DD207574A1 - METHOD AND DEVICE FOR IDENTIFICATION OF THE TOOL GUN - Google Patents

Abstract

The method for identifying tool breakage during machining with a geometrically defined cutting edge during machining and the device for carrying out the method relate to the display of tool breakage during machining, preferably during turning, milling and drilling, wherein no measuring devices present in the processing space of the machine tool are required , The tool breakage is identified by measuring the performance of the main drive and the feed drive or the relevant Motorstroeme and the resulting calculation of a quotient as the size of the tool wear and the constant comparison of this quotient with two adjustable limits (upper and lower limit). In Ueber-resp. If the limit value is undershot by the quotient, the indication "tool breakage" is immediately displayed and the machine tool control is influenced. Instead of the drive powers or motor currents, the sizes of the tensile stress components (F downs, F downwards v, F downwards p) or> optionally power and force variables can be used to calculate the quotient.

Description

Method and device for identification, the tool breakage. .- ^r ...

Field of application of the invention

The invention relates to a method for identifying the tool breakage in. Machining with geometrically determined cutting edges during machining, in particular turning, milling and drilling and a device for carrying out the method

Characteristics.der known technical solutions

Known is the detection of the tool break during processing xlurch by measuring and processing of process parameters, which are detected by means of additionally attached to the machine tool transducer or prepared tools are, and with appropriate.

15. Assessment by means of computing circuits or the like. Allow statements regarding the tool wear up to tool breakage. Furthermore, processes according to DDWP 54159 and DEOS 2654838 are known, in which parameters generated by the stressing process, such as forces, displacement ©, vibrations, temperature changes, mechanical and

, electrical power measurements, etc. are used for tool break detection. Other methods according to DEOS 2340253, DEOS 2747487 work on the opto-electrical principle, wherein z. B. a quantity of light, the

- 2 - oral .η

A gap between the tool and a measuring template emerges, is measured and evaluated. ^In 'another known method according to DDWP 109260, reflections from typical tool edges and 5. Areas means of television cameras or diode line "n are detected and used for evaluation of tool wear and tool breakage detection Further, a breakage monitoring device for rotating machine parts with a dedicated. Division according to WPG01M / 230431 known that forms equivalent signals using non-contact sensors of the division of the rotating machine part and this used in comparison with a speed-proportional signal for fracture detection.

15, There are further known solutions according to .DDWP 89870 and DDWP 146090, in which the wear on the free surface of the tool is measured by contact with thin layers. While in the invention DDWP, 89870 only prepared tools can be used, the solution according to DDWP 146090 probably allows the measurement of the worn open space, but a clear statement in tool breakage is not possible.

All these mentioned methods and devices have the drawback that additional devices in the form of sensors, sensor levers or light barriers limit the working space of the machine tool or restrict the technological process of machining workpieces or that special measuring devices are installed in the power flow of the machine tool which also affect the quality of workmanship.

When using the opto-electrical method occur > even more problems with regard to the use of coolants and the Sρanabführung that at least ens lead to disturbances of the measurement function and the accuracy '. .

An identification of the tool breakage by the drive power of the processing machine is not clearly possible because the drive power is dependent on a large number of influencing variables (eg friction loss in guides, accelerated and decelerated masses, etc.) Moreover, the drive power changes with some rotational variants (eg cross turning) continuously in accordance with the changing workpiece diameter.

O ' aim of the invention

The object of the invention is, preferably in automated operation, to immediately detect tool breakages without affecting the technical and technological characteristics of the machine tool and to reduce the disruption caused by tool breakage and possible damage in machine systems and production processes.

Presentation of the essence of the invention

The invention is based on the object, a method. To identify the tool break when machining with.

geometrically determined cutting edge too. To develop and create a device for which it is possible without dissecting the tool and without additional An ¹ and installation of mostly function-limiting devices for detecting necessary quantities, the. Immediately signal tool breakage during machining and generate an output signal for machine tool control (machine stop, tool change). , ....

