JP2017009227A - Mesh-belt type continuous sintering furnace and manufacturing method for sintered body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mesh-belt type continuous sintering furnace having a long-life mesh belt.SOLUTION: A mesh-belt type continuous sintering furnace includes: a furnace main body part having a preheating part, a sintering part, and a cooling part; an endless mesh-belt which is extended by an inlet side pulley and an outlet side pulley of the furnace main body part, travels from an inlet of the furnace main body part to an outlet thereof and carries a heating object. Therein, a tension dividing mechanism which divides an interval on which a predetermined tensile force is actuated between from an inlet end of the preheating part to an outlet end of the sintering part is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mesh belt type continuous sintering furnace used for manufacturing a sintered body, and a method for manufacturing a sintered body that can use the mesh belt type continuous sintering furnace. In particular, the present invention relates to a mesh belt type continuous sintering furnace having a long life.

  Sintered bodies obtained by sintering a molded body containing metal powder such as iron powder are used for automobile parts and general machine parts. Examples of these types of parts include sprockets, rotors, gears, rings, flanges, pulleys, bearings, and the like. A mesh belt furnace (mesh belt type continuous sintering furnace) is used for manufacturing the sintered body (Patent Document 1).

  A conventional mesh belt type continuous sintering furnace 100 will be described with reference to FIG. The mesh belt type continuous sintering furnace 100 includes a preheating unit 11 for preheating a heating target (not shown), a sintering unit 13 for sintering the preheated heating target to produce a sintered body, and a sintered body. And a cooling unit 14 for cooling, and a furnace main body 110 that conveys a heating target and continuously performs preheating, sintering, and cooling. The conveyance of the heating target is performed by placing the heating target on the endless mesh belt 30 that travels from the inlet to the outlet of the furnace body 110. The mesh belt 30 is stretched around an inlet side pulley 21 and an outlet side pulley 22 that are respectively arranged on the inlet side and the outlet side of the furnace body 110. At least one of the inlet side pulley 21 and the outlet side pulley 22 is used as a driving pulley, and the mesh belt 30 is driven by the driving. Here, the outlet pulley 22 is a drive pulley (the direction of rotation is indicated by an arrow), and the inlet pulley 21 is a driven pulley. The mesh belt 30 that has exited from the furnace body 110 passes under the furnace body 110 and returns to the entrance of the furnace body 110. In the vicinity of the inlet side pulley 21 and the outlet side pulley 22, tension pulleys 211 and 221 for adjusting the tension of the mesh belt 30 are provided.

Japanese Utility Model Publication No. 05-94695

  It is desired to extend the life of mesh belts. Since the mesh belt travels in the sintering furnace with a heating target placed thereon, a large load and tension are applied to the mesh belt, and the mesh belt is exposed to a very severe environment. As a result, the mesh belt stretches mainly due to high-temperature creep. Therefore, as a maintenance of the mesh belt, the mesh belt is regularly checked for elongation, and the mesh belt is cut and joined each time the specified elongation occurs. ing. When the elongation of the mesh belt reaches the limit, it is necessary to replace the mesh belt itself. These maintenance and replacement operations are very complicated.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a mesh belt type continuous sintering furnace having a long life of the mesh belt.

  Another object of the present invention is to provide a method for producing a sintered body that can utilize the mesh belt type continuous sintering furnace.

  The mesh belt type continuous sintering furnace according to one aspect of the present invention is stretched over a furnace body having a preheating part, a sintering part, and a cooling part, and an inlet side pulley and an outlet side pulley of the furnace body part, And an endless mesh belt that travels from the entrance to the exit of the furnace body to convey the object to be heated. The mesh belt type continuous sintering furnace has a tension dividing mechanism that divides a section where a predetermined tension acts on the mesh belt from the inlet end of the preheating section to the outlet end of the sintered section into an inlet side and an outlet side. Prepare.

  The manufacturing method of the sintered compact which concerns on 1 aspect of this invention is a manufacturing method of the sintered compact which performs each process of preheating, sintering, and cooling in order to the molded object conveyed by the traveling belt from the upstream to the downstream. Within the range corresponding to the end of the sintering process from the beginning of the preheating process, the section where the predetermined tension acts on the traveling belt is divided into the upstream side and the downstream side to convey the molded body. To do.

  In the mesh belt type continuous sintering furnace, the mesh belt has a long life.

  The manufacturing method of the said sintered compact can manufacture the sintered compact excellent in surface property with sufficient productivity.

1 is a schematic view showing a mesh belt type continuous sintering furnace according to Embodiment 1. FIG. It is the schematic which shows the conventional mesh belt type continuous sintering furnace.

