Method for operating a lathe for machining a workpiece by means of a rotating process, and lathe

Abstract

The invention relates to a lathe and to a method for operating a lathe (TMC) for machining a workpiece (WPC) by means of a rotating process. In order to automatically convert instruction sequences (SQC) without a manual intervention, it is proposed that the instruction sequence (SQC) involves: - defining a positive first coordinate direction (CFD) for all of the working modes (WMD), in each case in the direction of the spindle (SPD) which does not determine the rotation, and - defining a respective positive second coordinate direction (CSD) pointing away from the workpiece rotational axis (XWP) for all of the working modes (WMD) such that, by means of a chain of rotations, reflections, and / or shifts of the coordinate information (CDR) of the instruction sequence (SQC), the chain being defined for each possible change from one specific working mode (WMD) to another specific working mode (WMD), the coordinate information (CDR) is made compatible with the respective current working mode (WMD), the instruction sequence (SQC) further involving: - defining, for each working mode (WMD), a positive rotational direction (RTD) of the tool rotational axis (XTL) from the first coordinate direction (CFD) towards the second coordinate direction (CSD) over the shorter rotational angle, and - defining a zero angle (ZAG) of the tool rotational axis (XTL) for all of the working modes (WMD), in each case coincident with the respective second coordinate direction (CSD).

Description

[0001] Description

[0002] Method for operating a machine tool for machining a workpiece by turning

[0003] Technical field

[0004] The invention relates to a method for operating a machine tool for machining a workpiece by turning. Furthermore, the invention includes machine tools with a control unit.

[0005] Technical background

[0006] Up to now, it has been easy to adapt the geometry description [CAD data] of the workpiece as well as corresponding manufacturing instructions [CAM data] for the machine to the terminology or coordinate systems of the respective current working mode, for example in such a way that when the machine tool switches from a first working mode to a second working mode, the necessary coordinate transformations are carried out by means of rotations, reflections and / or translations of all coordinate specifications for the current second working mode.

[0007] This adaptation of the geometry description [CAD data], the manufacturing instructions [CAM data], and the coordinate specifications to the current working mode does not yet work for adjusting the tool position by rotating the tool holder around the third axis of rotation.

[0008] Summary of the invention

[0009] The object of the invention is to solve the problem described in the prior art. In particular, it is an object to further develop the method in such a way that the machine tool's handling of the instruction sequences of the manufacturing instructions [CAM data] is fully automated and does not require any manual adjustments to the rotation of the tool holder about the third axis of rotation based on the geometry description [CAD data] of the workpiece.

[0010] According to a first aspect of the invention, a method for operating a machine tool, in particular with offset oppositely directed spindles, for machining a workpiece by turning is described, wherein the machine tool has spindles or workpiece spindles comprising a main spindle and a counter spindle, each rotatable about a workpiece axis of rotation.

[0011] - wherein the machine tool has at least one tool holder and at least one

[0012] tool has

[0013] - wherein the tool holder holds the at least one tool for machining the workpiece and guides the movement of the tool,

[0014] - wherein the tool has at least one cutting edge for machining the

[0015] workpiece exhibits

[0016] - wherein the machine tool has a programmable control system which is operated by means of the

[0017] Execution of an instruction sequence that controls the movements of the spindles and at least one tool,

[0018] - wherein the tool holder, with which at least one tool is arranged in such a way as

[0019] The tool axis of rotation is designed to be rotatable so that a machining contact point of the cutting edge on the workpiece can be aligned at a predetermined angle to the workpiece surface, wherein the machine tool has different working modes of the tool with different specifications of a workpiece coordinate system.

[0020] Preferably, the spindles of the machine tool and the machine tool itself are designed in such a way that a workpiece can be transferred from the main spindle to the counter spindle independently or automatically during the execution of an instruction sequence.

[0021] The preferred application area of ​​the invention is multi-spindle machines, in particular twin-spindle machines, although the invention can also be applied to a single-spindle lathe. Machining can be performed both in front of and behind the center of rotation. Furthermore, some milling machines also allow turning operations, so the invention can also be applied to these machines.