According to the invention, this object is achieved by using known measuring devices for detecting the electrical drive power or the cutting forces,

40 2 6 7 0

further achieved by a per se known computation circuit with _{Quotrentenbildung>} and multiplication as well as from a Grenzwertsignalisator with zwei'einstellbaren limits and a Anzeiger and .Steuerteil characterized in that two or the two driving powers P "and Py elektrische.Größen equivalent, preferably the motor currents ., the electrical voltages or the components of Zerspankraft, (cutting force Pg, feed force Fy, passive force Pp) proportional Elektrisehen sizes constantly detected and set in eight different, links to each other in an arithmetic circuit ratio and multiplied by material and werkz.eugspezifischen constant C. and from this a new quotient X is continuously calculated, which represents a parameter of the respective existing tool wear.

The following links are 'possible'? / '. ·' '.' -

Σ_ π V τ _ η _JT

χ = C ₂ , p _s x = c ₆ ^

P '- P ^ OX ⁼ C-> έτ "X = C ™ TTT

, _{Σ σ} fl. ' _x _ _G ! l. ',:

", 4 F ₂ ; '''~ 8 Md

The constants Cj ... Cg contain, in addition to global parameter and material / cutting material-specific parameters, the conversion factors of. Performance quantities in force sizes and vice versa. ' The optional for the quotient. Required force components P ₃ , Py and Pp and the torque Md'den taken from the existing measuring equipment in machining centers, -The size of the constantly recalculated quotient X is

/ A ^ Γ 4 ί

with two adjustable limits, the upper limit: Y 'and the lower limit Y -continuously in one

II xil_LXX

Limit value comparator, wherein when exceeding the upper limit value Y _mv by the quotient X

Max

(X > Y) '·, or · falls below the lower limit Y. by the quotient X (X <· Y ^.

min, mm.

a corresponding signal is generated at the limit value signaliser, which is further processed in a downstream display and control section and used for immediate display of the tool breakage and for machine tool control (machine stop, tool change)). , :

The device consists essentially of a respective Yfandler in the main or feed drive the Werkzeügmaschine, a measuring device for the components of Zerspankraft P ₃ ; Fy * p _?> An input selector and an arithmetic circuit with downstream limit signaliser. Two setting _elements are used to set the upper limit Y _maÄ or, the lower limit value ^ _n H _n · If the limit values are exceeded or undercut, a display and control section responds which indicates the tool break immediately and the tool / machine control (z. B. machine stop, tool changing ^) acts ·

Executed by spi e1 ;

The invention will be explained below with reference to an embodiment example for the methods of turning, milling and drilling with reference to 4 drawings. In the accompanying drawings show:. '.

Fig. 1: The circuit diagram of the device for identifying the tool breakage

Fig. 2: The increase of the quotient X at tool break ... on a einschneidigem tool

- 6. -. Z4 u ^ - ο /

Fig. 3: The course of the quotient X at break one behind the other, lying cutting a milling head it; , ''

• Fig. 4: The ranges of the quotient X for working 5-sharp and broken twist drills ·

It has been proven that during cutting with a geometrically determined cutting edge a tool breakage during the cut leads to an abrupt increase in the ratio of the feed force to the cutting force (F - ^: Fg); causes. The course of this relationship does not change if, instead of the forces, the power consumption of the drive motors is considered analogously.

The drive power corresponding electrical size, eg. For example, the motor current or a voltage proportional to the current is removed by means of a converter 1 from the main drive of the machine tool and by means of a second converter 2 from the feed drive and fed to an input selector 4. At the same time, if necessary, the components of the cutting force as.

Cutting force Fg, feed force: F ^ and passive force Fp from an existing measuring device 3 also entered in, the input selector 4. · After selecting the to. Identification of the tool break provided sizes and determination of the constant C in the input selector 4 are these; a known per se calculation circuit fed · in which .the quotient formation and the multiplication with C running constantly and thereby a 'new quotient X is calculated. This quotient X is continuously in a downstream, Grenzwertsignalisator 6 'with two externally steadily on, adjustable limits, an upper limit Y and

  " Max

a lower limit: Y .- compared. At the output of the threshold signal indicator 6 arises when exceeding the quotient X on the upper limit Y.

, ·., - ·. Max

(X τ> Y _m "J 'uiid when the quotient X falls below the lower, limit value Y _nin (X <Y -S) a sign

which is further processed in a display and control part 9, and is used for the immediate display of the tool breakage and for the tool / machine control. The functions "machine stop" and "tool change" are preferably programmable.

