JP2993989B2 - Method for producing band-shaped compact by powder rolling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a strip-shaped compact by rolling a powder raw material such as a metal powder.

[Prior Art] As a method of obtaining a product having a predetermined shape from a powder raw material, various methods including press molding have been conventionally employed. Above all, powder rolling is suitable for mass production as a method for continuously and efficiently producing a strip-shaped compact.

In powder rolling, generally, a hopper for accommodating a powder raw material is arranged above a pair of rolling rolls provided horizontally or diagonally with respect to each other, and the powder raw material is poured into a roll gap from this hopper and compacted by a rolling roll. To form a band-shaped molded body.

At this time, since the powder raw material poured into the roll gap has fluidity, it tends to flow out to the side of the rolling roll. For this reason, the supply amount of the powder raw material tends to be insufficient at the end portion of the roll gap in the roll axis direction, which causes a decrease in density and a decrease in plate thickness at both end portions of the manufactured band-shaped body. In addition, when the powder material flows out of the roll gap significantly, the molding itself may not be possible.

Therefore, it is necessary to prevent the powder material from flowing out to the side, and various proposals have been made conventionally. For example, a method of providing a flange at the barrel end of one roll, a method of further arranging a pair of pressing rolls at both barrel ends of the roll, and a method of forming concave and convex caliber rolls for the roll are known. ing. However, in any of these methods, there is no flexibility in the width of the obtained compact because it is restricted by the barrel length of the rolling rolls. Therefore, only a product having a constant plate width is manufactured, and a manufacturing facility capable of producing a band-shaped molded body having a size corresponding to the market demand cannot be provided.

Further, in order to prevent the powder raw material from flowing out to the side and increase the degree of freedom regarding the plate width of the compact, it has been proposed to partition both ends of the roll gap in the roll width direction with side dams. In this method, as shown in FIGS. 4 and 5, a pair of flat rolls are used as the rolling rolls 1 and 2 and a side dam whose gap is adjusted according to the width of the compact is used.
3 and 4 are arranged in the powder reservoir 5, and the side weirs 3 and 4 prevent the powder raw material 6 from flowing out to the side.

However, even if the both ends of the powder pool 5 in the roll axis direction are partitioned by the side dams 3 and 4, the powder raw material 6 cannot be completely prevented from flowing out to the side. That is, the side weir 3,
4 has beak-shaped tapered tips 3a, 4a, and these tips 3a, 4a are used to hold powder pool 5 between rolling rolls 1, 2.
Is plugged in. From the point of completely eliminating the outflow of the powder raw material 6 to the side, the powder material 6 is compacted and the kissing points 7 of the rolling rolls 1 and 2 where the fluidity is completely lost.
Until then, it is necessary to insert the tip portions 3a, 4a of the side weirs 3, 4. However, the tip 3a, 4a up to the kissing point 7
In this case, the side weirs 3 and 4 themselves are bitten by the rolling rolls 1 and 2 and cannot be rolled.

Therefore, as shown in FIG. 5, it is required to set the tip portions 3a and 4a of the side weirs 3 and 4 at an intermediate position in the powder pool 5 between the rolling rolls 1 and 2, and Tip 3a, 4a
It is unavoidable that a gap 8 is formed between the roll and the peripheral surfaces of the rolling rolls 1 and 2. As a result, the powder raw material 6 flows out from the gap 8 to the side.

Further, both lower edges of the side weirs 3, 4 are formed into arcuate portions 3b, 4b having a shape along the peripheral surface of the rolling rolls 1, 2. However, the curvatures of the arc-shaped portions 3b and 4b are
It is not possible to completely match the curvature of the peripheral surface, and in fact, a slight gap is formed between the lower edge of the side weirs 3, 4 and the peripheral surface of the rolling rolls 1, 2. This gap is also a place where the powder raw material 6 leaks.

When such a powder material 6 flows out, the rolling rolls 1,
The supply amount distribution of the powder raw material 6 in the axial direction 2 becomes non-uniform, and the powder raw material 6 becomes insufficient particularly near the side weirs 3 and 4. As a result, defects such as low density and poor plate thickness occur at both ends in the width direction of the compacted compact. In order to obtain a product having uniform quality from the molded product, it is necessary to trim both ends, and this trimming greatly reduces the product yield.

