JP4165794B2 - shot - Google Patents

Description

【００１６】
表１において、Ｎｏ．１のショットは銅が添加されていない亜鉛製ショットであって、そのため硬さが低くブラスト時間を長くしてもバリを効果的に除去することができなかったばかりか、ショットの磨耗も大きくその寿命が短いものであった。また、処理後の表面肌の色調も光沢のない黒ずんだものとなってしまい、総合評価も不良であった。また、Ｎｏ．２、４、５のショットは何れも銅の含有量が本発明の範囲より低く、硬さも本発明の範囲より低い比較例である。このためブラスト時間、バリ取り効率、ショットの寿命、表面肌の色調の何れにおいても結果は○ないし△であって、従って、総合評価も○ないし△に留まってしまった。以上の比較例に対し、Ｎｏ．３および６〜１０の本発明の実施例であるショットは銅の濃度、硬さ何れも本発明の範囲内であってすべての項目に渡って極めて良好で総合的にも極めて良好なショットであった。
【００１７】
さらに、表１に示したショットのバリ取り性能を詳細に試験調査した。表２、はショットの投射速度が４５ｍ／ｓｅｃの場合のアルミニウムダイカストのバリ厚みとバリ取り時間との関係を調査した試験結果、表３はショットの投射速度が６０ｍ／ｓｅｃの場合のバリ厚みとバリ取り時間との関係を調査した試験結果であって、ブラスト時間３０秒でバリ取りを行うことができものを◎、６０秒でバリ取りを行うことができたものを○、９０秒でバリ取りを行うことができたものを△、９０秒ブラストしてもバリを取ることができなかったものを×と判定した。
【００１８】
【表２】