<< Description of Embodiments of the Present Invention >>
The present inventor has focused on high-temperature creep of the mesh belt in order to achieve a longer life of the mesh belt. Specifically, in the manufacturing process of the sintered body from preheating to cooling, paying attention to the position of the highest temperature in the sintered part where the highest temperature creep is likely to occur, the high temperature of the mesh belt in the vicinity of that position The reduction of creep was investigated. As a result, it has been found that the high temperature creep is greatly affected by the length between the position where the mesh belt reaches the maximum temperature and the position of the upstream pulley closest to the position. The "maximum temperature position" refers to the position where the maximum temperature is reached as the maximum value in the temperature distribution in the longitudinal direction of the mesh belt. When there is a range where the maximum temperature is reached, it means the position on the most downstream side of the range. In the following description, the “maximum position” and the “most downstream position” may be collectively referred to as a maximum temperature end point T. For example, the maximum temperature end point T is shown in the center of the sintered portion 13 in the transport direction for convenience of explanation in FIG. 2 described above (this is the same in FIG. 1 described later). If the distance between the highest temperature end point T and the pulley closest to the upstream side (hereinafter sometimes referred to as the heating belt section L) can be shortened, the load acting on the heating belt section L can be reduced, and the mesh belt It was found that the elongation associated with high temperature creep can be significantly suppressed. The present invention is based on these findings. First, the contents of the embodiments of the present invention will be listed and described.

  (1) A mesh belt type continuous sintering furnace according to an aspect of the present invention includes a furnace main body having a preheating part, a sintering part, and a cooling part, and stretched around an inlet side pulley and an outlet side pulley of the furnace main body part. And an endless mesh belt that travels from the inlet to the outlet of the furnace main body to convey the object to be heated. The mesh belt type continuous sintering furnace has a tension dividing mechanism that divides a section where a predetermined tension acts on the mesh belt from the inlet end of the preheating section to the outlet end of the sintered section into an inlet side and an outlet side. Prepare.

  According to said structure, it is easy to suppress the high temperature creep deformation | transformation of a mesh belt, and a mesh belt can be extended in life. Therefore, the number of times of maintenance of the mesh belt and the number of times of replacement of the mesh belt can be reduced. By dividing the section in which the predetermined tension acts on the mesh belt by the tension dividing mechanism, the section can be shortened compared to the conventional case. The tensions of the mesh belts in each section separated by this division do not substantially affect each other and are independent from each other. That is, since the length of the mesh belt acting on its own weight can be shortened, the load of the heating target placed in the shortened region can be made smaller than the load of the heating subject placed on the mesh belt before division.

  Moreover, according to said structure, it is easy to improve the productivity of a sintered compact. By making the tension of the mesh belt in each divided section independent from each other and shortening the section in which a predetermined tension acts on the mesh belt, the stress acting on the mesh belt can be reduced, and it is easy to stack and transport the mesh belt. For this reason, it is possible to change from single-stage conveyance to multi-stage stacking, to increase the number of multi-stage stacks, and to sinter more heating objects at a time.

  Furthermore, according to said structure, it is easy to manufacture the sintered compact which is excellent in the surface quality without a wrinkle and rough skin. Conventionally, a section where a predetermined tension acts on the mesh belt is a section from the pulley on the inlet side to the highest temperature end point T of the sintered portion, and this series of sections is very long. If the preheating part is lengthened, this series of sections becomes longer, so that the frequency of maintenance and replacement of the mesh belt may be excessive, and the preheating part cannot be lengthened. On the other hand, the length of the preheating portion can be increased by shortening the section in which the predetermined tension acts on the mesh belt by making the tension of the mesh belt in each section divided independent. For this reason, the heating target can be sufficiently preheated by making the length (time) of preheating longer than before. In particular, when the object to be heated contains a lubricant, the lubricant can be sufficiently removed, so that it is easier to produce a sintered body having excellent surface properties.

  (2) As one form of the mesh belt type continuous sintering furnace, the tension dividing mechanism is provided between the preheating part and the sintering part.

  According to the above configuration, the section of the mesh belt on which a predetermined tension acts can be divided into the preheating part side and the sintering part side of different treatments, so that the life of the mesh belt is extended and the productivity of the sintered body is increased. It is easy to achieve a high-level production of a sintered body with improved surface properties and surface properties. In addition, since the temperature range to be controlled is different between the preheating part and the sintering part, there are usually many structural differences such as heating means and heat insulating materials. It is easy to form a tension breaking mechanism.

  (3) As one form of the mesh belt type continuous sintering furnace, the tension dividing mechanism includes an intermediate conveyance mechanism that conveys the heating target on a tangent line connecting the inlet pulley and the outlet pulley.