[0022] According to the invention, the instruction sequence comprises:

[0023] - Defining a positive first coordinate direction for all working modes, each in

[0024] Direction of the spindle, which does not determine the rotation,

[0025] - Defining a positive second coordinate pointing away from the

[0026] Workpiece rotation axis for all working modes, such that, by means of a defined chain of rotations, reflections and / or displacements of the coordinate specifications of the instruction sequence, for each possible change from one specific working mode to another specific working mode, coordinate specifications for the respective current working mode are made compatible, wherein the instruction sequence further comprises:

[0027] - Defining a specific direction of rotation, preferably a positive one

[0028] Direction of rotation of the tool rotation axis for all working modes from the first coordinate direction via the shorter rotation angle to the second coordinate direction,

[0029] - Defining a zero angle of the tool rotation axis for all working modes, preferably coincident with the respective second coordinate direction, such that the rotation specifications of the instruction sequence for rotating the tool about the tool rotation axis are compatible for all working modes.

[0030] The teaching according to the invention consists in the fact that the arrangement of the coordinate systems for the different working modes or working areas of the machine tool or lathe is already coordinated in such a way that the rotation specifications of the instruction sequence for the rotation of the tool about the tool rotation axis are also compatible for all working modes.

[0031] This prevents manual adjustments, thus saving the valuable working time of qualified CNC programmers.

[0032] The terms used in this description of the invention have the following meanings.

[0033] The machine tool according to the invention is a machine tool used for the turning manufacturing process. Some machine tools also have additional equipment for grinding, milling, and / or broaching. Such machine tools with additional functions are also covered by the invention. Rotationally symmetrical workpieces (turned parts) are produced with a machine tool according to the invention.

[0034] Rotary spindles, workpiece spindles, or simply spindles, are used on a machine tool to rotate the workpiece for machining by turning. The workpiece is clamped to the spindle via a chuck. The rotating workpiece is machined by at least one turning tool, or tool, which is movably mounted on the machine tool. The tool, usually a turning tool, is attached to a tool holder, which is typically designed as a tool slide.

[0035] The tool has at least one cutting edge for machining the workpiece. For correct machining, it is advantageous if the cutting edge is aligned at a specific angle to the workpiece surface. This ensures a consistent quality of the resulting geometry and surface finish.

[0036] The center of rotation refers to the point on the surface of the workpiece around which it rotates when clamped on the machine tool. The center of rotation is the reference point around which the workpiece is turned and is considered the center of the rotational process. Typically, the center of rotation is located in the center of the workpiece, unless it is asymmetrical. Generally, the center of rotation lies on the workpiece's axis of rotation.

[0037] Modern machine tools have several tools that are held in a turret head of the tool holder and are used as needed.

[0038] The tool holder performs a feed movement with the tool, usually continuously removing a chip by moving the tool holder along the surface to be machined, either longitudinally or transversely to the axis of rotation of the workpiece.

[0039] The machine tool has a main spindle drive and one or more feed drives. The feed drives move the tool holder, while the main spindle drive rotates the workpiece.

[0040] For machining the workpiece all around, there are multi-spindle machine tools, especially twin-spindle machine tools with offset, opposing spindles. Once the first spindle has completed its program, it automatically transfers the workpiece to the second spindle, where the back side of the part is then machined. The first spindle is also generally referred to as the main spindle, and the second spindle is referred to as the counter spindle. The fact that "on one of the two 2024P14220WQ

[0041] 5

[0042] The way the workpiece is machined by spindles is described in such a way that the respective spindle determines the rotation of the workpiece.

[0043] A machine tool has straight main travel paths for the tool holder. A first main travel path typically extends parallel or antiparallel to the axis of rotation of the main spindle. The tool slide, which usually encompasses the tool holder and the tool, typically travels along this first main travel path.

[0044] A second main travel path typically extends perpendicular to the first main travel path, so that when the tool holder is moved along the second main travel path, the radial distance of the tool to the center of rotation changes.

[0045] For the purpose of positioning the tool along the main travel paths, each main travel path is assigned a coordinate axis of a coordinate system, whereby, during operation of the machine tool, the position of the tool holder is preferably verified at least indirectly by sensors in segments. To quantify the tool's position, the main travel paths are provided with a unit of measurement. In this way, the tool's position along the main travel paths can be specified by stating a real number.

