GB2151526A

GB2151526A - Metal forming process and lubricant

Info

Publication number: GB2151526A
Application number: GB08332884A
Authority: GB
Inventors: James Dunsmuir; Reginald Charles Saunders
Original assignee: APV International Ltd
Current assignee: APV International Ltd
Priority date: 1983-12-09
Filing date: 1983-12-09
Publication date: 1985-07-24
Also published as: GB8332884D0

Abstract

When forming sheet metal between tools, perforation of the metal may occur. In order to detect such perforations the metal forming lubricant layer 1 on one face 2 of the metal is provided with a marker material, such as a fluorescent dye. The other face 3 has lubricant without such a marker. If a perforation 9 appears during pressing, then some of the marker material will pass through the perforation and can be detected using an ultra violet light source, or otherwise. <IMAGE>

Description

SPECIFICATION Metal forming process and lubricant This invention relates to metal forming processes and to lubricants for use in such processes.

In the shaping of metal, the tools used are normally lubricated by the application of a layer of lubricant between the metal and each forming tool with which it is in contact.

In pressing and other forming operations, there is a risk that the metal will become perforated during formation, and in accordance with the invention such perforation is to be detected by incorporating a marker material into the lubricant on one face of the metal and monitoring the opposite face of the metal for the appearance of the marker material.

In a first aspect of the invention, there is provided a process of forming a metal sheet between tools, wherein a layer of lubricant is applied between each metal face and the corresponding tool, in which the layer of lubricant applied to one of the metal faces includes a marker material and in which the other face is inspected or monitored for the appearance of marker material to indicate perforation of the metal.

The invention is particularly applicable for the forming of plates for heat transfer apparatus.

Preferably, the marker material is a fluorescent dye to be detected by ultra violet lights.

Alternatively the monitoring may be achieved by including in the lubricant on the other face a substance to cause the marker material to become clearly visible whenever traces of it percolate through the metal. The dye may be encapsulated so that the capsules rupture during the forming operation.

In a second aspect of the invention, there is provided a metal article, such as a heat exchanger plate, when formed by a process in accordance with the invention as set forth above.

In a third aspect of the invention, there is provided a lubricant for use in a metal forming process according to the invention as set forth above, comprising a lubricant material having a dye distributed therein.

The invention wil be further described with reference to the accompanying diagrammatic drawings in which; Figure 1 is a sectional view of metal and lubricant layers (shown much exaggerated) prior to forming: Figure 2 shows the metal and lubricant layers after forming; and Figure 3 is a variation of Fig. 2, showing perforations in the meterial.

In accordance with a preferred form of the invention dye is encapsulated in the metalforming lubricant with the object of rapidly detecting perforations in the formed metal after the forming operation.

Fluorescent dye powder is mixed with a suitable solvent to produce a liquid fluorescent dye suitable for encapsulation. The cap sules produced may have any desired size.

preferably ranging from 1 5 to 400 microns.

The capsules so produced are mixed with the metal forming lubricant and applied as a layer 1 to one face 2 of the metal to be formed. Ordinary forming lubricant will be applied to the other face 3 as indicated at 4 in Fig. 1. The layer 1 is shown as having small discrete capsules 5 of dye.

Once the lubricant has been applied, the material is formed into the required shape as indicated in Fig. 2. The lubricant film also takes up this shape. During the forming operation the fluorescent dye capsules 5 will rupture and release the dye, as illustrated by the spreading of dye as shown by the larger blobs 6 in Fig. 2. The dye solution, having been selected for specific physical properties (i.e.

low surface tension and low volatility) will rapidly flow through even minute pertorations in the metal without undergoing excessive evaporation. By inspecting the formed metal with a source of ultra violet light and any fluorescent dye which has penetrated a perforation, as illustrated at 7 in Fig. 3 will be detected by the ultra violet light illustrated by the arrows 8.

Probably the main advantage of this process is that 100% of production may be inspected using this technique without a proportionate increase in work load and thus inspection may be carried out very quickly.

Various modifications may be made within the scope of the invention. Thus, the marker material does not need to be a fluorescent dye, other forms of dye could be used. Also, the detection by ultra violet light is not essential, other torms of detection or monitoring, automatic or visual, could be used. rye dye need not be encapsulated.

In a particular alternative, a dye, e.g. a red dye, is included in the lubricant on one side, encapsulated or otherwise, and the lubricant on the other face of the metal includes an ingredient, for example talc, to cause the dye to become readily visible should traces of the dye percolate through the perforations.

1. A process of forming a metal sheet between tools wherein a layer of lubricant is applied between each metal face and the corresponding tool, in which the layer of lubricant applied to one of the metal faces includes a marker material and in which the other face is jrispecced or monitored for tne appearance of marker material to indicate performation of the metal.