Therefore, rolling a powder raw material while feeding a wire into the inside of a side weir is introduced in Japanese Patent Publication No. Sho 62-54361. The wire fed into the inside of the side weir closes the gap between the side weir and the rolling roll, and prevents the powder material from flowing out. This wire is rolled integrally with the powder raw material and separated from the compact after rolling. Further, a method has been considered in which a powder material is kneaded with a binder or the like to reduce the fluidity itself of the powder material, thereby preventing the powder material from flowing out to the side.

[Problems to be Solved by the Invention] However, in the method of feeding the wire into the inside of the side weir, if the fed wire is caught in the powder raw material and separated from the side weir, the expected effect cannot be expected. Also, depending on the type and particle size of the powder raw material to be compacted,
The type, thickness, etc. of the wire rod that closes the gap between the side weir and the rolling roll and has the property of being easily separated from the formed body change. Therefore, it is difficult to select the type and diameter of the wire and to adjust the supply method, and it is still impossible to completely prevent the leakage of the powder material.

Also, in the method of kneading a binder or the like to the powder raw material,
Since the binder is contained in the compacted compact, it is necessary to remove the binder in the subsequent compact sintering process. Further, there arises a problem that it is difficult to supply the powder raw material to the powder rolling mill due to the deterioration of the material due to the binder and the decrease in the fluidity. For these reasons, the method of kneading the binder is not a satisfactory solution.

The present invention has been devised to solve such a problem, and by supplying a liquid to the surface of a rolling roll in contact with a side weir, it is possible to prevent powder material from flowing out to the side, and to prevent the powder material from flowing out in the width direction. An object is to produce a molded article having a uniform density and thickness.

[Means for Solving the Problems] In order to achieve the object, a method for producing a strip-shaped molded article of the present invention comprises the steps of: mixing a powder raw material between a pair of rolling rolls partitioned by a side weir movable in a roll axis direction; While supplying, when the powder raw material is rolled by the rolling roll to produce a band-shaped molded body, the lower edge of the side weir is on the surface of the rolling roll facing the lower surface, and the powder is supplied from the upstream side with respect to the rotation direction of the rolling roll. It is characterized by supplying a liquid for preventing material leakage.

As the liquid supplied to the peripheral surface of the rolling roll, an organic solvent can be used. Further, the supply amount is preferably adjusted to an amount at which the liquid that has entered the molded body evaporates in the air before sintering the molded body.

[Operation] The liquid supplied to the peripheral surface of the rolling roll wets the peripheral surface of the roll near the side weir. The wet roll peripheral surface has a large power of capturing the powder raw material, on which the powder raw material is deposited as an aggregate having a certain size. Then, since the lower edge of the side weir faces immediately near the roll peripheral surface of this portion, the gap between the lower edge of the side weir and the roll peripheral surface is closed by the powder aggregate. As a result, the powder raw material is prevented from flowing out to the side.

In addition, the powder aggregate is simply deposited on the wet roll peripheral surface, and is temporarily fed into the roll gap to form a compact and does not grow into a large lump.
Therefore, there is no adverse effect on the compaction of the powder raw material.

A method for manufacturing a strip-shaped molded article according to the present invention will be specifically described with reference to FIG.

A pair of flat rolls are arranged parallel to each other as rolling rolls 1 and 2, a roll gap between the rolling rolls 1 and 2 is partitioned by side dams 3 and 4, and a powder pool 5 is provided. Powder pool 5
Above the hopper, a hopper (not shown) containing the powder raw material is arranged, and the powder raw material 6 is supplied from the hopper to the powder reservoir 5.
Supplied to The powder raw material 6 is sent from the powder pool 5 to the kissing point 7 of the rolling rolls 1 and 2, and after being compacted, is sent out as a compact 9 from between the rolling rolls 1 and 2.

Here, the four points _{P 1, P 2, P 3} , P 4 in contact with the peripheral surface of the side dam 3, 4 rolling rolls 1, 2, four liquid supply nozzle 10a~10d
Are each oriented. Each contact portion from the liquid supply nozzle _{10a~10d P 1, P 2, P} 3, the liquid 11 toward the P ₄ is supplied. As a result, the peripheral surfaces of the rolling rolls 1 and 2 passing through the contact points P ₁ , P ₂ , P ₃ and P ₄ advance to the kissing point via the powder reservoir 5 while being constantly wet with the liquid 11.

