DE2207260A1 - Process for processing a piece of work with heat-resistant cutting tools and device for carrying out the process - Google Patents

Description

FATE N ADVOCATE

DR.-ING. H. FINCKE DIPL.-ING. H. BOHR DIPL.-ING. S. STAEGER

Telephone: * 26 6060

S MUNICH 5, Müllerstrasse 31

16. FEB. 1972

Folder 8988 Case »+798/71

description

from The Production Engineering Research Association of Great Britain

Melton Mowbray, Leicestershire / England concerning

"Method for machining a workpiece with heat-resistant cutting tools and device for performing the procedure "ό

Priorities! 17 ₀ 2 ₀ 1971 -)

) ENGLAND

The invention relates to a method and an apparatus sum processing of workpieces made of metal and other materials.

Primarily, but not exclusively, the

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Invention used in the machining of workpieces that are difficult or impossible to process using conventional methods, for example hardened and on 650 VPN tempered tool steel »

It is already known to apply strong heat to a workpiece in order to anneal it and facilitate machining. It has also already been established that in order to get the most benefit from the heating, the heat should be applied to the workpiece during the machining process. The most difficult problem with previous attempts at so-called "hot working ^N" is that the amount of heat to be supplied to the workpiece to improve the machinability is so great that the workpiece is damaged by the heat (warping or metallurgical changes) the heating was carried out inductively, easily lead to damage to the currently used processing tools <■

The invention is based on the object "to develop" an improved processing method.

According to the invention, a method for machining a workpiece with heat-resistant cutting tools when adding

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for strong heat transfer eu <5.em terketUckmater.lc-.X «. to Deesen Featigkei t reduce and Schnexdwirkung dee tools to verbessern- characterized in that the temperature is increased so far only in those material preparation Away ₅ to be anschlieesend removed from the tool t immediately before the machining operation, that the strength of these areas lowered sufficiently far so that the tool has a good cutting effect while the rest of the material is kept below this temperature.

It can be seen that, according to the method according to the invention, only those parts of the workpiece material which are just reached by the cutting tool are intensively heated, so that no permanent heat damage can occur on the workpiece. In addition, the fact that the material is easier to machine brings with it considerable advantages compared to the usual machining methods. For example, several of the advantages mentioned below usually result at the same time over the methods previously used: higher machining speeds j faster feed; lower machine performance, higher work "3ceugt" tandi: .eit. For example, Nimonic 115 _S ei η cold-hardening chrome manganese steel _s or hardened and tempered to BiJO Vi'H! «tool steel by the invention

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Process conventional processes at speeds »those in dam area ten times the speed of machining According to the conventional methods, all these metals can be used with the method according to the invention a cutting speed of about 150 m / min (500 ft / min) while the previously possible cutting speeds for these metals were in sequence: a maximum of 48 m / min (30 ft / min); 64 m / min (HO ft / min); unprocessable ,,

As an example of the advantage of lower tool wear, the fact that with EN 24, remunerated to 600 VPN (110 t tensile strength), tool wear fell to an eighth of that which was observed with the usual machining techniques, _etc.

Further advantages resulting from the application of the method according to the invention are the better surface condition of the machined workpiece and the possibility of Executing discontinuous cuts with success using tools made of brittle, wear-resistant material became

Preferably a plasma arc torch or a Another heating device with a narrowed arc is used to apply the localized strong heating to the workpiece achieve. Such a device can be used to

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tung., precisely control areas and intensity of heating =

In this case, dia device zweckmäsaigerweiee so gesture value that the surface of the workpiece-engaging on the heating sheet atwater equal to the cross-sectional area sections is dee _s has to perform the Sehneidwerkzöug =

In plasma arc is well calibrated as zweckmäseig _s proven electrical Leietungsaufnähme to a value in the range 10 kW to control bie CVGL "below) .-

In the context of the invention, other heating tongue devices, such as lasers or heat lances can be used.

In order to further reduce the risk of damage to the workpiece due to heat, it is possible immediately behind a cooling effect on the cutting tool on the workpiece »For example, a stream of .liquid nitrogen be directed at the workpiece surface.

That which is preferred in the context of the method according to the invention Cutting tool receives a ceramic cutting edge "Di" cutting can also be formed from metal-ceramic η in each

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In this case, cutting tools are preferably used.

