CS367490A3 - Process for hardening cutting edges of saw blades, knives and punches - Google Patents

Abstract

A process is disclosed for hardening the cutting edges of saws, knives and cutting tools, in particular for processing wood, paper, cardboard, plastic materials, leather and textiles, by means of an energy beam guided over the areas to be hardened of the tool. In order to obtain optimal hardness, a plasma beam is used as energy beam. The plasma beam (2) is guided with a relative speed (v) with respect to the cutting edge of the tool between 5 and 100 mm/sec., the gap between the outlet nozzle of the plasma torch (1) and the cutting edge extends between 2 and 14 mm, the power of the plasma beam is comprised between 1 and 10 kW, and the diameter (d) of the outlet nozzle of the plasma torch (1) is comprised between 3 and 7 mm.

Description

íS; i · F.L /. The invention further relates to the present invention

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hardening saw blades, particularly saws for wood processing, as well as a method of hardening knives and blades for: working with wood, paper, cardboard, plastics, leather or textiles. Cutting edges i i '' these '' tools! intended for quenching, are heated by energy rays. The cutting edges of saws, knives or punches for the

; z z! Worn purposes are subject to wear. The durability of these tools depends on the quality of the blades / on the used. . -i ·: the material, the method of hardening /, the nature of the sawn timber and the cut-1 [- / +; After the end of the service life, these tools are either cut or crushed. , 'ι ..' · í · '' 5 «· *! r '- · 1>..> j ·' v 't'. j '·'; the punch is made of carbon steel, which!

Many types of heat can be easily heated and then cooled rapidly í $; Since such quenching has always been associated with the inlet, a high hardness in the region is desirable. cutting edges. Other parts of the saw, knives or chain saw have a V 'k i ";?. I.! · Í: lower hardness but a higher toughness.

Known methods for partial quenching of cutting edges are the use of electron or laser beams as a source of energy. A drawback in the hardening of the electron beam or laser beam is the expensive 'glowing' needed to perform such procedures. For this reason, so many ways in. practice. '' * Another acquaintance; by way of hardening-is induction hardening. After the cutting edge is sharpened, the cutting edge area is heated by eddy currents obtained by high frequency magnetic alternating field and then quenched by rapid cooling. Furthermore, it is known from WO 85/00051 that it can be surface hardened by a flat surface with a plasma beam. Plasma quenching of the cutting edges has not yet been taken into account as such plasma beams exhibit too little stability. It is known to weld stellites to the tips of the teeth. The welded stellite material is then ground to the desired tooth tip shapes. However, this procedure is very costly. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for hardening cutting prisms, knives and punches using a simply obtainable and inexpensive energy beam. ‘I>. . . >

According to the invention, therefore, a plasma beam is used as the energy beam, the plasma beam being fed to the instrument with a relative speed of 5 to 100 mm / s and the distance between the plasma torch outlet nozzle and the cutting edge being 2 to 20. S ’{. '·! 14 mm and the power of the plasma torch is 1 to 10 kW, the diameter of the plasma nozzle of the plasma torch being 5 to 7 mm. that, if the parameters are adjusted precisely, it is possible to use a plasma jet to cut the cutting edges, and it is only possible with these parameters V. n - 4 - hardening by the so-called self-aligning, that is to say without additional cooling For example, by air or water, the heating speed and cooling rate are adjusted to the optimum values for different material thicknesses and for different cutting angles, in thinner sheets, in particular below 3 mm and at lower cutting angles in particular below 25 °, the velocity of the displacement must be greater because otherwise the cooling rate due to the limited heat dissipation of the base material is too small to sufficiently large turbidity. For example, at higher blade angles, the velocity of the slider can be chosen to be smaller for larger turbid zones. ; The plasma beam is achieved by ionizing argon or nitrogen or mixed gases. The ionization occurs by an arc electrode. 'Ϊ!

Itric discharge or excitation by high frequency electromagnetic radiation! ; . · A beam is drawn through a suitable shape of the electrodes or nozzles in which the temperature reaches up to 15,000 ° C. •} ’. 'H e · · *. •> i

If such a plasma beam is guided by the parameters according to the invention above the abraded cutting edge of a saw, a leg or a punch, the local edge is heated by the cutting edge. ending the energy supply, the cutting edge of the cutter is self-extinguishing, that is, by dissipating the heat into the base material, the nozzle is driven at cooling rates of up to 1000 ° C. The resulting martensite structure with a hardness of up to 1000 HV / Vickers hardness is important in the process according to the invention, however, it is important that the cutting

'SX * 5. - The edge has not melted during heat treatment. Nevertheless, there must also be sufficient heating in the area of the cutting edge to ensure that the required hardness is increased. This is achieved only by keeping the above parameters.

