WO2001047665A1

WO2001047665A1 - Method and device for grinding fluted tools

Info

Publication number: WO2001047665A1
Application number: PCT/EP2000/013019
Authority: WO
Inventors: Erwin Junker
Original assignee: Erwin Junker Maschinenfabrik Gmbh
Priority date: 1999-12-23
Filing date: 2000-12-20
Publication date: 2001-07-05
Also published as: CZ20022183A3; DE19962796A1; US20030060133A1; AU3015001A; EP1239995A1; WO2001047665B1; JP2003518443A

Abstract

The invention relates to a method and device for grinding fluted tools (10) that have an essentially circular envelope curve, in particular, for grinding spiral fluted tools. The device provided with a steady for guiding the tool to be ground comprises a guideway (8) with at least two inner lateral faces. The lateral faces each extend in planes in a manner that is essentially parallel to the longitudinal axis of the tool to be ground and they from an angle for accommodating the tool to be ground, whereby the tool to be ground rests each time with at least two circumferential points (a11, a12) of its essentially circular envelope curve at least on two of the inner lateral faces of the guideway. In order to carry out the inventive method, a tool to be ground is appropriately clamped and pressed into the guideway by means of at least one grinding wheel (41) while the flutes are ground.

Description

Method and device for grinding grooved tools

The invention relates to a method and a device for grinding grooved tools, in particular helically grooved tools.

In general, the device described and the method described are suitable for producing helically grooved tools. In particular, the manufacture of twist drills is described in this description.

It is generally known in the prior art that grooved tools, in particular twist drills, are ground in sleeves which serve to hold and guide the tools. For this purpose, a separate receiving sleeve is required for each tool diameter, which is matched to the nominal diameter of the tool to be manufactured. Thus, a lot of individually adapted accessories for the actual grinding machine are required for clamping and grinding the tools to be manufactured, which also means that when changing over to another tool to be produced, which has a different diameter, for example, in a variety of ways by exchange must be converted from parts. In particular, if the tools to be manufactured may have different nominal diameters, there must be a separate receiving sleeve at least for each nominal tool diameter. The high retrofitting effort and the high number of specific accessories are associated with a high expenditure of time and high costs, which make the manufacturing process of the tools more expensive. Furthermore, from the use of sleeves in which the tools to be ground are guided, the problem of the insufficient accuracy of the guidance arises. Due to the system, the adjusted sleeve diameters have a play of 1 - 2 hundredths of a millimeter compared to the actual diameter of the tool to be manufactured. If, for example, the grinding wheel is grinded against the tool to be grinded when grinding the tool to be manufactured, this lies under the influence of the cutting forces in a punctiform or linear manner against the inside of the guide sleeve and is supported essentially only at one point on it Extent against the cutting forces. The guide is therefore not spatially fixed and depends on the geometry and the direction of the force applied by the grinding wheel to the workpiece to be ground. This leads to increased tolerances for the finished tool.

The object of the present invention is to provide an apparatus and a method by means of which helically grooved tools to be ground can be produced in the same or less time in improved quality at a simultaneously lower cost.

The object is achieved according to the invention with a device according to claim 1 and a method according to claim 16.

Preferred developments of the invention are defined in the respective subclaims.

The device according to the invention is used for grinding grooved

Tools which have an essentially circular envelope curve, in particular for grinding helically grooved tools, by means of grinding wheels. Twist drills can be ground, but corresponding other tools, such as milling cutters, bolirers in general and possibly reamers, can also be ground. According to the invention the device for grinding grooved tools has a steady rest for guiding the tool to be ground. According to the invention, this bezel comprises a guideway with at least two inner side surfaces, each of which runs in planes essentially parallel to the longitudinal axis of the tool to be ground and enclose an angle for receiving the tool to be ground. The tool to be ground lies with at least two points on its circumference in each case against at least two of the inner side surfaces of the guideway, ie one of the at least two circumferential points lies against one of the at least two inner side surfaces.

