EP2953745B1 - Method for the punching of a blind hole in a metal billet - Google Patents

Description

The invention relates to a method, alternative to drilling, for creating a blind hole in a metallic workpiece having at least one curved surface, machining starting approximately from the horizontal contact rod and approximately transversely thereto in the direction of the material of the workpiece.

From the U.S. 5,502,994 A a method for producing a blind hole in a metallic workpiece is known, a part of the material being displaced by means of a lifting movement.

In the case of conventionally drilled blind holes, chips inevitably occur. In addition, such bores can only be made at a limited speed.

It is not possible to increase the drilling speed using conventional means. It should also be noted that the workpieces have to be cleaned and deburred, which takes additional time.

No evidence has yet been found of making the blind hole without a drill.

The invention is therefore based on the object of developing a method which the metallic bodies can be provided with blind holes with high precision and also at a significantly increased speed.

1. a) Versehen des Werkstücks mit einer matritzenartigen Aufnahme für das zu verdrängende Material;
2. b) Verschieben des Materials des Werkstücks mittels eines Stempels (18) in Achsrichtung der Aufnahme, wobei das von dem Stempel (18) getroffene Material anfangs in einem adiaba- tischen Zustand geschert wird und teilweise in die Aufnahme fließt; und
3. c) Beseitigen des bei der Aufnahme überstehenden Materials.

This object is achieved by the following method: A method for producing a blind hole in a metallic workpiece having at least one curved surface, starting approximately from the horizontally extending curvature tangent and approximately at right angles to it of the material of the workpiece, part of the material is moved by means of a lifting movement, with the steps:

1. a) providing the workpiece with a matrix-like receptacle for the material to be displaced;
2. b) moving the material of the workpiece by means of a punch (18) in the axial direction of the receptacle, the material hit by the punch (18) initially being sheared in an adiabatic state and partially flowing into the receptacle; and
3. c) Removal of the material protruding from the recording.

The essence of the invention is to put the corresponding material points in the metallic body into an adiabatic state in order to avoid plastic deformations in the area of impact. This does not require a drill that wears out quickly. Furthermore, there are no chips that could lead to process disruptions.

A further development of the invention provides that the diameter of the receptacle is smaller than the diameter of the punch.

This enables the depth and width of the blind hole to be set precisely, since the smaller diameter of the receptacle means that the material can be driven out in the correct ratio so that there is still enough material left over to form the bottom of the blind hole. In addition, the protrusion of the punch with respect to the receptacle enables a ring area that cannot be displaced too quickly, so that this ring area ensures that a bottom area remains during the punching or lifting process.

It is preferably provided that the receptacle for the displaced material is arranged above the workpiece.

Furthermore, it has proven to be advantageous if the impact speed <10 m / s, preferably 6 m / s to 8 m / s, is sufficient to generate the adiabatic state.

The impact speed of 7 m / s is particularly advantageous.

This is in contrast to the statement in the publication DE 103 17 185 , which states that the adiabatic state only occurs at a lifting speed of over 10 m / s.

It is particularly advantageous if the cross section of the metallic workpiece is triangular or semicircular, has at least one rounded corner, and the blind hole, starting from the highest point of the rounding, runs transversely to the line connecting the two other corners.

A further development of the invention provides that the workpiece is fed as a long material with the desired cross-section to the processing station for creating the blind hole and is then cut to size adiabatically or previously separated adiabatically to the final size and fed to the processing station.

It has proven to be particularly advantageous if this method is used for the production of slot nuts.

It is advantageous if this slot nut also has a through hole using the method for producing through holes of through holes according to the simultaneously filed and pending Patent application " Method for producing a through hole in a metallic body ", filed on February 5, 2013 , is provided.

Finally, provision can also be made to produce the through holes first and then the blind holes.

Fig.1

einen Querschnitt der Ausgangssituation, der an dem mit dem großen Pfeil gekennzeichneten Ort quer zur Herstellungsstraße betrachtet wird;

Fig.2

einen der Figur 1 ähnlichen Querschnitt, wobei allerdings der Stempel schon in den metallischen Körper, in diesem Fall den Nutenstein, eingedrungen ist;

Fig.3

eine der Figur 2 ähnliche Ansicht, wobei allerdings der Stempel vollständig eingefahren ist und der in der Aufnahme aufgenommene Stift gemäß der Zeichnung nach rechts abgeschert werden soll und durch das Sackloch abgeführt werden kann; und

Fig.4

eine der Figur 3 ähnliche Ansicht, wobei der Aufnahmeinhalt durch das Sackloch bereits abgeführt worden ist.

Further advantages and features of the invention emerge from the following description of an exemplary embodiment and from the drawings to which reference is made. It is expressly pointed out that the description is based on the production of a sliding block, but this is in no way restricted to this. Show it:

Fig.1

a cross-section of the initial situation, which is viewed at the point marked with the large arrow across the production line;

Fig. 2

one of the Figure 1 similar cross-section, although the punch has already penetrated the metallic body, in this case the slot nut;

Fig. 3

one of the Figure 2 Similar view, although the punch is fully retracted and the pin received in the receptacle is to be sheared off to the right according to the drawing and can be removed through the blind hole; and

Fig. 4

one of the Figure 3 Similar view, the contents of the picture having already been removed through the blind hole.