【００１９】
【表３】

【００２０】
表２、表３より本発明の実施例であるＮｏ．３および６〜１０のショットは比較例であるＮｏ．１、２、４、５のショットよりバリ取り効果が格段に優れていることが判る。
【００２１】
【発明の効果】
以上に説明したように、本発明のショットは、１．８〜１３．０質量％の銅と残部が亜鉛及び不可避的不純物からなる亜鉛−銅二元合金の溶湯が凝固する際に起こる包晶反応を利用して、金属組織を硬質なε相の周囲を軟質なη相が包囲したものとすることによって、硬質なε相により研掃効果を高めて従来よりも短時間でバリを除去することができるうえショットの消耗による寿命の低下を防止して寿命を延長することができる。また、軟質なη相がクッションの役目を果して被処理品の表面を荒らすことがなく、表面肌の色調を完全な銀白色のものとすることができる。従って、本発明のショットは、粉塵爆発の危険がなくて研掃効果が高く寿命が長いうえに、処理後の表面肌の色調を完全な銀白色とすることのできるものとして工業的価値大なものである。
【図面の簡単な説明】
【図１】 ショットの硬さと寿命比との関係図である。
【図２】 亜鉛−銅二元系平衡状態図の一部を示す説明図である。
【図３】 包晶組織の一例を示す模式図である。
【符号の説明】
１ ε相
２ η相[0001]
BACKGROUND OF THE INVENTION
The present invention is a shot used as a blasting material for the removal of burrs, burrs, etc. of light alloy products made of aluminum alloy, zinc alloy or magnesium alloy , scale and sand removal, improvement of casting surface, caulking and other surface treatments. It is about.
[0002]
[Prior art]
Conventionally, for surface treatment such as burrs and burrs of light alloy products such as die casting made of aluminum alloy, zinc alloy and magnesium alloy used for automobile parts, scale removal, sand removal, improvement of casting surface, coking, etc. On the other hand, a shot blast method in which a shot is projected onto a product to be processed at a high speed is widely adopted. The shot material used for this shot blasting is shot with aluminum, steel, stainless steel, etc., but aluminum shot is soft and has a small cleaning effect, and there is a risk of explosion of dust generated by wear. In steel shots and stainless steel shots, there is a problem that the surface of the article to be processed is roughened because the shot is too hard, and the generated dust may also explode.
[0003]
Zinc shots are preferred as shots because they are less sensitive to explosion and less dangerous for dust explosions than aluminum, steel, and stainless steel shots. As a result, the color becomes dark and grayish, and this darkness cannot be removed by washing or the like, resulting in a drop in commercial value. Further, there is a problem that the hardness is Hv 40 to 50 in Vickers display, and the hardness is soft and the polishing effect is small, so that the processing time becomes long and the productivity is inferior.
[0004]
In order to solve the problems of the conventional zinc shot described above, the inventors have made zinc contain 0.05 to 2.00% of copper as disclosed in JP-A-9-70758. A zinc alloy shot having an average particle size of 0.4 to 2.0 mm with a hardness of Hv 50 to 60 was first invented. However, in such a shot made of a zinc alloy, although the grayish darkening on the surface of the treated product after the shot blasting process is thin and considerably improved, it is difficult to say that it is completely silver white, and is still unsatisfactory. It was what remained. Further, although the hardness is increased to Hv 50 to 60, there is a problem that the blasting effect is still insufficient and the shot blasting process takes time.
[0005]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, has no risk of dust explosion, has a high scouring effect, and makes the surface skin color of the treated product after the shot blasting treatment completely silver white. It was made to provide a possible shot.
[0006]
[Means for Solving the Problems]
The present invention made to solve the above problems
A shot used for surface treatment of a light alloy product made of an aluminum alloy, a zinc alloy, or a magnesium alloy,
1.8 to 13.0% by mass of copper, and the balance is composed of a zinc-copper binary alloy consisting of zinc and inevitable impurities,
This zinc-copper binary alloy is a granular material obtained by dispersing and cooling the molten metal and cooling and solidifying it,
The metal structure is a peritectic structure in which the periphery of a hard ε phase is surrounded by a softer η phase using a peritectic reaction that occurs when the molten metal is cooled,
The hardness is over Hv60 to 150, the average particle size is 0.1 to 3.5 mm,
The hard epsilon phase improves the blasting effect and life of the shot, and the soft η phase makes the surface skin tone completely silver-white without roughening the surface skin of the product. It is characterized by being.
In the invention of claim 2, the average particle size is 0.6 to 1.2 mm, in the invention of claim 3, the average particle size is less than 0.1 to 0.6 mm, and in the invention of claim 4, the average particle size is The particle size is more than 1.2 to 3.5 mm.
[0007]
The shot of the present invention uses a peritectic reaction that occurs when the molten zinc alloy to which copper is added is cooled , and surrounds the hard ε phase with a soft η solid solution phase. In addition to enhancing the scouring effect, the soft η solid solution phase can act as a cushion and make the surface color completely silver white without roughening the surface of the workpiece. The invention will be described in detail.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The shot of the present invention is a zinc alloy containing copper, and is composed of 1.8 to 13.0% by mass of copper and the zinc-copper binary alloy consisting of zinc and inevitable impurities as shown below. . FIG. 1 shows the influence of alloying elements on the lifetime, assuming that the lifetime of metallic zinc is 100%. However, when alloying elements such as Mn and Ni are added to zinc, they are easier to crack than copper Life increases with increasing time. On the other hand, when copper is added to zinc, it can be seen that the lifetime increases as the hardness increases. In addition, although the purity of zinc and copper may be distribute | circulating as a general industrial material, content of copper in zinc shall be 1.8 to 13.0%. A part of the equilibrium diagram on the zinc side of the zinc-copper binary alloy is shown in FIG. 2. Zinc and copper undergo peritectic reaction at about 424 ° C. in the concentration range shown in the figure. Therefore, for example, at 300 ° C., a η phase is formed up to less than 2% of Cu, a peritectic structure of η + ε is formed up to 13%, and a ε single phase structure is formed above that. An example of the peritectic structure is shown in FIG. 3, which is a structure in which a relatively hard ε phase is wrapped with a soft η phase. Therefore, by using such a peritectic structure as the structure, the hard ε phase exhibits a sharpening effect when deburring and the like, while the soft η phase functions as a cushion during shot blasting. There is an advantage that the surface of the product is not roughened.
[0009]
However, if the content of copper in zinc is less than 1.8%, the proportion of η phase in the metal structure is large, the ε phase is small, the hardness is insufficient, and a sufficient blasting effect cannot be exhibited. On the other hand, when the content of copper in zinc exceeds 13.0%, the structure becomes the main component of the ε phase, the shot becomes too hard, the toughness is insufficient, the shot is cracked, and the life is shortened. Also, it may cause rough skin. Therefore, the copper content in zinc is 1.8 to 13.0%, particularly preferably 2.0 to 13.0%.
[0010]
Moreover, the reason why the hardness of the shot is over Hv60 to 150 is that when the hardness is Hv60 or less, the scouring effect is inferior and the surface skin of the product to be treated is darkened and cannot be made completely silver white. This is because if the hardness exceeds Hv150, the shot may be broken, leading to a decrease in life or roughening of the surface. In addition, it is desirable that the hardness of the shot is Hv60 over 125. When the hardness of the shot is Hv60 over 125, a good scouring effect and a long life can be obtained, and the surface skin of a light alloy product made of an aluminum alloy, a zinc alloy or a magnesium alloy after processing is silver white. It can be beautiful.
[0011]
The average particle size of the shot is 0.1 to 3.5 mm. This is because if the average particle size of the shot is less than 0.1 mm, the impact force is small and a large scouring effect cannot be obtained. If it exceeds 3.5 mm, the impact force increases and the surface becomes rough. is there. In addition, when the average particle diameter of the shot is less than 0.1 to 0.6 mm, it is possible to obtain a beautiful surface skin with little roughening of the skin, although the scouring effect is slightly reduced. Small shots are suitable for handling small parts. When the average particle size of the shot is more than 1.2 to 3.5 mm, surface treatment such as deburring is performed on the workpiece in a short time by exhibiting a high polishing effect although the surface properties are slightly inferior. Such a shot having a large average particle size is suitable for removing paint such as a paint hanger. Then, by setting the average particle size of the shot to 0.6 to 1.2 mm, it is possible to perform blasting that achieves both a high scouring effect and good surface properties. That is, the processed product can be processed in a short time due to a high scouring effect, and beautiful silver-white skin can be formed on the processed product without causing rough skin on the surface of the processed product. it can.
[0012]
In manufacturing the shot, first, a molten zinc-copper alloy obtained by blending a predetermined amount of copper into zinc is dispersed and flowed under a non-oxidizing atmosphere, and then cooled and solidified to obtain a granular material. By collecting and classifying the granular material by sieving or the like and sorting it by particle size, it is possible to obtain a shot having a predetermined copper content and a uniform particle size .
[0013]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Zinc alloy shots having various compositions, hardnesses, and particle sizes as shown in Table 1 were produced. The manufacturing method was a method of cooling and solidifying the molten zinc-copper alloy described above by dispersing it in a non-oxidizing atmosphere. 75 kg of the manufactured shot was projected onto an aluminum alloy die cast at a projection speed of 60 m / sec using a 5 HP centrifugal projector, and the shot performance was examined. The results are shown in Table 1.
[0014]
In Table 1, blasting time ◎ can be performed with a blasting time of 30 seconds and results are very good. Blasting time ◎, deburring efficiency ◎, burring can be performed with 60 seconds and good blasting time. ○, Deburring efficiency ○, Deburring can be done in 90 seconds Blasting time for slightly defective △, Deburring efficiency Δ, Blasting cannot be deburred even after blasting for 90 seconds Blasting time ×, deburring efficiency ×. Also, ◎ shots that were blasted for 15 hours and consumed as a fine powder were marked with ◎, those with little were marked with ◯, those with little amount were marked with △, and those with much amount were marked with ×. In addition, the surface skin after treatment was black, the one that was slightly dark was ○, the one that was shining silver white was ◎, the above blast time, deburring efficiency, shot life, surface skin Judgment was made by comprehensively considering the color tone, and ◎ was judged as being excellent in overall evaluation, ○ as being good, △ as being poor, and × as being poor.
[0015]
[Table 1]

