DE1502949A1 - Process to improve the stability in the machining of workpieces with constant cross-section - Google Patents

Description

"Method for improving the stability in the metal cutting machining of work pieces consistent iuerschnitts". The invention relates to a method for the machining of rods, rods, tubes, wires and the like. Endless profiles which can have round, square, polygonal or elliptical cross-section, whereupon the thus planed or peeled profiles are accessible for further non-cutting cold forming or surface processing. for cold working, e.g. B. drawing, extrusion, rolling and the like. It is often necessary to previously remove unwanted amounts of material from the surface of the Jerkstücks. A combination of the planing tool with a tool for reducing the cross section by plastic deformation is extremely advantageous. It is known that when peeling or planing on the surface, strong compressive loads occur in the material to be processed. This seems to be a logical explanation for the high stresses which lead to the various difficulties caused by the formation of so-called built-up edges on the cutting edges of the tool and to a poor surface quality. The removed chip surrounds the cutting edge of the planing tool and thus lifts it off the workpiece. The lifted material must necessarily be removed, this removal leads to severe, peripheral tensions, and even to cracks in the chips.

The built-up edges are based on the tendency of the material to which Cutting the planing tool to be welded on during planing. That on the cutting edges welded metal is hardened during the work process, for example by Stress hardening, so that the material build-up on the cutting edges is now stressed of the workpiece. With increasing approach to the cutting edge, it fluctuates periodically the actual chip thickness. The consequence of this is that of the surface of the workpiece lifted amount of material of a control or monitoring is inaccessible and a wavy surface is created. The lack of monitoring capability and the implied Surface roughness has a very detrimental effect on the following process steps for non-cutting shaping or surface processing. Apart from that from the formation of built-up edges also affects a certain instability the cutting performance and service life of the tools in all types of planing operations and the surface quality of the workpiece. The instability can be due to several causes are based. So z. B. moves the workpiece from one side of the tool to the other during its passage through the planing tool. The result is a wavy one Surface due to uneven chip removal. Just as harmful as hiking the Workpiece is also a hitting, so that various methods have become known and there are suggestions that this instability is greater during planing operations Material lengths can be avoided or at least largely reduced. Attempts have been made by appropriately designing the cutting edges and the tools even to increase the stability. But these methods and tools can also not yet fully satisfied.

The invention thus brings: -1measures to improve the stability during the machining with the help of planing tools and thus an essential one Improvement of the physical and mechanical properties of the machined Workpiece with excellent dimensional accuracy at the same time. The surface quality of workpieces treated in this way is such that a non-cutting shaping occurs immediately can connect. A smooth, clean surface is obtained without any waves afterwards Neither the workpiece moves, :: and hitting occurs during the planing process. To the execution of the process according to the invention, no special investments are high capital expenditures and no expenses for specially trained staff are required. Another Advantage of the method according to the invention for increasing the stability during a planing process can be seen in the fact that these machining processes have a tendency to Formation of built-up edges, i.e. the growth or welding of raised ones Material from the workpiece to the cutting edges of the planing tool, extraordinary is low.

The invention thus relates to a method for improving the stability when planing workpieces of constant cross-section, such as bars, rods, tubes and profiles, with the help of a planing tool of high heat resistance and is thereby characterized in that one during the planing process to increase the stability between Workpiece and tool an additional relative movement, d. i. a twisting motion or maintains a FORWARD-BACK movement in the axial direction. When turning it can be a continuous rotational movement in one direction or one act reciprocating movement over a certain part of a circle. When turning The tool preferably performs this movement. With the reciprocating Movement in the axial direction of the tool is preferably a FORWARD = backward movement of the tool, how to get it when you put it on a shaking table or the like. stretched. The FORWARD-BACK movement can be used for. all kinds of profiles with circular cross-sections as well as with elliptical, square and polygons Apply cross-sections. The radial movement can be used for all round cross-sections, So use circular bars, rods and tubes, with the machining of tubes can be done both on the inner and outer surface. In the case of that Tool executed relative movement is preferably the workpiece to be machined drawn linearly through the tool. For the movement of the tool and the passage of the workpiece are given a wide variety of design options.

The effectiveness of the proposed according to the invention - "measures a Relative movement between workpiece and tool can be attributed to various causes will. For example, the additional relative movement causes an additional one Heat development during machining, so that the temperature of the chip is increased. A higher chip temperature reduces the tendency for built-up edges to form and thus improves the planing process.

Another essential aspect of the method according to the invention can also be seen in the fact that due to the radial movement, for example, the rake angle of the work eye can be higher than without it. The fore-and-aft movement of the tool during axial oscillation also has an effect in this direction. It has proven to be particularly advantageous to combine the measures according to the invention during machining with subsequent non-cutting deformation. For this purpose z. E. a drawing tool arranged directly or at a distance combined with the planing tool. Good leadership must be ensured. For example, a guide member, such as a pair of concentric guides, is suitable for this.

A further increase in stability can be achieved by increasing the Force component due to friction between the chip and the tool. The inventive Measure acts in the direction that a positive radial (frictional) force component or force vector, is maintained while planing. Because it has showed that factors that increase friction, in the same way, lead to an increase of the radial force vector. One of these factors is the application of one Tool with a smaller clearance angle than is the case with a blunt tool, or with a tool with a negative rake angle. In practice it is preferred the use of a planing tool with a rake angle between 0 and 30o, depending of the lubricant used in each case.

Another factor influencing the frictional force component is in the selection of the lubricant to be used. There are available on the market for this Suitable for lubricants. The respective selection is made with a view to it on the materials to be planed and the desired working conditions.

Another factor is the intended chip thickness. The lower the Chip thickness, the greater the relative positive radial force component and thus the greater the stability during machining.

The use of a chip breaker can also improve the stability taking into account the above factors.

It has been shown that the contour of the tool and the material from which the Jerkzeug consists, a considerable influence on the stability when machining. 'If a softer @%' material is not used for the @ tools, so this has the same effect as a worse lubricant: riittel and thus a higher Y, radial force component. For planing the same ik "materials So you get higher stability with tools made of high-speed rotating steel compared to such from cemented carbides and the, -l.

A negative radial component is permissible if special _.a: @ notices are provided for increasing the stability. For example, guide members, as mentioned above, are suitable for this. The closer the guide member can be brought to the cutting edge of the planing tool, the greater the negative radial force is permissible. In general, however, guide members cannot be brought so close to the tool in order to influence the machining itself and the formation of built-up edges. In practice, it has proven to be expedient to arrange the guide members at least one chip thickness away from the planing tool. Although the distance can be greater, a distance between 1 and 10 times the chip thickness is desirable.

The balance of forces in the measure of the relative movement according to the invention between tool and workpiece in the radial or axial direction results from the Firg. 1 and. 2. Fig. 1 shows the force vector R as a positive vertical component and Fig. 2 as a negative component. If the component is positive, the stability of the planing process is significantly improved. The application of force as shown in FIG is, leads to instability.

Claims (4)

P atentanspr u ch e of workpieces of constant cross-section, characterized in that an additional relative movement is maintained between the tool and the workpiece during the planing process. 2. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t that one can have a continuous rotary motion or one over maintains a circular reciprocating rotary motion. 3. Procedure according to Claim 1, characterized in that there is a fore-and-aft movement maintains in the axial direction. 4. The method according to claim 3, characterized in that g e k e n It is not indicated that the tool is clamped on a vibrating table. Blank page