DE2334041A1 - Surface finishing wire, bars, and rods - by removal of surface imperfections followed by sizing and polishing - Google Patents

Abstract

The workpiece is initially sprayed with lubricant pref. graphite after an initial straightening operation then heated to >250 degrees F to remove the lubricant carrier ie. water or inert material medium, before passing through a lead die for sizing and working purposes. The workpiece then passes through a cutting or shaving tool to remove seams, laps, slivers, and decarburisation zones. A further lubricant coating is applied before the workpiece is passed through a finish die to size and polish the surface. Method is applicable to workpieces of strain hardened hot rolled carbon or alloy steels, tool steels etc. Improved cutting stability and uniformity are obtained together with improved surface finish with closer tolerances and minimum scrap.

Description

" Process for surface finishing of endless semi-finished products or profiles "

The invention relates to a method for the final surface treatment of semi-finished products of constant cross-section, i.e. of profiles or endless semi-finished products, with a lubricant, Heating to an elevated temperature, passing through a guide tool, a cutting tool (peeling tool) and an end tool in order to obtain materials with improved surface properties, mechanical and have physical properties.

The invention relates to cold working of metals, in particular

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special for simultaneous surface removal and warm or hot drawing of wires, rods, rods or the like, semi-finished products with recurring cross-sectional shapes great lengths.

In cold working processes, it is desirable to preliminarily remove unwanted metal from the surface. The use of coupled grinding, cutting or peeling and finishing tools is known (US-PS 3,157,093) This achieves some desirable properties. However, it has been found that a large number of Metals, such as hot-rolled carbon steels, stainless steels, Tool steels and other stress-hardened materials / for the formation of built-up edges on the cutting edges lead, and that these built-up edges replace the cutting edges of the tool. These construction edges consist of the Material of the workpiece that has been stress hardened as a result of the decrease in the chip. The built-up edge seems to weld at the cutting edge in such a way that it results in a planing of the softer material of the workpiece comes. Because of the formation of build-up edges on the cutting edges of the tool, it is difficult to obtain the required Comply with dimensional tolerances. In addition, pieces of the built-up edge fall off the tool from time to time and remain welded to the workpiece surface. This leads to a very poor surface quality and poor dimensional tolerance both before and after the workpiece has passed through a drawing die. Finally, the welded-on pieces of built-up edge that periodically fall off the cutting tool can lead to damage to the following drawing tool.

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According to US Pat. No. 3,116δ004, the metal is heated to soften and thus avoid or reduce the stress hardening that would otherwise occur in the metal through the Cutting occurs. According to this prior art, however, only a single tool, namely a Cutting tool, applied. In practice, the hot rolled workpiece is made by the cutting or peeling tool guided without additional support from the drawing dies before or after the peeling tool. After all, the workpiece is usually using hot rolled material non-symmetrical cross-section (due to the rolling tolerances, hot rolling mills are usually out of round). This makes a non-uniform tapping to remove all Surface defects of the hot rolled material required. All of these factors i.e. lack of additional support of the work piece, uneven racking and uneven Cutting forces. There are still many possibilities for improving the stability of the process, the service life of the cutting tools and the centric cutting processes.

According to the inventive method, the removal is possible unwanted surface defect of wires, rods or bars, inter alia, profiles _(while improving the physical and mechanical properties. At the same time the stability and uniformity is improved the peeling operation and the surface quality with lower tolerances and minimum of scrap. It is also noteworthy the extended service life of the peeling tool.

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drive to the surface treatment of wires, rods, Bars, strips or similar elongated workpieces with a constant cross-section are these with a Lubricants are coated and heated to subject them to hot drawing and peeling at the same time. The editing and the metal is removed by guiding the warm, lubricated workpiece through a guide> 3s or 2 drawing form is used for dogging or calibrating the warm workpiece and for guiding and supporting the workpiece and for improving the physical and mechanical properties serves.

After passing through this guide form, the workpiece passes through a cutting or peeling tool, which the workpiece encompassed all around to remove surface defects by removing superficial metal. After leaving the peeling tool the workpiece is again provided with lubricant and then passes through the final shape for calibration and polishing.

It has been found that workpieces machined according to the invention have a significantly improved surface quality at the same time have improved mechanical and physical properties. In addition, the stability and the uniformity of the peeling process is significantly improved; there is essentially no off-center cutting tighter (tolerances, better tool life and minimal welding incidents.

The invention is further illustrated by the accompanying figures.