2. A process as claimed in claim 1, in which the marker material is a fluorescent dye

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Metal forming process and lubricant This invention relates to metal forming processes and to lubricants for use in such processes. In the shaping of metal, the tools used are normally lubricated by the application of a layer of lubricant between the metal and each forming tool with which it is in contact. In pressing and other forming operations, there is a risk that the metal will become perforated during formation, and in accordance with the invention such perforation is to be detected by incorporating a marker material into the lubricant on one face of the metal and monitoring the opposite face of the metal for the appearance of the marker material. In a first aspect of the invention, there is provided a process of forming a metal sheet between tools, wherein a layer of lubricant is applied between each metal face and the corresponding tool, in which the layer of lubricant applied to one of the metal faces includes a marker material and in which the other face is inspected or monitored for the appearance of marker material to indicate perforation of the metal. The invention is particularly applicable for the forming of plates for heat transfer apparatus. Preferably, the marker material is a fluorescent dye to be detected by ultra violet lights. Alternatively the monitoring may be achieved by including in the lubricant on the other face a substance to cause the marker material to become clearly visible whenever traces of it percolate through the metal. The dye may be encapsulated so that the capsules rupture during the forming operation. In a second aspect of the invention, there is provided a metal article, such as a heat exchanger plate, when formed by a process in accordance with the invention as set forth above. In a third aspect of the invention, there is provided a lubricant for use in a metal forming process according to the invention as set forth above, comprising a lubricant material having a dye distributed therein. The invention wil be further described with reference to the accompanying diagrammatic drawings in which; Figure 1 is a sectional view of metal and lubricant layers (shown much exaggerated) prior to forming: Figure 2 shows the metal and lubricant layers after forming; and Figure 3 is a variation of Fig. 2, showing perforations in the meterial. In accordance with a preferred form of the invention dye is encapsulated in the metalforming lubricant with the object of rapidly detecting perforations in the formed metal after the forming operation. Fluorescent dye powder is mixed with a suitable solvent to produce a liquid fluorescent dye suitable for encapsulation. The cap sules produced may have any desired size. preferably ranging from 1 5 to 400 microns. The capsules so produced are mixed with the metal forming lubricant and applied as a layer 1 to one face 2 of the metal to be formed. Ordinary forming lubricant will be applied to the other face 3 as indicated at 4 in Fig. 1. The layer 1 is shown as having small discrete capsules 5 of dye. Once the lubricant has been applied, the material is formed into the required shape as indicated in Fig. 2. The lubricant film also takes up this shape. During the forming operation the fluorescent dye capsules 5 will rupture and release the dye, as illustrated by the spreading of dye as shown by the larger blobs 6 in Fig. 2. The dye solution, having been selected for specific physical properties (i.e. low surface tension and low volatility) will rapidly flow through even minute pertorations in the metal without undergoing excessive evaporation. By inspecting the formed metal with a source of ultra violet light and any fluorescent dye which has penetrated a perforation, as illustrated at 7 in Fig. 3 will be detected by the ultra violet light illustrated by the arrows 8. Probably the main advantage of this process is that 100% of production may be inspected using this technique without a proportionate increase in work load and thus inspection may be carried out very quickly. Various modifications may be made within the scope of the invention. Thus, the marker material does not need to be a fluorescent dye, other forms of dye could be used. Also, the detection by ultra violet light is not essential, other torms of detection or monitoring, automatic or visual, could be used. rye dye need not be encapsulated. In a particular alternative, a dye, e.g. a red dye, is included in the lubricant on one side, encapsulated or otherwise, and the lubricant on the other face of the metal includes an ingredient, for example talc, to cause the dye to become readily visible should traces of the dye percolate through the perforations. CLAIMS

2. A process as claimed in claim 1, in which the marker material is a fluorescent dye and the monitoring is achieved by exposure to ultra violet light.

3. A process as claimed in claim 1, in which the monitoring is achieved by including in the lubricant on the other face a substance to cause the marker material to become clearly visible whenever traces of it percolate through the metal.

4. A process as claimed in claim 3, in which the substance is talc.

5. A process as claimed in any of claims 1 to 4, in which the marker material is introduced into the lubricant in an encapsulated form, so that the capsules rupture during the forming operation.

6. A process of forming a metal substantially as hereinbefore described with reference to the accompanying drawings.

7. A metal article, such as a plate for a plate heat exchanger, when formed by a process as claimed in any of the preceding claims.

8. A lubricant for use in a metal forming process as claimed in any of claims 1 to 6, comprising a lubricant material having a dye distributed therein.

9. A lubricant as claimed in claim 8, in which the dye is encapsulated.