Are known to have some metal "and alloys, as' SuperforaÄnderungsvermögen ^'(: Superpiaeticity') designated characteristic (a phenomenon that by the disappearance of resistance in the metal and their replacement is characterized by expansion) arises Super Form & nderungs · capacity at a temperature which depends on the respective material, in general it is believed to be able to say that the super deformation capacity is set at a temperature in the range of 0.1 times the melting temperature ( ⁰ K) of the material,

If it is necessary to machine a workpiece from a material that exhibits this property, one can Control the heating so that the temperature of the material part to be removed from the cutting tool is heated up to the temperature range in which the superforming capacity occurs *

According to the invention, a device for performing the method is also provided, which is characterized through a holder for the workpiece to be machined, a cutting tool with heat-resistant cutting «, one

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ui'igy ■ * £ & fa- ¹ "-ns. Relative movement awi ^ -chen the workpiece and the tool for the construction? ¹ de?" that * the be removed from the cutting tool hervorruftο a strong local heating of the parts of the workpiece · _r immediately before the cut

To make the invention easier to understand and to facilitate their application in practice will then « send described an embodiment of the invention and explained by drawings which illustrate the following;

Figc 1 is a simplified perspective view of a cylindrical workpiece during machining according to the method according to the invention;

FIG. 2 shows a schematic representation of the according to FIG used plasma arc torch with the required electrical connections 5

Figure 3 is a top view on the schematißclvs Betriebeein "riehtunp.an the apparatus of _Fig: Ii

Fig * f shows the control circuit for the retrofiber directions shown in Fig. 3 -

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M S

According to FIG. 1, a ylindrisehes workpiece 1 let in a Lathe clamped and running at high speed A cutting tool 2 with ceramic cutting edge 3 is located next to the rotating workpiece and lifts material from the workpiece in a predetermined thickness. The cutting edge 3 therefore reduces the workpiece through » knife in the specified manner

According to the invention, a heating element * 4 with a narrowed Arch a strong localized heating of the work stack 1 immediately in front of the cutting tool 2. The heating leads to a reduction in the strength of the workpiece material immediately before the SehneidVorgang.

In the present case, a plasma torch forms the heating device O

Figo 2 shows schematically the burner 4 according to Fig, 1 <The burner is then composed of a housing h _t at its lower end a nozzle 3 formed and disposed a main electrode 7 in the axis As with such burners usual "is gas (in the present case Argon) into the housing 5 {, which puts a gas curtain around the sheet during operation. Ο In addition, cooling water is supplied.

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In normal «! * Operation, a direct voltage from ainer suitable®! * Voltage source to the electrode 7 or the workpiece 1 gal © gt ₄ and between these two parts an electrical arc discharge develops 8 ° around an auxiliary sheet 9 in the case have that the HauptbDger goes 8, a Wideretand 10 is placed between the one pole of the voltage source and the housing 5 ₀ wherein the HiIfsbog "η between the electrode 7 and the housing 5, developed at the nozzle

In Figo 3 of the burner according to FIGR 2 by the reference "number t designated PSU refers to the attached to the Branner ~ schlosaene current source _s in turn by an alternating" is power supplied (for example 260 V, 50 Hz) _n parallel to the Auegang the power source PSU is a voltage-controlled relay RLt switched. A solenoid-controlled switch SH is located in one of the output lines of the PSUo. The resistor 10 can be switched on by a manually operated switch SWH.

In Figo 3, MW denotes the main water supply for the burner in the line is "in manually operated switch Rl, a pressure-operated switch SWl and a solenoid-operated switch S1 ₀ Di" Argonxuleitung is denoted as A, and in the line are switches R2, 8W2 and S2

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Fig. 3 also shows the air line MA, which travels to the cross slide drive Cl of the lathe, the air supply is controlled by a solenoid operated switch S3 Finally there is one more from the lathe spindle lever controlled switch SW3 provided.

