JPH0155061B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The purpose of this invention is to process molybdenum materials, which cannot be plastically worked unless heated to a predetermined high temperature, while heating them together with a die to the required temperature. This invention relates to a hot working method using a swaging machine.

(Conventional technology and its problems) Hot forging using swaging has traditionally been known to process materials (wire rods or pipes) with low toughness into the required dimensions when sintering powder such as powder metallurgy products. However, during forging, the difference in temperature between the die and the forging temperature is usually extremely large.

To give an extreme example, when hot swaging a sintered tungsten rod, the initial reduction heats the material to 1500℃, but the temperature of the die that presses it is about 200℃ to 300℃. It is.

Therefore, because the temperature of the workpiece material drops quickly, the operator must quickly insert relatively short pieces of material into the swaging machine and withdraw the material before the temperature drops significantly.

Particularly when reducing the wall thickness of a pipe shape by hot working, as mentioned above, the heat capacity is even smaller than that of a solid material, so it is difficult to reduce the wall thickness during hot processing because it cools down extremely quickly. It was hot. A typical example is wall thickness reduction of molybdenum sintered pipes.

Conventionally, the objective can be achieved by heating the material immediately before processing, but it is difficult to heat each part of the forging machine to continue processing, and in reality, the die of a forging machine is heated at room temperature or at a relatively low temperature (for example, 300°C). used below).

(Means for Solving the Problems) However, the present invention solves the above-mentioned conventional problems by processing the material and the die while heating them to a high temperature with a difference of around 200° C. at most.

This invention makes the machining part of the die protrude into the air to increase the distance between the bucker and other power transmission members and the machining part as much as possible, and also takes a conductive heat shielding measure between the die and the buckker. By providing a cooling means, even when the die temperature is heated to be as close as possible to the material temperature, the power transmission member is configured to be kept at a relatively low temperature, and efficient heat transfer is possible. This allows for continuous processing, and since the temperature drop of the material is extremely small, the required processing time can be increased.

In other words, it is possible to create a large margin in both the pressing force and the machining time, and to provide a predetermined reduction, which has many advantages, such as the number of machining operations required to obtain the required dimensions.

In short, in order to manufacture products with the required dimensions from materials with relatively low tensile strength, such as materials molded by powder metallurgy, plastic working must be performed under high temperature heating, but even if the material is heated to high temperatures, the die will not work. When the temperature is normal or relatively low, the heated material cools rapidly, so it is necessary to process the material quickly until the necessary processing temperature and immediately reheat it when the temperature drops. However, it is extremely difficult to quickly manipulate high-temperature materials, and furthermore, it is extremely difficult to handle long materials such as pipes or wires in this manner. On the other hand, if the material is heated to the required temperature immediately before processing, the die will inevitably be heated, but if the die is heated,
The conduction heat heated up the backplane and other power transmission members, and there was a risk that it would become difficult to operate in practice. In order to solve the above-mentioned problems, the present invention makes the die protrude into space for a long time to minimize the effect of conduction heat, and also provides a conduction heat cutoff means and an active cooling means to reduce the high temperature heating of the die. They succeeded in processing the material in a way that did not adversely affect each part.

That is, in this invention, a conductive heat shielding means is provided between the die and the power transmission member, the heating part of the die is made to protrude into space, and the processing temperature of the molybdenum material is lowered.
This is a hot working method using a swaging machine with a tungsten carbide die heating temperature of 800°C to 1000°C and 800°C to 900°C.

Moreover, the heating was performed by direct flame heating using a gas burner.

The conduction heat cutoff means mentioned above is one that avoids surface contact between each processed member and provides a cooling means.

In this invention, it is recognized that the closer the material temperature is to the die temperature, the better;
Work problems also arise. Furthermore, if the temperature difference between the material and the die becomes less than 200°C, there is a risk that the significance of the high temperature will be rapidly lost.

Example 1 To explain with an example, the wall thickness is 3 mm and the inner diameter is 9 mm.
We were able to perform swaging reduction of molybdenum material with a thickness of 0.3 mm. The initial reduction in this hot processing uses a tungsten carbide mold (dice), which is constantly heated to 900 m
The temperature was kept at ℃.

Also, the core metal used for this was similarly made of tungsten carbide, and was kept integrally (fitted) with the material to be processed (pipe) at a temperature of 800°C to 850°C. The workpiece (pipe) that has been swaged under these conditions is
A temperature of 900°C was measured.