  According to said structure, by providing an intermediate conveyance mechanism, it can suppress that a heating target deviates from a conveyance path | route in the position of a tension | tensile_strength dividing mechanism, and a heating target is substantially linear ranging from the inlet of a furnace main-body part to an outlet. Can be transported.

  (4) As one form of the mesh belt type continuous sintering furnace, when the tension dividing mechanism includes an intermediate conveyance mechanism, the intermediate conveyance mechanism includes an intermediate drive pulley that bridges the mesh belt between the inlet pulley and an outlet. And an intermediate driven pulley that bridges the mesh belt with the side pulley. At this time, the mesh belt has a slack portion formed between the intermediate drive pulley and the intermediate driven pulley.

  According to the above configuration, the mesh belt on the upstream side of the tension dividing mechanism is driven by the intermediate drive pulley so that the tension acts by dividing the mesh belt on the downstream side of the tension dividing mechanism. Then, due to the slack portion of the mesh belt, the tension of the mesh belt between the inlet side pulley and the intermediate drive pulley and the tension of the mesh belt between the intermediate driven pulley and the outlet side pulley substantially influence each other. And can be independent of each other. Therefore, the tension dividing mechanism can be configured with a simple configuration.

  (5) As an embodiment of the mesh belt type continuous sintering furnace, when the intermediate transport mechanism includes an intermediate drive pulley and an intermediate driven pulley, the intermediate drive pulley and the intermediate driven pulley are mutually long in the transport direction of the heating target. It is mentioned that they are arranged at a larger interval. At this time, the intermediate transport mechanism includes a transport roll that is disposed so as to fill the gap without the mesh belt being bridged, and transports the heating target from the intermediate drive pulley to the intermediate driven pulley.

  According to said structure, compared with the case where an intermediate drive pulley and an intermediate driven pulley are mutually arrange | positioned at a space | interval smaller than the length of the conveyance direction of heating object, the intermediate drive accompanying the length of the conveyance direction of heating object There are few restrictions on the diameter of the pulley. The interval here refers to the distance between the pulley axes. When both pulleys are arranged at a distance smaller than the length of the object to be heated in the transport direction, the diameter of both pulleys must be adjusted to prevent the object to be heated from falling or tilting greatly between the two pulleys. Of the above length. On the other hand, according to said structure, the diameter of an intermediate drive pulley can also be enlarged, for example irrespective of the said length of heating object. In that case, if the diameter of the conveyance roll is adjusted, the object to be heated can be easily conveyed without being inclined between the pulleys.

  (6) As an embodiment of the mesh belt type continuous sintering furnace, when the intermediate transport mechanism includes an intermediate drive pulley and an intermediate driven pulley, the intermediate drive pulley and the intermediate driven pulley are mutually long in the transport direction of the heating target. It is mentioned that they are arranged at an interval smaller than that.

  According to said structure, compared with the case where an intermediate drive pulley and an intermediate driven pulley are mutually arrange | positioned at a space | interval larger than the length of the conveyance direction of heating object, and are provided with the said conveyance roll, it is intermediate from an intermediate drive pulley. It is easy to shorten the length of the conveyance path to the driven pulley. Therefore, it is difficult for the temperature of the heating target to decrease during the conveyance process from the intermediate driving pulley to be heated to the intermediate driven pulley. Therefore, it is easy to satisfactorily sinter the object to be heated in the sintered part, and it is easy to produce a sintered body excellent in surface properties without wrinkles or rough skin.

  (7) As one form of the mesh belt type continuous sintering furnace, when the tension dividing mechanism includes an intermediate transport mechanism and a slack portion of the mesh belt, the intermediate transport mechanism is further hung on the slack portion of the mesh belt. For example, a tension pulley for adjusting the tension of the mesh belt may be provided.

  According to the above configuration, the frictional resistance between the intermediate drive pulley and the mesh belt can be adjusted, and the traveling of the mesh belt can be easily adjusted. Moreover, it is easy to adjust the length of the slack portion of the mesh belt.

  (8) As one form of the mesh belt type continuous sintering furnace, the tension dividing mechanism may include an auxiliary heater for keeping the object to be heated.

  According to said structure, a heating object can be heat-retained in the conveyance process of the heating object from the upstream of a tension | tensile_strength dividing mechanism to downstream. Therefore, even if the tension dividing mechanism becomes longer due to the structure of the tension dividing mechanism (for example, the size of the intermediate drive pulley), it is possible to suppress a decrease in the temperature of the heating target during the conveyance process of the tension dividing mechanism. Therefore, it is easy to satisfactorily sinter the object to be heated in the sintered part, and it is easy to produce a sintered body excellent in surface properties without wrinkles or rough skin.

