JP6951500B2 - Continuous heat treatment furnace - Google Patents

Description

The present invention relates to a continuous heat treatment furnace that continuously heat-treats a plurality of objects to be treated in a muffle.

Conventionally, as a heat treatment furnace for heat-treating an object to be treated such as steel parts, a carburizing furnace has been known to cure only the surface layer by increasing carbon in the surface layer of the object to be processed to improve wear resistance and the like. Has been done. Further, as this type of carburizing furnace, an atmospheric gas such as hydrocarbon gas is supplied into a tubular muffle that is heated from the outside by a heating device, and a plurality of objects to be processed are sequentially conveyed into the muffle to be continuously transported. A continuous carburizing furnace is also known in which the carburizing treatment is carried out in a specific manner (see, for example, Patent Document 1).

Generally, a gas supply pipe for supplying atmospheric gas is connected to the muffle in this type of continuous carburizing furnace. The muffle is also surrounded by a heat insulating wall to block the flow of heat to the outside. Therefore, the gas supply pipe penetrates the heat insulating wall from the outside of the heat insulating wall and is connected to the muffle.

Japanese Unexamined Patent Publication No. 2014-70873

In the continuous carburizing furnace as described above, the muffle is thermally expanded by being heated. Further, since the gas supply pipe is directly connected to the muffle, it moves with the thermal expansion of the muffle. Therefore, it is necessary to move the heat insulating wall through which the gas supply pipe penetrates together with the gas supply pipe.
In the case of the technique described in Patent Document 1, a part of the heat insulating wall is configured to be movable together with the gas supply pipe over the entire length of the heat insulating wall. Moreover, a part of the movable heat insulating wall has a double structure inside and outside. Therefore, the structure of the heat insulating wall becomes very complicated, and a structure for supporting a part of the heat insulating wall that can be moved, a structure for guiding the heat insulating wall, and the like are required.

An object of the present invention is to provide a continuous heat treatment furnace capable of allowing the movement of piping members due to thermal deformation of a muffle without complicating the structure of a heat insulating wall.

The continuous heat treatment furnace of the present invention
A tubular muffle in which a heat treatment space for the object to be treated is formed inside and heated from the outside,
With the piping member connected to the muffle
A heat insulating wall surrounding the outside of the muffle, which is formed with an opening having a size that allows the piping member to pass through and move of the piping member due to thermal deformation of the muffle.
It includes a lid made of a heat insulating material that closes the opening in contact with the surface of the heat insulating wall and moves following the movement of the piping member.

According to this configuration, since the piping member moves within the range of the opening formed in the heat insulating wall due to the thermal deformation of the muffle, the entire heat insulating wall surrounding the outer circumference of the muffle can be fixed at a fixed position. Therefore, the structure of the heat insulating wall can be simplified. Further, since the opening is closed by the lid body, it is possible to suppress the heat for heating the muffle from being released through the opening. Since the lid body moves following the movement of the piping member, the lid body does not hinder the movement of the piping.

It is also preferable to further provide a position regulating means for restricting the movement of the lid body in a direction away from the heat insulating wall.
With such a configuration, it is possible to prevent the lid from separating from the heat insulating wall when the muffle thermally expands in the direction in which the heat insulating wall and the lid face each other.

The position regulating means preferably includes a pressing mechanism for pressing the lid against the heat insulating wall.
With such a configuration, the lid can be suitably maintained in contact with the heat insulating wall.

The pressing mechanism includes a pressing member that is arranged on the side opposite to the heat insulating wall with the lid body interposed therebetween and is movably supported in a direction opposite to the heat insulating wall and the lid body, and the pressing member is the lid body. It is preferable to include an urging member for urging toward.
According to such a configuration, the lid body can be pressed against the heat insulating wall by utilizing the urging force of the urging member.

According to the present invention, it is possible to allow the movement of the piping member due to thermal deformation of the muffle without complicating the structure of the heat insulating wall.

It is sectional drawing which shows the continuous heat treatment furnace which concerns on one Embodiment of this invention. It is a side view of the continuous heat treatment furnace. It is sectional drawing which shows the detail of the part A in FIG. FIG. 3 is a cross-sectional view taken along the line DD in FIG. It is sectional drawing which shows the detail of the part B in FIG. It is sectional drawing which shows the detail of part C in FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional explanatory view showing a continuous heat treatment furnace according to an embodiment of the present invention. FIG. 2 is a side view of the continuous heat treatment furnace.
The continuous heat treatment furnace 10 of the present embodiment hardens the surface layer of the object to be treated W by continuously performing carburizing treatment and the like while sequentially transporting a plurality of objects W to be processed such as steel parts, and has wear resistance. It is a continuous carburizing furnace that improves the above. The continuous carburizing furnace 10 includes a muffle 11, a transport device 12 for transporting an object W to be processed in the muffle 11, a heating device 13 for heating the muffle 11, and a gas supply pipe for supplying gas into the muffle 11. A piping member) 14, a heat insulating wall 15 that blocks heat from heating the muffle 11 from flowing to the outside, and a lid 16 are provided.

