Device for grinding saw teeth and a corresponding method

Abstract

A device for grinding pre-milled and hard metal-tipped teeth of saw bands, is provided. The device comprises a feed device for feeding a temporarily formed workpiece in a timed manner, wherein the temporarily formed workpiece is formed from a plurality of saw bands which are parallel to one another. The device further comprises a clamping device which clamps the plurality of saw bands against one another, and a grinding unit for simultaneously grinding a plurality of teeth. The grinding unit comprises a grinding wheel with a plurality of grinding profiles. A corresponding method is also provided, where the grinding unit grinds both the tooth backs and the tooth faces to final dimension in exactly one linear movement.

Claims

1. A device for grinding pre-milled and hard metal-tipped teeth of saw bands, the device for grinding comprising a feed device for feeding a temporarily formed workpiece in a timed manner, wherein a temporary workpiece is temporarily formed from a plurality of saw bands which are parallel to one another, the device for grinding further comprising a clamping device which clamps the plurality of saw bands against one another, the device for grinding further comprising a grinding unit for simultaneously grinding a plurality of teeth, wherein the grinding unit comprises a grinding wheel with a plurality of grinding profiles, wherein the grinding unit has a clearance arranged in the area of a tooth tip of the teeth of the saw bands in the direction of the tooth face of the teeth of the saw bands so that the grinding unit grinds both the tooth backs and the tooth faces of the teeth of the saw bands to a desired final dimension in exactly one linear movement of the grinding unit orthogonally to a longitudinal axis of the plurality saw bands such that the tooth tip in the area of the tooth back is not damaged while the tooth tip in the area of the tooth face is completely ground down to the final dimension, such that the saw bands of the temporarily formed workpiece are each ready for use and do not require further regrinding.

2. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 1, wherein the grinding wheel is designed as a roller which comprises a multiplicity of tooth face grinding profiles and tooth back grinding profiles.

3. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 1, wherein the device for grinding comprises a push-down unit and/or a timing unit.

4. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 1, wherein the device for grinding comprises spacers, which can be inserted between two adjacent saw bands of the temporarily formed workpiece.

5. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 4, wherein the spacers are band-shaped spacers.

6. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 5, wherein the spaces are segment-shaped spacers arranged in the clamping device in a stationary manner.

7. The device for grinding pre-milled and hard metal-tipped teeth of saw bands according to claim 1, wherein each grinding profile has a clearance so that the grinding unit grinds both the tooth backs and the tooth faces to final dimension in exactly one linear movement of the grinding unit orthogonally to a longitudinal axis of the plurality saw bands such that the tooth tip in the area of the tooth back is not damaged while the tooth tip in the area of the tooth face is completely ground down to the final dimension, such that the saw bands of the temporarily formed workpiece are each ready for use and do not require further regrinding.

8. A method for grinding hard metal-tipped teeth of saw bands, comprising the steps of clamping a plurality of saw bands using the device of claim 1, wherein the saw bands are parallel and aligned axially to one another, against one another to create a temporarily formed workpiece, simultaneously grinding a plurality of tooth backs and tooth faces of the temporarily formed workpiece in exactly one linear movement of the grinding unit, further transporting the processed temporarily formed workpiece and re-clamping to create a new temporarily formed workpiece.

9. The method according to claim 8, further comprising a method step after the step of simultaneously grinding a plurality of tooth backs and tooth faces in only one linear movement of the grinding unit, after which the remaining tooth backs and tooth faces of the temporarily formed workpiece are ground in further linear movements of the grinding unit.

10. The method according to claim 8, further comprising one or more of the following steps: pre-milling raw teeth in desired areas of a metal band, unwinding a plurality of saw bands each having pre-milled raw teeth and welded-on hard metal pins from a coil in each case, turning and aligning the respective saw bands, inserting spacers between two adjacent saw bands, pushing down a temporarily formed workpiece before clamping, and winding up at least one processed saw band to form a coil.

