JPS5910438A - Heating furnace for forging - Google Patents

Abstract

PURPOSE:To improve thermal efficiency and to decrease considerably scale loss by constituting one passage with two hollow cylinders which fit to each other freely slidably. CONSTITUTION:A passage for a blank material for forging is constituted of a hollow cylinder 7 having the inside diameter slightly larger than the inside diameter of said blank material and a hollow cylinder 8 fitting freely slidably onto the one end part of said cylinder 7, and two pieces a set of these cylinders 7, 8 are inserted into the combustion chamber 2 and preheating chamber 3 of a furnace body 1 in the direction where the cylinders penetrate through both chambers. The outside end part of the cylinder 7 having the smaller diameter of the two cylinders 7, 8 is fixed to the furnace wall at the terminal of the chamber 3 and the outside end part of the cylinder 8 to the furnace wall at the front end of the chamber 2, respectively immovably in the longitudinal direction. The cylinder 7 is made of stainless steel and the cylinder 8 of a silicon carbide material bound with silicon nitride.

Description

[Detailed Description of the Invention] The present invention relates to a heating furnace used to heat forging materials, and provides a furnace with high thermal efficiency and extremely low scale loss, and allows smooth supply and discharge of forging materials without any hindrance. The main objective is to make it possible to carry out the same operations as possible, and the secondary objective is to reduce the overall cost as much as possible by constructing the main parts of the furnace using inexpensive materials.

Conventional combustion furnace type heating furnaces have the disadvantage that the flame or combustion gas comes into direct contact with the forging material, resulting in significant scale formation, resulting in a large amount of material loss and the time required to remove the scale. .

In view of the above-mentioned drawback 1c of the conventional method, this invention first uses a hollow cylinder with a diameter slightly larger than that of the forging material as a passage for the material, and by installing this in the furnace, the material can be processed without coming into direct contact with flame or combustion gas. It is designed to be heated.

However, in this case, if a long hollow cylinder is simply installed in the furnace, the hollow cylinder will expand due to heating, and its end will protrude into the material supply side or discharge side, causing the material to be fed into the furnace. There is a risk that it may interfere with the discharge.

Therefore, in the present invention, one passage is constituted by two hollow cylinders whose bases are slidable relative to each other, so that the thermal expansion of the hollow cylinders is absorbed inside the furnace.

Further, in this invention, the two hollow cylinders are each made of a material that corresponds to the temperature at that position.

The details of the present invention will be explained below based on an illustrated embodiment.The furnace body 1 has a structure in which a combustion chamber 2 and a preheating chamber 3 extending horizontally from the combustion chamber 2 are formed inside. The burner 4 is installed with an opening 5 and a flue 6 communicating with the end of the preheating chamber 3. 7 and 8 are a pair of hollow cylinders that serve as passages for the forging material, one of which 7 has an inner diameter slightly larger than the material to be heated, and the other 8 has a slightly larger diameter. The inner end of the large-diameter hollow cylinder 8 is slidably fitted onto the inner end of the small-diameter hollow cylinder 7, and the two communicate in a straight line. The small diameter hollow cylinder 7 is made of stainless steel, and the large diameter hollow cylinder 8 is molded from a refractory material such as a silicon nitride bonded silicon carbide material. These hollow cylinders 7°8 are such that the small diameter hollow cylinder 7 is located on the side of the preheating chamber 3, and the large diameter hollow cylinder 8 is located on the side of the combustion chamber 2, and two of them penetrate both chambers 2 and 3. The outer end 7a of the small-diameter hollow cylinder 7 is placed on the furnace wall at the end of the preheating chamber 3, and the outer end 8a of the large-diameter hollow cylinder 8 is placed in the combustion chamber. 2. They are each fixed to the furnace wall at the front end so that they can rotate freely but remain immovable in the length direction. The outer end 7a of the small-diameter hollow cylinder 7 penetrates the furnace wall and opens to the outside, and the outer end 8a of the large-diameter hollow cylinder 8 is connected to the furnace wall while being located inside the combustion chamber 2. The direction toward the formed outlet 9 is open. It is assumed that these two sets of hollow cylinders 7.8 are installed in a plurality of rows along the width direction of the furnace body 1 (direction perpendicular to the plane of paper in FIG. 1).

A partition plate 10 is provided upright in the lower part of the preheating chamber 3, and each part of the hollow cylinders 7, 8 is supported by the partition plate 10. 11 is a partition plate provided at the upper part of the preheating chamber 3, and its hanging length can be adjusted. The furnace body 1 is divided into a lower part 1a and an upper part, and the upper part is further divided into a front part 1b and a rear part 1c.
are connected by.

