阅读说明：本技术 锌基合金丸粒及其制造方法 (Zinc-based alloy pellet and method for manufacturing the same ) 是由 加藤佑人 田沼直也 于 2018-06-21 设计创作，主要内容包括：一种锌基合金丸粒,其中,前述锌基合金丸粒由Al以及余量的Zn和不可避免的杂质组成,相对于前述锌基合金丸粒的Al的含量为1.0～6.0质量％,前述锌基合金丸粒的维氏硬度为50～100HV。另外,前述锌基合金丸粒可以进一步添加Cu作为微量添加元素,前述微量添加元素的添加量相对于前述锌基合金丸粒可以为0.0001～0.25质量％。(A zinc-based alloy pellet, wherein the zinc-based alloy pellet is composed of Al, and the balance of Zn and inevitable impurities, the content of Al relative to the zinc-based alloy pellet is 1.0-6.0 mass%, and the Vickers hardness of the zinc-based alloy pellet is 50-100 HV. In addition, Cu may be further added to the zinc-based alloy pellet as a trace additive element, and the amount of the trace additive element may be 0.0001 to 0.25 mass% with respect to the zinc-based alloy pellet.)

1. A zinc-based alloy pellet, wherein,

the zinc-based alloy pellets consist of Al and the balance of Zn and inevitable impurities,

the Al content of the zinc-based alloy pellets is 1.0 to 6.0 mass%,

the Vickers hardness of the zinc-based alloy pellets is 50-100 HV.

2. A zinc-based alloy pellet according to claim 1, wherein the vickers hardness of the zinc-based alloy pellet is 50-90 HV.

3. A zinc-based alloy pellet according to claim 1 or 2, wherein the zinc-based alloy pellet further adds Cu as a trace additive element,

the addition amount of the trace additive element is 0.0001-0.25% by mass relative to the zinc-based alloy pellets.

4. A zinc-based alloy pellet according to any one of claims 1 to 3, wherein the zinc-based alloy pellet is a granular body having a diameter of 0.2 to 2.0mm or a cylinder having a ratio of (1:0.8) or less (diameter: length) or less (1: 1.3).

5. The zinc-based alloy pellet according to any one of claims 1 to 4, wherein the zinc-based alloy pellet is a granular body, and when the length of the pellet in the longitudinal direction determined by a projection diagram is a, and the maximum diameter in the direction orthogonal to the longitudinal direction is b, the a/b of 60% or more of the pellets is in the range of 1.0 to 1.3.

6. A method for manufacturing zinc-based alloy pellets, which is the method for manufacturing zinc-based alloy pellets described in any one of claims 1 to 5, and which comprises:

weighing Zn and Al as raw material metals and, if necessary, Cu;

a step of heating the raw material metal to produce a molten metal;

transferring the molten metal to a molten metal holding vessel having a nozzle disposed at the bottom thereof;

dropping the molten metal into a liquid cooling medium through the nozzle;

solidifying the molten metal in the cooling medium to obtain a granular material; and

a step of classifying the granular bodies into a predetermined size,

in the classifying step, the diameter of the solidified molten metal is classified to 0.2 to 2.0 mm.

7. A method for manufacturing zinc-based alloy pellets, which is the method for manufacturing zinc-based alloy pellets described in any one of claims 1 to 4, and which comprises:

obtaining a bulk material having an alloy composition of Zn, Al and, if necessary, Cu as raw material metals;

obtaining a wire rod having a predetermined diameter from the block; and

a step of cutting the wire rod into a predetermined length,

the step of obtaining the wire rod includes a step of rolling the block and applying stress.

8. The method for producing zinc-based alloy pellets according to claim 7, wherein the wire rod is cut so that the diameter of the wire rod is (1:0.8) or less (1:1.3) or less in the step of cutting the wire rod.

9. The method for producing zinc-based alloy pellets according to claim 7 or 8, wherein in the step of obtaining the wire rod, the lump is processed so that the diameter of the wire rod is 0.4 to 2.0 mm.

Technical Field

The present invention relates to zinc-based alloy pellets (shot) used in sand blasting processing and a method for manufacturing the same.

