DE10238871B3 - Process for separating a bushing from a pipe clamped in a matrix comprises cutting the pipe material along a separating line using a cutting tool and separating the bushing by a brittle fracture produced on application of axial force - Google Patents

Abstract

Process for separating a bushing from a pipe (2) clamped in a matrix (3) comprises cutting the pipe material along a separating line (20) using a cutting tool and separating the bushing by a brittle fracture produced on application of axial force. The axial application of force is partly produced by penetration of the cutting tool and a radially inward-directed pre-tension is applied along the separating line by the matrix. The pre-tension causes elastic deformation which induces stress tension in the region of the separating line. Preferred Features: The diameter of the cutting tool is less than half of the inner diameter of the pipe.

Description

The invention relates to a method for separating a bush from a pipe according to the preamble of Patent Attorney 1.

In the DE 196 15 522 A1 a device is described which is suitable for separating waste pieces from a thin-walled pipe, for example an exhaust manifold.

In the DE 2758 543 A For example, a method of separating a sleeve from a pipe will be described. Here, a cutting tool is first inserted from the outside into the tube. The cutting process is stopped from a certain depth of cut, followed by an inner and outer finishing, then the sleeve is completely separated from the pipe. Although this process is chip-free as far as the separation process is concerned, it often leads to burrs and deformations on the cutting edge.

When separating thick-walled pipe material and higher. required precision, such as B. in the separation of cylinder liners from a However, round-kneaded pipe may be used in the application of the above Die come to deformations in the cutting area.

The object of the invention is a To provide a method for separating a socket, in which the cutting edge deformation is largely prevented.

The solution to the problem consists in a method according to claim 1.

To carry out the method is a tube clamped in a die. A rotatably mounted on a shaft Cutting tool is inserted into the pipe. The cutting tool performs a rotary motion from, at the same time, the shaft on an inner surface of the Along the pipe, wherein a section along a parting line through the cutting tool he follows.

Here, the pipe material is through the cutting tool torn inside wall. By penetration the cutting tool into the pipe material becomes an axial force exercised on the pipe. at certain brittle Materials, this force is sufficient, along a brittle fracture to trigger the dividing line. To increase the process safety will give this axial force another, of Outside superimposed applied axial force.

With the help of the procedure, a accurate, chip-free separation can be achieved. The socket is attached to the Partitions almost burr-free and does not have to be reworked, it needs no lubricant, which is beneficial from an environmental point of view is and there is no plastic deformation at the interface, which for one Reliable processing of the cylinder liner of importance is.

Furthermore, it is expedient that a pipe through a suitable jig around the cutting tool is turned. Here, the cutting tool either rigid standing on the shaft or is in support of the separation process as well turned. The cutting tool also goes along the dividing line emotional.

According to the invention, it has proved to be expedient to apply a circumferential bias in the radial direction along the pipe surface. The bias is preferred by or through a portion of Matrix exercised and she leads to a slight elastic deformation of the tube surface. By the elastic deformation becomes a notch stress along the parting line generated. This notch stress is at the dividing line from a critical Cutting depth of brittle fracture along the dividing surface initiated.

The bias can be through a wraparound wedge are generated. In this case, the Dividing line preferably directly on a wedge opposite Line.

It is also appropriate, a planar preload Apply, wherein the dividing line in the elastically deformed zone runs.

When applying a circulating Preload can also unsupportive to trigger the brittle fracture a force is applied to the pipe in the axial direction.

Also in support of the Separation process may additionally still a bending stress with at least one force component in radial direction are applied. The separation process is characterized accelerated.

Furthermore, it may be appropriate to apply the stresses in the form of vibrations. By suitable Choice of amplitudes and frequencies can be done this way in dependence the material to be separated creates a particularly uniform interface become.

By applying the matrix can at the same time a coinage a bush outer surface done. For this purpose, in clamping jaws of the die an embossing pattern, for example a Cross border introduced by a clamping operation on the surface of the Transfer socket becomes. The imprint on the socket surface is beneficial when pouring the bushing as a cylinder liner in a cylinder crankcase. A Connection of a cast metal and the cylinder liner is thereby improved. The connection consists of anchors, the casting metal on the rough socket surface and / or by partial melting.

Also advantageous with regard to the pouring of the bush into a cylinder crankcase is the production of a deviating from a right angle separation surface. Preferably, the win angle with respect to the pipe center axis between 85 ° and 45 °, in particular between 55 ° and 85 °. The resulting taper of the cylinder liner also serves to better fusion between the casting metal and the cylinder liner.

It has turned out that the diameter of the Cutting tools should be smaller than half the pipe inside diameter. In this way, the cutting tool can be made better angle and it creates more space for execution of the cut. In addition, due to a smaller diameter of the Cutting tool the specific surface pressure at a contact line increased by cutting tool and pipe.

Preferred embodiments of the inventive method become closer to the figures described.

Showing:

1 a representation of the method according to the invention with a tube, a die and a cutting tool,

2 an enlarged section in the region of a parting line with the course of a brittle fracture,

3 an enlarged section in the region of an angular dividing line with the course of a brittle fracture,

4 the application of a planar elastic preload at the parting line,

5 the application of a linear elastic preload.