In the above configuration, the forging materials are successively inserted from the outer end 7a of the hollow cylinder opened to the outside of the furnace at the rear end of the furnace main body 1, and thereby the materials are transferred from the hollow cylinder 7 to the outer end of the large-diameter hollow cylinder 8. Push the parts in order.

While the material moves through the rain hollow tubes 7 and 8, it is heated by the combustion heat of the burner 4, but since this material is surrounded by the walls of the hollow tubes 7 and 8, there is no flame or combustion. It is heated indirectly without direct contact with the gas. In addition, since the material moves sequentially from the low temperature area at the end of the preheating chamber 3 to the high temperature area, it is heated rapidly, and the material that has finished heating is pushed by the following material and taken out from the outer end 8a of the hollow cylinder 8. It falls into mouth 9.

Furthermore, the rain hollow cylinders 7 and 8 expand and expand due to heating, but the inner ends of each hollow cylinder 7 and 8 protrude inward by the amount of expansion, and the depth of the base of the rain hollow cylinders 7 and 8 becomes smaller. By increasing the depth, the expansion of the rain hollow cylinder 7°8 is absorbed. Rain hollow tube 7
, 8 are held in place on the furnace wall without moving longitudinally.

As mentioned above, in this invention, a hollow tube is installed inside the furnace body as a passage for the forging material, and since the material is moved inside the furnace body while being surrounded by the hollow tube, the material is exposed to flame. There is no contact with combustion gas, and there is significantly less scale generation1.
．． A.

In that case, simply installing a hollow cylinder inside the furnace body will not work.
It is expected that various problems will occur due to thermal expansion of the hollow cylinder. For example, if the end of the discharge side of a hollow cylinder protrudes into the outlet due to thermal expansion, that protruding part will be removed from the combustion chamber and will hardly be heated, so the material will cool down while passing through this protruding part and be forged. Adversely affect.

Further, if the supply side end of the hollow cylinder protrudes outside, the positional relationship with the material supply stage changes, so that the material cannot be transferred smoothly.

On the other hand, in this invention, two hollow cylinders are used as a set, and the inner ends of the hollow cylinders are mounted on a bottom that can be slid 1 nK toward each other, so that the thermal expansion of the hollow cylinders is absorbed by changes in the depth of the bottom of the hollow cylinders. The outer end of the hollow cylinder is held in a fixed position relative to the furnace wall, so that the above-mentioned disadvantages do not occur.

Furthermore, in the present invention, since one passage is constituted by two hollow cylinders, each hollow cylinder can be made of a material suitable for its temperature range, thereby reducing costs. As shown in the example, if the large-diameter hollow cylinder on the side of the combustion chamber is made of silicon nitride bonded silicon carbide material, and the small-diameter hollow cylinder on the preheating chamber is made of stainless steel, it can withstand the high temperature of the combustion chamber sufficiently. Moreover, the length of the hollow cylinder of expensive refractory material can be minimized.

Furthermore, because the hollow cylinder that serves as a passage for the forging material is supported in the space between the preheating chamber and the combustion chamber in the form of a bridge, extremely efficient heating can be achieved through average heat transfer from the entire circumference of the hollow cylinder, reducing fuel consumption. is reduced by half compared to the conventional method, making it extremely economical.

Note that the hollow cylinder may be cylindrical or rectangular.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of the heating furnace of the present invention. 1... Furnace body, 2... Combustion chamber, 3...
Preheating chamber, 7, 8... hollow cylinder, 7a, Rh...
outer end.

Claims (2)

[Claims] (1) A passage for the forging material is composed of a hollow cylinder with an inner diameter slightly larger than the forging material, and a hollow cylinder whose outer surface is slidably connected to one end of the hollow cylinder, and these two hollow cylinders are connected to each other. The set is inserted into the combustion chamber and preheating chamber of the furnace main body in a direction that penetrates both chambers, and the outer end of the small diameter hollow tube of the rain hollow tube is placed on the furnace wall at the end of the preheating chamber, and the large diameter hollow tube is inserted into the furnace wall at the end of the preheating chamber. A heating furnace for forging in which the outer ends of the cylinders are fixed immovably in the longitudinal direction to the furnace wall at the front end of the combustion chamber. (2) Claim 1, wherein the small-diameter hollow cylinder is made of stainless steel, and the large-diameter hollow cylinder is made of silicon nitride-bonded silicon carbide material.
The heating furnace for forging described in .