Particularly favorable conditions for quenching are, at the following values: 1 i plasma radiator power radiator diameter at the plasma torch outlet nozzle distance of the plasma torch exit nozzle cutting edge relative velocity of the plasma radiator to the cutting edge -. ...

1 to 5 kW 4 to 5.5 mm 5 to 9 mm M n, 1 »r nr? Hk £ - V; 'i f · Ci'> · '

Advantageously, the knife or punch is guided along the cutting edge by a plasma beam through a mechanical motion, the axis of the plasma t. . the emitter coincides with eight cutting edge symmetry. In the case of saws, the plasma beam is guided by mechanical movement of the plasma torch; : 'N-1F 1, across the saw blade across the back of the teeth in the upper ·, cut-. '' M. Thus, as far as possible, the effect of f J '·: i,' fc '‘5' 'is achieved? J ·. *; heat along the cutting edge of the tooth tip. For certain

Conversely, it is advantageous and technically easier to lead a plasma burner without transverse movement along the saw blade. By electromagnetic deflection by means of a coil arranged between the cathode and the lower edge of the nozzle, a defined expansion of the plasma beam is possible, thereby adapting the geometry of the tooth (e.g., a siphon with deflected teeth). The difference with the known method of electromagnetic deflection of the Plasma Plasma at 'fusion' is based on the fact that there is action. electro.- ... 0½> ^ Ί V; ’· m

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v 5l · '- 4V to V' l íp r *; v or 4 / i? i Ví; t'n • n i f! ! y in Fig. 2 V *, r Λ * r magnetic field in the area between the lower edge of the nozzle and the surface. In this method, the focal point of the arc must be located on the surface of the tool. This known method does not work with plasma quenching, since the arc must also burn between the cathode and the bottom edge of the nozzle. The energy efficiency of the quenching process can be achieved by 5-d in that the pulsed beam operates in pulse frequency pulse operation f where the saw blade feed rate divided by the tooth pitch, the time is between 0.2 and 0.8 seconds.

Furthermore, in the case of knives, it is possible that the axis of the plasma beam forms an angle (e.g. 90 °, 135 ° or half the angle of the cutting edge) with the axis of symmetry of the cutting edge. In this way, an unsymmetrical distribution of the quenching zone with respect to the symmetry axis can be achieved, thereby adapting to special wear situations. In particular, for knife ...: V, sheet thicknesses over 5 mm make it possible to adapt the tailored zone to a variety of cutting geometry.

The invention is illustrated in more detail by the accompanying drawings, in which: Fig. 1 is a schematic representation of the principle of 5 *: 'μ -'; - ', vfc · j. is an axonometric view of the tip of the saw blade tooth; ; ? FIG. 3 is a schematic diagram of a principal arrangement of a plasma unit using an example of hardening of a knife; Fig. 4 is a cross-sectional diagram of the plasma torch in the nozzle stage and the plasma power / kW / 2.5 of 4.0 3.5 ... 4.0 2, 4.0 ' in mm / Ί -, 5.0 6.0 4.0 feed rate / vv mm / s / 25.0 30.0 2o., 0 '· gas flow / l / min / 7.0 10.0 7 , 0 maxima Lni hardness / HV / 920,0 940,0, 900,0 - Practical tests on saws have shown a fivefold increase in lifetime. i and (! ξίi i * í! »;

R i. ri Ί jj. • 1 Example 2

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Hardening circular saw

Material ': B 412 saw blades, 50 teeth, 30 mm tooth pitch, 4.0 mm cutting blades, unprocessed hardness410 HV. plasma power / kVf / R 3.0 j ‘. beam diameter (d in mm). . 4.0 .mu.M, i ' ' ' ' ' i · row feed rate / v in mm / s / ¢. í r T '5O' ° Γ gas flow / l / min / * 8.0 maximum hardness / HV / øi -F 5 bsi i. and'.' ./ &amp; 7 ’i‘ 900,0 i i '<λ. '; ϊ 1 Example 3 ‘: B’ ’í <. “'<, Í,' - ':, ·

Hardening of band saw

Material: B 412 saw blade, strip length 6 m, rbztéčwžubů - "- 15 mm, cutting edge width 1.5 mm, unprocessed hardness 410 HV plasma power / kW /, 7 i 'i; · beam diameter / dv mm / *} distance / a in mm / feed rate / vv mm / s /! gas flow / l / min / Ϊ 'maximum hardness / HV / 1,5: 5,01 5,020,0 7,0 900,0 Example

