FR2577827A1 - PROCESS FOR MANUFACTURING THICK-WALLED TUBES WITH COLD FORMING OF A TUBULAR BLANK - Google Patents

Abstract

THE INVENTION CONCERNS A PROCESS FOR MANUFACTURING TUBES WITH THICK WALL ENDS BY COLD FORMING OF A TUBULAR BLANK, IN WHICH FROM THE THICK WALL ENDS, THE CENTRAL THIN WALL PART OF THE TUBE IS PRODUCED BY STRETCHING AND REDUCTION. SUCH A PROCESS IS ECONOMICALLY IMPLEMENTED ON SERIAL TUBE END FORMING MACHINES AND FOR THE MANUFACTURE OF HOLLOW PARTS BY COLD FORMING WITH GOOD DIMENSIONAL PRECISION.

Description

Method for manufacturing thick-walled end tubes

  by cold forming a tubular blank.

  The present invention relates to a method for manufacturing tubes with thick-walled ends by cold forming a tubular blank. Tubes of the aforementioned type are used, for example, as propeller shafts for propelling vehicles

  automobiles. Thus, it has already been proposed in the patent al-

  German 30 09 277, a transmission shaft in which the central zone of the tube has at least two parts, the wall thicknesses of which are calculated so that all the sections of the tube have the same mechanical resistance. A process of the aforementioned type is found in French patent 2,534,159. A hollow part of constant outside diameter is produced there by cold drawing in

  a direction. The starting point is a re-

  pick and a thickened end, which must be mechanically machined later or folded inwards

  in one or more times by means of a press. This process

  dice do not allow reductions, or even widening

  extremities on both sides. If you still have to achieve this, you must use a

special machine.

  German patent 30 21 481 describes a process

  special stretching that cannot be implemented eco-friendly

  nominally only in tube factories, on special stretching machines. It is certainly possible, with this known process, to thicken the walls

  of the tube in any desired location, both inward

  outside rather than outwards, but, with respect to the desired part, the correct position again depends on a correlating length accuracy, which requires, for example, specific measurement methods.

  This process does not make it possible to obtain either enlargement or

ductions at the extremities.

  To produce tubes with thickened ends,

  German patent 28 12 803 has disclosed a refoul-

  lement hot and a reduction of the ends of the tube.

  Not only does hot forming reveal

  scale, but we also get a damaged texture

  vorable. In addition, the cost of implementing such a

  process is considerably high.

  The present invention relates to a method for obtaining by cold forming parts

  hollow, in particular drive shafts

  before transmitting torques in motor vehicles

  mobile and favoring light construction, economical

  cally and with good dimensional accuracy, with thickened wall portions at the ends of the tube undergoing high stresses, and to obtain a total reinforcement of the starting material by cold forming. Furthermore, the aim is to implement this process on machines for forming tube end ends as standard, so as to no longer use special machines.

and costly separate.

  To achieve this objective, according to the invention, the thick-walled ends of the tube are left at the wall thickness of the blank and the intermediate central section and respectively the

  adjoining section on one side, thin-walled, by stretching.

  The path followed by the method according to the invention therefore consists in placing the thick-walled section in the initial part and in producing the thinner zones or other

  sections, for example by stretching and reduction, i.e.

  say without loss of material and without retouching. Thus, in the case of tube ends thickened on both sides, a residual part having the initial wall thickness is not affected by the stretch reduction process, while, for a tube end thickened d 'only one side, all the remaining part of the tube is stretched. One can thus not only reduce the diameter of the end or ends of the tube, but one can also widen them, if necessary, to an external diameter greater than the external diameter of the thin-walled tube part. The process according to the invention therefore makes it possible, when manufacturing tubes with thick-walled end portions, to obtain a considerable reduction in cost, already only by the economy of

  material, as well as an increase in resistance

  maple in the stretched area and having undergone the final forming, and this using standard tube forming machines. It is therefore essential in the context of the invention that it is possible, from a part in the form of a simple hollow body, to produce with great dimensional precision the most varied forms of parts, with the possibility of avoiding all exterior machining for

  predetermined drafts with corrected accuracy

  lative. If necessary, simply remove by take off

  the excess material due to mass of parts

  divergent, on the front faces.

  We will now describe the process according to the

  vention in more detail, using an unfolding plan shown in the accompanying drawing, including:

  Figure 1 shows the reduction in pre-

  first end of the tube; Figure 2 shows the profiling process of the first end of the tube; Figure 3 shows a first drawing process to produce the thin-walled central part of the tube; Figure 4 shows a second drawing process, to further reduce the thin-walled central part of the tube; Figure 5 shows an arrangement after completion of the first end of the tube; FIG. 6 represents the reduction in thickness of the second end of the tube;

  FIG. 7 represents a variant of enlargement

  the second end of the tube; Figure 8 shows another reduction of the second end of the tube; Figure 9 shows the process during tube calibration; Figure 10 shows the process when profiling the second end of the tube; Figures 11 and 12 show the process

  during enlargement of the reduced tip aupa-

  before. In the figures, there is shown only schematically a device for cold forming a tubular blank to make a tube 1. The components of the device and the blank or the tube itself are, in each case, shown in the state initial or before

  forming above a central line 2, while-

  below the central line 2, the device is shown each time in its state after forming,

so, as a consequence, as the tube.

  In Figure 1, the blank or tube 1 is fixed (e) in a set of jaws 3 of a clamp not shown in detail. A forming tool 4 can be passed from the position above the center line 2 to a position below the center line 2, as indicated by the arrow. A calibration mandrel 5, subjected to the spring action 6, is placed inside the forming tool 4. It is possible to

  insert a drawing mandrel 7 on the side opposite the man-

  calibration strand 5, through the other side of the tube 1. The stretching chuck 7 is certainly already inserted in the blank,

  but it has not yet reached its final position.