FIG. 1 shows the control circuit for the operating equipment from FIG. 3c

To the circuit, the switches SWl, SW2 and SW3 from Figo 3r The switches Sl include _t S2 and S3 of FIG. 3 actuated solenoids are designated by the same characters ge "indicates how the switch,

Hach Fig, I a start button PBl and a stop button PB2 is provided, as well as two relays RLl and RL2, their Contacts are labeled with RCl or RC2 - there are also three delayed relays RLDl or 2 or «3 in the circuit) the relay contacts are labeled RCDl or, 2 or 3. The delays built into the relays are:

60 sec (RLDl), 30 See (RLD2), -0 - S Seo (RLD 3) ο

In other words, if XLDl is de-energized, it takes ee 10 8e> -kuitfen until the contact «sohlieeeeno A fourth ·· (vers6 ~ geru« 4s-free) relay RLS in 4mm T irstasrwnfis sheil \\ «* ·

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ff

Circle btnitit contacts RCS-

Finally, the circuit also includes two signals " l & iapen 11 and 12 $ the first lamp shows the operational readiness βοηβ ft and the second the completed training dee ArchSc

In operation, the device works as follows

1, The switch Sk is closed whereby the auxiliary arc 9 between the housing 5 and the electrode 7 of the burner is ignited.

2ο The voltage source PSU is regulated in order to provide the correct power for the main arc of the plasma torch * when it is ignited * The correct level of power depends on the material to be processed _r the cutting depth and _nr

3 ^ The valve Rl in the water supply line is opened by hand, and the pressure switch SWl shuts off when the predetermined pressure is reached

Uo The valve R2 in the argon supply line is also opened » vrd the Druckeehelter SW? locks "if the predetermined

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Pressure reached ₀

S, The spindle lever of the lathe is operated, like this that the workpiece is set in rotation; thereby becomes the switch SW3 closed. From Fig. * »Can be seen» that after this sequence of switching processes the relay RLl is energized, whereby its contacts RCl are closed and the lamp 11 indicating the operational readiness lights up »

60 Now the torch and cutting tools become one another and Aligned with respect to the workpiece according to the dimensions of the machining to be carried out ο

If the depth of cut is large in relation to the distance between the plasma torch nozzle and the workpiece surface, it may be advisable to position the torch so that it points to the side cut by the cutting tool and not in the direction of the diameter removed by the cutting tool. In other cases, for example, _o in the copy turning, as may be zweokmflssig to adjust the burner so "that it with the union of the radial to the axial hexes zusammentrifft0

Regardless of what type of processing is being carried out, the arc plasma torch must be set and

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M 89Θ8.

such a cutting tool must be chosen that the Heating of the workpiece caused by the main arc - viewed in the cutting direction - takes place clearly in front of the cutting tool »whereby the reference to the The type of processing depends on »However, this setting is available in most cases not very critical and can be between a few millimeters and 1 meter (measured on the circumference) amount o

In any case, the work flow continues as follows:

7ο The switch PBl is actuated to »initiate the formation of the main arc» By pressing the button PBl the relay RL3 is excited because of the closed RCl but the second pair of contacts RC2 is fed ₀ The third pair of contacts feeds the relays RLDi, 2 and 3 »which close the associated contacts and open the so-holders S1, S2 and S * t So holder Rm in Fig »u is closed and the relay RLS is energized» This closes the RCS and the cross slide drive starts operating by opening the valve controlled by S3

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At the end of the cutting process, the switch PH2 is opened manually or by a micro switch located at the end of the processing section. In any case, this causes the relay RL2 to drop out; its contacts RC2 open, and the lamp 12 goes out ο Furthermore, the relays RLDl ₉ 2 and 3 are de-energized. These relays then drop out after their respective delay times have elapsed, unless the main arc has been re-started by pressing the push button P31 »The supply In this way, the gas and water sub-torch is maintained near the erIOs above the arc, so that the torch is sufficiently cooled down

You can see that the auxiliary sheet burned throughout the entire program. If necessary, however, arrangements can be made to delete it during the processing advance. For example, the relay RLH, since the production of the main arc · determines so can be modified, daft e · extinguishes the auxiliary arc «It could be re-ignited by, for example, the Button PB2 would be pressed. The worker can also initiate this process manually »

Of course, the system can also be used for face turning set up, i.e. for work in which the factory cleaning

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"thrust is perpendicular to the axis of rotation of the workpiece Similarly, one can also arrange for other filming, use for instance for drilling and hollow drilling _t if equipment and control systems are established accordingly, and finally, the arrangement let to Horizoutaldrehmaschinen, d" h. on center lathes and on turret lathes, as well as on vertical lathes _t d ^ h «on vertical boring mills and vertical lathes.

