Method for grinding a workpiece with a grinding tool

Abstract

The present invention relates to a method for grinding a workpiece with a grinding tool, wherein a rotational axis of the grinding tool is oriented perpendicular to a feed plane of the grinding tool, comprising the following steps: a) moving the grinding tool at a first speed into a processing area of ​​the workpiece, b) contacting a first entry area of ​​the workpiece with the grinding tool at a second speed, c) first moving the grinding tool at the second speed through the workpiece along a predefined contour lying in the feed plane, d) first removing the grinding tool at the second speed from a first exit area of ​​the workpiece, e) contacting a second entry area of ​​the workpiece with the grinding tool at a third speed,f) second movement of the grinding tool at the third speed through the workpiece along a horizontal travel direction lying in the feed plane, g) second removal of the grinding tool at the third speed from a second exit area of ​​the workpiece.

Description

[0001] The present invention relates to a method for grinding a workpiece with a grinding tool, wherein a rotation axis of the grinding tool is oriented perpendicular to a feed plane of the grinding tool, wherein the workpiece is formed in particular by a temporary workpiece comprising a plurality of mutually parallel saw bands.

[0002] Workpieces such as saw blades are of great economic importance in a variety of machining processes and are used extensively, particularly in trades for cutting, severing, or dismantling structural components, as well as in fire service rescue operations. Saw blades are also used in industry, particularly for machining metals, plastics, or wood, as well as in the food industry, particularly for frozen fish or meat products. Accordingly, high demands are placed on the precision of the tooth geometries. In general, high quality standards are required for workpieces manufactured using grinding processes.

[0003] Saw bands as possible workpieces generally have a lot of variability in terms of their tooth width and geometry. They are usually made from a blank by unwinding a metal strip from a coil, turning it if necessary and straightening it. This metal strip is then ground to produce the teeth. It is also common to arrange several metal strips next to each other for simultaneous grinding to produce the teeth. The saw bands are then cut to the required length if necessary, or the finished saw band is turned again and wound up into a saw band coil. The unwinding of the blank from the coil and the other subsequent work steps are usually carried out in cycles, at least to the extent of the work steps with which a saw band to be manufactured is continuously processed. In this case, it may be necessary toBuffer paths between the individual processing stations (machines) must be planned if the timing is not constant throughout the entire production line.

[0004] Methods for grinding workpieces are known from the prior art, which process the workpiece using a deep-feed grinding process, a creep-feed grinding process, or a plunge-feed grinding process. During a deep-feed grinding or creep-feed grinding process, the grinding tool is brought to the total infeed once and outside the workpiece, and this is removed from the workpiece in a single horizontal feed cycle. In the exchange grinding process, the grinding tool is brought vertically into the workpiece to a final dimension, which defines the total infeed, and then lifted vertically out of the machined workpiece.

[0005] A disadvantage of this state-of-the-art technology is the very slow feed rate during the deep-feed grinding or creep feed grinding process. This is due to the very high contact of the grinding tool with the workpiece, which leads to very high heat input and, in extreme cases, to structural changes in the workpiece and thus a potential deterioration in material quality. Therefore, increased cycle times are required. In the plunge grinding process, the width of the workpiece perpendicular to the feed direction is limited due to the fixed diameter of the grinding tool. The workpieces produced using this grinding process also have different dimensions due to the cross-sectional shape of the grinding tool.

[0006] The present invention is therefore based on the object of providing an efficient and cost-effective method for grinding a workpiece with the shortest possible cycle times.

[0007] This object is achieved by a method for grinding a workpiece with a grinding tool, wherein a rotation axis of the grinding tool is oriented perpendicular to a feed plane of the grinding tool, comprising the following steps: a) Moving the grinding tool at a first speed into a machining area of ​​the workpiece, b) contacting a first entry area of ​​the workpiece with the grinding tool at a second speed, c) First movement of the grinding tool at the second speed through the workpiece along a predefined contour lying in the feed plane, d) Firstly, the grinding tool is discharged at the second speed from a first exit area of ​​the workpiece, e) contacting a second entry area of ​​the workpiece with the grinding tool at a third speed, f) Second movement of the grinding tool at the third speed through the workpiece along a horizontal travel direction lying in the feed plane, g) Second discharge of the grinding tool at the third speed from a second exit area of ​​the workpiece.