In 1 an overview of the method according to the invention is given. It is a cutout of a pipe 2 shown in a matrix 3 with two jaws 4 . 6 by a: screw connection 8th are connected to each other, is clamped. In the tube 2 becomes a rotationally symmetrical cutting tool 10 introduced that on a wave 12 is arranged. The wave 12 runs in 1 parallel to a pipe center axis 14 ,

The wave 12 is with respect to the pipe center axis 14 displaceable in three dimensions in a Cartesian coordinate system 16 . 1 8, wherein a movement in the drawing plane is not shown here. To the pipe 2 in the axial direction a force F _a and in a radial direction a force F _{b is} applied. Both forces are swinging.

The cutting tool 10 gets through the shaft 12 preferably driven at a speed between 50 l / min and 500 l / min. During the cutting process, the cutting tool becomes 10 along a dividing line 20 emotional. The cutting tool penetrates to a critical depth of cut 24 ( 2 ) in a socket edge 22 on. Upon reaching the critical depth of cut 24 uses a brittle fracture that is in the 2 and 3 through the fault lines 26 is illustrated. The break direction 27 is determined by the position of the cutting tool 10 certainly.

The critical depth 24 depends on the brittleness and the fracture behavior of the material to be separated. Other parameters affecting the critical depth of cut 24 co-determine the forces F _a and / or F _b as well as those of the cutting tool 10 caused force F _S , in turn, by the geometry of the cutting tool 10 is dependent on the cutting area.

In the tube material to be separated in this example, a hypereutectic aluminum-silicon alloy having a Si content of 25%, the critical depth is 10% of the thickness of the socket edge 22 , The cutting tool 10 is preferably made of hard metal or ceramic, for example silicon nitride or zirconium oxide.

The brittle fracture creates a relatively rough separation surface, which in turn when pouring the cylinder liner in a cylinder crankcase is advantageous. The rough one surface (Interface) acts as an adhesion agent to an aluminum melt, through which the cylinder crankcase is formed.

The separation surface achieved by the method according to the invention has no burr at an inner cutting edge 25 on. As a rule, no reworking of the parting surface is required. The separation surface is divided into a cutting surface, which is produced by the cutting tool and into a fracture surface. Since the cut surface affects only a small part of the parting surface and the separation by brittle fracture takes place almost exclusively elastically, the separated bush in the area of the parting surface is almost free of plastic deformation. This causes a high dimensional accuracy and high process reliability in the production of the cylinder crankcase.

In 3 is an angle with respect to the pipe center axis shaft 12 with cutting tool 10 shown. By this arrangement, an angular cutting surface is achieved. The angled cut surface also offers advantages in pouring the bush into a cylinder crankcase.

Further advantageous embodiments of the invention are shown in the figures 4 and 5 shown. This is an additional bias on the pipe 2 applied, which in the vicinity of the section line 20 an elastic deformation 28 causes. Due to the elastic deformation 28 an additional axial force component is introduced into the tube, which also acts as a notch stress.

In 4 becomes the elastic deformation 28 flat by a protruding nose 30 on the clamping jaws 31 the matrix 3 caused. The dividing line 20 runs accordingly in the elastically deformed area 28 ,

In the 5 shown template 3 with the jaws 33 has a circumferential wedge 32 on, by the circumferential clamping force is applied. The notch effect generated thereby works analogous to the in 4 described notch effect. The dividing line 20 runs directly opposite to the thorn 32 ,

Claims (9)

Method for separating a bushing from a pipe ( 2 ), whereby the pipe ( 2 ) into a die ( 3 ), one on one shaft ( 12 ) rotatably mounted cutting tool ( 10 ) from inside the pipe ( 2 ), the wave ( 12 ) with respect to the pipe center axis ( 14 ) is moved eccentrically circumferentially, characterized in that the pipe material is cut by the cutting tool along a parting line ( 14 ) is cut and the further separation by a caused by an axial force brittle fracture ( 26 ), the axial force being partly due to the penetration of the cutting tool ( 10 ) and - by the die ( 3 ) a radially inwardly directed circumferential bias along the dividing line ( 14 ) is applied, - is caused by the bias an elastic deformation by a notch stress in the region of the dividing line ( 2 ) is induced. A method according to claim 1, characterized in that the elastic bias by a circumferential wedge ( 32 ) and a separation along the wedge ( 32 ) he follows. A method according to claim 1, characterized in that the elastic bias is applied by the die circumferential surface and the separation in the range of elastic deformation ( 28 ) he follows. Method according to one of claims 1 to 3, characterized that a force in the axial direction is applied to the tube. Method according to one of Claims 1 to 4, characterized a radial bending force is applied to the tube. Method according to one of claims 1 to 5, characterized the tensile force and / or the bending force are applied swinging. Method according to one of the preceding claims, characterized characterized in that the Buchsee on an outside through the matrix Depressions imprinted become. Method according to one of the preceding claims, characterized characterized in that a separating surface with an angle with respect to the Pipe center axis between 85 ° and 45 ° is cut out. Method according to one of the preceding claims, characterized in that the diameter of the cutting tool ( 10 ) is less than half of a pipe inside diameter.