Based on Figures 1 to 4 the production or the method for producing a blind hole 10 in a slot nut 12, which is metallic in this case and has a curved surface, will now be described. It is pointed out again that the description of the sliding block is only an example, since this method according to the invention is of course also for other metallic bodies with curved surfaces can be applied and used.

The Figure 1 shows the starting position for an adiabatic displacement of a blind hole 10. The workpiece 12, which in this case is of course a sliding block 12, is held in a holder 14 in such a way that the rounding of the semicircular cross-section in this case points downwards. The workpiece 12 to be machined is held on its upper side by a receptacle 16 which has a punch 18 in an aligned recess or a cavity for the material to be displaced.

The sliding block 12 or the unmachined section is therefore held from below and from above.

From the sketched production chain for all Figures 1 to 4 it can be seen that so-called through holes are created beforehand and also provided with a thread.

In all Figures 1 to 4 the large arrow always points in the direction of the section shown as a large cross-section.

Starting from the position according to Fig.1 now what is in Fig. 2 is shown, the material of the workpiece is displaced with the aid of a punch 18 in the axial direction of the receptacle 16, the material hit by the punch 18 transitioning into an adiabatic state and being partially displaced into the cavity 16 provided for this purpose.

Then according to Fig. 3 the receptacle 16 can now be moved freely to the right, since the punch 18 has already been pulled out of the blind hole 10.

The recording 16 is according to Fig. 4 Shifted to the right until the sheared pin reaches the through hole Du and can fall down through it.

So that when the excess material is punched out or moved into the receptacle 16, the material in the adiabatic state is not pressed through the surface of the slot nut 12 so that a hole is formed, the diameter d in the receptacle 16 is smaller than the diameter D of the punch 18. A small ring is formed in the region of the sliding block 12, which is more or less held back by the smaller diameter d of the opening of the receptacle 16. The receptacle 16 therefore holds an annular part of the later bottom of the blind hole 10 of the slot nut 12.

It is certainly also possible to reverse the arrangement to the Figures 1 to 4 to arrange. However, it has proven to be advantageous if the receptacle 16 for the displaced material is arranged above the workpiece 12.

Although, as already shown in the introduction, the document DE 103 17 185 A1 expressly mentioned that an adiabatic state only occurs at speeds above 10 m / s, it has been shown in the illustrated arrangement that lower speeds, for example 6 m / s to 8 m / s and preferably 7 m / s, can also be used to achieve an adiabatic state in the piercing process.

Unlike those in the Figures 1 to 4 However, it is also possible that the cross-section of the metallic workpiece 12 is triangular, with at least one rounded corner is present, which can be used as an entry for the punch or punch 18 to produce the blind hole 10.

From the Figures 1 to 4 it also results that the production of the metallic workpieces 12, in this case the sliding blocks 12, is used as the starting material of a long wire with the above-mentioned cross-sections in order to be able to use a production line-like processing. It is, however, also possible to cut the specific workpieces 12 to length beforehand and then to feed them to the individual processing stations in appropriate rails, just as with the assembly line.

With the help of the invention it has now been possible to produce blind holes which have a flat bottom and no longer have the conical depressions that are produced by the drills. In the case of the slot nuts in particular, this has the advantage that the springs inserted in the blind holes for supporting a ball always fit precisely and cannot move. With the exception of the spring travel, of course. So that the balls placed on the springs are held in the blind hole, the outer walls of the blind hole are caulked.

List of reference symbols:

10

Blind hole

12

workpiece

14th

bracket

16

admission

18th

stamp

D.

diameter

Claims (8)

1. Method for the punching of a blind hole (10) in a metallic workpiece (12) having at least one curved surface, wherein starting approximately from the horizontally extending curve tangent and approximately perpendicularly thereto in the direction of the material of the workpiece (12) a part of the material is displaced by means of a stroke movement, having the steps:

   a) equipping the workpiece (12) with a matrix-like receptacle (16) for the material (12) to be displaced

   b) moving the material of the workpiece (12) by means of a stamp (18) in axis direction of the receptacle (16), wherein the material impacted by the stamp (18) is sheared in an adiabatic state and flows partially into the receptacle (16); and

   c) removing the material (12) protruding at the receptacle (16).
2. Method according to claim 1, characterised in that the diameter (d) of the receptacle (16) is smaller than the diameter (D) of the stamp (18).
3. Method according to claim 1 or 2, characterised in that the receptacle (16) for the displaced material is arranged above the workpiece (12).
4. Method according to any of the preceding claims 1 to 3, characterised in that the adiabatic state is achieved at an impact speed of 6 m/s to 8 m/s.
5. Method according to claim 4, characterised in that the impact speed is 7 m/s.
6. Method according to any of claims 1 to 5, characterised in that the cross-section of the metallic workpiece (12) is triangular or semicircular, has at least one rounded corner and the blind hole (10) extends starting from the highest point of the rounding perpendicularly to the line connecting the two remaining corners.
7. Method according to any of claims 1 to 6, characterised in that the work piece (12) is supplied as a long material with desired cross-section to the processing station for punching the blind hole (10) and is then cut to final size in an adiabatic manner or is already previously isolated adiabatically at final size and supplied to the processing station.
8. Use of the method according to any of the preceding claims 1 to 7 for producing sliding block (12).

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