The hardness of the tungsten carbide mold (dice) and core metal at around 900°C is Rockwell hardness (approx. 50°RC), and the hot hardness of the workpiece is RC-
Since the temperature was 10 to 13 degrees, there were no problems with hot reduction.

Furthermore, if the reduction of the workpiece progressed, the workpiece (pipe) could be sufficiently worked at a hot working temperature of 600°C.

In that case, molybdenum-based high speed steel (JIS-SKH-9) could be used for the mold (dice) and core metal. In that case, the hot hardness of the mold at 600℃ is RC-52 to 51 degrees, and the hardness of the workpiece is RC-51.
Since the angle is around 15 degrees, reduction was possible with this processing method.

In the hot processing (swaging) method described above, the heating of the mold (dice), heating of the core metal, and material (pipe) to be pressed are all performed in an atmosphere of flame heated by a propane oxygen burner. It is.

Example 2 Next, other embodiments of the invention will be described.

A molybdenum pipe (formed by powder metallurgy) with an outer diameter of 12 mm and a wall thickness of 3 mm is heated to 1,000 yen using an open flame gas burner.
℃, inserted between tungsten carbide dies heated to 800℃, and swaged at a rate of 3 mm to 10 mm per second, resulting in a thickness of 30 mm in one pass.
The reduction was between % and 50%. Therefore, a pipe with an outer diameter of 9 mm and a wall thickness of 0.3 mm was obtained by passing through the pipe three times. This pipe later became a plain pipe that can be cold-plastically worked.

Embodiment 3 Next, an apparatus for implementing the present invention will be explained based on the drawings.

Thick plate-shaped housing 2 installed upright on machine base 1
A circular hole 3 is provided in the upper part of the housing 2 at right angles to the wide wall surface (front side), and the front part (fourth
The outer lace 4 is fitted to the left side in the figure, and the roller rack 5 is attached to the inside of the outer lace 4.
A large number of rollers 6, 6 (18 in the example)
are installed rotatably at equal intervals and concentrically. A circumferential recess 9 of a pulley 8 is rotatably fitted into the rear surface of the housing via a ball bearing 7 in the rear portion of the circular hole 3 (which has a slightly larger diameter than the front portion; on the right side in FIG. 4). do. A through hole 1 is provided in the center of the pulley 8 as shown in FIG.
0, and front fan-shaped spindles 11, 11a, 11b are bored on the outer surface of the through hole 10 at equal intervals and on the same circumference. The spindle 11,1
1a, 11b, the liners 12, 12, 12a, 12a, 12b, 12b are respectively fixed to the opposing walls, and the backer 13,
The size is such that 13a and 13b can be inserted therein.

Said liner 12, 12, 12a, 12a, 1
Two ball grooves 1 are provided on the opposing surfaces of 2b and 12b, respectively.
4 and 14 (circular cross section) are provided in parallel in the radial direction. Each liner (from now on, 12 will be used to represent all liners) has a backer 13, 13a, 1 having a front U-shaped recess in the middle.
3b is inserted, and the backers 13, 13a,
The bases of the dies 16, 16a, and 16b are fitted into the inside of the die 13b. The backer 13, 13
The liners 12, 12 are provided on the outer walls of a, 13b.
Ball grooves 17, 17 having an arcuate cross section are provided at positions corresponding to the ball grooves 14, 14, and a large number of balls 18, 18 (hard balls) are fitted between the ball grooves 14, 17. It is held so as not to escape by the tips of plate springs 19, 19a fixed to the inner and outer walls of the liner. Two ball grooves 20, 21 are provided facing each other on the inner walls of the buckers 13, 13a, 13b and the outer walls of the bases of the dies 16, 16a, 16b, respectively.
A large number of balls 2 are provided in each pair of ball grooves 20 and 21.
2 and 22 are respectively fitted, and each ball 22, 22 is prevented from escaping by a stop pin 23, 23 provided close to the inner end surface of the backer 13, 13a, 13b. Vent holes 24, 25 are provided in the backer 13, 13a, 13b and the dies 16, 16a, 16b in the horizontal direction, and the vent holes 24, 25 communicate with an air supply hole 26 provided in the center of the pulley 8. are doing. The spindle 11, 11a, 1
1b and the front end surfaces of the dies 16, 16a, 16b are provided with pins 27, 27a, 27b and stop pins 28, 28a, 28b, respectively, and plate springs 29, 29a, Both ends of the plate springs 29, 29a, 29b are hooked to the stop pins 28, 28a, 28b, so that each die 16,
A pre-pressure force is applied to 16a and 16b.