Background

Blasting has long been known in which particles called shot are caused to collide with a workpiece to perform surface treatment of the workpiece (deburring, rounding (R-chamfering), surface roughness adjustment, crepe texture processing, and the like). The material of the pill is selected according to the material and processing purpose of the workpiece. For example, in the case of sand blasting of die-cast products made of aluminum alloys, magnesium alloys, and zinc alloys, zinc pellets are selected in consideration of shot blasting ability and dust explosion resistance.

Patent document 1 discloses pellets formed of zinc. Since the Vickers hardness of the pellets is 40 to 50HV (defined by JIS Z2244), the shot blast cleaning ability is low.

Thus, pellets formed of zinc alloys have been developed. For example, patent document 2 discloses zinc-based alloy pellets formed of Zn — Mn. However, Mn is subject to PRTR system, and is not preferable from the viewpoint of safety and environmental protection.

Disclosure of Invention

Problems to be solved by the invention

In view of the above, an object of the present invention is to provide a novel zinc-based alloy pellet having high shot blasting capability and a long life, and a method for producing the same.

Means for solving the problems

By the present invention, the following zinc-based alloy pellets and a method for manufacturing the same are provided.

[1] A zinc-based alloy pellet which is a zinc-based alloy pellet,

the zinc-based alloy pellets consist of Al and the balance of Zn and inevitable impurities,

the Al content of the zinc-based alloy pellets is 1.0 to 6.0 mass%,

the Vickers hardness of the zinc-based alloy pellets is 50-100 HV.

[2] The zinc-based alloy pill according to the item 1, wherein the Vickers hardness of the zinc-based alloy pill is 50-90 HV.

[3] The zinc-based alloy pellet according to item 1 or 2, wherein the zinc-based alloy pellet further adds Cu as a trace addition element,

the addition amount of the trace additive element is 0.0001 to 0.25 mass% with respect to the zinc-based alloy pellet.

[4] The zinc-based alloy pill according to any one of the preceding 1 to 3, wherein the zinc-based alloy pill is a granular body with a diameter of 0.2 to 2.0mm or a cylinder with a ratio of (1:0.8) to (diameter: length) to (1: 1.3).

[5] The zinc-based alloy pellet according to the above 1 to 4, wherein the zinc-based alloy pellet is a granular body, and when a length of the pellet in a longitudinal direction determined from a projection view is a and a maximum diameter in a direction orthogonal to the longitudinal direction is b, a/b of 60% or more of the pellets is in a range of 1.0 to 1.3.

[6] A method for manufacturing zinc-based alloy pellets, which is the method for manufacturing zinc-based alloy pellets according to any one of the items 1 to 5, and which comprises:

weighing Zn and Al as raw material metals and, if necessary, Cu;

a step of heating the raw material metal to produce a molten metal;

transferring the molten metal to a molten metal holding vessel having a nozzle disposed at the bottom thereof;

dropping the molten metal into a liquid cooling medium through the nozzle;

a step of solidifying the molten metal in the cooling medium to obtain a granular material; and

a step of classifying the granular bodies into a predetermined size,

in the classifying step, the diameter of the solidified molten metal is classified to 0.2 to 2.0 mm.

[7] A method for manufacturing zinc-based alloy pellets, which is the method for manufacturing zinc-based alloy pellets according to any one of the items 1 to 4, and which comprises:

obtaining a bulk material having an alloy composition of Zn, Al and, if necessary, Cu as raw material metals;

obtaining a wire rod having a predetermined diameter from the block; and

a step of cutting the wire rod into a predetermined length,

the step of obtaining the wire rod includes a step of rolling the block and applying stress.

[8] The method of producing zinc-based alloy pellets according to the above 7, wherein in the step of cutting the wire rod, the wire rod is cut so that (1:0.8) or less (diameter of the wire rod: length of the wire rod) or less (1:1.3) is achieved.