[0008] The grinding tool is advantageously rotationally symmetrical and designed such that profile grinding or generating grinding can be carried out with it. The first and second entry regions as well as the first and second exit regions are preferably defined as those regions in which the grinding tool and the workpiece initially or finally contact each other, before or after the two are moved away from each other. Advantageously, both the grinding tool and the workpiece are arranged on movably mounted supports within a grinding machine. The movement, contact, and displacement of the grinding tool takes place via at least two linear axes of the grinding machine, with the grinding tool being moved in an interpolating manner via these linear axes.

[0009] The method for grinding the workpiece according to the invention divides the removal volume into two process steps by dividing the grinding process, thereby achieving a high travel speed and thus short cycle times and efficient workpiece removal from the grinding machine. Furthermore, the first to third speeds according to the invention are adapted to the respective engagement between the grinding tool and the workpiece in such a way that the load on these components is as uniform as possible, thus advantageously avoiding damage, particularly due to load peaks.

[0010] The contour is advantageously selected so that a uniform material removal rate is maintained throughout the entire grinding cycle after steps b) to g). Between steps d) and e), the feed rate of the grinding tool is decelerated from the second speed to 0 and then accelerated to the third speed before the grinding tool contacts the workpiece once more. The horizontal direction components of the second and third speeds are opposite to each other. In particular, the grinding tool rotates continuously at a constant peripheral speed.

[0011] The machining area extends along an outer shape of the workpiece and advantageously expands this in all directions by a maximum of 25 mm, preferably by a maximum of 20 mm, and particularly preferably by a maximum of 15 mm. The movement of the grinding tool into the machining area is achieved as soon as at least part of the grinding tool lies within the machining area.

[0012] In an advantageous embodiment of the invention, the grinding tool moves at the third speed with a total vertical infeed. The total infeed is preferably 1 mm to 10 mm. Accordingly, the workpiece is machined to its final dimensions by the movement of the grinding tool at the third speed. A further machining step on the newly created surface by the grinding tool at the third speed is advantageously eliminated, which further shortens the cycle time.

[0013] In an advantageous embodiment of the invention, it is provided that the first entry region is oriented vertically offset from the first exit region in the feed plane, wherein the first entry region and the first exit region are vertically offset from one another by a value less than or equal to the total vertical feed. The first entry region and the first exit region are advantageously vertically offset from one another such that the first entry region is positioned closer to the grinding tool than the first exit region.In a particularly advantageous embodiment, the grinding tool reaches the total vertical feed during the first removal from the workpiece, so that the grinding tool experiences a horizontal change of direction immediately after the removal and, in the total vertical feed along the horizontal travel direction, contacts the second entry area, moves through the workpiece and is removed from the second exit area.

[0014] Furthermore, in an advantageous development of the invention, the first inlet region extends over a substantially vertical first outer surface of the workpiece and a substantially horizontal outer surface of the workpiece adjacent to the vertical first outer surface, wherein the first outlet region extends over a substantially vertical second outer surface of the workpiece, wherein the vertical second outer surface is opposite the vertical first outer surface. Advantageously, the first inlet region in the feed plane thus has an L-shaped cross-section due to the vertical and horizontal portions, while the first outlet region, in particular, has an I-shaped cross-section, since the outlet occurs on the vertical surface opposite the vertical inlet surface.The first entry region advantageously extends from a corner point formed by the vertical first outer surface and the horizontal outer surface along the vertical first outer surface and the horizontal outer surface by a maximum of 6 mm, preferably by a maximum of 4 mm, particularly preferably by a maximum of 2 mm. The horizontal outer surface is defined as the one closest to the grinding tool. The vertical first and second outer surfaces are each oriented parallel to the axis of rotation and perpendicular to the horizontal travel direction and are advantageously indirectly connected by the horizontal outer surface. The horizontal outer surface is advantageously oriented parallel to the horizontal travel direction.

[0015] A maximum first method is formed in which the first entry region is positioned vertically at the height of the horizontal outer surface and the first exit region is positioned vertically at the height of the total infeed. Any intermediate vertical positioning of the first entry region and the first exit region is also possible, as long as the first entry region is positioned closer to the horizontal outer surface than the first exit region. By positioning the first entry region in this way, the machining area can be significantly reduced, and the grinding tool can thus be moved close to the workpiece without accidentally contacting it.

[0016] In a further development of the invention, it is provided that the first exit region extends over the substantially vertical second outer surface and the second exit region extends over the substantially vertical first outer surface, wherein a greater vertical offset is formed between the first inlet region and the second exit region than between the first exit region and the second inlet region. The first movement of the grinding tool therefore has an opposite horizontal directional component than the second movement of the grinding tool. Since the second movement takes place according to the invention along the horizontal direction of travel, the second inlet region and the second exit region are advantageously designed to be congruent and are arranged offset parallel to one another along the horizontal direction of travel.

