WO2019235028A1

WO2019235028A1 - Heat-treating furnace

Info

Publication number: WO2019235028A1
Application number: PCT/JP2019/012223
Authority: WO
Inventors: 山田　豊
Original assignee: 日本碍子株式会社; エヌジーケイ・キルンテック株式会社
Priority date: 2018-06-04
Filing date: 2019-03-22
Publication date: 2019-12-12
Also published as: JP2021181837A; TW202004111A

Abstract

This heat-treating furnace is for heat-treating an object to be treated. The heat-treating furnace is provided with: a heat treatment part provided with a heat treatment space where heat treatment is applied to the object to be treated; a plurality of conveyor rollers which are disposed in the heat treatment part and on which the object being treated is carried from one end to the other end of the heat treatment space; and a drive device for driving the plurality of conveyor rollers. Each of the conveyor rollers is configured to satisfy the relation: amount of deflection δ ≥ amount of warpage Z, wherein Z represents the amount of warpage of the conveyor roller in a no-load state in which no to-be-treated object is placed thereon, and δ represents the amount of deflection of the conveyor roller in a loaded state in which the to-be-treated object is placed thereon.

Description

Heat treatment furnace

The technology disclosed in this specification relates to a heat treatment furnace for heat-treating an object to be processed.

There is a case where an object to be processed is heat-treated using a heat treatment furnace (for example, roller hearth kiln). This type of heat treatment furnace includes a plurality of conveyance rollers, and conveys the workpiece by rotating the conveyance roller in a state where the workpiece is placed on the conveyance roller. For example, Japanese Patent Laying-Open No. 2015-64189 discloses an example of a heat treatment furnace.

In this type of heat treatment furnace, in order to increase productivity, a plurality of objects to be processed in a direction (hereinafter also referred to as the second direction) perpendicular to the transport direction (hereinafter also referred to as the first direction) on the transport roller. Are placed side by side, and the plurality of objects to be processed may be conveyed simultaneously. In such a case, the plurality of objects to be processed are simultaneously carried into the heat treatment furnace in a state where they are arranged in the second direction. However, the transport roller may be warped during manufacturing. If the conveyance roller is warped during conveyance of the workpiece, the contact area between the workpiece and the conveyance roller becomes narrow. Then, the conveyance of the object to be processed becomes unstable, and the conveyance object may be tilted during the conveyance. This problem is particularly noticeable in a heat treatment furnace having a long conveyance distance of the workpiece. When the object to be processed is conveyed at an angle, the object to be processed is meandering, which interferes with the conveyance of other objects to be placed side by side in the second direction or collides with the side wall in the heat treatment furnace. Problems can arise.

This specification discloses a technique for stably transporting a plurality of objects to be processed arranged side by side in a horizontal direction (second direction) perpendicular to the transport direction.

The heat treatment furnace disclosed in this specification heat-treats an object to be processed. The heat treatment furnace includes a heat treatment section having a heat treatment space for heat treating the object to be treated, a plurality of conveyance rollers disposed in the heat treatment part for conveying the object to be treated from one end to the other end of the heat treatment space, and driving the plurality of conveyance rollers. A driving device. Each of the plurality of transport rollers has a warpage amount of the transport roller in a no-load state where the workpiece is not placed as Z, and a deflection amount of the transport roller in a load state where the workpiece is placed as δ. In this case, the relationship of deflection amount δ ≧ warpage amount Z is established.

In the above heat treatment furnace, the relationship of the deflection amount δ ≧ the warpage amount Z is established for each of the plurality of transport rollers. That is, when the object to be processed is placed on the transport roller, the deflection amount δ tends to be larger than the warpage amount Z of the transport roller, and the deflection amount δ can be suppressed from being smaller than the warpage amount Z. For this reason, it can suppress that the contact area of the said conveyance roller and to-be-conveyed object becomes too narrow when a to-be-processed object is mounted in the conveyance roller. For this reason, conveyance of a to-be-conveyed object can be stabilized.