Then, the liquid 11 adhering to the peripheral surfaces of the rolling rolls 1 and 2 in a streak shape captures the powder raw material 6 that has entered between the side weirs 3 and 4 and the peripheral surfaces of the rolling rolls 1 and 2. The powdery raw material 6 wetted by the liquid 11 is temporarily accumulated as an aggregate on the peripheral surfaces of the rolling rolls 1 and 2, and the lower edges of the side weirs 3 and 4 and the rolling rolls 1 and 2.
Close the gap between the peripheral surface. As a result, the powder material 6 does not flow out of the powder reservoir 5 to the side.

In addition, even if the amount of the powder raw material 6 flowing out to the side is small, the product characteristics such as the density and the plate thickness become non-uniform, which causes a decrease in the yield when trying to obtain the product from the compact. . However, most of the powder material 6 is prevented from flowing out by the side weirs 3 and 4, and the amount of the powder material 6 leaking from between the side weirs 3 and 4 and the peripheral surfaces of the rolling rolls 1 and 2 is extremely small. It is slight. Therefore, the intended purpose can be sufficiently achieved even with a small powder capturing force of the liquid 11 attached to the peripheral surfaces of the rolling rolls 1 and 2.

The liquid 11 attached to the peripheral surfaces of the rolling rolls 1 and 2 is rolled together with the powder raw material 6 and penetrates into both ends of the compact 9. It is preferable that the liquid 11 evaporates and disappears by a subsequent step such as sintering of the compact. by this,
The operation of separating the liquid from the molded body in the subsequent process is not required.

The type of the liquid 11 to be used is not particularly limited as long as it wets the peripheral surfaces of the rolling rolls 1 and 2. For example, water, various organic solvents, and the like are used. However, the vaporization rate is somewhat small,
2. It is necessary that the liquid 11 supplied to the peripheral surface does not vaporize and disappear until the liquid 11 reaches the kissing point 7. Conversely, if the liquid 11 is difficult to vaporize or if the supply amount of the liquid 11 is too large, the subsequent process will be hindered. Therefore, it is necessary to determine the type and supply amount of the liquid 11.

The aqueous liquid 11 takes a relatively long time to be removed from the molded body 9 by vaporization. Further, the powder raw material 6 such as a metal powder may be contaminated by oxidation or the like. In such a case, it is preferable to use an organic solvent such as alcohol or trichloroethane, which has a higher vaporization rate than water.

When the liquid 11 is supplied in excess, the powder raw material 6 at both ends of the powder reservoir 5 is compacted in a slurry state, and characteristics such as density at both ends of the obtained molded body 9 are different from those at both ends. It will be. Moreover, sufficient evaporation and disappearance of the liquid 11 do not proceed until the subsequent step, and it is necessary to separate and remove the liquid 11 prior to sintering the molded body. For this reason, it is preferable to adjust the supply amount of the liquid 11 to an amount that easily vaporizes and disappears in the atmosphere.

Note that the viscosity of the liquid 11 depends on the
In capturing, higher is preferable. In this regard, for example, when an alcohol is used, relatively higher alcohols such as butyl alcohol are suitable as the liquid 11.
However, this type of higher alcohol has a disadvantage in that it is difficult to vaporize. Therefore, it is also possible to employ means for blowing hot air to both ends of the molded body 9 to promote the vaporization of the liquid 11. This hot-air blowing can be performed between the rolling rolls 1 and 2 shown in FIG. 1 and immediately before being sent out to the formed body 9 or to a subsequent step.

Example An example will be described below.

Example 1 Iron powder prepared to have a particle size of 150 μm or less was used as powder raw material 6. As the powder rolling machine, a pair of rolling rolls 1 and 2 arranged horizontally was used, and the both ends of the roll gap were separated by side dams 3 and 4 at an interval of 100 mm. Rolling speed 2
The feed rate of the powder raw material 6 from the hopper to the powder pool 5 was adjusted so that the density was set to 80% according to the rolling speed.

Further, the rolling rolls 1, 2 the peripheral surface of four positions P ₁ to P ₄ which side weirs 3 and 4 are in contact, in proportion to the rolling speed of one of the liquid supply nozzle 10a~10d per 2～10Cc / min feed rate Supplied butyl alcohol. For comparison, the powder raw material 6 was rolled under the same conditions except that butyl alcohol was not supplied.

 Table 1 shows the properties of the obtained molded body.

In the comparative method not using butyl alcohol, when the rolling speed was low, the ratio of the powder material flowing out to the side was large. As a result, as shown in Table 1, rolling was impossible. Even when the rolling speed is high, the shortage of the powder raw material 6 occurs at both ends of the powder reservoir 5 due to the outflow to the side, and the result is a wavy shape at the end of the compact. It is appearing. Moreover, the width of the molded product was significantly smaller than the interval between the side weirs of 100 mm.