  (9) A method for manufacturing a sintered body according to an aspect of the present invention is a method of manufacturing a sintered body that sequentially performs preheating, sintering, and cooling steps on a molded body that is conveyed from an upstream side to a downstream side by a traveling belt. A manufacturing method, in which a section in which a predetermined tension acts on a traveling belt is divided into an upstream side and a downstream side within a range corresponding to the end of the sintering process from the start end of the preheating process. Transport the body.

  According to said structure, the sintered compact excellent in surface property can be manufactured with sufficient productivity. By dividing the section where the predetermined tension acts on the traveling belt into an upstream side and a downstream side, the load on the traveling belt can be reduced and the high temperature creep characteristics can be improved. This is because it is easy to reduce the heating rate of preheating. By being able to slow the temperature increase rate of preheating, the length (time) of preheating can be taken longer than before, and the temperature rise of the molded body can be made smooth. Thereby, when the object to be heated contains a lubricant, it is easy to remove the lubricant sufficiently.

  (10) As one form of the manufacturing method of the said sintered compact, carrying out a multistage stacking and conveying a some molded object is mentioned.

  According to said structure, productivity of a sintered compact can be improved. This is because the life of the traveling belt can be extended, so that it is easy to stack in multiple stages, and a larger number of sintered bodies can be sintered at one time.

  (11) As one form of the manufacturing method of the said sintered compact, it is mentioned that the temperature increase rate of preheating is 40 degrees C / min or less.

  According to said structure, it is easy to manufacture the sintered compact which is excellent in surface property. Since the preheating length (time) can be taken longer than before by dividing the section where the predetermined tension acts on the running belt as described above, the rate of temperature rise can be 40 ° C./min or less, As a result, the temperature rise of the molded body can be smoothed. The preheating time can be, for example, 15 min or more. Then, when the object to be heated contains a lubricant, the lubricant can be sufficiently removed, and a sintered body free from surface stains, wrinkles, and rough skin can be produced.

<< Details of Embodiment of the Present Invention >>
Details of embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
A mesh belt type continuous sintering furnace 1 according to Embodiment 1 will be described with reference to FIG. The mesh belt type continuous sintering furnace 1 according to the first embodiment includes a furnace body 10 and an endless mesh belt 30. The furnace body 10 has a preheating part 11, a sintering part 13, and a cooling part 14, and a mesh belt 30 is stretched around the inlet side pulley 21 and the outlet side pulley 22 of the furnace body part 10. It is the same as that of the conventional mesh belt type continuous sintering furnace 100 described with reference to FIG. The main characteristic of the mesh belt type continuous sintering furnace 1 according to the first embodiment is that a predetermined tension acts on the mesh belt 30 between the inlet end of the preheating unit 11 and the outlet end of the sintering unit 13. It is in the point provided with the tension | tensile_strength dividing mechanism 12 which divides | segments an area into the entrance side and an exit side. That is, the mesh belt type continuous sintering furnace 1 according to the first embodiment is different from the furnace main body 110 of the conventional mesh belt type continuous sintering furnace 100 in the configuration of the furnace main body part 10, and the following description is different. Mainly. Constituent elements similar to those of the prior art are denoted by the same reference numerals as those in FIG. Then, the manufacturing method of the sintered compact using this mesh belt type continuous sintering furnace 1 is demonstrated.

[Overview]
The furnace body 10 preheats, sinters, and cools a heating target (not shown) that is placed on the mesh belt 30 and conveyed by the traveling of the mesh belt 30. The mesh belt 30 travels by driving at least one of the inlet side pulley 21 and the outlet side pulley 22 as a driving pulley. Here, the outlet pulley 22 is a drive pulley (the direction of rotation is indicated by an arrow), and the inlet pulley 21 is a driven pulley. The mesh belt 30 that has exited the outlet of the furnace body 10 passes under the furnace body 10 and is returned to the inlet of the furnace body 10. In the vicinity of the inlet side pulley 21 and the outlet side pulley 22, tension pulleys 211 and 221 for adjusting the tension of the mesh belt 30 are provided.