It is a figure which shows schematic structure of the heat processing furnace which concerns on an Example, and is a longitudinal cross-sectional view when a heat processing furnace is cut | disconnected by the plane parallel to the conveyance direction of a to-be-processed object. Sectional drawing in the II-II line | wire of FIG. The figure which shows the state by which the to-be-processed object was mounted on the conveyance roller. It is a figure for demonstrating conveyance of the to-be-processed object in the state in which the conveyance roller was curled, Comprising: (a) has shown the state which a conveyance roller is located below, (b) is a conveyance roller located in an upper direction Indicates the state to perform. It is a table | surface which shows the relationship between the deflection amount of a conveyance roller, and the stable conveyance of a to-be-processed object, Comprising: Experimental conditions (various numerical values) and an experimental result are shown.

The main features of the embodiment described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Characteristic 1) In the heat treatment furnace disclosed in this specification, the warp amount Z of the transport roller is the maximum warp amount measured when both ends of the transport roller are freely supported in a state where no external force acts on the transport roller. May be. The deflection amount δ of the conveying roller is calculated when the both ends of the conveying roller are supported freely in an ideal conveying roller in which the amount of warpage is zero while an external force generated when the workpiece is placed is applied. May be the maximum amount of deflection. According to such a configuration, the heat treatment furnace can be manufactured so that the relationship between the warpage amount Z and the deflection amount δ is established, and the relationship of the deflection amount δ ≧ the curvature amount Z can be more reliably established.

(Characteristic 2) In the heat treatment furnace disclosed in this specification, a workpiece is supported by n (≧ 2) transport rollers (specifically, a dimension in the transport direction of one workpiece). ). When the mass of the workpiece is M, the deflection amount δ of the transport roller may be calculated on the assumption that an M / n point load or distributed load acts on the position where the workpiece is placed. With such a configuration, it is possible to suitably calculate the deflection amount δ of the transport roller.

(Characteristic 3) In the heat treatment furnace disclosed in this specification, when the axial length of the transport roller is L, the warp amount Z of the transport roller may be 0.001 × L or less, and the deflection amount δ of the transport roller is It may be within the range of 0.001 × L to 0.0015 × L. According to such a structure, when a to-be-processed object is mounted on a conveyance roller, a conveyance roller can be bent in a suitable range. For this reason, conveyance of a to-be-conveyed object can be stabilized more.

Hereinafter, the heat treatment furnace 10 according to the embodiment will be described. As shown in FIG. 1, the heat treatment furnace 10 includes a heat treatment unit 20, a carry-in unit 34, a carry-out unit 40, and a transfer device 50. The heat treatment furnace 10 heat-treats the workpiece 12 while the workpiece 12 is transported through the heat treatment unit 20 by the transport device 50.

Examples of the object 12 include a laminate in which a ceramic dielectric (base material) and an electrode are laminated, a positive electrode material and a negative electrode material of a lithium ion battery, and the like. When a ceramic laminate is heat-treated using the heat treatment furnace 10, these can be placed on a flat setter and conveyed in the furnace. Moreover, when heat-treating the positive electrode material and the negative electrode material of the lithium ion battery using the heat treatment furnace 10, these can be accommodated in a box-shaped mortar and conveyed in the furnace. In the heat treatment furnace 10 of the present embodiment, a plurality of setters and mortars can be placed and transported in a transporting direction on a transporting roller 52 (described later). Hereinafter, in this example, the whole of the material to be heat-treated, the setter on which the heat-treated material is placed, and the mortar containing the material is referred to as “object 12”. In the following description, the direction in which the workpiece 12 is transported (direction perpendicular to the YZ plane in FIG. 1) may be referred to as “transport direction” or “first direction”, and is horizontal and perpendicular to the first direction. This direction (direction perpendicular to the XZ plane in FIG. 1) may be referred to as a “second direction”.

The heat treatment section 20 includes a substantially rectangular box-shaped furnace body, and a space 24 surrounded by an outer wall 22 is provided inside the furnace body. An opening 26 is formed on the front end surface (the end surface on the −X side in FIG. 1) of the outer wall 22, and an opening 28 is formed on the rear end surface (the end surface on the + X side in FIG. 1) of the outer wall 22. . The workpiece 12 is transported from the opening 26 into the heat treatment unit 20 by the transport device 50 and is transported from the opening 28 to the outside of the heat treatment unit 20. That is, the opening 26 is used as a carry-in port for the heat treatment unit 20, and the opening 28 is used as a carry-out port for the heat treatment unit 20.