The method described with reference to the drawings relates to a cylinder turning operation in which the cutting was carried out continuously. In many cases, however, an interrupted cut must be made. The simplest example is the repeated cutting along a workpiece} in this case the cutting process must be interrupted, when the tool reaches the end of the workpiece and the tool must be returned to the beginning of the cutting path. Other interruptions occur in the cutting direction or perpendicular to the cutting direction, for example Requires a workpiece that has a number of longitudinal slots in its outer surface, interruptions in the cutting direction o A workpiece with a recess in the circumferential direction in a perpendicular to its axis Level requires a break in the cut in the direction perpendicular to the cutting direction »This type of break also occurs when a number of individual workpieces

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are arranged in a different way and processed one after the other should be

In any case, if it becomes necessary to interrupt a cut, it may be necessary to extinguish the main arc or to reduce its power when the torch reaches a gap in the workpiece; then only the auxiliary arc is maintained. For example, reduction of a voltage or a current change corresponding to a change of the arc length, ₉ are applied to the Bogenleietung reduce "It is assumed that the control system required to perform such control functions adapted to the respective requirements. In some cases, for example, a fast-responding solid-state control can be expedient.

The processing system described above in its basic features can be adapted to a large number of applications on machine tools and can be, for example used for turning, planing, planing, drilling, hollow drilling, milling, boring, long milling, reaming, etc., examples of some of these types of work are briefly described below to be discribed"

Io planing and planing

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In general, the system described for lathe work for planing and short planing work can be adapted to p &eetsr; _: . -except that repeated cuts in short sections are on the clock. In those cases where the cut im? is in one direction, thus may be the control system ao ä.sgeführt that the main arc will be deleted during the return movement, when a double cut is executed _s ie> when cutting in both directions ;, can two Srennerj, DOHC a burner · for * Each cutting tool is provided ₀ which work in the same way but are offset from one another.

It can be seen that the work stroke may be a little longer must be chosen because the torch must be placed in front of the cutting tool

Anyway aeigt to ₀ that the device au © planing ho "rizontaler and vertical surfaces and aucfe for postforming" work of this kind is useful for?

2 ο milling

When milling with rotating milling cutters, the arrangement depends on the size of the milling cutter relative to the main arch η s> If both sizes are approximately ⁵ (e.g. when milling with an end mill), a single *

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t before the Fri-ässr herlaufender Br ^ Nui "iuareiokfcr C." However, if the in Fri-ässr large compared to the Grtf.'jfsfc -J ^ s-curved ₉ ea may be necessary wsrd & n, an A »» ordn ".i" .g to meet ρ with which the workpiece is heated along a ^ s : hm & l «n continuous strip on your edge of the cutter? But you can also provide a separate arc on each cutter tooth. that no arch is formed if a tooth does not cut, that is, after a tooth has made one cut and before beginning the next cut

Generally speaking, face milling can be seen as one Consider the type of interrupted cutting =

The invention can therefore be used with certain adaptation measures for milling on all types of machines on which milling work can be carried out, Z ₃ B ₀ on horizontal and vertical milling machines, jig drilling machines, horizontal drilling machines and floor drilling machines, long milling machines ο

3o rooms

Is removed at the areas where the metal by a series of straight moving teeth _s may be a plasma arc to be placed in front of each cutting edge, and

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ve raft

'>? ■■ * ν · ι · 2b -.-: - ·. \ η u'o ge9 '': «ufer-1 ν step ^ <iaß at the entrance of every 5th .. '. Ui ^ r. ij the workpiece is erased from the arc, if eier Qui-j'Kt'-hxiiic of the Räumwarkxfcugs perpendicular to the cutting direction (s ~ B "when making a wedge hole) consists of a plurality of teeth _s the arcs lying in a single plane can sum simultaneously Let work be done.