[0017] In a further development of the invention, the predefined contour has a substantially linear, parabolic, logarithmic, exponential, wave-like shape, or a superposition of at least two of the aforementioned shapes. Advantageously, the predefined contour is selected such that the material removal rate of the workpiece is as uniform as possible, thus ensuring that the loads on the grinding tool and workpiece are also as uniform as possible.

[0018] In an advantageous development of the invention, the predefined contour and the horizontal travel direction enclose an angle φ of 1° to 45°, preferably of 15° to 30°, particularly preferably of 20° to 25°. If the predefined contour does not have a linear shape, a linear mean of the predefined contour is used to define the angle φ. Another possibility for defining the angle φ is to create a straight line through the contact point and discharge point between the grinding tool and the workpiece. The angle φ depends, among other things, on a workpiece width defined perpendicular to the rotation axis, which is in particular between 10 mm and 60 mm.

[0019] In an advantageous embodiment of the invention, the first entry region ends vertically above the first exit region, so that the grinding tool always experiences a vertical directional component during a first movement, wherein an angle φ between the horizontal movement direction and the contour is always greater than 0.

[0020] In an advantageous embodiment of the invention, it is provided that the axis of rotation lies behind or within the first entry area in the feed plane during contact of the first entry area with the grinding tool along the horizontal travel direction.

[0021] Furthermore, in an advantageous development of the invention, the rotation axis lies in front of or within the second entry area in the feed plane during the first discharge and / or contacting of the second entry area along the horizontal travel direction. Depending on the type and requirements of the workpiece, the direction of rotation of the grinding tool around the rotation axis is defined, in particular to achieve the flattest possible surfaces or the shortest possible cutting time. Preferably, the direction of rotation of the grinding tool is defined in the opposite direction to the third speed.

[0022] In an advantageous embodiment of the invention, it is provided that the first speed is higher than the second and third speeds, wherein the second and third speeds differ from one another, wherein the second and third speeds are constant during a workpiece engagement of the grinding tool. While the grinding tool is moved at the first speed, it is not in engagement with the workpiece, after which there is no risk of damage to the workpiece and / or grinding tool. The second and third speeds are preferably selected such that the cycle time is as short as possible, but there is no change in the structure, in particular of a metallic workpiece, or no damage to the workpiece and / or the grinding tool.In a particularly advantageous manner, the second and third speeds are further selected such that the material removal rate of the workpiece is as uniform as possible.

[0023] Furthermore, in an advantageous embodiment, the workpiece is formed by a temporary workpiece consisting of a plurality of parallel saw blades, wherein a plurality of teeth of the temporary workpiece are ground simultaneously by the grinding tool. Advantageously, this combines several individual workpieces, namely the individual saw blades, into a temporary workpiece and is machined simultaneously. The more saw blades are formed into a temporary workpiece, the more the cycle time of an individual saw blade is reduced, which significantly increases the output of the grinding machine and thus enormously improves cost efficiency. The saw blades formed into the temporary workpiece are arranged in their longitudinal alignment parallel to the rotation axis of the grinding tool.

[0024] In a further development of the invention, the workpiece is held down and clamped before and / or during the movement of the grinding tool. Parallelizing these operations further reduces the cycle time for machining the workpiece. Since the workpiece and grinding tool are not in contact with each other during any of these operations, they can be performed independently of each other, provided the installation space of a grinding machine permits.

[0025] In a preferred embodiment of the invention, the workpiece is displaced parallel to the rotation axis after the second discharge, and at least steps b) to f) are repeated. A further machining process of the workpiece advantageously begins with pressing down and clamping the workpiece. This is followed by steps a) to f) according to the invention, after which the workpiece is ground. When grinding identical saw blades that form a temporary workpiece, steps a) to f) produce either tooth backs and / or tooth faces.The workpiece is then moved parallel to the rotation axis and at least steps b) to f) are repeated, whereby when grinding identical saw blades which form the temporary workpiece, the repetition of at least steps b) to f) produces either tooth backs and / or tooth breasts, depending on which were not produced during the first grinding process.

[0026] Preferably, the aforementioned grinding and shifting steps can be repeated at least once before the workpiece is released from its clamped state, which further shortens the cycle times.