In the space 24, a plurality of transport rollers 52 and a plurality of

heaters

30 and 32 are arranged. The heaters 30 are arranged at equal intervals in the conveying direction at positions above the conveying rollers 52, and the heaters 32 are arranged at equal intervals in the conveying direction at positions below the conveying rollers 52. When the

heaters

30 and 32 generate heat, the space 24 is heated. In the present embodiment, the

heaters

30 and 32 are arranged at equal intervals in the transport direction, but are not limited to such a configuration. For example, the heater may be appropriately changed and disposed at a desired position in accordance with the type of the object 12 to be processed, the heat treatment conditions of the heat treatment section 20, and the like. In the present embodiment, the

heaters

30 and 32 are disposed in the space 24, but the present invention is not limited to such a configuration. What is necessary is just to heat the inside of the space 24, for example, you may install a gas burner etc. in the space 24. FIG.

As shown in FIG. 2, in the heat treatment unit 20, a plurality of objects to be processed 12 are conveyed side by side in the second direction. In this embodiment, in the heat treatment section 20 (that is, the entire heat treatment furnace 10), the three objects to be processed 12 are transported side by side in the second direction. For this reason, in the present embodiment, the dimension in the second direction of the heat treatment section 20 is larger than the dimension in which three workpieces 12 are arranged in the second direction, but the dimension in the second direction of the heat treatment section 20 is There is no particular limitation. The size of the heat treatment unit 20 in the second direction may be a size that allows more than three workpieces 12 to be arranged and transported in the second direction. Further, the objects to be processed 12 may be transported side by side more than three in the second direction, or may be transported side by side with fewer than three. Moreover, although the dimension of the conveyance direction of the heat processing part 20 is comparatively large with about 100 m, the dimension of the conveyance direction of the heat processing part 20 is not specifically limited. For example, the dimension of the heat treatment unit 20 in the conveyance direction may be smaller than 100 m, 30 to 100 m, or larger than 100 m. In addition, the to-be-processed object 12 is continuously carried in into the heat processing part 20 at predetermined intervals in the conveyance direction. For this reason, the to-be-processed object 12 is arrange | positioned along with not only the 2nd direction but the conveyance direction.

The carry-in unit 34 is located on the upstream side of the heat treatment unit 20 (that is, on the upstream side in the transport direction, and in the −X direction of the heat treatment unit 20 in FIG. 1). The carry-in unit 34 receives the workpiece 12 carried from the outside of the heat treatment furnace 10 and carries the received workpiece 12 into the space 24 of the heat treatment unit 20. A transport roller 52 is installed in the carry-in unit 34, and the workpiece 12 transported from the outside of the heat treatment furnace 10 is transported by the transport roller 52.

The unloading unit 40 is located on the downstream side of the heat treatment unit 20 (that is, on the downstream side in the transport direction, and in the + X direction of the heat treatment unit 20 in FIG. 1). The unloading unit 40 unloads the workpiece 12 from the space 24 of the heat treatment unit 20 and delivers the unloaded workpiece 12 to the outside of the heat treatment furnace 10. A transport roller 52 is installed in the carry-out unit 40, and the workpiece 12 is transported out of the space 24 by the transport roller 52.

The conveyance device 50 includes a plurality of conveyance rollers 52, a driving device 60, and a control device 62. The conveyance device 50 conveys the workpiece 12 conveyed to the carry-in unit 34 from the carry-in unit 34 through the opening 26 into the space 24 of the heat treatment unit 20. Further, the transport device 50 transports the workpiece 12 from the opening 26 to the opening 28 in the space 24. Then, the transport device 50 transports the workpiece 12 from the space 24 through the opening 28 to the carry-out unit 40. The workpiece 12 is conveyed from the carry-in unit 34 to the carry-out unit 40 by the conveyance roller 52.