and ^ hollow drilling

For boring and hollow drills; * uä one si * the cutting tool η about © v ^ räneierr. 'im ΐί, η &

the problem to f.lnc «n. _; de. "^:; * '" · ■■ * -' ten "-r-ii-cau

a cutting edge au - * ^. '^ -m 9ir ^ s'.: hi; i ϋ ^ η .fs - = most material is made. For elier- '*: ^ ra :: - * i5iia 3working task, the inventi ^ fSÄeo ¹ ^ λ ■ * "> ■ *» (· «- ^τ · ^« ^ is supposed to be a rotating * ire' j '■ t · ^ «_>« ^ '· i> enut2t, which look like a>, ι *? · "■ · ί t <. * ·'<'*A'ύ: - (ζ ,, B-, sum Drilling a Gewe * ι ? -N,. J - - t

but does not need cutting oil »" - '

mabrenner drilling tool würda wi. «Oi λ - ¹ χ * 2 ύ

to be introduced into the workpiece * aa "prove necessary, the tool p ^ vixA ^ ch ι« - * it _v um

to remove the drilling plant

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BAD ORFOENAL

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To clarify the mode of operation of the invention some results are given below that illustrate the difference between cold working and normal cold working

In the hot working experiments, the workpiece was tapered with a torch heated; the torch was developed from a standard 200 A TIG welding torch. The burner was on one 300 A transformer rectifier arc welding generator with an open circuit voltage of 80 V and a falling characteristic, a simple stream of pure argon was used passed through the normal gas duct in the burner with a throughput of 0.3 m / hour (10 cu «ft.per hour)« The plasma nozzle opening had a diameter of about 2.5 mm (0.1 inch) «

The workpiece was clamped in a lathe and the plasma torch was brought close to the workpiece surface, see above that these were heated very narrowly. That heated Material was removed by normal turning with a single-edged disposable tool with a chisel insert »

The torch was welded like the metal arc operated, making sure that the circuit across the workpiece and the lathe by a brush

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M 8988 · λ

Drainage closed * '- urda ₃ which touched the rotating machine spindle.

The plasma torch was inclined at about 90 ° against the rotating tool and was about the same distance from the workpiece,

Dax * Work flow was adjusted to the _rectifier's and various work materials were filmed with a ceramic tool The following results were ersielt:

Experiment number 1

Agbeitfjwrkstoffι Specification 'S ₃ 6 * 2c ¹ high-speed steel (hardness 58Rc) ο diameter and length 76.2 χ 69.9 ge O in χ 2 3/4 in)

Schnei dwer kaaujfs Keramik Kennametal CO6 Plasma; classification;

Current 100 A.

Voltage HS V Output «* _t S kW

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Sonitfcgeechwjndigjcsiv 15? m / me. (500 ft / tniu) feed Ο ».1575 nun / Umdro (0.0082 in.- ' rev)

Depth of cut I ₅ 2 5 wm (0.05 in)

Total ", satisfactorily well turned length (of the work piece)

210 mm (8 l / K in)

Experiment number 2

3ESSSlSSIIlIt

As in experiment No. I _1, however, the plasma is set as follows:

Current SO A

Voltage * 5 V

Power 2, 25 kW Total, satisfactorily well turned length

279 ma (11 in)

From experiments nos. 1 and 2 it can be concluded that the power consumption of the plasma is usually below 2.2S kW could be reduced «

Mr attempt ₀ 3

Among other things, the results obtained in experiments 1 and 2 To compare results on conventional machines

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ι! c : · ι (.; ι. 99

dt-y Vsr's;. · -.!; ^:>:. 1 rjlcthir ":;" t ,, jaiooh without rx ^ E ^ oiiftwiitau ^ g ) 'iio. Sf.:lri>?tiv:,r::;obMiiiili Genealogie;,!c.(üit "became on 15., 2 π" pure instead of IS? M.'rnir »ί? .O ft / min instead of SOO ft / min). The total length turned with Lefr-iedigendeai success was only 50 mm {?. in).

Experiment no.- U

Experiment no. 1 was repeated on a workpiece made of 1 **% manganese steel of the following dimensions; 60 now 0 _S 88.9 mm long (?. In ß, 3 1'2 in longK The entire _t satisfactorily turned axietle length was 229 mm (9 in> c

Experiment No. 5

Again, the difference compared to the usual way of working To point out, experiment no. ^ without plasma heating became repeated. The cut was as in the experiment Nr 3 heratgeaetzto The shot with satisfactory success Total length was only 13 mm (1/2 in> "

Experiment no ₀ 6

The experiment Kr, 1 was carried out on a workpiece from Nimonie,

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κ »ta

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3I ₈ 8 mis 0, 101.6 mm long (1 3A in 0, t in long) repeated The satisfactorily rotated total axial length was 101.6 mm ik in).