The muffle 11 is made of a heat-resistant steel cylinder. The muffle 11 includes an outer wall 24 including a substantially flat bottom plate 21, left and right side plates 22, and an arch-shaped upper plate 23. The inside of the muffle 11 surrounded by the outer wall 24 is used as a heat treatment space for heat-treating the object W to be treated. As shown in FIG. 2, a carburizing zone Z is set in the middle of the muffle 11 in the longitudinal direction. Atmospheric gas is positively blown to the object W to be treated in the carburizing zone Z, and the carburizing treatment is promoted.

The transport device 12 is composed of a belt conveyor having a transport belt 12a that runs in the muffle 11 along the longitudinal direction. The transport belt 12a is made of a mesh belt or the like, and transports the object to be processed W placed on the upper surface thereof in the muffle 11. In the following description, the transport direction of the object W to be processed, that is, the longitudinal direction of the muffle 11 is also referred to as a front-rear direction.

The heating device 13 includes a plurality of heaters 13a and 13b arranged on the upper side and the lower side of the muffle 11. The heating device 13 is configured to heat the muffle 11 from the outside by a plurality of heaters 13a and 13b to raise the heat treatment space in the muffle 11 to a predetermined temperature. As the heaters 13a and 13b, electric resistance heating type heaters can be used. Further, as the heating device 13, a gas combustion heating type can be used. In addition, when heating the heat treatment space in the muffle 11, an electric resistance heating type heat ray may be embedded in the heat insulating wall 15 to be described later and heated.

The gas supply pipe 14 (the piping member of the present invention) creates a predetermined atmosphere by supplying gas into the muffle 11. In the present embodiment, the hydrocarbon gas and the inert gas are supplied as the atmospheric gas. As the hydrocarbon gas, for example, acetylene gas gas is adopted, and as the inert gas, for example, nitrogen gas is adopted. The gas supply pipe 14 is a first supply pipe 31 arranged along the vertical direction and connected to the upper plate 23 of the muffle 11, and a second supply pipe 31 arranged along the vertical direction and connected to the bottom plate 21 of the muffle 11. It includes a pipe 32 and a third supply pipe 33 arranged along the left-right direction and connected to the side plate 22 and the upper plate 23 of the muffle 11.

As shown in FIG. 2, the first supply pipe 31 and the second supply pipe 32 are provided corresponding to the carburizing zone Z. A plurality of the first supply pipe 31 and the second supply pipe 32 are provided in the carburizing zone Z at intervals in the front-rear direction. Further, as shown in FIG. 1, a plurality of rows of the first supply pipe 31 and the second supply pipe 32 are provided in the left-right direction.

As shown in FIG. 2, a plurality of third supply pipes 33 are provided at intervals in the front-rear direction over the entire length of the muffle 11. Further, as shown in FIG. 1, a plurality of rows of the third supply pipes 33 are provided in the vertical direction.
As shown in FIG. 4, each of the gas supply pipes 14 is composed of a double pipe composed of an outer pipe 14a and an inner pipe 14b, gas flows in the inner pipe 14b, and the outer pipe 14a is an inner pipe. It protects 14b from the outside. The outer tube 14a is integrally attached to the muffle 11, and the inner tube 14b is inserted inside the outer tube 14a. The inner pipe 14b is attached to the outer pipe 14a via a mechanism (not shown) arranged outside the heat insulating wall 15 described later. The inner tube 14b can be removed from the outer tube 14a and pulled out to the outside. As a result, the inner pipe 14b can be replaced, and maintenance against wear due to use is possible.

As shown in FIG. 1, the heat insulating wall 15 is arranged below the muffle 11, the upper heat insulating wall 41 arranged above the muffle 11, the side heat insulating walls 42 arranged on both the left and right sides of the muffle 11. It has a bottom insulating wall 43 and surrounds the entire outside of the muffle 11. The heat insulating wall 15 is fixed at a fixed position by the support frame 17. The support frame 17 is configured by connecting a plurality of plate-shaped members. Although not shown, the upper heat insulating wall 41, the side heat insulating wall 42, and the bottom heat insulating wall 43 of the heat insulating wall 15 are each divided into a plurality of blocks in the front-rear direction, and the plurality of blocks are divided into a plurality of blocks in the front-rear direction. It is composed by arranging in. The heat insulating wall 15 can be made of a hard heat insulating material formed into a thick plate shape using, for example, ceramic fibers.