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Fig. 1 shows schematically the sequence of the invention Method based on the surface treatment of wire. " Fig. 2 the tools in detail,

A wire 10 is withdrawn from a reel (not shown), possibly fed to a first calibration machine and then coated with lubricant by spraying with the aid of a nozzle 14 from the lubricant supply 16.

The best lubricant for the purpose according to the invention has been found to be a dispersion of graphite in water or a other liquid medium. It is applied in such an amount that there is a uniform coating forms over the workpiece 10.

Now the workpiece is heated to an increased temperature Removal of water or other inert liquid medium from the lubricant, leaving behind a fine graphite coating and to bring the workpiece to the processing temperature. The workpiece is normally heated to a temperature above 120 ° 0, but below the lower critical temperature. It is obvious that the sequence, application of the lubricant and heating can also be reversed in order to obtain a warm lubricant-coated workpiece.

The warm wire with the fine graphite coating now arrives by the guide form 22, which can be a conventional construction of support and nibbling insert 32. As mentioned above, the guide form 22 is not only used for .Abstützung of the workpiece for the. following stages of work, but also

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for rounding and calibrating the warm workpiece and urailm to give the desired properties.

Binding and calibrating the workpiece is advantageous for at least two reasons:

1) Because all commercially available hot-rolled bars, rods or wires are out of round to some extent and because of surface defects are often found on the circumference of the cross-section, therefore rounding and calibrating leads to Reducing the amount of scrap formed and ensuring the removal of any imperfections. Has for example a workpiece with an oval or elliptical cross-section would become the peeling tool without rounding and calibrating must be dimensioned so that the necessary amount of metal is removed from the minor axis of the ellipse, at the same time however, excessive metal is removed from the major axis and excessive scrap is generated.

2) Was found to be rounding and calibrating

leads to better service life of the peeling tools. Since the stitch has a detrimental effect on the service life of the tool, a stitch check leads to even wear over the entire circumference of the peeling tool and thus significantly reduces premature failure of the peeling tool due to uneven loading.

It has been found that the guiding function of the guiding distance ensures that once the workpiece is round, the surface removal is carried out by peeling coaxially to the workpiece, so that a more complete removal the surface defect occurs. In addition to its effectiveness

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As a guide, the guide tool also serves to remove kinks and sharp bends the deformation and the associated stress on the workpiece in the tool.

The guide tool is also used to improve the mechanical and physical properties of the workpiece by plastic deformation within the tool.

After leaving the guide tool, the warm workpiece passes through the peeling tool 24, which removes the unwanted Removes surface defects such as overrolling, overrolling seams, mill splinters and decarburization. As as can be seen more clearly from FIG. 2, the peeling tool 24 completely surrounds the tool and takes from it a surface layer or chips 36 from.

When carrying out the method according to the invention, it is essential that the temperature of the workpiece or at least the metal to be removed at over 120 ° C, however, is below the lower critical temperature of the metal for steel workpieces. Furthermore, the temperature should of the metal to be removed close to or within the hot working temperature during the material removal to prevent or reduce stress shardened et em metal on the cutting edges of the Peeling tool. The heat energy required for this is usually transferred to the workpiece during the removal process of the superficial metal supplied.

It is obvious that the work

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The amount of heat developed depends on the linear speed with which the workpiece is pulled through the peeling tool will. Depending on the thermal energy applied by the heating units 18, 20, it was possible to determine that the feed speed from 3 m to 107 m / min for the required temperature rise in the metal to be processed.

The geometry of the peeling tools is essential. Pure best Results are preferred exn ° with a rake angle of + 20 to -20 ° and a clearance angle of +15 to -15 °.

After leaving the peeling tool, the workpiece is again coated with an aqueous graphite dispersion as a lubricant coated over the spray device 26. Since the workpiece is at an elevated temperature, it is coated again with fine graphite, which is used as a lubricant during the further processing stages works. The application of the lubricant immediately after leaving the peeling tool also serves to cool down of the workpiece and to significantly reduce unwanted oxidation that would otherwise occur would.

The workpiece, provided with a thin graphite layer, now reaches the end tool, which is used to guide, Calibrating and polishing the workpiece is used and gives it the properties ultimately sought. Its guiding effectiveness is similar to that of the leadership tool 22. The guide and end tools support the workpiece so that it is coaxial with the peeling tool

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is held to an even stitch and enhanced To ensure tool life.

In the end tool, the cross-section is reduced to the final dimensions of the product. The end tool is also used for polishing and ultimately also to increase the mechanical and physical properties, such as tensile strength, yield point and hardness.