[0027] In a preferred development of the method, after the second removal, the workpiece is released from its clamped state, moved, and clamped again, and at least steps b) to f) are repeated. Here, too, the workpiece is moved parallel to the rotational axis of the grinding tool, thereby generating a machining cycle within the method. The steps of releasing, moving, and clamping are particularly necessary for workpieces that are machined multiple times at different positions using the method according to the invention. Clamping and releasing are advantageously carried out by at least one clamping unit arranged on the grinding machine.The displacement is either also carried out by the clamping units, whereby the clamping units are guided parallel to the rotation axis via a linear guide on the grinding machine, or the workpiece is offset parallel to the rotation axis by another offset unit and then re-clamped by means of the clamping units so that the grinding tool engages in the workpiece.

[0028] The invention is described by way of example in several preferred embodiments with reference to a drawing, wherein further advantageous details can be taken from the figures of the drawings.

[0029] Functionally identical parts are provided with the same reference symbols.

[0030] The figures in the drawing show in detail: Fig. 1 Side view of the grinding tool and the workpiece while a first entry area is contacted, Fig. 2 Side view of the grinding tool and the workpiece during the first application, Fig. 3 Side view of the grinding tool and the workpiece while a second entry area is contacted, Fig. 4 Side view of the grinding tool and the workpiece during the second application Fig. 5 Side view of the workpiece as a temporary workpiece

[0031] Fig. 1 shows a side view of the grinding tool 2 and the workpiece 1 during contact with a first entry region 6, wherein the entry region 6 extends along a vertical first outer surface 12 and a horizontal outer surface 13 of the workpiece 1. Contact is therefore defined as the point in time at which the grinding tool 2 and the workpiece 1 initially touch. In this context, initial means a first contact and each further contact after which the grinding tool 2 and workpiece 1 were spaced apart from one another. For the sake of clarity, the grinding tool 2 is only shown in detail in the figures and has a substantially cylindrical shape that extends along the rotation axis 3. The side view shown is oriented parallel to the feed plane 4 and perpendicular to the rotation axis 3 of the grinding tool 2.During contact with the first entry area 6, the grinding tool 2 moves at a second speed v2, which in this exemplary embodiment is linear and has a horizontal and a vertical directional component. The second speed v2 is generated by a movement of the rotation axis 3 in the feed plane 4, whereby it is transmitted in parallel to a vertically lowest point of the grinding tool 2. A contact point between the vertically lowest point of the grinding tool 2 and the workpiece 1 also lies within the entry area 6. Before the workpiece 1 comes into contact with the grinding tool 2, the grinding tool 2 is moved at a first speed v1 into a processing area 5 surrounding the workpiece 1.

[0032] Fig. 2 shows a side view of the grinding tool 2 and the workpiece 1 during the first removal process, wherein a first exit region 8 is positioned along a vertical second outer surface 14 of the workpiece 1 and is defined by a last contact point between the grinding tool 2 and the workpiece 1 before they move away from each other. Due to the previous movement of the grinding tool 2 through the workpiece 1 along a contour 7, this contour 7 is transferred to the workpiece 1 and a new contour outer surface 17 defined by the contour 7 is formed. In this exemplary embodiment, the contour 7 and thus the newly formed contour outer surface 17 have a linear shape. The hatched region of the workpiece 1 was removed by the first movement of the grinding tool 2 and is no longer part of the workpiece 1. The first removal process also takes place at the second speed v2 of the grinding tool 2.

[0033] Fig. 3 shows a side view of the grinding tool 2 and the workpiece 1 while a second entry region 9 of the workpiece 1 is contacted by the grinding tool 2, wherein the second entry region 9 in this embodiment is positioned congruently with the first exit region 8 on the vertical second outer surface 14 of the workpiece 1. However, the grinding tool 2 contacts the workpiece 1 at a third speed v3. The grinding tool 2 moves at the third speed v3 along a horizontal travel direction 10 through the workpiece 1.

[0034] Fig. 4 shows a side view of the grinding tool 2 and the workpiece 1 during the second discharge, wherein the grinding tool 2 is moved at a third speed v3. The grinding tool 2 emerges from the second exit region 11 of the workpiece 1. By the second movement of the grinding tool 2 along the travel direction 10, the workpiece 1 is ground to its final dimension. During the movement at the third speed v3, the grinding tool 2 has reached its total vertical infeed z at least during the second movement. The angle φ is formed between the horizontal travel direction 10 and the contour 7, wherein this angle is dependent in particular on the position of the contact between the grinding tool 2 and the workpiece 1 in the entry region 6, the total infeed z and a workpiece width b of the workpiece 1.