The upper heat insulating wall 41, the side heat insulating wall 42, and the bottom heat insulating wall 43 are each formed with openings 20 for passing the gas supply pipe 14. Specifically, the upper heat insulating wall 41 is formed with an opening 20 for passing the first supply pipe 31, and the bottom heat insulating wall 43 is formed with an opening 20 for passing the second supply pipe 32. The side heat insulating wall 42 is formed with an opening 20 for passing the third supply pipe 33. Each opening 20 is formed in a hole shape having a larger outer diameter than the outer diameter of the gas supply pipe 14 and having a closed outer circumference.

The muffle 11 is thermally expanded by being heated by the heating device 13, and is thermally contracted by being dissipated (cooled) by stopping heating. Then, the gas supply pipe 14 connected to the muffle 11 moves with the thermal deformation such as thermal expansion and thermal contraction. On the other hand, the heat insulating wall 15 is fixed at a fixed position. The opening 20 formed in the heat insulating wall 15 is formed in a size capable of allowing the gas supply pipe 14 to move with respect to the heat insulating wall 15, thereby preventing the gas supply pipe 14 from interfering with the heat insulating wall 15. ..

In a long structure such as the muffle 11, the amount of thermal deformation in the longitudinal direction is the largest. Therefore, as shown in FIG. 2, each opening 20 has an elongated hole shape that is long in the front-rear direction (longitudinal direction of the muffle 11). Is formed in. Further, since the muffle 11 is thermally deformed in the vertical direction in the side plate 22 and also in the horizontal direction in the bottom plate 21 and the upper plate 23, there is a gap between the muffle 11 and the gas supply pipe 14 in these directions as well. The dimensions of the opening 20 are set so that they are formed.

As shown in FIG. 1, the lid 16 is arranged to face the outer surface of the heat insulating wall 15 and is in contact with the outer surface. Further, the lid 16 closes the opening 20 through which the gas supply pipe 14 is inserted from the outside. The lid 16 is made of a material having high heat insulating properties, for example, a heat insulating material substantially the same as that of the heat insulating wall 15. The lid 16 is formed with a hole 19 through which the gas supply pipe 14 penetrates. The hole 19 is formed in such a size that it is in close contact with the gas supply pipe 14 or a slight gap is formed. Further, the lid body 16 is provided for each gas supply pipe 14, that is, for each opening 20.

FIG. 3 is a cross-sectional view showing the details of part A in FIG. FIG. 4 is a cross-sectional view taken along the line DD in FIG.
As shown in FIGS. 3 and 4, the opening 20 formed in the side heat insulating wall 42 is entirely closed by the lid body 16a. The lid 16a is made of a rectangular parallelepiped block. Further, the lid body 16a moves following the third supply pipe 33 by moving the third supply pipe 33 within the range of the opening 20 due to the thermal deformation of the muffle 11. The lid 16a is formed in a size capable of maintaining the state in which the opening 20 is closed even if the lid 16a moves following the third supply pipe 33.

The continuous carburizing furnace 10 of the present embodiment includes a position regulating means 50 that restricts the movement of the lid 16a in the direction away from the side heat insulating wall 42. Further, the position regulating means 50 includes a pressing mechanism 51 that presses the lid 16 toward the side heat insulating wall 42 in a direction approaching the side heat insulating wall 42.
The pressing mechanism 51 includes a pressing member 52 and an urging member 53. The pressing member 52 is arranged further outside the lid body 16a, that is, on the side opposite to the side heat insulating wall 42 with the lid body 16a interposed therebetween. The pressing member 52 includes a rod 52a formed in a rod shape and arranged along the left-right direction, a flat plate-shaped backing plate 52b provided at one end of the rod 52a in the longitudinal direction, and the other end of the rod 52a in the longitudinal direction. A retaining member 52c provided in the rod 52a and a spring receiving member 52d provided in the middle of the rod 52a in the longitudinal direction are provided. The retaining member 52c and the spring receiving member 52d are provided so as to be adjustable in position in the longitudinal direction of the rod 52a.