[9] The method of producing zinc-based alloy pellets according to claim 7 or 8, wherein in the step of obtaining the wire rod, the lump is processed so that the diameter of the wire rod is 0.4 to 2.0 mm.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can provide zinc-based alloy pellets with high shot blasting capability and long service life. By containing a prescribed amount of Cu, it is possible to provide zinc-based alloy pellets in which not only the occurrence of blackening of the work is suppressed, but also the shot blasting ability, life, and tensile strength are improved.

Drawings

Fig. 1 is a flow chart for explaining an embodiment of a method of manufacturing zinc-based alloy pellets of the present invention.

Fig. 2 is a flow chart for explaining another embodiment of the method for manufacturing zinc-based alloy pellets of the present invention.

Detailed Description

One aspect of the invention is a zinc-based alloy pellet. The zinc-based alloy pellets consist of Al with the balance of Zn and unavoidable impurities. And the Al content relative to the zinc-based alloy pellets is 1.0-6.0 mass%. And the Vickers hardness of the zinc-based alloy pellets is 50-90 HV.

Since the zinc-based alloy pellet according to an aspect of the present invention contains Al, the zinc-based alloy pellet has higher hardness and higher shot blasting capability than zinc. In addition, the impact resistance (toughness) is improved, and therefore, the life is long. Further, since Al is relatively inexpensive, zinc-based alloy pellets having high shot blasting capability and a long life can be produced at a low cost.

In one embodiment of the invention, the zinc-based alloy pellets can further add Cu as a trace additive element. The amount of the trace additive element added to the zinc-based alloy pellet may be 0.0002 to 0.25 mass%. By adding a small amount of Cu, the occurrence of blackening can be suppressed during the blast processing.

Another embodiment of the invention is a zinc-based alloy pellet, which is a zinc-based alloy pellet,

the zinc-based alloy pellets are composed of Al, Cu as a trace additive element, and the balance of Zn and inevitable impurities,

the Al content of the zinc-based alloy pellets is 1.0 to 6.0 mass%,

the Cu content of the zinc-based alloy pellets is 0 to 0.25 mass%,

the zinc-based alloy pellets are granular bodies with the diameter of 0.2-2.0 mm or cylinders with the ratio of (1:0.8) to (diameter: length) to (1:1.3),

the Vickers hardness of the zinc-based alloy pellets is 50-90 HV.

One embodiment of the invention is a method of making zinc-based alloy pellets. The production method may include the following steps (1) to (6).

(1) Weighing Zn and Al as raw material metals, and if necessary, Cu.

(2) And a step of heating the raw material metal to produce a molten metal.

(3) Transferring the molten metal to a molten metal holding vessel having a nozzle disposed at the bottom thereof.

(4) And dropping the molten metal into a liquid cooling medium through a nozzle.

(5) And a step of solidifying the molten metal in a cooling medium to obtain a granular material.

(6) And classifying the granular bodies into a predetermined size.

In the step (6), the granular particles may be classified so as to have a diameter of 0.2 to 2.0 mm. In the present specification, "diameter" refers to a diameter.

By containing Al, the fluidity of the molten metal is improved. Therefore, the nozzle is not clogged with the molten metal, and the dropping can be performed well. Further, when the diameter of the granular material is 0.2 to 2.0mm, granular material having a relatively uniform shape can be obtained.

One embodiment of the invention is a method of making zinc-based alloy pellets. The production method may include the following steps (11) to (13).

(11) Obtaining a bulk having an alloy composition of Zn, Al and, if necessary, Cu as raw material metals.

(12) And a step of obtaining a wire rod having a predetermined diameter from the block.

(13) And cutting the wire rod into a predetermined length.

The step of obtaining the wire rod may include a step of rolling the block and applying stress thereto.

By containing Al, the toughness of the alloy is improved. As a result, when the block is rolled and processed into a wire rod shape, the block is not broken during the processing. Further, by applying stress to the wire rod when rolling the block, the mechanical properties are improved.