[0046] A point on the axis of rotation of the main spindle is appropriately chosen as the origin of the coordinate axes.

[0047] Thus, for each main travel path, there are two possibilities for a positive coordinate direction. Combining the two possibilities for each of the two coordinate axes results in four ways to define a coordinate system. These coordinate systems can be transformed into one another by means of rotations, reflections, and / or translations. These four different coordinate systems of the workpiece are also referred to as working areas, and subsequently as the working modes of the machine tool.

[0048] The geometry of the workpiece to be manufactured is described in a workpiece coordinate system, for example as a CAD data set.

[0049] The workpiece coordinate system is either defined from the outset as one of the coordinate systems described above or can be transformed into the coordinate systems or working modes described above by means of rotation, reflection, and / or translation. The tool can be rotated about a third axis of rotation by means of the tool holder. In this way, the tool can be aligned with the contour of the workpiece to be machined, such that the angle to the surface enables good chip removal and prevents collisions of the parts of the tool that are not intended to be in direct contact with the workpiece.

[0050] According to a further aspect of the invention, a machine tool is described comprising a control unit and an interface for receiving a sequence of instructions for machining a workpiece. The invention provides that the control unit is configured and prepared to execute the method according to one of the claims.

[0051] The advantages associated with this aspect of the invention have already been explained above.

[0052] Embodiments of the invention

[0053] Further developments of the invention, describing variants, are explained below without limiting the basic idea of ​​the invention.

[0054] The invention provides that the individual working modes with reference to a division plane along the workpiece rotation axis are as follows: in a first working mode, the contact point is on a first side of the workpiece rotation axis and the main spindle determines the rotation of the workpiece; in a second working mode, the contact point is on a first side of the workpiece rotation axis and the counter spindle determines the rotation of the workpiece; in a third working mode, the contact point is on a second side of the workpiece rotation axis and the main spindle determines the rotation of the workpiece; in a fourth working mode, the contact point is on a second side of the workpiece rotation axis and the counter spindle determines the rotation of the workpiece.

[0055] The dividing plane can be vertical. A horizontal dividing plane is also possible, as is a dividing plane that runs at any angle to the vertical. 2024P14220WQ

[0056] 7

[0057] Such a specification is expedient and advantageously enables the fully automated implementation of instruction sequences.

[0058] According to one variant, the aspects of the invention explained above are determined by the fact that the machine tool has an additional milling function for machining a workpiece by means of milling.

[0059] One advantage of this variant is that the workpiece can be completely machined without the need for time-consuming reclamping on another machine - possibly only on the machine tool.

[0060] According to a variant of the invention, it is provided that the rotation of the tool rotation axis for aligning the cutting edge at the machining contact point on the workpiece is accompanied by a compensating movement on the part of the tool holder, such that the rotation of the tool about the tool rotation axis has no influence on the position of the contact point of the cutting edge on the workpiece.

[0061] One advantage of this variant is that optimal alignment of the cutting edge of the tool can take place independently of the other manufacturing processes, and consequently the quality of the workpiece surface is uniform.

[0062] Exemplary embodiments of the drawing

[0063] Further details of the invention are described below with reference to the drawing. Identical or corresponding drawing elements are provided with the same reference numerals in each figure and are only explained more than once to the extent that differences arise between the individual figures.

[0064] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual variants of the invention, which can be considered independently of one another. Each of these variants further develops the invention independently and can therefore be considered part of the invention individually or in a combination other than that shown. Furthermore, the described components can also be combined with the variants of the invention described above. Specifically, the drawings show: Figure 1: a schematic three-dimensional representation of a workpiece during machining using a tool on a tool holder of a machine tool (not otherwise shown);

[0065] Figure 2: an illustration showing individual working areas of the machine tool;

[0066] Figure 3: an illustration showing the angular positions of the cutting edge of a tool in the individual working areas without the invention.

[0067] Figure 4: an illustration showing the angular positions of the cutting edge of a tool according to the invention in the individual working areas.