The above tools can usually be permanently mounted on a twist draw bench or the like. It is essential that a corresponding distance between (a) the guide tool 22 and the peeling tool 24 and (b) the Peeling tool 24 and the end tool 30 maintained becomes / It is obvious that the exact distance depends on of type, caliber and cross-section reduction in every tool. For most applications there is a distance between 50 and 760 mm between the guide and Peeling tool and a similar distance between peeling and end tool.

The inventive method can be applied to a Variety of metal materials, especially stress-hardened steels such as hot-rolled carbon steels, Use special alloys, tool steels and the like. It was found that the inventive method It is particularly suitable for the post-processing of patented wire, in order to give it a significantly improved To give surface.

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The invention is explained in more detail using the following example.

example

0 - ( "χ 10 10" ⁵ 0.431) containing 0.36 jo C, 1.5% Mg, 0.012% P, as the material a cold drawn ßtahldraht C-1041 used in the form of a collar with a diameter of 11.11 mm , 21 % S, 0.19 % Si, 0.10 % Gr, 0.10 % Ni, balance iron. Checking this bond resulted in a maximum decarburization of 76 Ai, interrupted overrolling of less than 0.1 mm in depth and the following mechanical properties:

Tensile strength 7400 kg / cm ² (105,000 psi); Yield strength '4150 kg / cm ² (59,000 psi); Elongation 27.5 ^C M
Constriction 66 %.

The sample was coated with an aqueous graphite dispersion as a lubricant before it was fed to a pair of inductively heated coils (Fig. 1). The heating evaporated the water, leaving a fine graphite coating. The graphite-coated wire was then passed through the arrangement of guide tool, peeling tool and end tool at a speed of 36.6 m / min and a temperature of 425 ° C 12 ° 0. The peeling tool had an angle of 5 ° and a clearance angle of 5. The dimensions of the tools were as follows:

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Guided tour - 0.405 / 0.406
Sharks - 0.391 / 0.392
End - 0.374 / 0.375.

The finished product showed no overrolling and decarburization, a final caliber of 0.375 * 0.000 to 0.002, hardness 30 to 32 RC, surface roughness VO, 38 nm (15 / U-inches), this collar behaved normally and the finished product was free from surface defects, such as "barber-poling", tearing or fish scales. The mechanical properties changed at 10 600 kg / cm ² (151 000 psi) tensile strength, 9000 kg / cm ² (128,000 psi) yield strength, elongation and 7% 42 / Ό constriction.

In addition, it was found that the workpieces treated according to the invention improved deformability showed. The deformability can be determined by taking a sample of the treated workpiece is subjected to compression, the deformability being expressed as the ratio of the original height to the final height (upsetting ratio).

Although it is not equivalent to that of the present invention Procedure, it was found that it is possible and in some cases desirable the peeling tool when carrying out the method according to the invention in combination with one of the guide or Ihdform /. In this case there is _ the forum tool either before or after the peel tool and serves to deform the workpiece and to improve the mechanical and physical properties as well as

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- 12 its guidance through the peeling tool.

Regardless of whether the tool is before or after the peeling tool, it is preferable to use lubricant onto the workpiece before it passes through the peeling tool (Fig. 1) to apply.

CLAIMS:

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Claims (8)

EXPECTATIONS f 1) J A method for finishing the surface of netallwerkstücken constant cross-section, characterized in that coating the workpiece with a lubricant, is heated to a temperature above 120 ⁰ C, by means of a first tool for shaping and calibration of the workpiece and then through a peeling tool leads to the superficial removal of metal at a temperature close to the hot deformation temperature, furthermore applies lubricant to the workpiece and then leads it to deformation through a second workpiece, the first and second tools and the peeling tool being axially aligned. 2) Method according to claim 1, characterized in that the lubricant used is graphite, in particular an aqueous graphite slurry applies. 3) Method according to claim 1 or 2, characterized in that the workpiece is on a temperature above 120 ° to below the critical temperature warmed up. 409885/0043 -AH- 4) Method according to claim 1 or 2, characterized in that one by appropriate Selection of the feed speed by the peeling tool the temperature required for the material removal brings up. 5) Method according to claim 1 to 4-, characterized in that one is at a working speed works from 3 to 107 m / min. 6) Method according to claim 1 to 5 »characterized in that a peeling tool with a rake angle of +20 to -20 ° and a clearance angle of +15 to -15 °. 7) .Verfahren according to claim 1 to 6, characterized in that between the first tool and the peeling tool and between the peeling tool and the second tool one Maintains a distance of 50 to 762 mm. 8) Method according to claim 1 to 7 »characterized in that a workpiece is made tension-hardened et eai St & hl machined 40 9 885/0043