11. The method according to claim 8, comprising a step of cutting a processed saw band to length instead of winding it up.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In detail, the figures of the drawings show:

(2) FIG. 1: a saw band in the raw state,

(3) FIG. 2: a temporarily formed workpiece from 40 saw bands,

(4) FIG. 3: a partial view of a device according to the invention,

(5) FIG. 4: a detail view of the grinding unit,

(6) FIG. 5: a detail of a grinding wheel, and

(7) FIG. 6: a further partial view of the device according to the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(8) FIG. 1 shows a saw band in the state prior to processing by the device according to the invention, which is already designated here as saw band 3, even though it is still in the raw state. Milled-in raw teeth 18, already comprising welded-on hard metal pins 17 in the area between the later tooth face and the tooth back can be seen. Another advantage of the invention can be seen, namely that raw teeth 18 are milled in specifically only into certain areas of the saw band 3, namely into those which are later processed into saw blades by means of a cutting unit. This reduces the manufacturing time because no teeth need to be milled in at the areas which are omitted later. According to the invention, such a band, which is pre-milled and provided with hard metal pins 17, is unwound from a coil or is fed to a device according to the invention after welding.

(9) FIG. 2 shows a temporarily formed workpiece 5 formed here from 40 saw bands 3 which are parallel to one another, in the raw state. Between these saw bands there are 39 spacers 16, thus in each case one spacer 16 between two adjacent saw bands 3. The individual saw bands 3 of the temporarily formed workpiece 5 are aligned axially to one another, so that a grinding process transversely to the longitudinal direction of the saw bands can take place such that all teeth of all saw bands 3 can be manufactured with the same dimension. The feed direction is indicated with an arrow, the processing direction with a double arrow since, according to the invention, the processing can be performed orthogonally in both directions to the longitudinal axis. A timing unit 14, which is designed here as recess in a saw band 3, can also be seen. According to the invention, a correspondingly shaped mandrel engages in these recesses, which are also aligned and flush, and thus ensures for each positive connection that the orientation of the bands relative to one another is maintained even after clamping.

(10) FIG. 3 shows a device 1 according to the invention in partial view. A bundle of, in this case, 40 parallel saw bands 3 coming from the right is conveyed into the device 1. A clamping device 6, which is not shown here, clamps the bundle of saw bands 3 in the area of the grinding unit 7 and thus temporarily creates a workpiece 5 during the grinding process. The clamping device 6 is covered by the push-down unit 13. The temporarily formed workpiece is pushed onto a defined support, in particular by means of a multi-finger push-down unit 13, so that a defined, dimensionally stable tooth tip height can be obtained across all teeth. The push-down unit 13 is designed to be displaceable and can thus be displaced into a non-interfering position outside of a grinding process area after pushing down and clamping the saw blades/bands. A supply device 25 is illustrated on the right.

(11) In FIG. 3, a feed device 4 is shown on the left, wherein the clamping of the temporarily formed workpiece is released during the timed conveying through the device 1 while the feed device 4 already clamps the saw band bundle. The feed device then continues to convey the saw band bundle, stops, releases the clamping, whereupon the clamping unit 6, in turn, clamps in the operating area of the grinding unit 7 and thus creates a temporarily formed workpiece 5. By means of this intermittingly changing clamping, a timed transport is ensured on the one hand, and, on the other hand, a precise grinding process is made possible. A base plate for the grinding unit 7 as well as a pivoting device 20 are illustrated; the movements are indicated by means of arrows. If the workpiece 5 is conveyed further by the feed device, the grinding unit 7 is pivoted away from the workpiece 5 by the pivoting device 20 before and after this and then pivoted in again so that a feed of the workpiece 5 is not blocked by the grinding unit 7.

(12) FIG. 4 shows a detail view of the grinding wheel 8 according to the invention of the grinding unit 7 in the installed position in the device 1 according to the invention, as well as the clamping device 6. The grinding wheel 8 is designed as roller 10, the grinding profile of which is designed according to the tooth pitch to be manufactured. When changing the tooth geometry to be manufactured, the grinding wheel 8 has to be changed as well. It can be clearly seen that all raw teeth below the grinding wheel 8 of a saw band 3 of the temporarily formed workpiece 5 are ground simultaneously, wherein the grinding wheel 8 is moved transversely to the longitudinal direction of the workpiece 5 in order to process all of the teeth of a saw band section within the grinding wheel operating width.