The transport roller 52 has a cylindrical shape, and its axis extends in a direction perpendicular to the transport direction. The plurality of transport rollers 52 all have the same diameter, and are arranged at regular intervals with a constant pitch in the transport direction. In the present embodiment, the transport rollers 52 installed in the heat treatment furnace 10 all have the same diameter, but are not limited to such a configuration. All the conveyance rollers installed in the heat treatment unit 20 have the same diameter, all the conveyance rollers installed in the carry-in unit 34 have the same diameter, and all the conveyance rollers installed in the carry-out unit 40 are the same. The diameter of the conveyance roller installed in the heat processing part 20 should just have a diameter, and the diameter different from the conveyance roller installed in the carrying-in part 34 and the carrying-out part 40 may be sufficient as it. Further, the conveyance rollers 52 installed in the heat treatment unit 20 may be arranged at a different pitch from the conveyance rollers 52 installed in the carry-in unit 34 and the carry-out unit 40. The transport roller 52 is supported so as to be rotatable about its axis, and rotates when the driving force of the driving device 60 is transmitted. Specifically, the conveying roller 52 has one end in the axial direction (end on the + Y direction side in FIG. 2) connected to the driving device 60, and the other end (end on the −Y direction side in FIG. 2) is free. It is the end. In the following description, the end side (that is, the + Y direction side) where the conveyance roller 52 is connected to the driving device 60 in the axial direction of the conveyance roller 52 may be referred to as “drive side”. The end side (that is, the −Y direction side) may be referred to as a “driven side”. A plurality of conveyance rollers 52 are arranged in the heat treatment unit 20, the carry-in unit 34, and the carry-out unit 40. The dimension of the conveyance roller 52 in the axial direction is larger than the dimension of the heat treatment unit 20 in the second direction (see FIG. 2).

The plurality of transport rollers 52 arranged in the heat treatment unit 20 are designed to bend downward due to the load of the workpiece 12 when the workpiece 12 is placed on the transport roller 52. The transport roller 52 may be warped during manufacturing. The conveyance roller 52 disposed in the heat treatment unit 20 is configured such that when the workpiece 12 is placed on the conveyance roller 52, the amount of bending due to the load of the workpiece 12 is greater than the amount of warpage generated during manufacturing. Designed.

In the present embodiment, the amount of warp generated during manufacture of the transport roller 52 (hereinafter also referred to as “the warp amount of the transport roller 52”) refers to the transport roller 52 along the axial direction (that is, the second direction or the Y direction). This means the amount of warpage of the portion where the warp is the largest among the portions in the axial direction of the transport roller 52. In other words, when no external force is applied to the transport roller 52 (that is, in a no-load state), when the both ends of the transport roller 52 are freely supported, the amount of warpage of the portion of the transport roller 52 in which the warp is the largest is obtained. It is a size. Hereinafter, the warpage amount of the transport roller 52 is assumed to be Z. The warp amount Z of the transport roller 52 may be measured using a measuring instrument such as a dial gauge, for example. Specifically, a dial gauge is installed in a certain part of the transport roller 52 in the axial direction, the transport roller 52 is rotated once around the axis, and the transport roller 52 is not warped when it is positioned at the uppermost position. Measure the difference from the state. The same measurement may be performed at a plurality of portions in the axial direction of the transport roller 52, and the warp amount of the portion having the largest warp amount may be used as the warp amount of the transport roller 52. In the present embodiment, the conveyance roller 52 in which the warpage amount Z is within 0.1% of the axial length (that is, the dimension in the second direction or the Y direction) L of the conveyance roller 52 is disposed in the heat treatment unit 20. .

Further, the amount of bending of the conveying roller 52 due to the load of the workpiece 12 (hereinafter also referred to as “the amount of bending of the conveying roller 52”) refers to the amount of bending of the workpiece 12 when the conveying roller 52 is not warped at all. It refers to the amount of bending at the position where the conveying roller 52 is most bent by the load of the workpiece 12 when placed on the conveying roller 52. In other words, when an ideal force (virtual external force) generated when the workpiece 12 is placed is applied to the ideal transport roller 52 in which the warp amount is 0 with both ends freely supported. In addition, the amount of bending at the position where the conveying roller 52 is most bent by the load of the workpiece 12 is shown. Hereinafter, the amount of deflection of the transport roller 52 is assumed to be δ. The deflection amount δ of the transport roller 52 is calculated based on the material and shape of the transport roller 52, the mass of the workpiece 12, and the like. A theoretical value obtained by calculation can be used as the deflection amount δ of the transport roller 52, and the calculation method is not particularly limited to the one exemplified below. Alternatively, the workpiece 12 may be actually placed on the transport roller 52 and the amount of deflection δ at that time may be measured.