[0068] Figure 1 schematically shows, in three dimensions, the machining of a round workpiece WPG using a tool TOL clamped in a tool holder TH D. Further physical details of the machine tool TMC are not shown here. The workpiece WPG has a workpiece coordinate system CWP, and the tool TOL is rotatable about a tool rotation axis XTL, with the tool holder THD performing the respective rotation. By rotating the tool TOL about the tool rotation axis XTL, an almost optimal alignment (target angle SAG) of a cutting edge GTE of the tool TOL on the workpiece WPG is achieved at all times. In this way, a consistent surface quality of the workpiece WPG can be achieved during manufacturing.

[0069] Figure 2 schematically illustrates the individual working areas, or operating modes (WMD), of the TMC machine tool. On the left side of the illustration, a main spindle (MSP) is simplified as a cylinder. On the right side, a counter spindle (CSP) is shown as a mirror image, also as a cylinder. The interaction of the main spindle (MSP) and the counter spindle (CSP) enables clamping machining on the TMC machine tool even in areas where one of the two spindles (SPD) temporarily holds the workpiece (WPC) and controls its rotation. Machining in the clamping area of ​​the workpiece (WPC) is made possible by the opposing spindle (SPD) holding the workpiece (WPC) or taking it over from the original spindle (SPD) and thus controlling its rotation, while the original spindle (SPD) releases the workpiece (WPC) for machining.The spindles SPD rotate the workpiece WPC around a workpiece axis XWP during machining. For machining purposes, a cutting edge GTE of the tool TOL is brought into contact with the workpiece WPC until chip removal begins. The machine tool TMC has a programmable control CTR, which controls the movement of the tool TOL and the movement of the spindles SPD, in particular the rotation of the workpiece WPG and the transfer to the other spindle SPD, by executing instruction sequences SQC. The movement of the tool TOL includes a movement of the tool holder THD along main travel paths, one main travel path extending essentially parallel to the workpiece axis XWP and another main travel path extending essentially radially to the workpiece axis XWP.The main travel path, extending radially to the workpiece rotation axis XWP, is generally two-dimensional, allowing the tool TOL to move in a radial plane by changing its radial distance to the workpiece rotation axis XWP. This results in a degree of spatial mobility. The tool holder THD is rotatable with the tool TOL about the tool rotation axis XTL, enabling the clamping contact point TPT of the cutting edge CTE on the workpiece WPC to be aligned at a predetermined angle SAG to the workpiece WPC or its surface.

[0070] The total working area of ​​a TMC machine tool is regularly divided into various sub-working areas. Since this division is not purely spatial, but rather relates to the determination of the rotation (speed, direction of rotation RTD) by the main spindle MSP or the counter spindle CSP, the term "working mode WMD" is used here instead of "working area." A characteristic of each working mode WMD is that the TMC machine tool has a workpiece coordinate system (CWP) specific to that particular working mode.Specifically, the WMD working modes, with respect to a vertical division plane SPP along the workpiece rotation axis XWP, are characterized as follows: in a first WMD working mode, the contact point TPT is on a first side FHF of the workpiece rotation axis XWP and the main spindle MSP determines the rotation of the workpiece WPC; in a second WMD working mode, the contact point TPT is on a first side FHF of the workpiece rotation axis XWP and the counter spindle CSP determines the rotation of the workpiece WPC; in a third WMD working mode, the contact point TPT is on a second side SHF of the workpiece rotation axis XWP and the main spindle MSP determines the rotation of the workpiece WPC, 2024P14220WQ.

[0071] In a fourth working mode WMD, the contact point TPT on a second side SHF of the workpiece rotation axis XWP and the counter spindle CSP determines the rotation of the workpiece WPG.

[0072] Based on this definition of the WMD operating modes, the invention provides that the instruction sequence SQC includes:

[0073] - Defining a positive first coordinate direction CFD for all working modes WMD in the direction of the spindle SPD, which does not determine the rotation,

[0074] - Defining a positive second coordinate direction (CSD) pointing away from the

[0075] Workpiece rotary axis XWP for all WMD working modes.

[0076] In this way, it is possible to make a defined chain of rotations, reflections and / or translations of the coordinate data CDR of the instruction sequence SQC compatible for the respective current working mode WMD by means of a change from one specific WMD working mode to another specific WMD working mode.