[Tension splitting mechanism]
The tension dividing mechanism 12 divides a section where a predetermined tension acts on the mesh belt 30 between the inlet end and the outlet side between the inlet end of the preheating portion 11 and the outlet end of the sintered portion 13. The tension of the mesh belt 30 in each section divided by the tension dividing mechanism 12 is substantially independent of each other and is in an independent state. That is, the section where the tension acts independently on the mesh belt 30 can be shortened. In particular, the length between the highest temperature end point T and the pulley closest to the upstream side (hereinafter referred to as a heating belt section L) can be shortened as compared with the prior art. Although the maximum temperature termination point T is shown in the center of the sintered portion 13 in the conveyance direction in FIG. 1 for convenience of explanation, it may differ in practice. Thereby, since the stress which acts on the mesh belt 30 can be reduced, high temperature creep deformation of the mesh belt 30 can be suppressed, and the life of the mesh belt 30 can be extended. The installation location of the tension dividing mechanism 12 can theoretically be provided in the middle of the preheating part 11 or in the middle of the sintering part 13 (particularly upstream of the maximum temperature termination point T). Provided between the sintered portion 13. The tension dividing mechanism 12 of this example includes an intermediate conveyance mechanism 120 that conveys a heating target on a tangent line that connects the inlet pulley 21 and the outlet pulley 22, and a slack portion 31 of the mesh belt 30 formed by the intermediate conveyance mechanism 120. With.

(Intermediate transport mechanism)
The intermediate transport mechanism 120 includes an intermediate drive pulley 121 that bridges the mesh belt 30 between the inlet side pulley 21 and an intermediate driven pulley 122 that bridges the mesh belt 30 between the outlet side pulley 22.

<Intermediate drive pulley>
The intermediate drive pulley 121 is separated from the mesh belt 30 on the downstream side (sintered portion 13 side) with respect to the tension dividing mechanism 12 so that the tension acts on the upstream side (the preheating portion 11 side). ) Mesh belt 30 is driven. The intermediate drive pulley 121 forms a slack portion 31 of the mesh belt 30 described later.

  The diameter and number of the intermediate drive pulley 121 are not particularly limited as long as a predetermined contact length (friction resistance) with the mesh belt 30 can be secured, and can be selected as appropriate. The larger the diameter of the intermediate drive pulley 121 is, the larger the contact length (friction resistance) with the mesh belt 30 is, and it is preferable. However, if the diameter is too large, the conveyance path from the preheating unit 11 to the sintering unit 13 tends to be long. There is a possibility that the temperature of the object to be heated is lowered during this conveyance process. For example, when the diameter of the intermediate drive pulley 121 is large, the number can be one, and when the diameter of the intermediate drive pulley 121 is small, the number can be plural.

<Intermediate driven pulley>
The intermediate driven pulley 122 spans the downstream side of the slack portion 31 of the mesh belt 30 and conveys the mesh belt 30 along the surface of the sintered portion 13. The diameter of the intermediate driven pulley 122 may be smaller than the diameter of the intermediate drive pulley 121. This is because the intermediate driven pulley 122 does not need to ensure frictional resistance with the mesh belt 30, unlike the intermediate drive pulley 121. If the diameter of the intermediate driven pulley 122 is made smaller than the diameter of the intermediate drive pulley, the friction resistance with the mesh belt 30 can be reduced and the mesh belt 30 can be easily driven. Moreover, since the conveyance path from the preheating unit 11 to the sintering unit 13 can be easily shortened, it is easy to suppress a temperature decrease of the heating target in the conveyance process.

  The mutual arrangement relationship between the intermediate drive pulley 121 and the intermediate driven pulley 122 is (1) an interval larger than the length in the conveyance direction of the heating target, or (2) an interval smaller than the length in the conveyance direction of the heating target. It may be arranged in. The length of the heating target in the transport direction is the length of the transport unit that behaves integrally. When the individual heating target (molded body) is placed directly on the mesh belt 30, the heating target (molding) Body) itself, and when a plurality of heating objects (molded bodies) are arranged in a tray and the tray is placed on the mesh belt 30, it is the length of the tray. This interval refers to the length between the shafts of the pulleys 121 and 122. In the case of (1) above, the intermediate transport mechanism may further include a transport roll 123 (described later) disposed so as to fill the gap so that the heating target does not fall between the pulleys 121 and 122. It is done. In the case of the above (2), it is considered that the interval is preferably half or less of the length of the heating target in the transport direction. This is because the intermediate driven pulley 122 can support the object to be heated before tilting between the pulleys 121 and 122. Here, the intermediate drive pulley 121 and the intermediate driven pulley 122 are arranged at a distance larger than the length of the heating target in the conveyance direction, and a conveyance roll 123 is provided therebetween.

<Transport roll>
The conveyance roll 123 is disposed so as to fill the gap between the pulleys 121 and 122 without the mesh belt 30 being bridged, and conveys the heating target from the intermediate drive pulley 121 to the intermediate driven pulley 122. Thereby, even if the mutual arrangement relationship between the intermediate drive pulley 121 and the intermediate driven pulley 122 is arranged at a larger interval than the length in the conveyance direction of the heating target, the heating target falls between the pulleys 121 and 122, It doesn't tilt greatly. The number of the transport rolls 123 can be appropriately selected according to the size and the length of the interval, and a plurality of transport rolls 123 are used here. The transport roll 123 is a driven roll in this example, but may be a drive roll.

