CZ63097A3 - Method of machining spherical surface and apparatus for making the same - Google Patents

Abstract

The invention concerns the method of machining a spherical surface (41) of a sphere (4) on a stem (5) with the possibility of free spinning around the axis of the stem (5) and/or with the stem (5), during which the sphere is (4) pressed against the rotationally symmetric inner working surface (3) of the spinning tool (1) and the angles of the axes of the stem (5) and tool (1) are changed in relation to one another. The tool (1) is maintained in axial direction in an unchanging position and the spherical surface (41), pressed against the inner working surface (3) of the rotating tool (1), is worked under the disengaged line of the spherical surface (41) in one constant direction perpendicular to the axis of the stem of the spherical surface (41). The apparatus consists of the rotating tool (1) with rotationally symmetric inner working surface (3), on which the spherical surface (41) of the sphere (4), freely pivoted on the stem (5) and/or freely spinning with the stem (5), is engaged with the possibility of changing the mutual axial angles. The ratio of the radius (rB) of the spherical surface (41) to the radius of the curved inner working surface (3) of the tool (1) on the plane of the axis of this tool (1) ranges between 0 and 0.8.<IMAGE>

Description

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method of machining a ball surface of a ball on a shaft with free rotation about and / or together with the shaft, wherein the ball is pressed against the rotationally symmetrical inner working surface of the rotating tool. and tools. The invention further relates to an apparatus for carrying out this method, which consists of a rotating tool with a rotationally symmetrical inner working surface, on which the spherical surface of a ball mounted freely rotatable on the shaft and / or freely rotatable with said shaft abuts.

BACKGROUND OF THE INVENTION

The prior art uses grinding or honing the inner edge of a pot tool to process a spherical surface. The tool is clamped in the spindle of a dedicated grinding or honing machine and is movable along the spindle axis. The ball is rigidly guided against it either by gripping the shaft if provided, or by guiding it beyond the spherical surface - in double, guided by conical prismatic rollers. A disadvantage of the first method is the complicated and time consuming clamping of the shank due to the often small clamping space between the ball and the gripping site and due to the large diameter difference between the ball and the smaller shank, whose clamping surface is often conical. The disadvantage of the second method is the difficult and time-consuming adjustment of the center of the ball to the spindle axis due to the high accuracy required. In both methods, the disadvantage is the difficulty of cutting the tool into the engagement after dressing with dressing discs.

US-A-5,319,891 discloses a method and a tool for fine machining at least a portion of a spherical surface that is. The tool is machined by a tool having a working surface which has an explicitly equal radius of curvature to the machined spherical surface. There is described rotation of the workpiece about its axis, rotation of the tool about its axis, pressing the workpiece against the tool, and grinding the workpiece while positioning its axes such that they form an obtuse angle of less than 180 degrees. In one embodiment shown, the working surface is in the form of a spherical canopy and is apparently abrasive in all cases. The disadvantage of this solution is that for a given radius of the ground ball surface, a tool with a working surface with the same radius of curvature must always be used. It is not possible to speak about self-centering and the grinding process itself is not optimal either, because the solution has the inevitable tendency to seize surfaces. The grinding efficiency is further reduced by the unresolved removal of the abraded material and particles of the released or consumed abrasive.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and a device corresponding thereto which makes it possible to substantially simplify existing technologies and thus to reduce the cost of both machinery and machining.

SUMMARY OF THE INVENTION

This object is solved and the drawbacks of known methods and apparatus of this kind largely eliminate the method of machining the surface of the spherical surface of the ball on the shaft with the possibility of free rotation about the axis of the shaft and / or together with the shaft. of the rotating tool and the angle of the axes of the shaft and the tool relative to each other varies according to the invention.

I

The tool is held in the axial direction in an invariant position and the spherical surface is machined by the free working of the spherical surface in at least one direction perpendicular to the shaft axis of the spherical surface with pressure against the inner working surface of the rotating tool.