[0016]
In Table 1, no. No. 1 shot is made of zinc to which copper is not added. Therefore, not only the burrs were effectively removed even if the blasting time was low, but also the wear of the shot was large and its life was long Was short. Moreover, the color tone of the surface skin after a process also became a dull and dark thing, and the comprehensive evaluation was also unsatisfactory. No. The shots 2, 4, and 5 are all comparative examples in which the copper content is lower than the range of the present invention and the hardness is lower than the range of the present invention. For this reason, in any of blasting time, deburring efficiency, shot life, and surface skin tone, the results were ◯ to △, and therefore the overall evaluation was only ◯ to △. For the above comparative example, No. The shots according to the embodiments of the present invention of 3 and 6 to 10 were shots within the scope of the present invention, both of the copper concentration and hardness, and were very good over all items, and very good overall. It was.
[0017]
Further, the shot deburring performance shown in Table 1 was examined in detail. Table 2 shows the test results of investigating the relationship between the burr thickness of the aluminum die casting and the deburring time when the shot projection speed is 45 m / sec, and Table 3 shows the burr thickness when the shot projection speed is 60 m / sec. The test results of investigating the relationship with the deburring time, ◎ that can be deburred with a blast time of 30 seconds, ○ that can be deburred in 60 seconds, ○, 90 seconds The ones that could be removed were judged as Δ, and the ones that could not be deburred even after blasting for 90 seconds were judged as ×.
[0018]
[Table 2]