In general, the tools to be ground can be tapered over their length, in particular slightly tapered. In particular, they can be conically tapered from their end face to their shaft. For the inventive installation of such a tool to be ground on the at least two inner side surfaces of the guideway, these essentially follow a weak taper of the tool, in which case they then run in planes essentially parallel to the longitudinal axis of the tool to be ground. In the case of a non-tapered tool to be ground, in which the diameter of the envelope does not change over the length (usually in the case of a weak taper by a few hundredths of a millimeter), the at least two side surfaces of the guideway run parallel. In the case of a more pronounced taper of the tool to be ground, the course of the at least two inner side surfaces of the guideway can essentially follow the tool contour in longitudinal section, the planes of the side surfaces then being inclined in relation to one another, in some cases even differently over the length, in space.

The inventive design of the device, wherein the tool to be ground is guided in a guideway of a steady rest and rests at least on two circumferential points in this guideway, is one play-free storage and installation of the tool to be ground possible. In contrast to this, in the state of the art the tool is guided in a sleeve and, viewed in cross section of the tool to be produced, lies only at one point on the side wall of the sleeve, as a result of which no reliable guidance can be achieved. Compared to the sleeve of the prior art, according to the invention, at least two side faces of the guideway enclose an angle in which the tool to be ground is guided, and it is possible that, since the guideway in cross section with these side faces essentially widened, for example in a V-shape opens for receiving the tool, according to the invention tools with different diameters are ground. The tools are supported and guided on at least two side surfaces of this guideway, the respective contact point being able to lie at a different location depending on the work step carried out or the diameter of the tool to be ground, or a linear contact on at least two lines can be. Thus, the special construction for guiding the tool to be ground according to the invention eliminates the need to use different guide sleeves depending on the diameter of the tool to be ground, and thus to have to hold many individual parts. Also, when changing to another tool to be ground, for example with a different diameter, the grinding machine does not necessarily have to be converted in a time-consuming manner.

Usually, the tool to be ground is guided according to the invention at the at least two adjacent circumferential points in the guide path of the steady rest and is pressed against the side surfaces by the grinding forces, for example by a grinding wheel, which results in particularly good guidance since the grinding pressure over the at least two circumferential points affects the guideway. The direction of force of the grinding pressure is thus divided into partial forces in the direction of at least two circumferential points of the tool to be ground, in particular in the form of a parallelogram of forces, which is determined by the geometry and thus by the position of these points. According to the invention, it can now be particularly advantageous that the grinding device also has, in addition to the guideway, a tensioning lever which can be pivoted in the direction of the guideway in order to press or tension the tool to be ground. In this way, for example, in the face machining of grooved tools, in particular spiral-grooved twist drills, the tool to be ground is guided in a particularly safe and, in this case, play-free manner.

It should be noted that the length of the guideway and, accordingly, the length of the tensioning lever correspond at least to the length of a slope of a groove helix of the tool to be ground. This is particularly advantageous since it ensures that there is essentially always at least part of the circular envelope of the tool to be ground for abutment with at least two circumferential points on the side surfaces.

Of course, the steady rest including the guideway and the clamping lever, but also the guideway and / or the clamping lever, for use in the manufacture of extra-long tools, in particular twist drills, can be movable in the axial direction of the tool to be ground, so that it can be used in the area of the respective grinding work the tool to be ground always guarantee optimal support and guidance.

It is particularly advantageous that the position of the steady rest and / or the guideway, of course possibly also the position of the clamping lever, can also be set as a function of the diameter of the tool to be ground, the position of the longitudinal axis of the tool to be ground being predetermined and being different can result in particular from the geometry of the grinding machine used with the corresponding grinding units. This enables a particularly flexible, fast and precise manufacture of the tools to be ground, which requires little changeover effort. This advantage is particularly preferably also given in that the guideway can be adapted as a function of the diameter of the tool to be ground. In particular, it can be advantageous to design the guideway for tools of larger or smaller diameter to be ground, in particular in the event of large jumps in diameter between individual tool batches to be produced. It can also be particularly preferred to make the angle changeable for adaptation, for example by providing an adjustment mechanism. This also increases the flexibility of the device while at the same time maintaining the good and exact guidance of the tools to be ground.

An angle of 90 ° is preferred, but in principle essentially everyone is

Angles smaller than 180 ° are possible.

The guideway is preferably made of HSS (high-performance high-speed steel). The tension lever can also be made of HSS.