The principle of the device for carrying out this method, which consists of a rotating tool with a rotationally symmetrical inner working surface, on which the spherical surface of a ball mounted freely rotatable on the shaft and / or freely rotatable with the shaft rests The invention is characterized in that the ratio of the radius of this spherical surface to the radius of curvature of the inner working surface of the tool in the plane in which the tool axis lies is in the range of 0 to 0.8.

In practice, this means that the radius of curvature of the inner working surface of the tool is noticeably larger than the radius of the ground spherical surface, including if the radius of curvature of the internal working surface of the tool is infinite, as is the case of the conical inner working surface. It is even possible if the center of the curvature of the inner surface of the tool lies on the opposite side of the ground spherical surface, as is the case with a hyperboloid belt or canopy.

P.růběh. Thus, the curvature ... / of the inner working surface of the tool can be essentially arbitrary, subject to the above-mentioned condition, but for practical, in particular manufacturing reasons, it is advantageous if the inner working surface of the tool is frusto-conical or spherical, paraboloid, paraboloid , hyperboloid belt or hyperboloid canopy.

Said internal working 'flat' tool is provided with abrasive not on its part. Especially practical is the design, in i

4, wherein the inner working surface of the tool is provided, at least in part, with an abrasive applied to the abrasive strip arranged on the inner working surface. This solution makes it easy to renew the abrasive when it is worn or to replace the existing abrasive with another abrasive.

In order to further simplify the replacement or replacement of the abrasive, the solution is furthermore advantageous in that the inner working surface of the tool is provided at least in part with an abrasive applied to the abrasive tape, which is fastened to the inner working surface by inserting it into slits formed. in the axially outer edge of the tool.

Thus, the ball is machined by a tool clamped in a fixed, i.e. axially fixed, spindle and provided with an inner working surface of a generally conical shape into which the ball is guided so that the axes of the spindle and the ball shaft are parallel.

In a practical case, this may be the technology of machining the connecting rod outer balls of the piston rods for hydrostatic transducers, especially after hardening the surfaces of the complete piston by nitriding or cementation. The principle of the solution consists in that the complete piston, guided manually by the outer surface of the piston itself, is inserted into the inner conical bore of the grinding tool by means of the outer connecting rod ball, the grinding surface, i.e. the inner working surface. and .axis tools are mixed. By rotating the grinding tool, it is entrained and rotates with the tool, and due to the commonity of the two axes, the driving speeds in contact between the connecting rod ball and the tool cone are different so that the outer surfaces of the ball and tool are relative. By repeatedly changing the angle between the tool axis and the piston axis, these surfaces move relative to the entire surface of the ball, thereby varying the connecting rod.

- 5 • * to its overall grinding.

The advantage of the solution according to the invention is the automatic adjustment of the center of the ball to the spindle axis, simple guiding of the workpiece to the tool, easy change of the pressure between the tool and the workpiece, turning the workpiece by rotation and easy change of the grinding surface. Another important advantage is the fact that the tool is largely versatile, ie one tool can be used for grinding spherical surfaces of different radii, it is also substantially abrasive residues, better removal which brings increased

A significant advantage of the abraded material and the efficiency and speed of grinding.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention is further illustrated by the following non-limiting examples, which are described with reference to the accompanying drawings, in which:

FIG

FIG

FIG. 2a

Fig. 2b shows the relative position of the tool and the ball on the shaft during machining of the spherical surface, the shape of the tool when using abrasive applied directly to the inner working surface of the tool having a frusto-conical shape an embodiment of a tool with an inner working surface in the form of a parabblb;

_rrs * «» ·· ♦ * · P _r 9 · · * * * _yy - · · 9 »* *

Fig. 2c shows an alternative embodiment of a tool with an internal working surface in the form of a hyperboloid belt,

FIG. 3 shows, in axial section and front view, the shape of the tool using an abrasive applied to the abrasive strip and inserted into the tool.

