Title of Invention

A DOUBLE DRAW SINGLE PASS DIE FOR THE MANUFACTURE OF A METAL TUBE

Abstract

A double draw single pass die for the manufacture of a metal tube,comprising primary and secondary die bodies provided with means,the primary die body being intended for the initial reduction of the said area,both die bodies having a relieving angle at each outlet,characterised in that the said bodies are fastned together end to end,to forma single unit,with the outlet of the primery die body abutting the inlet of the secondary die body,the entry angle at the mouth of the primary die body is substantially 17 degrees,while the secondary die body does not have any entry angle but only a curvature at is mouth and the outlet of the primary die body has a predetemined relieving distance for preventing the draw material from getting deformed while leaving the primary die body and before entring the secondary die body.

Full Text

This invention relates to double draw single pass die for the manufacture of a metal tube. The conventional system consists of two independent single piece dies. The material passes through one die to obtain a tube of a given reduction and thereafter the drawn tube, after heat treatment, is again drawn through a second die for further reduction. The conventional system is thus two pass two stage. On the other hand, with the die proposed herein, sizes reduction, which is conventionally achievable in two stages, can be achieved in one stage. With the die proposed herein, the amount of reduction achievable in a single stage is more than that achievable according to the conventional system involving two stages. With the die proposed herein, the heat treatment process involved in the conventional system is eliminated. Wim the die proposed herein there is increase in productivity and saving in process time and man hours. With the die proposed herein the equipment capacity can be released to process other orders. There is also a re duct, on of consumables and material movement. Various other features of this invention will be apparent from the following further description thereof. According to this invention, there is provided a double draw single pass die for the manufacture of a metal tube, comprising primary and secondary die bodies provided with mandrel means, me primary die body being intended for the initial reduction of the cross-sectional area of the tube and the secondary die body for further reduction of the said area, both die bodies having a relieving angle at each outlet, characterized in that the said bodies are fastened together end to end, to form a single unit, with the outlet of the primary die body abutting the inlet of the secondary die body; the entry angle at the mouth of the primary die body is substantially 17 degrees, while the secondary dm body does not have any entry angle but onfy a curvature at its mouth; and the outlet of the primary die body has a predetermined relieving distance for preventing the drawn material from getting deformed while leaving the primary die body and before entering the secondary die body. This invention will now be described by reference to the accompanying drawings, wherein; Figs-1 md 2 illustrate the conventional separate single piece dies for two stage operation. Figs. 3 and 4 illustrate the mandrel respectively used with said dies. Figs. 5. and 6 illustrate, by way of example, one of possible embodiments of the singlejdieproposed herein, with its two parts depicted separately. Fig.7 illustrates the said embodiment with its two parts fastened together (that is. with the said embodiment assembled). Fig. 8 illustrates the end view of the view in Fig.7 looking in the direction of the arrow Z And Fig.9 illustrates one of the mandrels which can be used with the said embodiment The conventional system comprises the two single piece dies Dl and D2» each provided with mandrels Ml and M2 (Figs.l to 4). Die Dl is intended for the initial reduction of the cross-sectional area of the tube and die D2 for further reduction of the cross-se4ctional area. Both dies Dl and D2 have entry angles Al, A2 and relieving angles Bl B2 at the inlet and outlet respectively. After the material is drawn through the die Dl, it is heat treated and then drawn through the die D2 for further reduction in the cross-sectional area. The main drawbacks associated with the conventional system have already been discussed. However, in the case of the proposed double draw single pass die for the manufacture of a metal tube, primary and secondary die bodies D3 and D4 are provided, the primary die body being intended for the initial reduction of the cross-sectional area of the tube and the secondary die body for further reduction of the said area. The 4k bodies D3 and D4 are fastened together end to end e.g. by means of bolts at T, the outlet of the die body D3 thus abutting the inlet of the die body D4. Both die bodies have relieving angles B3 B4 at die outlet In the die proposed herein the entry angle A3 at the mouth of the primary die body is substantially 17 degrees, while the secondary die body does not have any entry angle but only a curvature F at it* mouth, fi.rtl.or more the outlet of the primary die body has a predetermined relieving distance V (e.g.4 mm) for preventing the drawn material from getting deformed while leaving die primary die body and before entering die secondary die body. The said relieving distance V is predetermined by considerations such as the material drawn, dimensions of the drawn material and the speed at which drawing* takes place. Mandrel means are provided for the primary 4k body. Where necessary such mandrel means are provided for both die bodies (as illustrated in Fig J), the portion M3 being seated in the first die body and the portion M4 being seated in the second die body. The portion M4 when provided for the secondary die body has an external periphery of a circular or polygonal configuration to provide a similar external configuration of the tube drawn therefrom. The terms and expressions in this specification are of description and not of limitation there being no intention in the UK of such terms and exprotione of excluding any equivalents of the features illustrated and described, but it is understood that various other embodiments of the die proposed herein are possible without departing from die scope and ambit of this invention. We claim: 1. A double draw single pass die for the manufacture of a metal tube, comprising primary and secondary die bodies provided with mandrel means, the primary die body being intended for the initial reduction of the cross-sectional area of the tube and the secondary die body for further reduction of the said area, both die bodies having a relieving angle at each outlet, characterized in that the said bodies are fastened together end to end, to form a single unit, with the outlet of the primary die body abutting the inlet of the secondary die body; the entry angle at the mouth of the primary die body is substantially 17 degrees, while the secondary die body does not have any entry angle but only a curvature at its mouth; and the outlet of the primary die body has a predetermined relieving distance for preventing the drawn material from getting deformed while leaving the primary die body and before entering the secondary die body, 2. A dk as claimed in Claim 1 wherein the mandrel means are provided for the primary die body, 3. A die as claimed in Claim 1 or Claim 2 wherein the mandrel means are provided for both die bodies. 4. A die as claimed in any one of the preceding Claims 1 to 3 wherein the mandrel means provided for the secondary die body have an external periphery of a circular or polygonal configuration. 5. A doable draw single pass dit for the manufacture of a metal tube, substantially as herein described with reference to, and as illustrated in Figs.5 to 9 of the accompanying drawings.

Documents:

131-mas-1997- abstract.pdf

131-mas-1997- claims duplicate.pdf

131-mas-1997- claims original.pdf

131-mas-1997- correspondence others.pdf

131-mas-1997- correspondence po.pdf

131-mas-1997- descripition complete duplicate.pdf

131-mas-1997- descripition complete original.pdf

131-mas-1997- drawings.pdf

131-mas-1997- form 1.pdf

131-mas-1997- form 26.pdf

131-mas-1997- other documents.pdf

131-mas-1997- pct.pdf