Here, an example of a calculation method for calculating the deflection amount δ of the transport roller 52 will be described. As shown in FIG. 3, the transport roller 52 can be divided in the axial direction into regions A and B on the end side where the workpiece 12 is not placed and a central region C where the workpiece 12 is placed. . When calculating the amount of deflection δ of the transport roller 52, it is assumed that the mass M of the workpiece 12 acts as an evenly distributed load within the region C. Here, the mass M of the workpiece 12 is the mass of the workpieces 12 arranged in the second direction when a plurality of the workpieces 12 are placed side by side in the second direction (ie, the Y direction). The sum of For example, in FIG. 3, the mass M of the workpiece 12 is the sum of the masses of the three workpieces 12 arranged in the second direction. Further, when the workpiece 12 is placed on the transport roller 52, the workpiece 12 is supported across n (n is an integer, n ≧ 2) transport rollers 52. When the number of transport rollers 52 that support the object to be processed 12 varies depending on the placement state of the object to be processed 12, the minimum number is set to a value of n. For example, in FIG. 1, the workpiece 12 is supported across three transport rollers 52. However, depending on the mounting state of the workpiece 12 (for example, when shifted in the transport direction (X direction)), the workpiece 12 may be supported by the four transport rollers 52. That is, in FIG. 1, the workpiece 12 is supported by 3 to 4 transport rollers 52. Therefore, the value of n is 3 as the minimum number. The deflection amount δ of the transport roller 52 is calculated on the assumption that an evenly distributed load of M / n acts on the region C. When calculating the amount of deflection δ of the transport roller 52, the deflection due to the weight of the transport roller 52 may be taken into consideration. As a result, the deflection amount δ of the transport roller 52 can be calculated with higher accuracy. Alternatively, the amount of deflection δ of the conveying roller 52 may be calculated assuming that the mass M of the workpiece 12 acts as a spot load. Further, the amount of deflection δ of the conveying roller 52 may be calculated assuming that the roller is placed at room temperature. In this embodiment, the conveyance roller 52 disposed in the heat treatment unit 20 has a deflection amount δ of 0.1% to 0.15 of the axial length L of the conveyance roller 52 (that is, the dimension in the second direction or the Y direction) L. Designed to be%.

The load acting on the transport roller 52 varies depending on the state of the transport roller 52 (for example, the position where the maximum warpage occurs and the amount of warpage thereof) and the temperature of the transport roller 52. Therefore, the actual amount of deflection δ of the conveying roller 52 that occurs during conveyance differs from the amount of deflection calculated by the above-described calculation method. However, when the workpiece 12 is heat-treated in the heat treatment furnace 10, the workpiece 12 is continuously charged into the heat treatment furnace 10, and the amount of warping of the transport roller 52 is within 0.1% of the total length L. It can be suppressed to a relatively small value. For these reasons, even when the deflection amount δ is calculated on the assumption of the ideal state as described above, it is possible to suitably realize the conveyance of the object to be conveyed.

In the heat treatment furnace 10 of the present embodiment, the conveyance roller 52 is arranged in the heat treatment unit 20 so that the relationship of the amount of bending δ ≧ the amount of warpage Z is established. For this reason, in the heat treatment unit 20, when the workpiece 12 is placed on the transport roller 52, the transport roller 52 does not warp, but is slightly bent or is not warped or bent. . As described above, the amount of bending actually generated in the transport roller 52 is different from the amount of bending δ calculated at the time of design. For this reason, depending on the situation, there may occur a case where (actual deflection amount of the transport roller 52) <(warp amount Z of the transport roller 52). However, by designing so that the relationship of the deflection amount δ ≧ the warpage amount Z is established, the state where the conveyance roller 52 is not warped becomes dominant, and the meandering of the workpiece 12 can be effectively suppressed. it can.