[0077] Furthermore, according to the invention, the instruction sequence SQC comprises the following steps:

[0078] - Defining a specific RTD rotation direction, preferably defining a positive one

[0079] Direction of rotation RTD, the tool rotation axis XTL for all working modes WMD from the first coordinate direction CFD via a specific rotation angle, preferably the shorter rotation angle, towards the second coordinate direction CSD,

[0080] - Defining a zero angle ZAG of the tool rotation axis XTL for all

[0081] Working modes WMD, preferably coincident with the second coordinate direction CSD.

[0082] Figure 3 shows the initial state without the complete implementation of the invention. Rotation parameters of the instruction sequence SQC for the rotation of the tool TOL about the tool rotation axis XTL for all WMD working modes must be individually adjusted for each working area. For the four different WMD working modes shown in Figure 3, excerpts from instruction sequences SQC are given below, which effect an angular positioning of the cutting edge CTE of the tool TOL according to the prior art. The individual workpiece coordinate systems CWP can each be transformed into one another from a reference coordinate system using a transformation instruction TRC. This transformation instruction does not apply to the angle parameters concerning the rotation of the tool holder THD about the tool rotation axis XTL. The instruction sequences SQC of the four WMD working modes are listed in sequence from left to right and from top to bottom:

[0083] Here, N10, N20, N30, N40 represent the positions of the GTE cutting edge during the manufacturing process.

[0084] The individual angle specifications refer to the initial zero angle ZAG shown in the middle of Figure 3 and the positive direction of rotation RTD.

[0085] - in the first WMD working mode:

[0086] ;Parts program 1

[0087] activation

[0088] TRAFOON(XY)

[0089] ; contour

[0090] N10 G1 Z250 X 100 SP=0

[0091] N20 G1 Z200 SP=-45

[0092] N30 G1 X60

[0093] N40 G1 Z100 SP=45

[0094] - in the second operating mode WMD:

[0095] ;Parts program 1

[0096] activation

[0097] TRAFOON(XY)

[0098] ; contour

[0099] N10 G1 Z250 X 100 SP=0

[0100] N20 G1 Z200 SP=45

[0101] N30 G1 X60

[0102] N40 G1 Z100 SP=-45

[0103] - in the third operating mode WMD:

[0104] ;Parts program 1

[0105] Activation TRAFOON(XY) ; Contour

[0106] N10 G1 Z250 X 100 SP=180

[0107] N20 G1 Z200 SP=225

[0108] N30 G1 X60

[0109] N40 G1 Z100 SP=135

[0110] - in the fourth operating mode WMD:

[0111] ;Parts program 1

[0112] Activation TRAFOON(XY) ; Contour

[0113] N10 G1 Z250 X 100 SP=180

[0114] N20 G1 Z200 SP=135

[0115] N30 G1 X60

[0116] N40 G1 Z100 SP=225

[0117] Figure 4 illustrates the effect of the configuration according to the invention, which results in the rotation specifications of the instruction sequence SQC for the rotation of the tool TOL about the tool rotation axis XTL being compatible for all WMD working modes. Accordingly, the invention achieves the goal of a fully automatic implementation of the instruction sequence SQC on machine tools TMC, which are divided into the four different WMD working modes defined above. In contrast to the four different WMD working modes shown in Figure 3, the inventive configurations of the workpiece coordinate systems CWP and the associated transformation instructions TRC are shown. The individual angle specifications PHI refer to individual initial zero angles ZAG and positive rotation directions RTD, specified for each WMD working mode at the origin of the respective workpiece coordinate system CWP.

[0118] - The following applies equally to all WMD operating modes: ;Parts program 1

[0119] activation

[0120] TRAFOON(XY)