<Others>
The intermediate transport mechanism 120 preferably includes a tension pulley 124 that is hung on the slack portion 31 of the mesh belt 30 and adjusts the tension of the mesh belt 30. The intermediate transport mechanism 120 may include an idler pulley 125 in addition to the tension pulley 124, but the idler pulley 125 may not be provided.

  The tension pulley 124 adjusts the contact length (friction resistance) between the intermediate drive pulley 121 and the mesh belt 30 in the circumferential direction. By adjusting the contact length, the tension of the mesh belt 30 between the inlet pulley 21 and the intermediate drive pulley 121 is applied independently of the mesh belt 30 between the outlet pulley 22 and the intermediate driven pulley 121. The contact length can be adjusted by adjusting the position of the tension pulley 124. In addition, the tension pulley 124 contributes to the length adjustment of the slack portion 31 of the mesh belt 30. Here, the tension pulley 124 is hung on the upstream side of the slack portion 31.

  The idler pulley 125 defines a slack amount of the slack portion 31 of the mesh belt 30 and a travel route to the intermediate driven pulley 122 of the mesh belt 30. That is, the slack amount of the slack portion 31 and the travel route of the mesh belt 30 are based on the position of the idler pulley 125. Here, the idler pulley 125 is provided between the tension pulley 124 and the intermediate driven pulley 122.

  The pulley at the position of the tension pulley 124 in FIG. 1 may also be driven as a plurality of intermediate drive pulleys. In that case, the pulley at the position of the idler pulley 125 may be a tension pulley.

(Auxiliary heater)
The tension dividing mechanism 12 may be provided with an auxiliary heater 126 (indicated by a two-dot chain line) that keeps the heating target conveyed from the preheating unit 11 warm. The periphery of the conveyance path to be heated in the tension dividing mechanism 12 is covered with a heat insulating material. Therefore, if the temperature drop of the heating target in the tension dividing mechanism 12 is small, the auxiliary heater 126 is not necessary and only the heat insulating material is required. However, for example, depending on the size of the intermediate drive pulley 121 and the length of the interval between the intermediate drive pulley 121 and the intermediate driven pulley 122, the length between the preheating unit 11 and the sintering unit 13 may be increased. . If the auxiliary heater 126 is provided, even if the length between the preheating unit 11 and the sintering unit 13 is increased as described above, the temperature of the preheated heating target is changed from the preheating unit 11 to the sintering unit 13. It can suppress that it falls from predetermined temperature in a conveyance process.

(Loose part)
The slack portion 31 of the mesh belt 30 divides a section where a predetermined tension acts on the mesh belt 30 upstream and downstream. By this division, the heating belt section L can be made to have a length L1 (FIG. 1) from the highest temperature end point T to the intermediate driven pulley 122, and a length L2 from the highest temperature end point T to the inlet side pulley 21 (FIG. 2). ), Which is shorter than the conventional heating belt section L. In addition, due to the presence of the slack portion 31, the tension of the mesh belt 30 between the inlet pulley 21 and the intermediate drive pulley 121 and the tension of the mesh belt 30 between the intermediate driven pulley 122 and the outlet pulley 22 Are substantially independent of each other and are independent of each other. Thereby, since the stress which acts on the mesh belt 30 in the sintered part 13 can be reduced, high temperature creep deformation of the mesh belt 30 can be suppressed, and the life of the mesh belt 30 can be extended.

[Effects of mesh belt type continuous sintering furnace]
According to the mesh belt type continuous sintering furnace 1 according to the embodiment described above, a section in which a predetermined tension acts on the mesh belt 30 between the preheating unit 11 and the sintering unit 13 by the tension dividing mechanism 12. Can be divided. Due to the division, the heating belt section L is made shorter than before, and the tension acting on the mesh belt 30 on the preheating part 11 side and the mesh belt 30 on the sintering part 13 side does not substantially affect each other. , They become independent from each other. As a result, the mesh belt type continuous sintering furnace 1 can exhibit the following effects.

  (1) Since the high temperature creep deformation of the mesh belt 30 can be suppressed, the life of the mesh belt 30 can be extended. Therefore, the number of times of maintenance of the mesh belt 30 and the number of times of replacement of the mesh belt 30 can be reduced.

  (2) The heating objects are easily stacked and conveyed, and a large number of heating objects are easily sintered at a time, so that the productivity of the sintered body is easily improved.

  (3) Since the length of the preheating portion 11 can be increased and the length (time) of the preheating can be made longer than before so that the heating target can be sufficiently preheated, the sintered body is excellent in surface properties without wrinkles or rough skin. It is easy to manufacture.

