Grinding tool

Abstract

A grinding tool for machining an inside surface of a cylinder bore in a workpiece, the grinding tool having an axis of rotation, a grinding region which is cylindrical with respect to the axis of rotation and a conical grinding region axially adjoining the cylindrical grinding region. A diameter of the conical grinding region increases starting from the cylindrical grinding region in an axial direction with respect to a diameter of the cylindrical grinding region.

Claims

1. A set comprising: a first grinding tool; and a second grinding tool, wherein: each of the first grinding tool and the second grinding tool is configured to machine an inside surface of a cylinder bore in a workpiece; each of the first grinding tool and the second grinding tool has an axis of rotation; the first grinding tool has a grinding region which is cylindrical with respect to the axis of rotation of the first grinding tool; the second grinding tool has a grinding region which is conical with respect to the axis of rotation of the second grinding tool; the first grinding tool and the second grinding tool are separate and distinct such that only one of the first grinding tool and the second grinding tool is configured to rotate at a time; a diameter of the grinding region of the second grinding tool increases in an axial direction of the second grinding tool starting from a smallest diameter of the grinding region of the second grinding tool which corresponds to a diameter of the grinding region of the first grinding tool which is separate and distinct from the second grinding tool; the second grinding tool has a free end and an opposite end, and the grinding region of the second grinding tool adjoins the free end on the second grinding tool; the second grinding tool includes a flange configured to fix the second grinding tool to: (i) a machining head of a CNC machine; or (ii) an adaptor connected to the machining head of the CNC machine; and the flange is formed at the opposite end of the second grinding tool.

2. The set as set forth in claim 1, wherein the second grinding tool also has a non-grinding region.

3. The set as set forth in claim 2, wherein the non-grinding region is cylindrical with respect to the axis of rotation of the second grinding tool.

4. The set as set forth in claim 1, wherein the grinding region of the second grinding tool has a taper angle, with respect to an axis parallel to the axis of rotation of the second grinding tool, of between 0.014 and 0.039.

5. The set as set forth in claim 1, wherein the grinding region of the first grinding tool is of a diameter of between 60 mm and 70 mm.

6. The set as set forth in claim 1, wherein the diameter of the grinding region of the second grinding tool increases in the axial direction of the second grinding tool over a length of the grinding region of the second grinding tool from the smallest diameter of the grinding region of the second grinding tool to a largest diameter of the grinding region of the second grinding tool; and a maximum difference between the smallest diameter of the grinding region of the second grinding tool and the largest diameter of the grinding region of the second grinding tool is between 50 m and 110 m.

7. The set as set forth in claim 1, wherein the grinding region of the first grinding tool and the grinding region of the second grinding tool are coated uniformly with a same grinding agent.

8. The set as set forth in claim 2, wherein a difference between the smallest diameter of the grinding region of the second grinding tool and a diameter of the non-grinding region of the second grinding tool is between 100 m and 600 m.

9. The set as set forth in claim 1, wherein the grinding region of the first grinding tool is of a length of between 40 mm and 60 mm, and the grinding region of the second grinding tool is of a length of between 80 mm and 100 mm.

10. The set as set forth in claim 1, wherein: the first grinding tool has a central bore parallel to the axis of rotation of the first grinding tool; and the second grinding tool has a central bore parallel to the axis of rotation of the second grinding tool.

11. The set as set forth in claim 10, further comprising: a plurality of passages extending between the central bore of the first grinding tool and the grinding region of the first grinding tool; and a plurality of passages extending between the central bore of the second grinding tool and the grinding region of the second grinding tool.

12. The set as set forth in claim 11, wherein: the plurality of passages of the first grinding tool is arranged in a spiral form; two adjacent passages of the plurality of passages of the first grinding tool are: (i) arranged such that an angle between the two adjacent passages of the plurality of passages of the first grinding tool is between 40 and 60; and (ii) spaced apart from each other in an axial direction of the first grinding tool by between 2 mm and 4 mm; the plurality of passages of the second grinding tool is arranged in a spiral form; and two adjacent passages of the plurality of passages of the second grinding tool are: (i) arranged such that an angle between the two adjacent passages of the plurality of passages of the second grinding tool is between 40 and 60; and (ii) spaced apart from each other in the axial direction of the second grinding tool by between 2 mm and 4 mm.