[0121] ; contour

[0122] N10 G1 Z250 X 100 PHI=0

[0123] N20G1 Z200 PHI=45

[0124] N30 G1 X60

[0125] N40 G1 Z100 PHI=-45

[0126] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

Patent claims 1. Method for operating a machine tool (TMC) for machining a workpiece (WPC) by turning, wherein the machine tool (TMC) has spindles (SPD), comprising a main spindle (MSP) and a counter spindle (CSP) which are arranged by a The workpiece rotary axis (XWP) is rotatable, and a workpiece (WPC) is automatically transferred from the main spindle (MSP) to the counter spindle (CSP) for machining during the execution of an instruction sequence (SQC), the machine tool (TMC) having at least one tool holder (THD) and at least one tool (TOL), the tool holder (THD) holding the at least one tool (TOL) for machining the workpiece (WPC) and guiding the movement of the tool (TOL), the tool (TOL) having at least one cutting edge (CTE) for machining the workpiece (WPC), the machine tool (TMC) having a programmable control (CTR) that executes the instruction sequence (SQC) for controlling the movements of the spindles (SPD) and the at least one tool (TOL), the tool holder (THD) with the at least one tool (TOL) being rotatable about a tool rotary axis (XTL).that a cutting contact point (TPT) of the cutting edge (CTE) on the workpiece (WPC) can be aligned at a target angle (SAG) to the workpiece surface (SWP), whereby the machine tool (TMC) offers different working modes (WMD) of the tool (TOL) with different specifications of a, The workpiece coordinate system (CWP) has the following individual working modes (WMD) with reference to a division plane (SPP) along the workpiece rotation axis (XWP): in a first working mode (WMD), the contact point (TPT) is on a first side (FHF) of the workpiece rotation axis XWP, and the main spindle (MSP) determines the rotation of the workpiece (WPC); in a second working mode (WMD), the contact point (TPT) is on a second side (SHF) of the workpiece rotation axis (XWP), and the main spindle (MSP) determines the rotation of the workpiece (WPC); in machine tools (TMC) with offset, oppositely oriented spindles (SPD), in a third working mode (WMD), the contact point (TPT) is on a first side (FHF) 2024P14220WQ 15 of the workpiece rotary axis (XWP) and the counter spindle (CSP) determines the rotation of the workpiece (WPG); in a fourth operating mode (WMD) the contact point (TPT) is on a second side (SHF) of the workpiece rotary axis (XWP) and the counter spindle (CSP) determines the rotation of the workpiece (WPC); characterized in that the instruction sequence (SQC) comprises the following steps: - Defining a positive first coordinate direction (CFD) for all working modes (WMD) in the direction of the spindle (SPD), which does not determine the rotation, - Defining a positive second coordinate direction (CSD) pointing away from the workpiece rotation axis (XWP) for all working modes (WMD), wherein the definitions of the workpiece coordinate systems (CWP) for the various working modes (WMD) of the machine tool (TMC) are coordinated such that rotation specifications of the instruction sequence (SQC) for the rotation of the tool about the tool rotation axis (XTL) are compatible by means of a chain of rotations, reflections and / or translations of the coordinate specifications (CDR) for the respective current working mode (WMD) defined in the instruction sequence (SQC) for all working modes (WMD) and for each possible change from a first specific working mode (WMD) to another specific working mode (WMD), wherein, in order that the rotation specifications of the instruction sequence (SQC) for the rotation of the tool (TOL) about the tool rotation axis (XTL) are compatible for all working modes (WMD), wherein,so that the rotation data of the instruction sequence (SQC) for the rotation of the tool (TOL) about the tool rotation axis (XTL) are compatible for all working modes (WMD), the instruction sequence (SQC) continues to include the following steps: - Defining a specific direction of rotation (RTD) of the tool rotation axis (XTL) for each of the working modes (WMD) from a first coordinate direction (CFD) via a specific rotation angle to a second coordinate direction (CSD), - Defining a zero angle (ZAG) of the tool rotation axis (XTL) for all Operating modes (WMD) ).

2. Method according to claim 1, wherein the machine tool (TMC) has an additional milling function for machining a workpiece (WPC) by milling.

3. Method according to claim 1 or 2, wherein the rotation of the tool rotation axis (XTL) for aligning the cutting edge (GTE) at the machining contact point (TPT) on the workpiece (WPG) on the part of the tool holder (THD) is accompanied by a compensating movement (CMV) such that the rotation of the tool (TOL) about the tool rotation axis (XTL) has no influence on the position of the contact point (TPT) of the cutting edge (GTE) on the workpiece (WPG).

4. Machine tool with a control unit (CTR) and an interface for receiving an instruction sequence (SQC) for machining a workpiece (WPG), characterized in that the control unit (CTR) is designed and prepared to execute the method according to one of claims 1 to 3.

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