[0035] Fig.Figure 5 shows a side view of the workpiece 1 as a temporary workpiece 15, which is formed from a plurality of parallel saw blades 16. The grinding tool 2 is shown in dash-dotted lines as an example in possible positions during the method according to the invention. Furthermore, the direction vectors of the second and third speeds v2, v3 are shown, which also form the angle φ between them. LIST OF REFERENCE SYMBOLS 1 workpiece 2 grinding tools 3 rotation axis 4 feed level 5 Editing area 6 first entrance area 7 Contour 8 first exit area 9 second entrance area 10 horizontal travel direction 11 second exit area 12 vertical first outer surface 13 horizontal outer surface 14 vertical second outer surface 15 temporary workpiece 16 saw band 17 Outer contour surface v1 first speed v2 second speed v3 third speed b Workpiece width z total vertical delivery φ angle

Claims

[1] Method for grinding a workpiece (1) with a grinding tool (2), wherein a rotation axis (3) of the grinding tool (2) is oriented perpendicular to a feed plane (4) of the grinding tool (2), comprising the following steps: h) moving the grinding tool (2) at a first speed (v1) into a machining area (5) of the workpiece (1), i) contacting a first entry area (6) of the workpiece (1) with the grinding tool (2) at a second speed (v2), j) First movement of the grinding tool (2) at the second speed (v2) through the workpiece (1) along a predefined contour (7) lying in the feed plane (4), k) First removal of the grinding tool (2) at the second speed (v2) from a first exit area (8) of the workpiece (1), I) contacting a second entry area (9) of the workpiece (1) with the grinding tool (2) at a third speed (v3), m) Second movement of the grinding tool (2) at the third speed (v3) through the workpiece (1) along a horizontal travel direction (10) lying in the feed plane (4), n) Second discharge of the grinding tool (2) at the third speed (v3) from a second exit area (11) of the workpiece (1). [2] Method for grinding a workpiece (1) according to claim 1, wherein the grinding tool (2) moves at the third speed (v3) in a vertical total feed (z). [3] Method for grinding a workpiece (1) according to claim 2, wherein the first entry region (6) is oriented vertically offset from the first exit region (8) in the feed plane (4), wherein the first entry region (6) and the first exit region (8) are vertically offset from one another by less than or equal to the total vertical feed (z). [4] Method for grinding a workpiece (1) according to claim 1, 2 or 3, wherein the first entry region (6) extends over a substantially vertical first outer surface (12) of the workpiece (1) and a substantially horizontal outer surface (13) of the workpiece (1) adjacent to the vertical first outer surface (12), wherein the first exit region (8) extends over a substantially vertical second outer surface (14) of the workpiece (1), wherein the vertical second outer surface (14) is opposite the vertical first outer surface (12). [5] Method for grinding a workpiece (1) according to claim 4, wherein the first exit region (8) extends over the substantially vertical second outer surface (14) and the second exit region (11) extends over the substantially vertical first outer surface (12), wherein a larger vertical offset is formed between the first inlet region (6) and the second exit region (11) than between the first exit region (8) and the second inlet region (9). [6] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the predefined contour (7) has a substantially linear, parabolic, logarithmic, exponential, wave-like shape or a superposition of at least two of the aforementioned shapes. [7] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the predefined contour (7) and the horizontal travel direction (10) enclose between them an angle (φ) of 1° to 45°, preferably of 15° to 30°, particularly preferably of 20° to 25°. [8] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the rotation axis (3) lies behind or within the first entry region (6) in the feed plane (4) during contact of the first entry region (6) with the grinding tool (2) along the horizontal travel direction (10). [9] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the rotation axis (3) lies in front of or in the second entry region (9) in the feed plane (4) during the first discharge and / or contacting of the second entry region (9) along the horizontal travel direction (10). [10] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the first speed (v1) is higher than the second and third speeds (v2, v3) respectively, wherein the second and third speeds (v2, v3) differ from one another, wherein the second and third speeds (v2, v3) are each constant during a workpiece engagement of the grinding tool (2). [11] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the workpiece (1) is formed by a temporary workpiece (15) comprising a plurality of mutually parallel saw bands (16), wherein a plurality of teeth of the temporary workpiece (15) are ground simultaneously by the grinding tool (2). [12] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the workpiece (1) is held down and clamped before and / or during the movement of the grinding tool (2). [13] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the workpiece (1) is displaced parallel to the rotation axis (3) after the second discharge and at least steps b) to f) are repeated. [14] Method for grinding a workpiece (1) according to one of the preceding claims, wherein the workpiece (1) is released from its clamped state after the second removal, displaced and clamped again and at least steps b) to f) are repeated.

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