With one-cutting. Tools, eg. For example, when turning, the feed force · Fy and the passive force Pp increases partially when the tool break during the cut with high significance, as the corresponding cutting force Fg,

d. H. the quotient X increases abruptly to a value which is significantly higher than that of the non-brittle tool. There were quotient increases up to 6 times regi- '. strated. '

With multi-bladed tools, especially when milling, · only the power or forces that are caused by the sum of the individual cutting edges can be determined with little effort. Breakage of one or more consecutive cutting edges will inevitably increase the feed per tooth for the next unbroken cutting edge. It follows from the chipping theory that the quotient X initially becomes significantly smaller. The signaling of one or more broken edges is made by falling below the value X below the lower limit value ^ _m 4 _n · If all cutting edges in multi-bladed tools break, the behavior of the quotient X is similar to that of the single-edged tool; to the typical and sudden increase and exceeding of the upper limit

Similar behavior was noted when drilling with twist drills (double-edged tools). In Fig. The ranges of the quotient X are shown at different drill diameters D, at sharp and broken 'tools, ... _:

The limit value Y depends on the drill diameter · D

UIcL Λ.

and the feed s of the tool »

The device for carrying out the method consists essentially of a converter 1 in the main drive and a converter 2 in the feed drive for obtaining the drive power-proportional electrical quantities, an input selector 4 for the selection of the desired force and / or power variables, an arithmetic circuit. 5 for the quotient formation and a downstream threshold value signaliser β with a Sinstellglied 7 .. for the upper limit Y ^, _ "and a Sinstellglied 8 for the lower limit ^v ^ _min · iäin GrenzV / signalisator β formed output signal reaches a display and control part 9, where once the immediate display of the tool break is made and the machine tool control is still affected. '

Claims (3)

-a 'AQ? 6 7 Brfindungaanaprach 1. A method for identifying the tool breakage during machining with a geometrically defined cutting edge during machining, in particular when turning, milling and drilling, using known MeBeinrichtungen for detecting the electrical drive power and / or the cutting forces, a known calculation circuit for quotient formation and multiplication and a limit signal with two adjustable limit values and a display and control part, characterized in that two electrical quantities equivalent to the two drive powers Pg and Py, preferably the motor currents or the resulting electrical voltages or the components of the cutting force cutting force. F _g , feed force Fy, passive force Fpproportional electrical variables are constantly detected and set in eight different relationships to each other in a computing circuit (5) and with a material- and tool-specific Konstanten.C be multiplied 'from it constantly a new quotient X> is calculated as a parameter of each existing tool wear, whereupon the size of the constantly recalculated quotient X with two adjustable limits,. an upper limit ^ _max ¹¹ ^ d a lower limit Y _mi - continuously in a Grenzsignalsignalisator (6) are compared, wherein when exceeding the upper limit Y _max by ä.exi quotients X, or falling below the lower limit Y ", - "By the quotient X at the output dea limit signal (6), a corresponding signal is produced, which in a downstream display and control part (9), further processed> such that the tool break immediately.angezeigt and the machine tool control is affected accordingly ·. 2. The method according to item 1, characterized in that in the arithmetic circuit (5) the following links to the calculation de, s' quotients X are feasible: - Π Ύ - Π T? 'P -X- τ ρ ^ν 3 F ₃ · ^{7 Md} wherein the constants G-j to Cg contain, in addition to global parameter and material / substance specific characteristics, the factors for converting output quantities into force quantities and vice versa, 3. Procedure according to point 1, characterized:, marked,. that the optionally required for the quotient power components 3? ς,;, Fy; Fp or »the torque Md are taken from the measuring devices present in machining centers. 4. Sinrichtung for carrying out the method according to item 1 to 3, characterized in that it consists essentially of a converter (1) in the main drive and a converter (2) in the feed drive, a chucking device (3) for the components of the cutting force Fg; F ^; Fp, eineai input selector (4), the Reehenschaltung (5) it nachgeschalt et em Grenzwertsignalisator (6) and that at one, "Sinsteliglied (7) set upper limit value Y _ma" and at a -Einstellglied (8) set lower Limit value Yj _n -? Η are assigned to the limit value signal or (6), and that when exceeding or falling below the limit values A O 2 6 7. - 11 - £, 4U Υ _φ · 'or Y; , by the quotient X a display and control part (9) is controlled, which indicates the tool break immediately and the machine tool control, z * B. in the form of a command for the machine tool stop or tool change. For this 3 sheets of drawings