AND

Hardening of punch for leather and textiles

Material: strip steel CK 60 / number: material 1.1221 /, thickness 2 mm, hardness v; raw state 300 HV / Vickers / plasma power / kW / 1 2 4 beam diameter / d in mm /; -4 4; 4 distance / a in mm /: 4 6> 8 i. 'J .. * angle between the axis of the plasma beam f. .......... and the axis of the cutting edge / ° / i | . 0 0 0 1. · V 1 f: I i il J.,, ”r ti. i '1 i feed rate / v in mm / s / Γ! 25 55 50! 'P' in? f r = '/ gas flow' / l / min / '5 5 5. * 1, í maximum «hardness / HV / 860 890 940 Example 5L ': f

Hardening of the planer knife for woodworking 11

Material: "80CrV 2 / material number 1,2255 /, thickness 8 mm", '' hardness in raw state 280 HV / Vickers / • 6

plasma power / kW / 2 3 5! beam diameter / dv mm / ...... 4 4 ... 4 distance / a in mm / 4 6 8 angle between plasma beam axis and cutting edge axis / 0/60 90 120 feed rate / vv mm / s / 20 30 40 gas flow / l / min / 5 5 6 maximum hardness / HV / 840 880, 905 li

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Claims (9)

- 11 - PATENT REQUIREMENTS <1 · Method of hardening cutting edges of saws, knives and punches, especially 1 '* especially for the processing of wood paper, cartons, plastic materials, leather and textiles, by one energy beam that. }: 1 i S f χ is directed over hardening areas, characterized by i. ; a plasma beam is used as the energy beam, and the plasma beam (2) is guided relative to the cutting edge of the machine by a relative velocity (v / equal to 5 to 100 mm / s), wherein the 3 ' the cutting edge is 2 to 14 mm and the power of the plasma emitter is 1 to 10 µ. . 1 kW and the diameter / d / of the plasma torch outlet nozzle (1) is, 1 to 3 mm. : 5, .J. i 1 t ', -f - i 2. The method of claim 1, wherein the plasma power is applied. l · · i. ,, H emitter is 1 to 5 kW. / i / 1 'i i; 2. The method of claim 1 or 2, wherein the plasma jet diameter (41) is equal to the plasma jet (2) at the exit nozzle. The plasma torch is 4 to. 6 mm. ,,?! ‘’ ». ? ' · 4 ”c i i .. ·. »| 4. The method of claim 1 to 3, characterized in that the distance .beta. the output nozzle / plasma torch (1) from <cutting / playing 1 to 3 mm. 5. A method as claimed in claim 1, wherein the relative velocity (v) of the plasma beam (2) is equal to the cutting edge. and 1 1 '; 15 to 50 mm / s. . ; ‘, -. π · j <; and 6. A process as claimed in claim 1, wherein the plasma jet (2) is mechanical. by moving the plasma torch (1) across the saw blade (5) over the tooth back (1) in the upper region. • 1 cutting edge. . , í ‘J 7. A method as claimed in claim 6, wherein during the transverse movement of the beam the saw is at rest and then displaced further by the pitch of the tooth, whereupon further transverse movement of the plasma beam quenches the subsequent tooth tip (5). . 8. A method according to claim 1, wherein the plasma beam is directed to the center of the tooth tip of the aflistpila when continually quenching the saws. 5 beats. 9. Method according to claim 8, characterized in that the plasma beam operates in pulsed operation with a pulse frequency of f equal to &quot; &quot;. l-IMi t of the blade feed rate and tooth pitch; wherein J; 'p * 4!' · Pulse time is 0.2 to 0.8 seconds. '«. ; 1 to 1. , jp; . ί> Method according to claim 8, characterized in that the saw blade (5) moves in the direction of the toothing while the plasma beam (2) performs a transverse movement with a frequency of 10 to 200 Hz called by electromagnetic deflection between the tip (s) and the lower edge of the plasma torch nozzle. Í · · 11. The method of claim 1, wherein the axis of the plastic beam coincides with the axis of symmetry of the cutting edge of the knife. 13. A method according to claim 1, wherein the beam axis forms an angle T'V 'i ......, with the axis of symmetry of the cutting edge of the knife. ¢ (í which corresponds to approximately half the angle of the edge β · 15. A method according to claim 1, wherein the axis of the plasma beams forms a carbon-like 90 with the axis of symmetry of the cutting edge of the knife; - K * 4! ; 14 *. 5. A method according to claim 1, wherein the axis of the plasma beam forms an angle of approximately 135 DEG with the axis of symmetry of the cutting edge. ,; . i i i! 'I · Ί ]! í * f », * Ť , * y y fclt í ‘,‘ f &amp;,; and in · 4 of 1 ! ii