The rod 52a is movably supported in the left-right direction by a support frame 17 arranged outside the lid 16a. Specifically, the rod 52a is inserted into the through hole 17a formed in the support frame 17 so as to be movable in the left-right direction. The backing plate 52b is in contact with the outer surface of the lid 16. The retaining member 52c is composed of a nut or the like attached to the rod 52a, and is arranged further outside the support frame 17. The spring receiving member 52d is arranged inside the support frame 17. By adjusting the positions of the retaining member 52c and the spring receiving member 52d in the longitudinal direction of the rod 52a, the urging force of the urging member 53 can be adjusted.

The urging member 53 is composed of a compression coil spring, and is externally fitted between the retaining member 52c of the rod 52a and the spring receiving member 52d. One end of the urging member 53 is in contact with the inner surface of the support frame 17, and the other end is in contact with the spring receiving member 52d. Therefore, the urging member 53 urges the lid 16a in the direction of pressing it against the side heat insulating wall 42.

In this way, the lid 16a is pressed against the side heat insulating wall 42 by the pressing mechanism 51 in the position regulating means 50, so that the state of contact with the side heat insulating wall 42 is maintained. Therefore, it is possible to preferably prevent heat from being released from the opening 20 to the outside.

FIG. 5 is a cross-sectional view showing the details of the portion B in FIG.
The opening 20 formed in the bottom heat insulating wall 43 is closed by the lid body 16b. Also in the lid body 16b, the movement in the direction away from the bottom heat insulating wall 43 is restricted by the position regulating means 50.
Further, the position regulating means 50 includes a pressing mechanism 51 that presses the lid body 16b toward the bottom heat insulating wall 43 in a direction approaching the bottom heat insulating wall 43. The pressing mechanism 51 has the same configuration as the above-mentioned pressing mechanism 51 (see FIG. 3) except that the direction in which the lid body 16b is pressed is different.

The support frame 17 that supports the heat insulating wall 15 includes a receiving member 17b that receives the bottom heat insulating wall 43 from below. The lid body 16b is formed with a concave retracting portion 16b1 for avoiding the receiving member 17b. Further, one of the lids 16b adjacent to each other in the left-right direction is formed with a convex portion 16b2 protruding toward the other, and the other is formed with a concave portion 16b3 into which the convex portion 16b2 is inserted.

When the evacuation portion 16b1 for avoiding the receiving member 17b is formed on the bottom heat insulating wall 43, the contact area between the bottom heat insulating wall 43 and the lid 16b is reduced by that amount, and heat can easily escape between the two. Therefore, in the present embodiment, by forming the concave portion 16b3 and the convex portion 16b2 in the lids 16b adjacent to each other, the passage through which heat escapes can be bent and the heat release can be suppressed.

FIG. 6 is a cross-sectional view showing the details of the portion C in FIG.
The opening 20 formed in the upper heat insulating wall 41 is closed by the lid body 16c. The lid 16c is placed on the upper heat insulating wall 41 and is in contact with the upper surface of the upper heat insulating wall 41 by its own weight. Further, a position regulating means 50 for restricting the movement of the lid body 16c in the direction away from the upper heat insulating wall 41 is provided.

The position regulating means 50 includes holding members 54 arranged on both the left and right sides of the lid body 16c. The pressing member 54 regulates the movement of the lid body 16c and suppresses the movement within a certain range. The pressing member 54 is pressed against the heat insulating wall side by the support frame 17. The pressing member 54 includes a pressing portion 54a that projects upward from the lid body 16. The pressing portion 54a is arranged above the lid 16 with a slight gap. Therefore, the lid 16 does not move upward beyond this gap, and heat can be prevented from being released from the opening 20 as much as possible. Further, the pressing member 54 regulates the movement of the lid 16 in the rotation direction so as not to exceed a certain range. The pressing member 54 is formed of a material having high heat insulating properties, for example, a heat insulating material substantially the same as that of the heat insulating wall 15. Therefore, it is possible to suppress the release of heat through the pressing member 54.

As described above, in the continuous carburizing furnace 10 of the present embodiment, the heat insulating wall 15 surrounding the outside of the muffle 11 is formed with an opening 20 that allows the gas supply pipe 14 to move due to thermal deformation of the muffle 11. Therefore, the heat insulating wall 15 itself does not need to be moved following the gas supply pipe 14 and can be fixed at a fixed position, and the structure of the heat insulating wall 15 can be simplified. Further, since the opening 20 formed in the heat insulating wall 15 is closed by the lid body 16, it is possible to suppress the heat for heating the muffle 11 from flowing to the outside through the opening 20. Further, since the lid 16 moves following the movement of the gas supply pipe 14 due to the thermal deformation of the muffle 11, the opening 20 can be closed without hindering the movement of the gas supply pipe 14.