In this embodiment, both end portions of the transport roller 52 are machined. That is, the driving end of the transport roller 52 is machined, and the driven end of the transport roller 52 is also machined. Since the driving side end of the transport roller 52 is connected to the driving device 60, a metal cap (not shown) is usually joined. The end portion on the driving side of the transport roller 52 is machined to join with the metal cap. As a result, between the plurality of transport rollers 52, the end portion on the driving side has a relatively small variation in outer diameter. On the other hand, the driven end of the transport roller 52 is a free end. For this reason, in the conventional conveyance roller, the end part of the driven side is not machined. For this reason, the end of the driven side has a large variation in the outer diameter between the plurality of conveying rollers, and the conveying speed of the object to be processed 12 disposed on the driving side and the object to be processed 12 disposed on the driven side. There may be a difference between the conveyance speed. Then, there may arise a problem that the conveyance of other objects to be processed 12 placed side by side in the second direction is obstructed or collides with a side wall in the heat treatment furnace 10. The transport roller 52 of this embodiment is machined not only at the driving end but also at the driven end. For this reason, between the plurality of transport rollers 52, the variation in the outer diameter of both the driving side end and the driven side end is reduced, and the transport speed and the driven speed of the workpiece 12 disposed on the driving side are reduced. It can suppress that a difference arises with the conveyance speed of the to-be-processed object 12 arrange | positioned at the side. For this reason, it can suppress that a difference arises between the conveyance speeds of the some to-be-processed object 12 arrange | positioned along with the 2nd direction, and the some to-be-processed object 12 placed in the 2nd direction is placed. It can suppress meandering and being conveyed. In this embodiment, the end portion on the driving side of the transport roller 52 is machined and the end portion on the driven side of the transport roller 52 is also machined. However, the present invention is not limited to such a configuration. The conveyance roller 52 only needs to be designed so that the relationship of the deflection amount δ ≧ the warpage amount Z is established, and the end portion on the driven side of the conveyance roller 52 may not be machined.

The driving device 60 (see FIG. 1) is a driving device (for example, a motor) that drives the transport roller 52. The driving device 60 is connected to the conveyance roller 52 via a power transmission mechanism. When the driving force of the driving device 60 is transmitted to the transport roller 52 via the power transmission mechanism, the transport roller 52 rotates. As the power transmission mechanism, a known mechanism can be used. For example, a mechanism using a sprocket and a chain is used. The driving device 60 drives each of the transport rollers 52 so that the transport rollers 52 rotate at substantially the same speed. The driving device 60 is controlled by the control device 62.

Next, the operation of the heat treatment furnace 10 when heat treating the workpiece 12 will be described. In order to heat-treat the workpiece 12, first, the

heaters

30 and 32 are operated to set the atmospheric temperature of the space 24 to a set temperature. Next, the three objects to be processed 12 are respectively moved from the outside of the heat treatment furnace 10 onto the conveyance rollers 52 installed in the carry-in unit 34. At this time, three workpieces 12 are placed side by side in the second direction. Next, the driving device 60 is operated, and the three objects to be processed 12 arranged in the second direction are conveyed from the carry-in section 34 through the opening 26 into the space 24 of the heat treatment section 20. The workpiece 12 transferred into the space 24 is transferred from the opening 26 to the opening 28 in the space 24. Thereby, the workpiece 12 is heat-treated. Then, the heat-treated object 12 is conveyed to the unloading unit 40 through the opening 28 and is unloaded from the unloading unit 40.

The transport roller 52 may be warped during manufacturing. When the workpiece 12 is placed on the conveyance roller 52, the conveyance roller 52 is deflected by the mass of the workpiece 12, and the amount of deflection is the mass of the workpiece 12, the placement position of the workpiece 12, and the conveyance roller 52. It is determined by the material, shape, etc. However, if the amount of warpage of the conveyance roller 52 is larger than the amount of deflection, the conveyance roller 52 on which the workpiece 12 is placed is placed even if the conveyance roller 52 is bent by placing the workpiece 12 on the conveyance roller 52. May be warped. If the transport roller 52 may be warped even when the workpiece 12 is placed, the contact area between the lower surface of the workpiece 12 and the transport roller 52 changes greatly as the transport roller 52 rotates. To do. Specifically, as shown in FIG. 4A, when the transport roller 52 is positioned at a rotation position where the warping direction of the transport roller 52 is downward, the contact area between the transport roller 52 and the workpiece 12 is determined. Is relatively wide. That is, the workpiece 12 contacts the conveyance roller 52 in the vicinity of both ends in the Y direction. On the other hand, as shown in FIG. 4B, when the transport roller 52 is positioned at a rotational position where the warping direction of the transport roller 52 is upward, the contact area between the transport roller 52 and the workpiece 12 is narrowed. . That is, the workpiece 12 contacts the transport roller 52 only near the center in the Y direction. For this reason, if the conveyance roller 52 can be warped even when the workpiece 12 is placed, the contact area between the conveyance roller 52 and the workpiece 12 changes periodically, and the workpiece by the conveyance roller 52 is processed. 12 becomes unstable, and the workpiece 12 becomes easy to meander.