Furthermore, in a further preferred embodiment of the device, it is advantageous to make at least the surface of the guideway and / or the surface of the clamping lever, in particular the part of the clamping lever which comes into contact with the workpiece to be ground in the event of being pressed on, from hard metal. It is e.g. possible to make this hard metal version in the form of strips which are attached to the corresponding surface of the guideway or the tensioning lever.

For grinding, in particular tools made of hard metal, the surface of the guideway and at least the surface of the clamping lever can also consist of polycrystalline diamond (PCD). Through the suitable choice of material for the execution of the guideway and / or the clamping lever, it is possible to ensure safe guidance in coordination with the material of the tool to be ground, in particular without the risk of the tool to be ground running in the area of its adjacent circumferential points Guideway and / or the tension lever. Nevertheless, and precisely because of this, the costs for the device according to the invention can be kept as low as possible.

In general, the device can be provided for grinding tools made of HSS and / or for grinding tools made of hard metal. In the case of tools which are made from HSS, corundum grinding wheels and / or CBN grinding wheels can preferably be used. In the event that hard metal tools are ground, diamond grinding wheels can preferably be used as the abrasive.

The method for grinding according to the invention relates to the production of grooved tools which have an essentially circular envelope curve, in particular to the grinding of helically grooved tools by means of grinding wheels. Twist drills can be ground, but corresponding other tools, such as milling cutters, drills in general and possibly reamers, can also be ground.

In the method for grinding twist drills, the tool to be ground is clamped according to the invention in such a way that a steady rest with a guide track with at least two inner side surfaces, each of which runs in planes essentially parallel to the longitudinal axis of the tool to be ground and an angle for receiving the include a grinding tool, in particular a steady rest with a guideway according to claim 1, the tool to be ground at least at two circumferential points, each of which abuts at least two of the inner side surfaces of the guideway, leads. The tool to be ground is pressed according to the invention by means of at least one grinding wheel when grinding the grooves into the guideway.

If a back of the tool to be ground is ground, it is preferred in this case also that the tool to be ground is pressed into the guideway during grinding.

For particularly reliable guidance of the tool to be ground, when grinding face edges and / or in the case of grinding the end face of the tool in general, the tool to be ground is additionally pressed into the guideway with a clamping lever.

It is particularly preferred to grind the tool to be ground, in particular face cuts, grooves and possibly back of the tool, in one setting.

The invention is explained below using an embodiment with reference to the accompanying drawings. It shows

Figure 1 is a plan view of a grinding machine with a device according to an embodiment of the invention.

Figure 2 is a section on the line B-B of Figure 1; and

3 to 6 in cross section an embodiment of the device, various working steps of the method according to the invention are shown using the example of grinding a twist drill.

1 shows a top view of a grinding machine and device for grinding grooved tools in one embodiment of the invention. The grinding machine is made up of the following main groups: the machine stand 1, the grinding headstock 2 with swiveling grinding spindle unit 3 and with an HF grinding spindle 4, the grinding table 5 with a workpiece headstock 6, the steady rest with the guideway 8, and the dressing device 9.

A grinding headstock 2, which can be moved by means of a CNC axis (X axis), is mounted on the machine stand 1 in the rear area. Furthermore, the height of the grinding spindle unit 3, which can be pivoted about an axis (A axis), can be moved vertically along an axis (Y axis). In the front area of the machine stand 1, the grinding table 5 is built on guides (not shown), which can be moved in the direction of an axis (Z axis). The workpiece headstock 6, which is equipped with a collet head 61, is built up on the grinding table 5. The collet head 61 is accommodated on a quill which is driven in rotation about a CNC axis (C axis). According to the invention, the steady rest with the guideway 8 is constructed to support the tool to be ground on the grinding table 5. Furthermore, the dressing device 9 is arranged on the grinding table 5 with a rotationally driven diamond wheel 91 for dressing the grinding wheels used. All axes mentioned are designed as CNC axes.

FIG. 2 shows a section along the line B-B of FIG. 1. The HF grinding spindle 4 is shown pivoted upward about 90 ° about the A axis, contrary to the illustration in FIG. 1. As in FIG. 1, the X, Y and A axes are each drawn in and represented symbolically.