13. The set as set forth in claim 1, wherein the flange includes at least one opening configured to receive a screw.

14. A CNC machine comprising: a first grinding tool; a second grinding tool; and a control program, wherein: each of the first grinding tool and the second grinding tool is configured to machine an inside surface of a cylinder bore in a workpiece; each of the first grinding tool and the second grinding tool has an axis of rotation; the first grinding tool has a grinding region which is cylindrical with respect to the axis of rotation of the first grinding tool; the second grinding tool has a grinding region which is conical with respect to the axis of rotation of the second grinding tool; the first grinding tool and the second grinding tool are separate and distinct such that only one of the first grinding tool and the second grinding tool is configured to rotate at a time; a diameter of the grinding region of the second grinding tool increases in an axial direction of the second grinding tool starting from a smallest diameter of the grinding region of the second grinding tool which corresponds to a diameter of the grinding region of the first grinding tool which is separate and distinct from the second grinding tool; the second grinding tool has a free end and an opposite end, and the grinding region of the second grinding tool adjoins the free end on the second grinding tool; the second grinding tool includes a flange configured to fix the second grinding tool to: (i) a machining head of a CNC machine; or (ii) an adaptor connected to the machining head of the CNC machine; the flange is formed at the opposite end of the second grinding tool; and the control program is adapted to: introduce at least one of the first grinding tool and the second grinding tool into the cylinder bore in the workpiece; move the at least one of the first grinding tool and the second grinding tool to the inside surface of the cylinder bore in the workpiece; guide the at least one of the first grinding tool and the second grinding tool at least once in a circle along the inside surface of the cylinder bore in the workpiece, in which case the at least one of the first grinding tool and the second grinding tool rotates about the axis of rotation of the at least one of the first grinding tool and the second grinding tool; lift the at least one of the first grinding tool and the second grinding tool off the inside surface of the cylinder bore in the workpiece; and move the at least one of the first grinding tool and the second grinding tool out of the cylinder bore in the workpiece again.

15. A set comprising: a first grinding tool; and a second grinding tool, wherein: each of the first grinding tool and the second grinding tool is configured to machine an inside surface of a cylinder bore in a workpiece; each of the first grinding tool and the second grinding tool has an axis of rotation; the first grinding tool has a grinding region which is cylindrical with respect to the axis of rotation of the first grinding tool; the second grinding tool has a grinding region which is conical with respect to the axis of rotation of the second grinding tool; the first grinding tool and the second grinding tool are separate and distinct such that only one of the first grinding tool and the second grinding tool is configured to rotate at a time; a diameter of the grinding region of the second grinding tool increases in an axial direction of the second grinding tool starting from a smallest diameter of the grinding region of the second grinding tool which corresponds to a diameter of the grinding region of the first grinding tool which is separate and distinct from the second grinding tool; the first grinding tool has a central bore parallel to the axis of rotation of the first grinding tool; the second grinding tool has a central bore parallel to the axis of rotation of the second grinding tool; the first grinding tool includes a plurality of passages extending between the central bore of the first grinding tool and the grinding region of the first grinding tool; the first grinding tool includes grooves in the grinding region of the first grinding tool; the plurality of passages of the first grinding tool open into the grooves in the grinding region of the first grinding tool; the second grinding tool includes a plurality of passages extending between the central bore of the second grinding tool and the grinding region of the second grinding tool; the second grinding tool includes grooves in the grinding region of the second grinding tool; and the plurality of passages of the second grinding tool open into the grooves in the grinding region of the second grinding tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details and advantages of the present invention are described more fully hereinafter by means of the specific description with reference to the drawings in which:

(2) FIG. 1 shows a perspective view of the grinding tool according to a preferred embodiment,

(3) FIGS. 2A and 2B show a cross-sectional view of the grinding tool in the longitudinal direction,

(4) FIG. 3 shows a cross-sectional view through the conical grinding region of the grinding tool,

(5) FIG. 4 shows the combination of the grinding tool and an HSK adaptor,

(6) FIG. 5 is a view in principle to illustrate the cylindrical grinding region and an axially adjoining conical grinding region,

(7) FIGS. 6A through 6F show diagrammatic views of the machining process for the inside surface of a cylinder bore in a workpiece by means of the grinding tool according to the invention,

(8) FIGS. 7A and 7B show the first grinding tool of the set according to the invention in a preferred embodiment, more specifically as a side view with adaptor (FIG. 7A) and as a cross-sectional view (FIG. 7B), and

(9) FIGS. 8A and 8B show the second grinding tool of the set according to the invention in a preferred embodiment, more specifically as a side view with adaptor (FIG. 8A) and as a cross-sectional view (FIG. 8B).