  When the forming tool 4 is brought, for example by a working cylinder (not shown), to the end of the tube situated on the right in the figure, it

  a change in shape occurs, the external geometry

  of the end of the tube corresponding to that of the forming tool and the internal geometry of the blank to that of the calibration mandrel 5, as regards the

  i5 cylindrical deformation zone.

  After this reduction of the end, the tube 1

  remains subject to clamping of the jaws 3, a tool for pro-

  wiring 8 (Figure 2) allowing, by moving in the

  direction indicated by the arrow, to profile the end

  reduced tube mite in FIG. 1, for example in the

  with fluted teeth that can be used

  read later to transmit a couple. It goes without saying that one can also form an internal toothing at the reduced end of the tube by means of a

appropriate conformation.

  In FIG. 3, the drawing mandrel 7 is

  brought against an inner shoulder of the tube 1 is

  before connecting with the reduced end of the tube.

  Finally, we bring all of the tube 1 and the mandrel

  7 against the clamping jaws 3

  killing a fixed stop, the jaws 3 then closing.

  A stretching tool 9 moves along the tube 1 and at the same time it stretches the material to a determined extent, so that a thinned wall appears in the central or contiguous part of the tube, and the initial wall

  remains in the terminal area of tube 1.

  To ensure that the tube 1 remains attached to the drawing mandrel 7 when removing the drawing tool

9, a telescope 11 is provided.

  another drawing process has been shown in FIG. 4. The drawing is carried out here by means of a second drawing tool 12 in a similar manner to the

  the procedure of Example 3, and it corresponds to it for all

  your other possible stretching operations.

  There is shown, in Figure 5, the withdrawal of the drawing mandrel 7. For this, the jaws 3 open easily, so that the drawing mandrel 7 can be removed without hindrance, the clamping jaws

  3, however, playing the role of extractor for the tube 1.

  So that the tube 1 remains on the working line, a prismatic seat 13 is provided which is brought from below onto the working line, before the mandrel is withdrawn.

stretch 7.

  Figures 6 to 10 show the form

  additional mage from the second end of the tube and other operations. To modify the shape of the second end of the tube, we bring back, in Figure 6, so

  appropriate, tube 1 semi-finished by machine, after

  tation of 180, since a whole series of machining stages can still be carried out subsequently. Finally, the tube 1 is brought, with a clamping mandrel 14, with the thickened end towards the outside, in the working position. By means of a reducing tool 15 and an internal calibration mandrel 16, a reduction of

  high dimensional accuracy of the diameter of the end

  mite, and this in correspondence with the diameter of the

  central part of the tube reduced by stretching.

  Instead of the reduction of the second end of the tube, shown in Figure 6, one can make a widening of this end of the tube, and this, as shown in Figure 7, by means of a widening mandrel 17 and an external tool 19 pushed

forward by means of springs 18.

  Figure 8 shows how the second end of the tube can be further reduced by another forming tool 21. When using forming tool 4 and the

  calibration mandrel 5 according to FIG. 1, it is possible to perform

  kill the reduction by adjusting it exactly to the same

  dimensions at the first end of the tube.

  Instead of or in addition to the reduction in FIG. 8, it is also possible, for example, to carry out a calibration according to FIG. 9, by calibrating the tube 1 with a calibration tool 22 over the entire length with a stretched diameter of the

tube 1.

  In Figure 10, the second end of the tube is profiled using the profiling tool 8 already used for the first end of the tube.

  Finally, we have shown in Figures 11 and 12 how

  a tube 1, manufactured by the stages of Figures 1 to 3, has been stretched to its reduced end on the right side

  on the rest of the tube. For this, we moved the

  the drawing wire 9 beyond the left end of the tube 1.

  As shown in Figure 12, the label mandrel

  rage 7 is slightly removed, the clamping jaws 3 slightly open playing the role of extractor. Then, the tube 1 is tightened on the mandrel in the reduced part

  by stretching and widening at the same time and with cali-

  brage the thickened straight end of the tube with a tool

indoor and outdoor 23.

Claims (8)

  1. Method for manufacturing tubes with ends at   thickened wall by cold forming of a tubular blank   laire, characterized in that the ends of the thick-walled tube are left at the wall thickness of the blank and the intermediate central part is produced, or   adjoining thin-walled tube by stretching.   2. Method according to claim 1, characterized in   that from the blank, we first reduce the diameter   inner meter and the outer diameter of a thick-walled end of the tube, then the outer diameter of the central or contiguous wall is reduced   thin by stretching in one or more steps.   3. Method according to any one of the claims   1 and 2, characterized in that the end of the tube, previously reduced after the stretching operation, is enlarged to an outside diameter greater than the outside diameter   of the thin-walled part of the tube (Figures 11, 12).   4. Method according to any one of the claims   1 to 3, characterized in that the other end is reduced   thick-walled mite (remaining section) of the tube (event-   after rotation of 1800) to the outside diameter   of the thin-walled part of the tube (Figure 6).   5. Method according to any one of the claims   1 to 3, characterized in that the other thick-walled end of the tube is widened to a larger outside diameter   the diameter of the thin-walled part of the tube (Figure 7).   6. Method according to any one of the claims   1 to 4, characterized in that the internal diameter is reduced   the outside diameter of the other end has thick wall of the tube (Figure 8).   7. Method according to any one of the claims   1 to 6, characterized in that the tube is calibrated over its entire length, preferably the length of the most large diameter (Figure 9).   8. Method according to any one of the claims   1 to 7, characterized in that the ex-   thick-walled hoppers of the tube with regard to their internal diameter and / or their external diameter, for example by forming a serration with grooves (FIGS. 2 and 10).