furnace to which the metal workpiece is transferred;
Tempering in the transferred tempering furnace;
With
The switching process is a heat treatment method in which the switching is performed while continuing the processes of the quenching process, the tempering process, and the transfer process.

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