[Method for producing sintered body]
In the method of manufacturing a sintered body, preheating, sintering, and cooling steps are sequentially performed on a molded body that is conveyed from an upstream side to a downstream side by a traveling belt. The main feature of this method of manufacturing a sintered body is that, in the traveling belt, a section in which a predetermined tension acts on the traveling belt within the range corresponding to the end of the preheating step to the end of the sintering step is upstream. It is in the point which divides | segments into a downstream side and conveys a molded object. In the following description, after explaining the outline of the molded body to be heated, conveyance, preheating, sintering, and cooling of the molded body will be described in order. Here, the mesh belt type continuous sintering furnace 1 is used for the production of the sintered body, and the mesh belt 30 corresponds to the traveling belt.

(Molded body)
The molded object to be heated is, for example, a material for a machine part that is commercialized through sintering described later. Examples of the mechanical parts include sprockets, oil pump rotors, gears, rings, flanges, pulleys, and the like. The molded body is formed by compression molding raw material powder containing metal powder. The type of the metal powder can be appropriately selected according to the type of the machine part, and examples thereof include iron and iron alloys containing iron as a main component. The molded body preferably contains a lubricant. This is because when the raw material powder is compression-molded as described above to produce a compact, the raw material powder contains a lubricant, so that the lubricity at the time of molding is enhanced and the moldability is improved. The shape / size of the molded body is the shape / size along the final shape of the machine part.

(Transport)
The said molded object is conveyed to the above-mentioned furnace main-body part 10. FIG. The compact is conveyed to the furnace body 10 by being placed on the mesh belt 30 described above. On the mesh belt 30, a molded body may be directly placed, or a tray on which the molded bodies are arranged may be placed. When transporting a plurality of molded bodies, the plurality of molded bodies may be transported without being overlapped on the mesh belt 30, but the plurality of molded bodies may be stacked and transported on the mesh belt 30. This is because the mesh belt type continuous sintering furnace 1 can shorten the section in which the predetermined tension acts on the mesh belt 30 as described above, and can reduce the stress acting on the mesh belt 30. If stacked in multiple stages, the productivity of the sintered body can be increased. Multi-stage stacking of compacts can be performed by attracting the compacts with an electromagnet or a vacuum pad, or by gripping the compacts with a manipulator such as a robot hand.

  The compact is conveyed by dividing a section where a predetermined tension acts on the mesh belt 30 into an upstream side and a downstream side. Since the mesh belt type continuous sintering furnace 1 described above is used, the section that acts on the mesh belt 30 is divided between the preheating unit 11 and the sintering unit 13 with the intermediate drive pulley 121 and the slack portion 31 of the mesh belt 30. To do.

(Preheating)
Heat the molded body before sintering. By increasing the temperature of the molded body to a certain level or more by this preheating, the lubricant contained in the molded body can be removed. Thereby, when the molded body is sintered, wrinkles and rough skin are hardly generated, and it is easy to produce a sintered body having excellent surface properties. This preheating is performed by the preheating unit 11 described above. The preheating temperature can be appropriately selected according to the material of the lubricant contained in the molded body, and examples thereof include 300 ° C. or higher, and further 500 ° C. or higher. Examples of the preheating temperature include 730 ° C. or lower, and further 700 ° C. or lower.

  The heating rate by preheating can be slowed because the length of the preheating part 11 can be increased. The length of the preheating portion 11 can be increased when the tension dividing mechanism 12 is provided so that a section in which a predetermined tension acts on the mesh belt 30 can be shortened compared to the conventional case, and the tension dividing mechanism 12 is not provided. This is because the tension acting on the mesh belt 30 can be reduced in comparison. By slowing the heating rate, the temperature rise of the molded body can be made smooth, and it is easy to produce a sintered body excellent in surface properties without rough skin. The temperature rising rate can be set to 40 ° C./min or less, for example. For example, the temperature increase rate may be 10 ° C./min or more. If it does so, it will be easy to suppress the productivity fall of a sintered compact. The temperature rising rate is further set to 30 ° C./min or less.

(Sintering)
The molded body is sintered to produce a sintered body. This sintering is performed by the above-described sintered portion 13. As the sintering temperature, a temperature necessary for sintering can be appropriately selected according to the material of the molded body. For example, in the case of an iron-based sintered body, it is 1000 ° C. or higher, further 1100 ° C. or higher. The upper limit of the sintering temperature depends on the heat resistance of the mesh belt 30, but may be 1160 ° C. or lower, for example. The sintering time is about 20 minutes to 150 minutes.

