JPS6021387Y2 - Heat treatment trolley - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a trolley for normalizing heat treatment of steel materials.

One of the processing methods for steel is Ac
After heating to an appropriate temperature of 3 points or Acm point or higher, there is usually an operation of cooling in air, and this is called normalizing.

This normalizing process is specified in JISB6911, and when air cooling is used for 1 cooling as part of the 6°2 section, each part of the processed material must be uniformly cooled at an appropriate cooling rate. do.

It is written as yo. On the other hand, in normalizing using a bogie furnace in actual operation, spacers 5 are installed on the bogie 2, as shown in the examples in FIGS. A commonly used method is to pile up the workpieces 6 through a heat treatment furnace 1, heat them to a predetermined level in the heat treatment furnace 1, and then pull the cart 2 out of the furnace and cool them with air.

In these figures, reference numeral 3 indicates wheels for running the trolley 2, 4 indicates a rail, 7 indicates a furnace door, and 8 indicates a part of a chain for opening and closing the furnace door 7.

In this case, it is easy to see that there is a considerable difference in the cooling rate of the workpiece 6 between those loaded at the outer periphery and those loaded at the center, even though they have the same heat treatment loft. can.

Although this is effective in removing the influence of the pre-processing of the workpiece 6 and refining the crystal grains, it has a significant effect on the mechanical properties, especially the hardness and tensile strength, resulting in large variations. There is.

As described above, normalizing by conventional methods is inconvenient for heat treatment of parts that require stable strength (hardness).

On the other hand, in order to obtain stable strength (hardness), it is sufficient to reduce the amount of loaded workpieces 6 and ensure that all products are in a stable air-cooled state. This results in problems such as excessive use of energy, reduced heat treatment efficiency, and increased processing costs.

The present invention aims to solve these problems relatively easily and to obtain stable normalizing strength (hardness) without reducing the loading amount as much as possible, thereby contributing to energy saving. It was proposed for this purpose.

In other words, the present invention aims to make the cooling rate of the inside and outside as uniform as possible and to obtain stable normalizing strength (hardness) even if pile-up operation is performed in a normalizing furnace for steel materials. It is an object of the present invention to provide a heat treatment trolley equipped with a mechanism for uniformly ejecting cooling gas between workpieces.

The present invention will be specifically explained below with reference to embodiments shown in FIGS. 3 to 5.

In those figures, 13 has multiple pairs at the bottom (3 pairs in this example)
A trolley body 9 has running wheels 13a, and a plurality of (five in this example) cooling gas supply holes are provided near the bottom of the trolley body 13 in parallel with each other and at equal intervals. A plurality of cooling gas supply pipes 9 are provided, and one end of each of the plurality of cooling gas supply pipes 9 is communicated with a communication pipe 9a as shown in FIG. 5, and each other end is closed.

Furthermore, one of the cooling gas supply pipes 9 extends to the outside of the truck body 13, and an on-off valve 11 is attached to the extending end.

9b is a plurality of branch pipes (in this example, four branch pipes for each cooling gas supply pipe) branched from each cooling gas supply pipe 9 at appropriate intervals and having an upper end opening on the upper surface of the truck 13. A cooling gas injection pipe 10 having a large number of cooling gas injection holes 10a at appropriate intervals along the vertical direction on the peripheral wall is attached to the upper end opening of each branch pipe 9b.

(See Figures 3 and 4) 14.14' is a workpiece loaded between the cooling gas injection pipes 10, 15 is a spacer, and 12 is a lid that closes the upper end opening of the branch pipe 9b as necessary. are shown respectively.

One embodiment of the heat treatment trolley of the present invention is constructed as described above, and when heat treating (normalizing) the workpieces 14, 14', etc. with this trolley, first, the cooling gas injection pipe is A spacer 15 is placed on the upper surface of the truck body 13 between the spacers 10 and 10.
After loading the truck body 13 through a heat treatment furnace, the trolley body 13 is introduced into a heat treatment furnace as shown in FIG. 2, and a predetermined heat treatment operation is performed.

(In this case, the on-off valve 11 is closed, and the cooling gas injection pipe 10 is connected to the branch pipe 9 as appropriate depending on the size of the workpiece.)
A lid 12 is fitted between the upper ends of the branch pipe 9b and does not require an opening of the branch pipe 9b.

) Next, after pulling the truck body 13 out of the furnace, the on-off valve 11 is opened and high pressure cooling air is introduced into the cooling gas supply pipe 9 from a high pressure cooling gas source (not shown).

Then, the high-pressure cooling gas is sent to each cooling gas injection pipe 10 through each cooling air supply pipe 9, communication pipe 9a, and branch pipe 9b, and is sent to the red-hot workpiece 14, 14 from a large number of cooling gas injection holes 10a. ' sprayed onto the workpiece 14.1
4' is uniformly cooled at a cooling rate with little variation.

Since the heat treatment trolley of the present invention has the above-mentioned configuration and function, according to the present invention, the entire surface of the workpiece is cooled uniformly at a cooling rate with little variation. The practical effect is that stable normalizing strength (hardness) of the workpiece can be obtained.

According to an embodiment of the present invention, a diameter of 100s++ is 5
When 45C round bars are normalized in piles using the conventional method, the hardness is HB205 at the outer periphery and HB165 at the center.The variation in hardness within the heat treatment loft is HB4Q. On the other hand, according to the present invention, results were obtained in which the variation in hardness between the inside and outside was kept to about HB20 at most.

In the above embodiment, an example of normalizing processing of a workpiece with a relatively simple shape was given. If loading is difficult or if there are small holes in the workpiece, do not install the cooling gas injection pipe 10 at the upper end opening of each branch pipe 9b. Alternatively, cooling gas may be directly injected from the upper end opening of each branch pipe 9b to cool the workpiece.

In addition, in the case of a workpiece with a complicated shape, the cooling gas injection pipe 10
may be bent as appropriate to match the shape of the workpiece.

[Brief explanation of drawings]

1 and 2 are schematic explanatory views of the state of heat treatment of a workpiece using a conventional heat treatment trolley, in which FIG. 1 is a vertical front view, FIG. FIG. 5 is a schematic explanatory diagram of an embodiment of the present invention, and FIG. 3 is a longitudinal sectional front view;
FIG. 4 is a longitudinal side view, and FIG. 5 is a view taken along the line ■-■ in FIG. 3 to 5, 9: cooling gas supply pipe, 9a: communication pipe, 9b = branch pipe, 1
0: Cooling gas injection pipe 10a: Cooling gas injection hole, 11:
Opening/closing valve, 13: Cart body, 14, 14': Workpiece.

Claims (1)

[Scope of utility model registration request] It has a plurality of branch pipes 9b that are bored parallel to each other at appropriate intervals near the bottom of the truck body 13, are branched at appropriate intervals along the longitudinal direction, and open to the upper surface of the truck body 13. A heat treatment trolley, characterized in that it is equipped with a plurality of cooling gas supply pipes 9, one end of each of which is communicated via a communication pipe 9a, and a plurality of cooling gas supply pipes 9, each of which is communicated with a high-pressure cooling gas source via an on-off valve 11.