The HF grinding spindle 4 is firmly connected to the swiveling grinding spindle unit 3. The grinding wheels 41, 42, 43 are accommodated in the front area of the HF grinding spindle 4, the HF grinding spindle 4 being designed such that both corundum, CBN or diamond grinding wheels are used can be included. For grinding tools made from HSS steel, either CBN or corundum grinding wheels are predominantly used as abrasives. Diamond grinding wheels are preferably used for grinding hard metal (HM).

In the front area of the machine stand 1, the grinding table 5 is shown, on which the steady rest is fastened with the guideway 8. To guide and support the tool 10 to be ground, this lies against the circumference of the guide track of the bezel 8. To grind end cutting edges, for example by means of a conical surface grinding, the clamping lever 83 is pivoted in the direction of the guideway in order to better guide the tool 10. To adjust the position depending on the diameter of the tool to be ground, the steady rest and / or the guideway can be manually adjusted in the direction of arrow 85.

3 to 6, the structure of the device according to the invention, in particular the steady rest, with the guideway 8 is shown in cross section or in plan view from the end face of the tool to be ground, and the advantageous use of the device is illustrated by the method according to the invention using the example the grinding of twist drills explained in more detail. For this purpose, the structure of the bezel in the clamping area is shown in FIGS. 3 to 6.

The tool 10 to be ground is a twist drill in the present case. The twist drill to be ground is in the workpiece headstock 6 by means of. a collet clamped at one end of the shaft. The clamping there serves only to transmit torque, the guidance is achieved through the bezel with the guideway. For this purpose, the shank of the tool 10 to be ground which projects freely from the collet is supported on the guideway 8. The tool 10 is supported via its free shaft length on the lateral surface 11 or the circumference of the essentially circular envelope curve on at least two circumferential points of the envelope of the tool 10 to be ground on at least white inner side surfaces of the guideway, which in the exemplary embodiment according to FIGS. 3 to 6 essentially has a prism shape as a cross section. The system at two circumferential points forms a “play-free” guidance of the tool 10 to be ground. The guideway can consist of HSS or can be equipped with hard metal strips or PCD strips. As already described for FIG. 2, even better guidance and pressing can be carried out of the tool 10 to be ground can be achieved in that, if the grinding wheel does not work in the corresponding area, a clamping lever 83 is pivoted in this area, so that the tool to be ground between three circumferential points, seen in cross section in the form of a triangle around the Scope of the tool to be ground are arranged distributed, can be guided or clamped without play.

In contrast, when guiding the tool to be ground in a sleeve according to the prior art, there is always a certain play of approx. 0.01-0.02 mm between the inside of the sleeve and the tool to be ground in this sleeve, so that Tool lies at a single point or along its length linearly on the inside of the sleeve. This point of contact or this line of contact and their direction is directly related to the direction of grinding and he or she will always be on the opposite side of the loop engagement, since the force is straight from there at the corresponding point or line against the leading sleeve supports. In a sleeve according to the prior art, the tool to be ground is therefore only supported to a limited extent and only guided at one point. The radial force is accepted as a geometry error. The service life of the tool that processes the tool that is actually to be ground is also reduced by the fact that the tool to be ground is not clamped and guided 100%. Fig. 3 shows how a tool to be ground according to the invention is clamped and guided with its pivoted lever 83 over its shaft length. The linear systems are represented by points A1, A12 and A13. The radial rotation of the tool 10 to be ground takes place during machining through the C-axis of the workpiece headstock 6. The tool 10 to be ground is clamped by means of the collet 61. This must be exactly aligned with the guideway. The length of the guideway is determined by the length of the tool to be ground, the shape of the groove, the length of the groove and the pitch of the coiled grooves. The groove pitch has the influence that at least one complete groove helix must be covered by the length of the guideway. However, it is possible to design the steady rest with the guideway and / or the clamping lever so that it can also be displaced in the direction of the longitudinal axis of the tool to be ground, in order to enable the machining of excessively long twist drills or generally excessively grooved tools.

In the clamping according to FIG. 3, the frontal cutting edges of a twist drill can be ground, for example, in a conical surface by means of the grinding wheel 41.