In this embodiment, the heat roller 20 is provided with a conveyance roller 52 that satisfies the relationship of deflection amount δ ≧ warpage amount Z. For this reason, even if the conveyance roller 52 is warped, the conveyance roller 52 is bent downward when the workpiece 12 is placed on the conveyance roller 52. That is, in this embodiment, when the workpiece 12 is placed on the transport roller 52, the state (bent state) as shown in FIG. The state shown in 4 (b) (warped state) is not obtained. For this reason, it can suppress that the contact area of the conveyance roller 52 and the to-be-processed object 12 becomes narrow. Therefore, it can suppress that conveyance of the to-be-processed object 12 by the conveyance roller 52 becomes an unstable state, and the to-be-processed object 12 can be conveyed stably.

According to an experiment conducted by the present inventor, the amount of deflection δ of the transport roller 52 arranged in the heat treatment unit 20 is set to 0. 0 of the axial length of the transport roller 52 (that is, the dimension in the second direction or the Y direction) L. It has been confirmed that by setting the content to 1% to 0.15%, the workpiece 12 can be stably conveyed. As shown in FIG. 5, in Experimental Examples 1 to 5, the furnace length (length in the conveying direction of the heat treatment unit 20), the load applied to one conveying roller 52, the axial length L of the conveying roller 52, the conveying roller 52 The workpiece 12 was conveyed in the heat treatment furnace 10 having a different amount of deflection δ. The heat treatment furnace 10 of Experimental Examples 1 and 2 has a furnace length of about 50 m, and the heat treatment furnaces 10 of Experimental Examples 3 to 5 have a furnace length of about 100 m. In the experiment, a conveyance roller 52 having an outer diameter of 40 mm was used. Further, the conveyance roller 52 in which the warpage amount Z of the conveyance roller 52 is within 0.1% of the axial length (that is, the dimension in the second direction or the Y direction) L of the conveyance roller 52 was used.

The load of the workpiece 12 per conveyance roller 52 is the mass of the workpiece 12 (that is, the sum of the masses of the plurality of workpieces 12 arranged in the second direction) and one workpiece 12. It was calculated from the number of transport rollers 52 that support. For example, in Experimental Example 1, six workpieces 12 having a mass of about 11.26 kg were arranged and transported in the second direction. Further, the workpiece 12 was supported by the four transport rollers 52. Therefore, in Experimental Example 1, the load of the workpiece 12 per one transport roller 52 was calculated to be about 17 kg. When six of these workpieces 12 are placed side by side on the transport roller 52 having an axial length L of 3,100 mm, it is assumed that an evenly distributed load acts on the transport roller 52, and the amount of deflection δ of the transport roller 52 is as follows. Was calculated. As a result, in Experimental Example 1, the deflection amount δ of the transport roller 52 was calculated to be 3.5 mm. Since the axial length L of the conveying roller 52 is 3,100 mm, the deflection amount δ of the conveying roller 52 is about 0.11% of the axial length L of the conveying roller 52, and is between 0.1% and 0.15%. It became. When the workpiece 12 is transported in the heat treatment furnace 10 of Experimental Example 1, the workpiece 12 is transported with almost no meandering (the transport evaluation in FIG. 5 is ◯), and the workpiece 12 is transported stably. It was confirmed.

