WO1997008366A1

WO1997008366A1 - Apparatus for fastening a workpiece to position for electrolytic treatment

Info

Publication number: WO1997008366A1
Application number: PCT/FI1996/000453
Authority: WO
Inventors: Juha Ilmoniemi; Juhani Hallomaa; Matti Ahde
Original assignee: Oy Galvatek Ab
Priority date: 1995-08-24
Filing date: 1996-08-22
Publication date: 1997-03-06
Also published as: FI953971A0

Abstract

The invention relates to an apparatus for fastening a workpiece to be treated electrolytically, for instance an article to be anodized, in position at least for the duration of the electrolytic treatment. The apparatus comprises members for supporting the electrolytically treated workpiece and members for creating compression in between the support members and the treated workpiece in order to facilitate the fastening. The fastening member also comprises a horizontal support member provided with two essentially vertical rack members. According to the invention, the rack members (10, 11) of the support member are at least partly flexible (4, 12), so that while fastening the article (7) to be treated electrolytically to the rack member (10, 11), the total width of the rack member (10, 11) can be adjusted in order to reduce the pressure force required of the fastening member.

Description

APPARATUS FOR FASTENING A WORKPIECE TO POSITION FOR ELECTROLYTIC TREATMENT

The present invention relates to an apparatus for fastening a workpiece to position for electrolytic treatment, at least for the duration of the electrolytic treatment, so that the energy stored in the support member of the workpiece is utilized in the fastening process.

In the electrolytic treatment of metal articles, for instance in the anodizing of aluminum, the articles are supported by a member comprising a horizontal bar provided with two vertical racks for fastening both ends of the articles to be treated to said shafts. During the treatment, the vertical racks are, along with the articles to be treated, at least partly immersed in an electrolytic solution. Now the rack members and the fastening mechanisms of the supported articles attached thereto are subjected to said electrolytic treatment. Generally the rack members are made of the same material as the treated workpieces; for instance in the anodizing of aluminum, they are made of aluminum. Other possible materials for the rack members in the anodizing of aluminum are titanium and zirconium. The mechanism for fastening the treated workpieces to the rack members is advantageously manufactured of the same material as the rack members, because possible electric cells created of two different materials during the treatment are then advantageously avoided. However, the functional efficiency of the fastening mechanisms requires a compression between the rack member and the article under treatment, and this pressure can be created mechanically.

From the EP patent application 94,812, there is known a support jig for workpieces to be anodized, wherein said workpieces are stacked on top of each other, so that they rest on spacer elements located in between the workpieces. The construction formed by the workpieces and the spacer elements is further pressed together by means of a jack screw joint located in the top part of the support jig. However, this arrangement is fairly heavy in structure, which increases the total expenses of the process.

From the US Patent 5,076,903, there is known a support rack used in an anodizing apparatus, said rack comprising a horizontal member with vertical rack members provided therein. The rack members are further provided with members used for holding the articles to be anodized, and the compression of the anodized article against the rack member is created by means of an operating screw provided in the support member. A screw compression is applied in the anodizing apparatus described in the US Patent 4,664,771 , too. Here the article to be anodized is compressed against the support rack by intermediation of an central piece. The central piece is further pressed against the support rack by means of an elastic band, so that by using a screw inserted through both ends of the band the anodized article, the central piece and the band are compressed around the support rack. However, when using a screw for pressure, it must be observed that also the screw threads are subjected to the anodizing bath throughout the anodizing treatment. Consequently, there is the risk that the threads may be destroyed in several successive anodizing treatments.

The object of the present invention is to eliminate some of the drawbacks of the prior art and to achieve an improved apparatus for fastening a workpiece to position for electrolytic treatment, at least for the duration of the electrolytic treatment, which apparatus utilizes the energy stored in the support member of the workpiece, advantageously by means of the material of the support member. The essential novel features of the invention are apparent from the appended claims.