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 is a diagrammatic perspective view of the grinding tool 1 according to the invention in a preferred embodiment. It is of a substantially rotationally symmetrical configuration about an axis of rotation 4 extending in the longitudinal direction 26. The grinding tool 1 has a free end 14 and an opposite end 15 at which there is provided a fixing means 16 in the form of a flange for fixing the grinding tool 1 to a machining head of a CNC machine or an adaptor connected thereto (see FIG. 4). Provided in the fixing flange 16 are six openings 24 respectively displaced through 60 for receiving screws.

(11) The grinding tool 1 has a main body 11 of steel which includes the fixing flange 16 and a component which projects therefrom and at the peripheral surface of which are arranged a grinding region 5 which is cylindrical with respect to the axis of rotation 4 and adjoining same a conical grinding region 6. In this case the cylindrical grinding region 5 is arranged adjacent to the fixing means 16 and the conical grinding region 6 is arranged adjacent to the free end 14 of the grinding tool 1. The transition between the cylindrical and the conical grinding regions 5 and 6 is indicated by means of a dotted line. The cylindrical grinding region 5 and the conical grinding region 6 are uniformly covered with the same grinding agent, namely CBN (cubic boron nitride). The coating is produced galvanically. Arranged in the working region are a total of seven grooves 23 which extend over the cylindrical grinding region 5 and the conical grinding region 6 and substantially in the longitudinal direction 26 of the grinding tool 1. Opening into those grooves 23 are passages 21 which are of a diameter of 2 mm. In total there are 42 such passages 21, the passages 21 being arranged in a spiral shape, more specifically such that each two adjacent passages 21 are rotated through an angle of 50 and are axially displaced by 3 mm.

(12) FIGS. 2A and 2B show cross-sectional views of the grinding tool along a central section plane parallel to the axis of rotation 4 or the longitudinal direction 26. In that respect FIG. 2A shows the section as a perspective view and FIG. 2B shows the same section viewed from a direction perpendicular to the cross-sectional plane.

(13) It can be seen from these views that the grinding tool 1 further has a central bore 18 parallel to the axis of rotation 4, the bore 18 being of a diameter 19 of 12 mm and a length 20 of 170 mm. Extending between the bore 18 and the cylindrical grinding region 5 and the conical grinding region 6 are the passages 21 which, as already described, open into the grooves 23. The bore 18, the passages 21 and the grooves 23 overall form a coolant guide system which makes it possible for a centrally fed coolant to be efficiently passed on to the working region, that is to say the cylindrical grinding region 5 and the conical region 6, and to be distributed there.

(14) In the specific embodiment shown by way of example the grinding tool 1 is of the following dimensions: the cylindrical grinding region 5 is of a diameter 8 of 65 mm. The diameter 7 of the conical grinding region 6 increases over the length 9 of the conical grinding region in the axial direction 26 by 80 m with respect to the diameter 8 of the cylindrical grinding region 5. In that case the cylindrical grinding region 5 is of a length 13 of 50 mm and the conical grinding region 6 is of a length 9 of 90 mm. The thickness of the cylindrical and the conical grinding regions is 300 m.

(15) Those dimensions are respectively adapted to the workpiece to be ground (engine block). It is important in that respect that the overall length of the cylindrical and the conical grinding regions at least corresponds to the depth of the cylinder bore so that the grinding operation can be effected in one working step without the grinding tool having to be displaced in the direction of the depth of the cylinder bore during the machining process.

(16) FIG. 3 shows a further cross-sectional view of the grinding tool 1 along a plane in which one of the passages 21 extends between the central bore 18 and one of the grooves 23.

(17) FIG. 4 shows the combination of a grinding tool 1 and a so-called HSK adaptor 17 which in a simple way makes it possible to fit the grinding tool 1 to a machining head of a CNC machine. The connection between the grinding tool 1 and the HSK adaptor 17 is made by way of six screws 25 which are disposed in the openings in the fixing flange 16 and which engage into threads on the adaptor 17. The CNC machine can be a usual three-axis machine.