(cooling)
Cool the sintered body. Since the temperature of the sintered body immediately after sintering is very high, the sintered body is cooled to lower its temperature. This cooling is performed by the cooling unit 14. The cooling includes, for example, blowing a refrigerant gas into the cooling unit 14. For example, nitrogen gas can be used as the refrigerant gas.

[Effects of sintered body manufacturing method]
According to the method for producing a sintered body described above, a plurality of molded bodies can be stacked and conveyed, or the preheating temperature can be increased, and a sintered body having excellent surface properties can be produced with high productivity. Can be manufactured.

  In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included. For example, two endless mesh belts may be provided for one furnace body 10. In this case, one mesh belt is stretched between the inlet pulley 21 and the intermediate drive pulley 121, and the other mesh belt is stretched between the intermediate driven pulley 122 and the outlet pulley 22. In this form, the slack portion 31 as described above is not necessary for each mesh belt. However, it is preferable to provide an intermediate conveyance mechanism as described above between the mesh belts in order to enable smooth conveyance of the heating target.

  A mesh belt type continuous sintering furnace and a method of manufacturing a sintered body according to one aspect of the present invention are used for firing various general structural parts (sprockets, rotors, gears, rings, flanges, pulleys, bearings and other mechanical parts such as bearings). It can be suitably used for the production of a ligated component.

DESCRIPTION OF SYMBOLS 1,100 Mesh belt type continuous sintering furnace 10,110 Furnace body part 11 Preheating part 12 Tension | splitting mechanism 120 Intermediate | middle conveyance mechanism 121 Intermediate drive pulley 122 Intermediate driven pulley 123 Conveyance roll 124 Tension pulley 125 Idler pulley 126 Auxiliary heater 13 Sintering Part 14 Cooling part 21 Inlet pulley 22 Outlet pulley 211, 221 Tension pulley 30 Mesh belt 31 Slack part

Claims (11)

A furnace body having a preheating part, a sintering part, and a cooling part, and stretched between an inlet side pulley and an outlet side pulley of the furnace body part, and travels from an inlet to an outlet of the furnace body part to be heated. A mesh belt type continuous sintering furnace comprising an endless mesh belt to be conveyed,
A mesh belt type continuous firing provided with a tension dividing mechanism that divides a section where a predetermined tension acts on the mesh belt into an inlet side and an outlet side from an inlet end of the preheating portion to an outlet end of the sintered portion. Blast furnace.   The mesh belt type continuous sintering furnace according to claim 1, wherein the tension dividing mechanism is provided between the preheating portion and the sintering portion.   The mesh belt type continuous sintering furnace according to claim 1, wherein the tension dividing mechanism includes an intermediate conveyance mechanism that conveys the heating target on a tangent line connecting the inlet pulley and the outlet pulley. The intermediate transport mechanism is
An intermediate drive pulley that bridges the mesh belt with the inlet pulley;
An intermediate driven pulley that bridges the mesh belt with the outlet pulley;
The mesh belt type continuous sintering furnace according to claim 3, wherein the mesh belt has a slack portion formed between the intermediate drive pulley and the intermediate driven pulley. The intermediate drive pulley and the intermediate driven pulley are arranged at a larger distance from each other than the length of the heating target in the transport direction,
The said intermediate conveyance mechanism is arrange | positioned so that the said mesh belt may not be spanned, and it may be arrange | positioned so that the space | interval may be filled, The conveyance roll which conveys the said heating object from the said intermediate drive pulley to the said intermediate driven pulley may be provided. Mesh belt type continuous sintering furnace.   The mesh belt type continuous sintering furnace according to claim 4, wherein the intermediate driving pulley and the intermediate driven pulley are arranged at a distance smaller than the length of the heating target in the transport direction.   The mesh belt type continuous firing according to any one of claims 4 to 6, wherein the intermediate transport mechanism includes a tension pulley that is hung on the slack portion of the mesh belt and adjusts the tension of the mesh belt. Blast furnace.   The mesh belt type continuous sintering furnace according to any one of claims 1 to 7, wherein the tension dividing mechanism is provided with an auxiliary heater for keeping the heating object warm. A method of manufacturing a sintered body, in which pre-heating, sintering, and cooling steps are sequentially performed on a molded body conveyed from the upstream side to the downstream side with a traveling belt,
Within the range corresponding to the end of the sintering process from the start end of the preheating process, the section where the predetermined tension acts on the travel belt is divided into the upstream side and the downstream side, and the molded body is conveyed. A method for manufacturing a sintered body.   The method for producing a sintered body according to claim 9, wherein a plurality of the molded bodies are stacked and conveyed.   The method for producing a sintered body according to claim 9 or 10, wherein a temperature increase rate of the preheating is 40 ° C / min or less.

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