In one embodiment of the present invention, in the step of obtaining the wire rod, the block is processed so that the diameter of the wire rod is phi 0.4 to 2.0mm, and in the step of cutting the wire rod, the wire rod is cut so that (1:0.8) ≦ (diameter of the wire rod: length of the wire rod) ≦ 1:1.3), or (1:0.8) ≦ (diameter of the wire rod: length of the wire rod) ≦ 1: 1.2). If the diameter of the wire rod is 0.4mm or more, a wire rod having mechanical strength required for the blasting process can be obtained. Further, if the diameter is 2.0mm or less, the workpiece is not damaged more than necessary even when blasting a relatively soft workpiece such as an aluminum die-cast product. By cutting the wire rod so that the ratio of the diameter to the length of the cut wire rod falls within this range, blasting with less variation in finish quality can be performed.

An embodiment of the zinc-based alloy pellet and the method for manufacturing the same according to the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments, and can be appropriately modified within the equivalent range. In the following description, "%" indicating the alloy composition means "% by mass" unless otherwise specified.

The zinc-based alloy pellets of an embodiment contain Al. Al improves vickers hardness and impact resistance (toughness) of the zinc-based alloy by a synergistic effect with Zn. If the content of Al is too small, the added effect cannot be obtained. When too large, the influence of physical properties of Al is too strong, and the impact resistance of the zinc-based alloy tends to be lowered. In one embodiment, the Al content (based on 100% of the total amount: the same applies hereinafter) is 1.0 to 6.0%, or may be 1.3 to 5.8%, or may be 2.9 to 5.6%.

Cu is an element added as needed to improve the corrosion resistance of the zinc-based alloy pellet. As a result of improving the corrosion resistance, when the zinc-based alloy pellets are subjected to sand blasting, the occurrence of blackening on the surface of a workpiece can be suppressed. However, the addition amount of Cu is preferably a very small amount because the impact resistance of the zinc-based alloy pellets is lowered by excessive addition of Cu. In one embodiment, the amount of Cu added (based on 100% of the total amount: the same applies hereinafter) is 0 to 0.25%, may be 0.0001 to 0.25%, may be 0.0002 to 0.25%, and may be 0.0002 to 0.05%.

Cu also has the effect of improving the Vickers hardness and impact resistance of the zinc-based alloy pellets. The addition of a small amount of Cu not only provides an effect of suppressing the occurrence of blackening to the work but also has an effect of further improving the shot blasting ability and the life of the zinc-based alloy shot.

The zinc-based alloy pellets are also used for workpieces with relatively low hardness, such as die-cast products made of aluminum alloy, magnesium alloy and zinc alloy. If the hardness of the zinc-based alloy shot is too low, the shot blasting capability of the workpiece is insufficient, and if the hardness is too high, the appearance of the surface of the workpiece is affected. In consideration of the physical properties of the workpiece and the purpose of shot blast cleaning, the Vickers hardness of the zinc-based alloy shot may be 50 to 100HV, 50 to 90HV, or 70 to 90HV, and the content of Al or the amount of Cu may be adjusted so as to have the hardness.

The zinc-based alloy pellet of an embodiment is composed of Zn and Al, or Zn, Al, and a trace amount of Cu, but may contain other unavoidable impurities. However, if the content of the inevitable impurities is increased, the impact resistance is lowered, resulting in a decrease in the life. Therefore, the total content of unavoidable impurities is preferably as small as possible.

The Al content of the zinc-based alloy pellets is 1.0-6.0%,

the Cu content of the zinc-based alloy pellets is 0.0001 to 0.25 mass%,

the zinc-based alloy pellets with the Vickers hardness of 50-100 HV are particularly preferred.

The Al content of the zinc-based alloy pellets is 1.3-5.8%,

the Cu content of the zinc-based alloy pellets is 0.0002 to 0.05 mass%,

the zinc-based alloy pellets of which the Vickers hardness is 70-90 HV are further particularly preferable.

Next, a method for manufacturing zinc-based alloy pellets according to an embodiment will be described below with reference to fig. 1.

S01: procedure for weighing raw materials

The metals to be the raw materials were weighed. For example, the Al raw material (base metal) includes JISH2102 aluminum base metals special 1 (99.90% or more), JISH2111 (or ICS77.120.10) purified aluminum base metals special (99.995% or more), 1 (99.990% or more), 2 (99.95% or more), and the Cu raw material (base metal) includes JISH2121 electrolytic copper base metal (99.96% or more).