(18) As the geometry of the cylindrical grinding region 5 and the adjoining conical grinding region 6 cannot be perceived with the naked eye on the grinding tool 1 according to the above-described embodiment that geometry is shown once again in exaggerated form to illustrate it in FIG. 5: the effective grinding region is composed of a cylindrical grinding region 5 of a length 13 and a diameter 8 and an adjoining conical grinding region 6 of a length 9 and a diameter 7 which, starting from the cylindrical grinding region 5, increases in the axial direction 26 with respect to the diameter 8 of the cylindrical grinding region 7. The overall increase in the diameter 7 of the conical grinding region 6 at the free end 14 corresponds to double the illustrated distance 10. The taper angle of the conical grinding region 6 is denoted by reference 32.

(19) The sequence of FIGS. 6A through 6F serves to illustrate an advantageous machining process for the inside surface 2 of a cylinder bore 3 in a workpiece, for example an engine block. The views are each shown diagrammatically perpendicularly to the cylinder bore, more specifically from the side which is opposite the side from which the grinding tool 1, 27 or 28 (see FIGS. 7A, 7B, 8A and 8B) is introduced into the bore. The view if therefore on to the free end of the grinding tool 1, 27 or 28.

(20) In a first step (transition from FIG. 6A to FIG. 6B) the grinding tool 1, 27 or 28 is introduced into the cylinder bore 3 substantially centrally and with the cylindrical and/or conical grinding region. The grinding tool 1, 27 or 28 is then moved to the inside surface 2 of the cylinder bore 3, as shown in FIG. 6C. After that the grinding tool 1, 27 or 28 is passed at least once in the circle along the inside surface 2 of the cylinder bore 3, in which case it rotates about its axis of rotation 4. It should be noted that the grinding tool 1, 27 or 28 can also already be caused to rotate prior to or after the actual grinding operation.

(21) After the grinding operation has been effected the grinding tool 1, 27 or 28 is lifted off the inside surface 2 of the cylinder bore 3 again, that is to say it is moved into a substantially central position in relation to the cylinder bore 3 (see FIG. 6E) and finally passed out of the cylinder bore 3 again (transition between FIG. 6E and FIG. 6F).

(22) FIG. 6D indicates by way of example by arrows a given direction of movement of the grinding tool 1, 27 or 28 along the inside surface 2 of the cylinder bore 3 and a given direction of rotation of the grinding tool 1, 27 or 28 about the axis of rotation 4. In principle both directions of rotation are possible for those respective movements.

(23) In general it should also be noted that this machining operation in the case of metallic workpieces can be effected both directly at the untreated surface and also at a coated, for example AWS-coated, surface. In this case AWS stands for arc wire spraying which is a special coating process with a wire which is converted into the plasma phase.

(24) FIGS. 7A, 7B, 8A and 8B show advantageous embodiments of the set according to the invention, wherein FIGS. 7A and 7B show the first grinding tool 27 and FIGS. 8A and 8B show the second grinding tool 28in FIGS. 7A and 8A in each case together with an adaptor 17 connected to a fixing means 16 in the form of a flange.

(25) The first grinding tool 27 has a grinding region 5 which is cylindrical with respect to the axis of rotation 4 and is of a diameter 8.

(26) The second grinding tool 28 has a grinding region 6 which is conical with respect to the axis of rotation 4, wherein the diameter 7 of the conical grinding region 6, starting from a smallest diameter 29 which corresponds to the diameter 8 of the cylindrical grinding region 5 of the first grinding tool 27, increases in the axial direction.

(27) Besides same the second grinding tool 28 has a grinding agent-free region 30. That is of a configuration which is cylindrical with respect to the axis of rotation 4, of a diameter 31 which is reduced by 3 mm with respect to the smallest diameter 29 of the conical grinding region 6.

(28) The length of the grinding agent-free region of the second grinding tool 28 corresponds to the length 13 of the cylindrical grinding region 5 of the first grinding tool 27.

(29) The overall length of the second grinding tool 28 corresponds to the overall length of the grinding tool 1 which has both the cylindrical grinding region 5 and also the conical grinding region 6.

(30) Both the first grinding tool 27 and also the second grinding tool 28 have a central bore 18 each extending approximately over the entire grinding tool 27 and 28 respectively. The length of the bore 18 is denoted by references 33 and 20 respectively.

(31) As in the case of the grinding tool 1 which has both the cylindrical grinding region 5 and also the conical grinding region 6 the first grinding tool 27 and the second grinding tool 28 of the set have passages 21 extending between the central bore 18 and the cylindrical grinding region 5 and the conical grinding region 6 respectively. There are no such passages 21 provided in the grinding agent-free region 30 of the second grinding tool 28.