A screw hole 30 is horizontally bored in the lower part of the housing 2, and a mounting ring 32 of a motor 31 is screwed into the screw hole 30 to fix the motor 31 horizontally.
Pulley 34 fixed to shaft 33 of motor 31
A plurality of V-belts 35 are attached to the pulley 8 and the pulley 8. In the figure, 15 is a liner interposed between the end face of the die and the inner wall of the backer. In the above embodiment, three dice are arranged radially, but the number of dice is not limited to three, and two to four can be used as appropriate. In addition, the die is made of a material such as tungsten carbide that maintains the same hardness as special steel even at high temperatures (e.g., 800°C). The balls 18 and 22 are made of tungsten carbide, stainless steel, or other special steel. The heating of the die end in this invention uses a gas burner or other known means, and is not limited to the heating means.

Next, as shown in the front view, the die of this implementation device protrudes into space for a long time, and as shown in FIG. The heating device for the material and dies is placed on the left side (center left), and the processed material removal side (right side in Figure 2) is equipped with a material heat retention device or an inert gas, argon gas, hydrogen gas, etc. Special equipment can also be attached, such as providing an oxidation-preventing area with an atmosphere. In the figure, 40 is a front cover, and 41 is a rear cover.

Next, the operation of this implementation device will be explained.

Start the motor 31, heat the workpiece 36 to an appropriate temperature (for example, 1000°C), and insert it as shown by the arrow 37 in FIG.
Heat the processed end of 3b to 800℃. At this time, the spindles 11, 11a, 11b are rotated in the direction of arrow 38 by the pulley 34, belt 35 and pulley 8 (FIG. 3). As the spindle rotates, the backers 13, 13a, 13b also rotate in the same direction, so the contact between the outer end curve of the backer and the roller 6 causes the backers 13, 13a,
3b is pushed out toward the center as shown by arrow 39,
As a result, the dies 16, 16a, and 16b are also pushed out in the same direction to process the workpiece 36 into a predetermined external shape. In this case, since the processing end of the die is heated to 800° C., the temperature of the workpiece 36 hardly decreases, and continuous processing is possible. On the other hand, the die and the backer are in contact through the ball and the liner 12, but the ball is in line contact and the amount of heat transferred is severely limited due to thermal saturation, and the liner 12 is in contact with the air passing through the ventilation hole. (Same goes for the ball part) Since the ball part is cooled, the amount of heat conducted from that part is small, and since the backer and liner are also separated by the ball, the use of conductive heat becomes less and less. Since the total amount of heat conducted to the ball bearing is reduced, there is almost no adverse effect caused by the temperature rise in the vicinity of the ball bearing.

(Effects of the Invention) That is, according to the present invention, conduction heat isolation means is provided between the die and the power transmission member, and the swaging process is performed while the die is heated to the required processing temperature, so that the tensile strength is relatively low. Even small materials can be easily and efficiently plasticized.

However, as a result of heating the die, the temperature of the material being processed does not drop and is kept above a certain temperature.
Similar to cold working, continuous processing can be performed as many times as required.
In addition, since there is no temperature drop in the material, there is no need to take the material in and out for heating, which significantly improves work efficiency. It has great practical effects, such as being able to process even thin-walled pipes made of steel to the point where they have enough tensile strength to be drawn.

[Brief explanation of drawings]

Fig. 1 is a front view of the device used to carry out the invention, Fig. 2 is a partially cut side view, and Fig. 3 is a partially cutaway side view.
Figure 4 is a partially enlarged front view with the front cover removed, Figure 4 is a partially enlarged vertical side view, Figure 5 is an enlarged perspective view of the pulley with spindle, and Figure 6 is the liner, backer, and die. FIG. 2...Housing, 6...Roller, 8...Pulley, 11, 11a, 11b...Spindle,
12... Liner, 13, 13a, 13b... Backer, 18, 22... Ball, 24, 25...
Air vent.

Claims (1)

[Claims] 1. A conductive heat shielding means is provided between the die and the power transmission member, the heating part of the die is made to protrude into space, and the processing temperature of the molybdenum material is set to 800°C to 1000°C.
and the tungsten carbide die heating temperature is
Hot processing method using a swaging machine at 800℃ to 900℃. 2. A hot working method using a swaging machine according to claim 1, wherein the heating is direct heating using a gas burner.