The material (base metal) of Zn as the base element is not particularly limited, and various grades specified in JIS H2107 (or ISO 725: 1981) can be used. In consideration of the quality stability of the pellets, high purity zinc-based metals such as JISH2107 ordinary zinc-based metal (99.97% or more), purest zinc-based metal (99.995% or more), and special zinc-based metal (99.99% or more) can be used.

S02: melting step

After the weighed amount of metal is charged into the crucible, the crucible is heated (e.g., about 600 ℃). The metal is melted by heating to form a molten metal having a composition of Zn-Al or Zn-Al-Cu.

S03: molten metal transfer process

Molten metal is charged into a molten metal holding vessel. The molten metal holding vessel is provided with a heating means, and can hold the molten metal so that the molten metal is not cooled more than necessary when the zinc-based alloy pellets are manufactured. The molten metal holding temperature at this time varies depending on the alloy composition and the production scale, but may be set as appropriate within a range of 500 to 600 ℃.

A nozzle for dropping molten metal is provided at the bottom of a molten metal holding vessel, and a cooling tank into which a cooling medium is charged is disposed below the nozzle. The cooling medium is liquid, and may be water, oil, or the like.

S04: granulation step

The molten metal in the molten metal holding vessel is dropped from the nozzle. The cooling medium is spheroidized by the influence of surface tension from the nozzle until reaching the cooling medium. The molten metal that has reached the cooling medium and has come into contact therewith is rapidly cooled and solidified in a spherical state.

The cooling medium is brought into contact with the molten metal to be dropped, and the temperature of the cooling medium increases, which causes inhibition of rapid cooling of the molten metal. Therefore, the cooling medium is kept at the set temperature by the cooling means. For example, in the case of water, the set cooling temperature may be usually 60 ℃ or lower, or may be 30 to 40 ℃.

S05: classification procedure

The granular zinc alloy is deposited on the bottom of the cooling medium. The zinc-based alloy pellets are recovered, dried by a dryer, and classified by a classifier to obtain zinc-based alloy pellets. The classification is performed so as to form a predetermined particle diameter in accordance with the purpose of use of the zinc-based alloy pellet.

Here, when the molten metal is dropped from the nozzle, the shape of the molten metal drop is not a perfect sphere, but is elongated in the dropping direction to form a deformed sphere or an ellipse. Therefore, the shape of the obtained granular body, that is, the shape of the pellet particles, is formed into a slightly deformed spherical shape, a rotated elliptical shape, or a cylindrical shape with smooth corners. When the length of the pellet in the longitudinal direction obtained from the projection view of the pellet is represented by a and the maximum diameter in the direction orthogonal to the longitudinal direction is represented by b, the a/b ratio of 60% or more of the pellets is preferably in the range of 1.0 to 1.3, and also preferably in the range of 1.0 to 1.2. Since the shot is close to a true sphere and has small shape variation, a more uniform shot blast effect can be obtained. When the diameter of the granular material is 0.2 to 2.0mm, the ratio of the pellets having an a/b value of 1.0 to 1.3 or 1.0 to 1.2 is increased, and thus classification can be performed so that the particle diameter falls within this range.

The Al content of the zinc-based alloy pellets is 1.0-6.0%,

the Cu content of the zinc-based alloy pellets is 0.0001 to 0.25 mass%,

the zinc-based alloy pill is a granular body with the diameter of 0.2-2.0 mm,

when the length of the pellets in the longitudinal direction determined from the projection is defined as a and the maximum diameter in the direction orthogonal to the longitudinal direction is defined as b, the a/b ratio of 60% or more of the pellets is in the range of 1.0 to 1.3,

the zinc-based alloy pellets with the Vickers hardness of 50-100 HV are particularly preferred.

The Al content of the zinc-based alloy pellets is 1.3 to 5.8 mass%,

the Cu content of the zinc-based alloy pellets is 0.0002 to 0.05 percent,

the zinc-based alloy pill is a granular body with the diameter of 0.2-2.0 mm,

when the length of the pellets in the longitudinal direction determined from the projection is defined as a and the maximum diameter in the direction orthogonal to the longitudinal direction is defined as b, the a/b ratio of 60% or more of the pellets is in the range of 1.0 to 1.2,

the zinc-based alloy pellets of which the Vickers hardness is 70-90 HV are further particularly preferable.