Try no 7

exasasrsxnsst

Experiment 6 was repeated without plasma heating and a cutting speed of 12.2 m / min (instead of 152 m / min) (»» Ο ft / min instead of 500 ft fain) was used The total length rotated with satisfactory results was only 19 mra (3, -4 in) »

It is to be expected that for most materials it is best to supply electrical power in the order of magnitude of 10 kV / air, although in special cases it may be expedient to exceed this value Material but also on the depth of the cut made with the tool from ₀

Claims;

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Claims (2)

M 3988 «- .. Patents sp £ 'üc h β '. Ιοί Process for machining a workpiece with heat-resistant «^ cutting tools? bsi supplying strong warm to the workpiece material ^ i & l, in order to reduce its strength and improve the shrinking effect of the tool characterized ₉ daae the temperature only in those _s Materialbareiahen the v ansehiiesaend weggsnoimnan of the tool? intended ard "n _t that dic-i is decreased sufficiently stability of these areas is itvingevoi increased immediately before: redeem / Garig so far _s, so dac V / ool exerts a good cutting effect, whereas daa is held Uby-strength material below this Tenparatur _o 2. The method according to claim I ₅ -. a & € \ ivoh. gökeftrisaicteet- ,, da £. Then the workpiece is heated by means of an Ex-heating device with a narrowed arc in the form of "inos plasmab ^ anna ^ s heated" whose electrical power consumption is kept at a t hi "SU about 10 kW" -25 ~
209842 / 062S ^ÖAD O ^{R! G! NAL} Method according to claim 1 or 2 _9, characterized in that the area of the work piece immediately behind the cutting tool is treated by a cooling device ο Ho method according to claim 1 »2 or 3, characterized in that the material of the workpiece has the property dee super deformability (superplaeticity) _D the heat supplied to the workpiece is controlled so that the material parts ₉ away from the cutting tool» are taken, are at a temperature which is in the temperature range in which the material has the property mentioned 5ο Device for performing the method according to one of the preceding claims, characterized by a holder for the workpiece _{9 to be} machined, a cutting tool (3) with a heat-resistant «? Cutting, a device which brings about a relative movement between the workpiece and the tool for the duration of the action of the cutting tool on the workpiece, and a device (U) ₉ which causes strong local heating of the parts of the workpiece which are affected by the cutting tool (3 ) away- BATH ORIGINAL 209842/0625 η «earth. immature, ta! bar before the cut « before. calls,. 6 _C device according to claim 5, characterized in _fc that the device sum inducing n a strong local heating of a plasma torch (U) with ainer means "electrode (7) in a housing (S),"? Construed _r, the gas and cooling fluid during operation are supplied, wherein a DC power supply to the electrode and the workpiece (1) to feführt actual einsn between them major questions burn zn lascunt UNFI wherein a resistor (10) "wipe the housing and. 'Kirbindur.g switched between the power supply and the workpiece (1) and _{9 can} be switched around an auxiliary arc within the housing (I) . 7 _: Device according to claim 8 _P dÄ by gekeimasichnet »that a manually operated switch (SWU) is provided which switches the resistor (10) at the right moment between the power supply (PSU) and the housing (5) * 8- device according to claims S and 6 «characterized in that the power supply (PSU) ₉ the gas - 27 * '2 09842/0625 BATH supply CMW) and the coolant supply line (A) dee BrennerG (4) and the device (Cl) that controls the relative movement between the workpiece (1) and the tool (3) is controlled by a manually triggered system - which causes the power supply (PSU) to the burner («0 is connected to a The arc can only be ignited when the gas supply (MW) and the coolant supply line (A) are connected and the device (Cl) for producing the relative movement is in operation. 9c Device according to Claim 8, characterized in that the control system contains timing elements (RLDl ₉ RLD2, RLD3) which, when the system is switched off, cause the gas discharge (MW) and the coolant supply line (A) to continue during predetermined periods of time after the Main archβ remain effective » For: The Froduction Engineering Research Association of Great Britain 209842/0625 PATENT ADVOCATE OIL-IMG. H. f INCKE, DIPL.-ING. H. SOHI OtPL-INO. ·. STAEGER 28 - BATH