In an apparatus according to the invention, the support member of electrolytically treated articles comprises a horizontal support member and two rack members connected to this support member. The horizontal support member, whereby the electrolytically treatable workpieces are lowered down and respectively lifted up from the electrolytic bath, is provided with two vertical rack members, so that the workpieces are advantageously supported essentially near to both ends thereof. At least one of the rack members is movably attached to the support member, so that the location of the rack member can be adjusted according to the length of the article under electrolytic treatment.

According to the invention, in an apparatus used for anodizing articles advantageously made of aluminum, the workpieces are prior to the treatment fastened to rack members provided in a support member located outside the electrolytic bath, said rack members being at least partly flexible, so that the total width of the rack member is adjustable by means of external pressure. By means ofthe flexible rack member employed according to the invention, energy needed in the fastening of the metal article can be stored in the support member, and said energy can then be used for reducing the pressure force required of an external fastening member with respect to the support member. According to the invention, when fastening the article to be treated electrolytically to the rack member, by means of the flexible part of the rack member, the total width of the rack member can be adjusted in order to reduce the pressure force required of the fastening mechanism. By employing a fastening member external to the support member, it is possible to simultaneously attach electrolytically treatable articles on both sides of the rack member.

In the apparatus according to the invention, the fastening member of electrolytically treatable articles comprises at least one part. When installing the fastening member around the workpieces, the fastening member is first bent so that the ends of the fastening member and an essential part thereof are placed adjacently, essentially parallel with respect to each other. After the described shaping, the fastening member is pressed around the rack member and the workpiece by rotating the fastening member at both ends around its lengthwise axis. When the fastening member comprises two parts, both parts thereof are first bent so that the corresponding ends of the parts and an essential part of the fastening member are located adjacently, in an essentially parallel direction with respect to each other. The rotation of the parts of the fastening member around its lengthwise axis is carried out so that in connection with the rotating, the corresponding ends of the respective parts are interconnected, and the result is a ring compressed around the articles to be treated electrolytically. Owing to the flexibility of the rack members, pressure is applied during the compression of the fastening member, both from the support-arm side surface ofthe support member ofthe workpieces, and from the surface on the side of the fastening mechanism. When distributing the pressure force over two different surfaces, the pressure force directed to the fastening member proper can advantageously be reduced.

In the apparatus according to the invention, the rack members of the support member are advantageously made of two parts, so that the essentially inflexible base part is connected with a flexible contact part. The base part is advantageously made of aluminum, titanium or zirconium. The flexible material employed in the contact part can advantageously be metal, for example in a spring-like form, or some material flexible as such, for example rubber or plastic. The metallic material employed in the contact part of the rack member can advantageously be the same metal as in the base part, so that the base part and the contact part are easily connected. If the contact part of the rack member is made of some non-conductive material, the base part of the rack member makes the electric current flow into the article under electrolytic treatment, when the base part of the rack member is designed so that in between the workpiece and the base part, there can be created a metallic contact while the workpiece is attached to the rack member. The rack member can also be made of some electro conductive, non-metallic flexible material, in which case the metallic contact between the rack member and the electrolytically treated article can be avoided.

In the apparatus according to the invention, the at least partial flexibility of the rack members can advantageously be utilized for instance by forming the support member to be such that at the contact point of the metal article to be supported and the support member, the flexibility of the rack member is within the range of 5 - 30 %, advantageously 10 - 20 % of the total width of the rack member. The flexibility of the support member is advantageously achieved so that the workpiece to be fastened reduces the total width of the support member, or so that inside the support member, there is provided an essentially empty space, and the total width of the support member in relation to the workpiece can be extended by means of pressure fed into said empty space.

The invention is explained in more detail below, with reference to the appended drawings, where figure 1 illustrates a preferred embodiment of the invention, seen in partial cross- section, figure 2 illustrates the embodiment of figure 1 , seen in partial cross-section when the article to be supported is attached to the support member, figure 3 is a side-view illustration of the support member of figure 1 , and figure 4 illustrates another preferred embodiment of the invention, seen in partial cross-section.