The method of manufacturing the zinc-based alloy pellets is not limited to the above-described method. An example of another manufacturing method will be described below with reference to fig. 2.

S11: process for producing cake

A bulk having a composition of Zn-Al or Zn-Al-Cu is produced from the metal as a raw material. For example, a cylindrical lump called billet (billet) can be produced by smelting a metal to be a raw material.

S12: wire rod manufacturing process

In the present embodiment, a wire rod is manufactured from a billet. A billet is inserted into a plurality of dies and drawn, whereby the diameter of the billet is reduced by plastic deformation to produce a wire rod having a desired diameter. The billet of the present embodiment has good sliding properties with respect to the die because it contains Al. Therefore, when the wire rod is manufactured, the wire rod can be prevented from being cut or microcracked in the middle.

In addition, the tensile strength of the zinc-based alloy is improved by adding Cu as a trace additive element. As a result, the wire rod can be prevented from being cut or microcracked in the middle of the production of the wire rod.

Since the billet made of the zinc-based alloy can pass through the die well by the addition of Al and Cu, the zinc-based alloy can be subjected to stress by plastic deformation and friction with the die. As a result, the mechanical properties (e.g., toughness) required for the pellets can be improved. For example, the mechanical properties can be adjusted by changing the billet drawing speed and the diameter and number of dies.

The zinc-based alloy is improved in mechanical properties by applying stress to the zinc-based alloy by making the wire rod smaller in diameter, but is damaged by such processing if the wire rod is made smaller than necessary. If the diameter is too large, stress cannot be sufficiently applied, or if a workpiece having relatively low hardness is subjected to blasting, the surface of the workpiece is damaged. Based on the above, the diameter of the wire rod may be phi 0.4mm to 2.0 mm.

S13: cutting step

The obtained wire rod was cut in series to have a predetermined length to obtain pellets. If the difference between the length and the diameter of the granular material is large, the finish quality of the workpiece after the blasting process varies. In view of this, the wire rod may be cut in such a manner that (1:0.8) ≦ (diameter of wire rod: length of wire rod) ≦ (1:1.3), and also may be cut in such a manner that (1:0.8) ≦ (diameter of wire rod: length of wire rod) ≦ (1: 1.2).

S14: rounding process

The resulting pellets have corners because they are cylindrical. When the workpiece is damaged by the corner portion in the sandblasting process, the corner can be rounded by projecting the granular material in advance onto the wall or the like. This step may be omitted depending on the physical properties of the workpiece and the purpose of the blast processing.

The Al content of the zinc-based alloy pellets is 1.0-6.0%,

the Cu content relative to the zinc-based alloy pellets is 0.0001-0.25%,

the zinc-based alloy pellets are cylinders having a ratio of (1:0.83) or less (diameter: length) or less (1:1.25),

when the length of the pellets in the longitudinal direction determined from the projection is defined as a and the maximum diameter in the direction orthogonal to the longitudinal direction is defined as b, the a/b ratio of 60% or more of the pellets is in the range of 1.0 to 1.3,

the zinc-based alloy pellets with the Vickers hardness of 50-100 HV are particularly preferred.

The Al content of the zinc-based alloy pellets is 1.3-5.8%,

the Cu content of the zinc-based alloy pellets is 0.0002 to 0.25 percent,

the zinc-based alloy pellets are cylinders having a ratio of (1:0.83) or less (diameter: length) or less (1:1.25),

when the length of the pellets in the longitudinal direction determined from the projection is defined as a and the maximum diameter in the direction orthogonal to the longitudinal direction is defined as b, the a/b ratio of 60% or more of the pellets is in the range of 1.0 to 1.2,

the zinc-based alloy pellets of which the Vickers hardness is 70-90 HV are particularly preferable.

Next, results of evaluating the zinc-based alloy pellet of an embodiment will be described.