When the deflection amount δ of the conveying roller 52 was calculated in the same manner as in Experimental Example 1, in Experimental Example 2, the deflection amount δ of the conveying roller 52 was calculated as 2.5 mm, and the axial length L of the conveying roller 52 (experimental example) 2 (3,000 mm). That is, in the heat treatment furnace 10 of Experimental Example 2, the deflection amount δ of the transport roller 52 is smaller than 0.1% of the axial length L of the transport roller 52 and not between 0.1% and 0.15%. When the workpiece 12 is transported in the heat treatment furnace 10 of Experimental Example 2, the workpiece 12 is slightly meandered and transported (the transport evaluation in FIG. 5 is Δ), and the workpiece 12 is transported stably. I couldn't say that. Therefore, from the results of Experimental Examples 1 and 2, in the heat treatment furnace 10 having a furnace length of about 50 m, the deflection amount δ of the transport roller 52 is between 0.1% and 0.15% of the axial length L of the transport roller 52. In some cases, it was confirmed that the workpiece 12 can be stably conveyed as compared with the case where the deflection amount δ of the conveying roller 52 is smaller than 0.1% of the axial length L of the conveying roller 52.

Also, as shown in Experimental Examples 3 to 5, a similar experiment was performed for the heat treatment furnace 10 having a furnace length of about 100 m. When the deflection amount δ of the conveying roller 52 was calculated in the same manner as in Experimental Example 1, in Experimental Example 3, the deflection amount δ of the conveying roller 52 was calculated as 4.5 mm, and the axial length L of the conveying roller 52 (experimental example) 3 was about 0.14% of 3,300 mm). In Experimental Example 4, the deflection amount δ of the transport roller 52 was calculated to be 3.0 mm, which was about 0.11% of the axial length L of the transport roller 52 (2,800 mm in Experimental Example 4). In Experimental Example 5, the deflection amount δ of the transport roller 52 was calculated to be 2.0 mm, which was about 0.07% of the axial length L of the transport roller 52 (2,800 mm in Experimental Example 5). That is, in the heat treatment furnace 10 of Experimental Examples 3 and 4, the deflection amount δ of the transport roller 52 is between 0.1% and 0.15%, and in the heat treatment furnace 10 of Experimental Example 5, the deflection of the transport roller 52 is. The quantity δ was less than 0.1%. When the workpiece 12 was transported in the heat treatment furnace 10 of Experimental Examples 3 to 5, the workpiece 12 was transported with almost no meandering in the heat treatment furnace 10 of Experimental Examples 3 and 4 (the transport evaluation in FIG. In the heat treatment furnace 10 of Experimental Example 5, the workpiece 12 is meandered and conveyed (the conveyance evaluation in FIG. 5 is x), and the workpiece 12 is stable. And was not transported. Therefore, from the results of Experimental Examples 3 to 5, even in the heat treatment furnace 10 having a furnace length of about 100 m, the deflection amount δ of the transport roller 52 is between 0.1% and 0.15% of the axial length L of the transport roller 52. In this case, it was confirmed that the workpiece 12 can be stably conveyed as compared with the case where the deflection amount δ of the conveying roller 52 is smaller than 0.1% of the axial length L of the conveying roller 52.

Although specific examples of the technology disclosed in the present specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

Claims

A heat treatment furnace for heat treating a workpiece,
A heat treatment section comprising a heat treatment space for heat treating the workpiece;
A plurality of conveying rollers arranged in the heat treatment section, for conveying the object to be treated from one end to the other end of the heat treatment space;
A drive device for driving a plurality of transport rollers,
Each of the plurality of transport rollers has a warp amount of the transport roller in a no-load state where the workpiece is not placed as Z, and the deflection of the transport roller in a load state where the workpiece is placed. A heat treatment furnace in which the relationship of deflection amount δ ≧ warpage amount Z is established when the amount is δ.
The amount of warpage Z of the transport roller is the maximum amount of warpage measured when both ends of the transport roller are freely supported in the state where no external force acts on the transport roller.
The deflection amount δ of the transport roller is obtained when the both ends of the transport roller are freely supported in the state in which an external force generated when the workpiece is placed is applied to an ideal transport roller having a warp amount of 0. The heat treatment furnace according to claim 1, wherein the heat treatment furnace is a calculated maximum deflection amount.
The object to be processed has a size supported by n (≧ 2) of the conveying rollers,
The amount of deflection δ of the transport roller is calculated on the assumption that an M / n point load or distributed load is applied to a position where the workpiece is placed, where M is the mass of the workpiece. 2. A heat treatment furnace according to 2.
When the axial length of the transport roller is L, the warp amount Z of the transport roller is 0.001 × L or less, and the deflection amount δ of the transport roller is in the range of 0.001 × L to 0.0015 × L. The heat treatment furnace according to any one of claims 1 to 3, wherein