On the other hand, in the method of the present invention in which butyl alcohol was supplied to the peripheral surface of the rolling roll, a molded product having a linear end portion was obtained. Further, the plate width of the molded product corresponded to the interval between the side weirs.

FIG. 2 is a graph showing a density distribution in a sheet width direction of a compact manufactured at a rolling speed of 5 m / min. As is clear from FIG. 2, the molded product manufactured by the comparative method has a very small portion where the target density ratio can be obtained. On the other hand,
It can be seen that the density distribution in the sheet width direction is significantly improved in the molded article manufactured by the method of the present invention.

Example 2 A high-speed tool steel powder having a particle size of 100 μm or less was used as a powder raw material, and a compact having a thickness of 2 mm and a width of 180 mm was produced by a powder rolling mill having an equipment configuration as shown in FIG. . At this time, the rolling speed was set to 2 m / min, and the powder raw material 6 was transferred from the hopper to the rolling roll 1 at a flow rate such that the density ratio became 85%.
The powder was supplied to the powder reservoir 5 between the two.

The side weirs 3 and 4 rolling rolls 1, 2 the peripheral surface of four positions P ₁ to P ₄ in contact with the rolling rolls 2, one of the liquid supply nozzle 10a~10d
Trichloroethane was supplied at a supply rate of 15 cc / min.
As a comparison, a molded body was produced under the same conditions except that trichloroethane was not supplied.

FIG. 3 shows the density distribution in the width direction of the obtained molded body.
As is apparent from FIG. 3, it is understood that the molded article having a substantially uniform density distribution in the width direction is manufactured by the method of the present invention. On the other hand, in the molded body manufactured by the comparative method,
The portion satisfying the target density ratio of 85% was only an area having a distance of up to 20 mm on both sides with respect to the center in the width direction. Further, the plate width itself of the molded body was only about 130 mm, which was much smaller than the set interval of the side weirs of 180 mm. From this comparison, according to the method of the present invention, it is possible to increase the sheet width of the molded body and to make the density distribution uniform in the sheet width direction.

[Effects of the Invention] As described above, in the present invention, the liquid is supplied from the upstream side in the rotation direction of the rolling roll to the peripheral surface of the rolling roll facing the lower edge of the side weir movable in the roll axis direction. By wetting the peripheral surface of the rolling roll, the powder raw material that is about to flow out to the side is captured, and the powder raw material is temporarily deposited on the wet peripheral surface portion to close the gap between the side weir and the roll peripheral surface. . As a result, the powder raw material supplied to the powder reservoir is prevented from flowing out to the side, and a compact having the target plate width and having a uniform density ratio in the plate width direction is manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of the equipment configuration in which the method of the present invention is carried out, FIG. 2 is a graph showing the density distribution of the compact obtained in the first embodiment, and FIG. FIG. 4 is a graph showing the density distribution of the compact obtained in the example, FIG. 4 shows a state of powder rolling using a side weir, and FIG. 5 is a side view thereof. 1,2 ... rolling roll, 3,4 ... side weir 5 ... powder pool, 6 ... powder material 7 ... kissing point, 8 ... gap 9 ... compact, 10a ~ 10d ... liquid supply nozzle 11… Liquid P _{1 to} P ₄ : Where the side weir contacts the peripheral surface of the rolling roll

Continuation of the front page (72) Inventor Michio Miyamoto 111-1 Showa-cho, Kure City, Hiroshima Prefecture Inside the Steel Research Laboratory of Nisshin Steel Corporation (56) References JP-A-63-93804 (JP, A) JP44 −21532 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22F 3/18

Claims (2)

(57) [Claims] When a powder material is rolled by said rolling rolls while a powder raw material is supplied between a pair of rolling rolls partitioned by side weirs movable in the roll axis direction, a strip-shaped body is produced. A method for producing a strip-shaped body, comprising supplying a liquid for preventing leakage of powdery raw material to a surface of the rolling roll facing a lower edge of the side weir from an upstream side in a rotation direction of the rolling roll. 2. The liquid supply according to claim 1, wherein the liquid is an organic solvent, and the supply amount of the organic solvent is adjusted to an amount such that the liquid that has entered the molded body evaporates in the atmosphere before the sintering step of the molded body. A method for producing a strip-shaped molded body.