According to figure 1 , a rack member 10 according to the invention is formed of a base part 1 , to which is connected a flexible contact part. The contact part further comprises a base part 3 and at least one projecting part 4 connected to the base part. With respect to the base part 3, the projecting part 4 is installed so that in its free position, the projecting part 4 is left, at least at its end located furthest away from the base part, outside the surface 6 uniform with the wall 5 of the base part 3 used for supporting the metal article. Now, when the workpiece is adjusted in place, it touches the projecting part 4 in the first stage.

In figure 2, two articles 7 to be supported are attached to the support member, to both sides of the rack member 10, said articles being compressed against the projecting part 4 and the base part 3 by a pressure member 8. In its functional position, the projecting part 4 is pressed in. Thus, owing to the co-effect of the pressure member 8 and the projecting part 4, the workpiece 7 receives pressure forces both to its wall on the side of the projecting part 4 and to its wall on the side of the pressure member 8.

In figure 3, the rack members 10, which are interconnected by an essentially horizontal beam 15, are provided with several spaced-apart vertical workpieces 7. At least one of the rack members 10 is horizontally movable with respect to the beam 15.

In figure 4, the flexible part 12 ofthe rack member 11 is provided with a space 13, which is connected to a pressure source. While attaching an article to be treated electrolytically to its support position, pressure is conducted into the space 13, so that the total width of the part 12 grows, and the part 12 creates a force directed to that surface of the article which is located nearest to the rack member.

Claims

1. An apparatus for fastening a workpiece to be treated electrolytically, such as an article to be anodized, to position at least for the duration of the electrolytic treatment, said apparatus comprising members for supporting the article to be treated electrolytically and members for creating the necessary compression between the support member and the article under treatment in order to facilitate the fastening, which support member comprises a horizontal support member and two essentially vertical rack members connected to the support member, characterized in that the rack members (10, 11) of the support member are at least partly flexible (4, 12), so that while the article (7) to be treated electrolytically is attached to the rack member (10, 11), the total width of the rack member (10, 11) can be adjusted by means of the flexible part (4, 12) of the rack member in order to reduce the compression force required of the fastening member.

2. An apparatus according to claim 1 , characterized in that at the contact point of the workpiece (7) to be treated electrolytically and the rack member (10, 11), the flexibility of the flexible part of the rack member is 5 - 30 %, advantageously 10 - 20 % of the total width of the rack member (10, 11).

3. An apparatus according to claim 1 or 2, characterized in that when fastening a workpiece (7) to be treated electrolytically to the rack member (10, 11), the total width of the rack member (10, 11) can be adjusted by means of the flexible part (4, 12) of the rack member in order to reduce the compression force required of the fastening member.

4. An apparatus according to claim 1 or 2, characterized in that when fastening a workpiece (7) to be treated electrolytically to the rack member (10, 11), the total width of the rack member (10, 11) can be increased by means of the flexible part (4, 12) of the rack member in order to reduce the pressure force required of the fastening member.

5. An apparatus according to any of the preceding claims, characterized in that at least one of the rack members (10, 11) is movable with respect to the support member (15) of the rack member.

6. An apparatus according to any of the preceding claims, characterized in that the rack member comprises a base part (1) and a flexible part (4, 12).

7. An apparatus according to claim 6, characterized in that the flexible part (4, 12) of the rack member is made of metal.

8. An apparatus according to claim 6 or 7, characterized in that the flexible part (4, 12) of the rack member is made of aluminum.

9. An apparatus according to claim 6 or 7, characterized in that the flexible part (4, 12) of the rack member is made of titanium.

10. An apparatus according to claim 6 or 7, characterized in that the flexible part (4, 12) of the rack member is made of zirconium.

11. An apparatus according to any of the preceding claims 1 - 6, characterized in that the flexible part (4, 12) of the rack member is made of rubber.

12. An apparatus according to any of the preceding claims 1 - 6, characterized in that the flexible part (4, 12) of the rack member is made of plastic.

13. An apparatus according to any of the preceding claims, characterized in that the rack member is made of some flexible material (12).