[0019]
[Table 3]

[0020]
From Tables 2 and 3, No. 1 is an example of the present invention. The shots Nos. 3 and 6 to 10 are comparative examples. It can be seen that the deburring effect is remarkably superior to the shots of 1, 2, 4, and 5.
[0021]
【The invention's effect】
As described above, the shot of the present invention is a peritectic crystal that occurs when a melt of 1.8 to 13.0% by mass of copper and the balance of zinc-copper binary alloy consisting of zinc and inevitable impurities solidifies. By utilizing a reaction to make the metal structure surrounded by a soft η phase around a hard ε phase, the hard ε phase enhances the blasting effect and removes burrs in a shorter time than before. In addition, it is possible to extend the life by preventing a decrease in the life due to wear of the shot. In addition, the soft η phase plays the role of a cushion and does not rough the surface of the article to be treated, and the surface tone can be made completely silver white. Therefore, the shot of the present invention has a great industrial value as it has no danger of dust explosion, has a high scouring effect and has a long life, and the surface tone after treatment can be completely silver white. Is.
[Brief description of the drawings]
FIG. 1 is a relationship diagram between shot hardness and life ratio.
FIG. 2 is an explanatory diagram showing a part of a zinc-copper binary equilibrium diagram.
FIG. 3 is a schematic diagram showing an example of a peritectic structure.
[Explanation of symbols]
1 ε phase 2 η phase

Claims (4)

A shot used for surface treatment of a light alloy product made of an aluminum alloy, a zinc alloy, or a magnesium alloy,
1.8 to 13.0% by mass of copper, and the balance is composed of a zinc-copper binary alloy consisting of zinc and inevitable impurities,
This zinc-copper binary alloy is a granular material obtained by dispersing and cooling the molten metal and cooling and solidifying it,
The metal structure is a peritectic structure in which the periphery of a hard ε phase is surrounded by a softer η phase using a peritectic reaction that occurs when the molten metal is cooled,
The hardness is over Hv60 to 150, the average particle size is 0.1 to 3.5 mm,
The hard epsilon phase improves the blasting effect and life of the shot, and the soft η phase makes the surface skin tone completely silver-white without roughening the surface skin of the product. A shot characterized by being. The shot according to claim 1, wherein the average particle diameter is 0.6 to 1.2 mm. The shot according to claim 1, wherein the average particle diameter is less than 0.1 to 0.6 mm. The shot according to claim 1, wherein the average particle diameter is more than 1.2 to 3.5 mm.

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