Since the continuous carburizing furnace 10 of the present embodiment includes the position regulating means 50 for restricting the movement of the lid 16 in the direction away from the heat insulating wall 15, the lid 16 is insulated due to thermal deformation of the muffle 11 or the like. It is possible to prevent a large distance from the wall 15 and suppress the flow of heat to the outside. Further, the position regulating means 50 provided for the lids 16a and 16b that close the openings 20 of the side heat insulating wall 42 and the bottom heat insulating wall 43 makes the lids 16a and 16b the side heat insulating wall 42 and the bottom heat insulating wall. Since the pressing mechanism 51 that presses against the 43 is provided, the state in which the lids 16b and 16c are in contact with the heat insulating walls 42 and 43 can be suitably maintained.

The present invention is not limited to the above embodiment, and can be appropriately modified within the scope of the invention described in the claims.
For example, the piping member in the present invention is not limited to the gas supply pipe that supplies gas to the muffle, and may be a gas discharge pipe for discharging the gas in the muffle.
Further, the continuous heat treatment furnace according to the present invention is not limited to the continuous carburizing furnace for carburizing the object to be treated, and may be a heat treatment furnace for performing other heat treatment.
The lid may be provided inside the heat insulating wall (muffle side).

10: Continuous carburizing furnace (continuous heat treatment furnace)
11: Muffle 14: Gas supply pipe (piping member)
15: Insulation wall 16: Lid body 16a: Lid body 16b: Lid body 16c: Lid body 20: Opening 31: First supply pipe 32: Second supply pipe 33: Third supply pipe 50: Position regulating means 51: Pressing mechanism 52: Pressing member 53: Biasing member W: Object to be processed

Claims (5)

A tubular muffle in which a heat treatment space for the object to be treated is formed inside and heated from the outside,
With the piping member connected to the muffle
A heat insulating wall surrounding the outside of the muffle, which is formed with an opening having a size that allows the piping member to pass through and move of the piping member due to thermal deformation of the muffle.
Insulation lid and
With
The opening is closed by the lid in a state where the inner surface side of the lid is in contact with the outer surface of the heat insulating wall.
The lid body is a continuous heat treatment that follows the movement of the piping member and moves along the longitudinal direction of the outer surface and the vertical or horizontal direction of the outer surface while closing the opening. Furnace. The continuous heat treatment furnace according to claim 1, further comprising a position regulating means for restricting the movement of the lid body in a direction away from the heat insulating wall. The continuous heat treatment furnace according to claim 2, wherein the position regulating means includes a pressing mechanism for pressing the lid against the heat insulating wall. A tubular muffle in which a heat treatment space for the object to be treated is formed inside and heated from the outside,
With the piping member connected to the muffle
A heat insulating wall surrounding the outside of the muffle, which is formed with an opening having a size that allows the piping member to pass through and move of the piping member due to thermal deformation of the muffle.
Insulation lid and
With
The opening is closed by the lid in a state where the inner surface side of the lid is in contact with the outer surface of the heat insulating wall.
The lid body moves following the movement of the piping member in a state of closing the opening .
The lid body is formed in a size capable of maintaining a state in which the entire opening is closed even if the lid body moves following the movement of the piping member.
Continuous processing furnace. A tubular muffle in which a heat treatment space for the object to be treated is formed inside and heated from the outside,
With the piping member connected to the muffle
A heat insulating wall surrounding the outside of the muffle, which is formed with an opening having a size that allows the piping member to pass through and move of the piping member due to thermal deformation of the muffle.
Insulation lid and
With
The opening is closed by the lid in a state where the inner surface side of the lid is in contact with the outer surface of the heat insulating wall.
The lid body moves following the movement of the piping member in a state of closing the opening .
The piping member has at least one of a first piping member connected to the bottom plate of the muffle in the vertical direction and a second piping member connected to the side plate of the muffle in the horizontal direction.
The heat insulating wall has at least one of a bottom portion in which the opening is formed through which the first piping member is passed and a side portion in which the opening is formed through which the second piping member is passed.
The lid body closes the opening in a state of being in contact with the bottom portion from the lower side in the vertical direction and moves following the movement of the first piping member, and the lid body moves from the horizontal direction with respect to the side portion. A continuous heat treatment furnace that is at least one of a second lid that closes the opening in contact and moves following the movement of the second piping member.

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