4 shows the guideway of the steady rest 8 with the tensioning lever 83 open (not shown), the cutting forces applied by the grinding wheel pressing the workpiece 10 to be grinded against the guideway on two contact lines in the flute grinding shown. This guarantees a safe and play-free position of the tool to be ground during grinding, even without the clamping lever 83. In the present case, grinding is carried out by means of the grinding wheel 43, which is pivoted according to the pitch angle of the grooves to be ground to the position of the longitudinal axis 11 of the tool to be ground. 5 shows the grinding of the back of a twist drill, the processing being carried out by means of the grinding wheel 41. The position of the central axis of the HF grinding spindle 4 is preferably axially parallel to the longitudinal axis of the tool 10 to be ground.

6 shows the sharpening of the transverse cutting edge of the tool to be ground, in this case the twist drill 10, this working step being carried out with the grinding wheel 42. The machining is carried out on the end face or tip of the twist drill so that the clamping lever 83 is pivoted in again for clamping the tool to be ground.

All of the work steps shown in FIGS. 3 to 6 are only indicated schematically and the machining is illustrated by the lines in a top view of the end face of the tool or twist drill to be ground. The essentially circular envelope of the tool can also be seen. The work steps are all done in one setup.

Claims

claims

1. Device for grinding grooved tools with an essentially circular envelope, in particular helical grooved

Tools, by means of grinding wheels, characterized in that a steady rest for guiding the tool to be ground has a guide track (8) with at least two inner side surfaces, each in planes essentially parallel to the longitudinal axis of the tool to be ground

Tool (10) run and enclose an angle for receiving the tool to be ground, the tool to be ground at least with two circumferential points (Al l, AI 2) of the substantially circular outer curve in each case at least on two of the inner side surfaces of the guide track (8) ,

2. Device according to claim 1, characterized in that a clamping lever (83) for pressing the tool to be ground (10) in the direction of the guide track (8) can be pivoted.

3. Anspnich 1 or 2, characterized in that the position of the bezel and / or the guide track (8) depending on the diameter of the tool to be ground (10) with respect to the position of the longitudinal axis of the tool to be ground is adjustable.

4. Device according to one of claims 1 to 3, characterized in that the angle is variable depending on the diameter of the tool to be ground (10).

5. Device according to one of claims 1 to 4, characterized in that the device for grinding tools (10) is made of HSS.

6. Device according to one of claims 1 to 5, characterized in that the device for grinding tools (10) is made of hard metal.

7. Device according to one of claims 1 to 6, characterized in that the guide track (8) consists of HSS.

8. Device according to one of claims 2 to 7, characterized in that the clamping lever (83) consists of HSS.

9. Device according to one of claims 1 to 8, characterized in that the guide track (8) has at least one surface made of hard metal.

10. Device according to one of claims 2 to 9, characterized in that the clamping lever (83) has at least one surface made of hard metal.

1 1. Device according to one of claims 1 to 8, characterized in that the guide track (8) from at least one surface. polycrystalline

Diamond (PKD).

12. The device according to one of claims 2 to 8 or according to claim 1 1, characterized in that the clamping lever (83) has at least one surface made of polycrystalline diamond (PCD).

13. Device according to one of claims 5 to 12, characterized in that the grinding wheels are corundum grinding wheels.

14. Device according to one of claims 5 to 12, characterized in that the grinding wheels are CBN grinding wheels.

15. The device according to one of claims 6 to 12, characterized in that the grinding wheels are diamond grinding wheels.

16. A method for grinding grooved tools with a substantially circular envelope, in particular helical grooved tools, which are clamped in such a way that a steady rest with a guideway which has at least two inner side surfaces, each in planes substantially parallel to the longitudinal axis of the Grinding tool run and enclose an angle to accommodate the tool to be ground, the tool to be ground at least at two circumferential points, each of which abuts at least two of the inner side surfaces of the guideway, and the tool to be ground by means of at least one grinding wheel when grinding the grooves is pressed into the guideway.

17. The method according to claim 16, wherein the tool to be ground is pressed into the guideway by at least one grinding wheel when grinding the back.

18. The method according to any one of claims 16 or 17, wherein when grinding end cutting edges, the tool to be ground is additionally pressed into the guideway with a clamping lever.

9. The method according to claim 18, characterized in that face cutting, grooves and backs are ground in one step.