(13) FIG. 5 shows a section of a grinding wheel 8 according to the invention as a roller 10 as well as a corresponding section of a saw band 3 with pre-milled raw teeth 18 and hard metal pins 17, each of which are welded on. The tooth tips are formed by the carbide pins 17 already ground in the present illustration. The grinding wheel 8 has a grinding profile 9 formed by a plurality of identical tooth face grinding profiles 11 and identical tooth back grinding profiles 12. In a transition of tooth face grinding profiles 11 and tooth back grinding profiles 12, a clearance 15 is provided in each case, which in the present example is rounded due to simple design-related advantages but, alternatively, can also be designed differently. According to the invention, the clearance 15 is designed in particular in such a manner that both the tooth back 27 and the tooth faces are ground in only one linear movement of the grinding unit and the tooth tip remains intact. For this purpose, the clearance 15 has an area which, in a state applied to the tooth tip, runs parallel to the tooth back 27 but does not rest against it. This allows a straight cut of the tooth back 27 and a clear tooth tip without any roundings. The entire tooth face 26 is ground over its entire length despite the clearance since the grinding wheel 8 is designed as a roller 10 and thus various angular sections of the grinding wheel 8 come into contact with the tooth face 26 during a linear movement. For the reasons mentioned, the clearance allows simultaneous processing of the tooth backs 27 and the tooth faces 26 by only one linear movement.

(14) FIG. 6 shows a further view of a device 1 according to the invention. The base plate for the grinding unit 7 as well as a pivoting device 20 comprising a drive 23 can be seen. A pivot bearing 21 and three fastening devices 24 as well as a rotary encoder 22 for the pivoting device 20 are illustrated. The grinding unit 7 is moved and the temporarily formed workpiece is created by means of these assembly groups.

(15) Depending on the different tooth geometries to be manufactured, in particular relating to the clamping angle at the tooth face and the free angle at the tooth back, the grinding unit 7 is pivoted about a corresponding angle by means of a pivoting device 20, which is arranged downstream of the base plate (on which the grinding unit 7 is mounted).

(16) The pivoting device 20 consists of a stable pivot bearing 21 comprising a high-resolution rotary encoder 22 for the exact angle adjustment as well as an NC-controlled drive 23 (pivoting movement initiated via a tooth pinion and a tooth segment) as well as an automatic fastening device 24.

(17) To support the unwinding process of the individual coils on the inlet side, a supply device 26, which is timed with the same timing as the feed device 4, is provided to the right of the clamping device 6.

(18) Like the feed device 4, the supply device 25 consists of a clamping unit, a guide unit and a drive unit.

(19) The invention thus achieves tooth processing times that are a factor of 20 or more below the present processing times, even if up to several minutes of machining time are required per temporarily formed workpiece. However, since often more than 2,000 teeth are finished here at the same time, or even more depending on the tooth geometry, the tooth processing times are correspondingly short.

(20) In a highly advantageous manner, the grinding process according to the invention allows for high manufacturing speeds while simultaneously ensuring highest processing precision, for the purpose of which a grinding wheel and a saw band bundling had to be developed.

(21) For this purpose, the core method according to the invention consists of the steps of clamping a plurality of parallel saw bands, which are aligned axially to one another, against one another to temporarily create a temporarily formed workpiece, simultaneously grinding the temporary workpiece at a plurality of locations which are axially spaced apart, and further transporting the processed temporarily formed workpiece, and re-clamping to create a new temporarily formed workpiece. The following steps are added for a complete manufacturing process: pre-milling of raw teeth in desired areas of the saw band, unwinding a plurality of saw bands, each comprising pre-milled raw teeth and welded-on hard metal pins, from a coil in each case, turning and aligning the respective saw bands, inserting spacers between two adjacent saw bands, pushing down a temporarily formed workpiece during grinding, as well as after the core steps of winding up a processed saw band to form a coil, alternatively cutting a processed saw band to length instead of winding it up.