DETAILED DESCRIPTION OF THE INVENTION

In the tool 1 clamped in the spindle 2 and rotating with the spindle 2 about a common axis, an inner working surface 3 is formed. Its dimensions are suitably chosen such that the ball 4 on the shaft 5, for example formed by a connecting rod connected to the piston 6 by a connection allowing rotation of the connecting rod within the piston 6, when supported by the working surface 3, supported on this working surface 3 not far from its axially outer edge 11. The thus formed assembly, i.e. the connecting rod representing the stem 5 and the piston 6 is guided manually beyond the outer surface 2 of the piston 6 so that the ball 4 on the shaft

5. with its surface supported on the inner working surface 2 of the tool 1, the centering of the ball 8 in the axis of the spindle 2 is adjusted automatically. By contacting the inner working surface 3 of the tool 2 with the surfaces of the ball 2 on the shaft 2, the piston 6 is guided so that the axis of the piston 2 and hence the shaft 2 and the axis of the spindle 2 and hence the tools 2 are parallel. 2 and the balls 2 are distances between the points of contact from the axis of the piston 2 different, as shown in FIG. 1, the contact points a and B the distance from the axis of the piston 2 are described by a radius r _a, r _B. The shaft 5 formed in the illustrated embodiment by means of a connecting rod which can rotate freely about its axis in the piston 2 is carried by the contact of the ball 2 ^{with the} inner working surface 2 of the tool 2 so that it rotates with the tool 2. relative to the axis of rotation, relative movement occurs between the ball 2 and • ·

Ι ·

The angle of inclination between the two axes, i.e. the spindle 2 and the shaft 5, changes continuously during the working process, so that all the points of the surface of the ball 4 gradually change. become the contact points A, B with the working surface 3 and thus the whole surface of the ball 4 is abraded.

In practice, the inner working surface 3 of the tool 1, with the shape shown in FIG. 2, is provided near its axially outer edge 11 with an abrasive strip 91 on which a suitable abrasion 9 with high wear resistance, for example, is applied. diamond dust or cubic boron nitride. The shape of the tool 1 shown in FIG. 3 is suitable for use with an abrasive applied on a resilient substrate, for example an emery cloth. The tool is provided at the axially outer edge 11 of its inner working surface 3 with notches 10 into which the abrasive strip 91 is inserted, which abuts against the inner working surface 3, the notches 10 being. held against movement and the abrasive surface points towards the ball to be machined ..

The principle of the invention has been described in an exemplary embodiment by means of a specific example of its use for grinding a ball 4 connected firmly to the end of the shaft 5, which in this case consists of a connecting rod rotatably mounted in the piston. However, it is obvious that the solution according to the invention can generally be used for machining spherical surfaces 41 for all parts which allow rotation of the machined ball 4 about an axis different to the axis of the tool 1, i.e. its spindle 2, with the possibility of ball rotation.

4 can also be achieved by guiding the workpiece with the machined spherical surface 41 in a suitable holder.

Specifically, this can be done so that the fifth shaft, on whose one end is fixedly arranged ball "j" e ^- their '-druhým- -koncem-- - clamped in a freely rotatable chuck which thus replaces the piston 6 _RRR · ·· # * · »rr" _rr 9 »Er * e ·« r _r - r 9 ♦ 9 · » 'r - - - -""e" * * »*"

- 8 described in connection with a specific example of the use of the solution. It must be ensured that the angle of the chuck axis to the spindle axis 2 can be varied.

Another practical possibility is that the ball 4 itself is already rotatable about its axis at the end of the shaft 5. Said chuck or piston 5 described in connection with a particular application can then be replaced by a non-rotatable shaft holder 5, and, as in the previous case, it must be possible to vary the amount of angle between the shaft axis 5 and the axis of the spindle 2.

Claims (9)

PATENT CLAIMS A method of machining a ball surface on a shaft with and free to rotate about and / or together with the shaft, wherein the ball is pressed against the rotationally symmetrical inner work surface of the rotating tool and the angle of the shaft and tool axes relative to each other characterized in that the tool (1) is held in the axial direction in a fixed position and the spherical surface (41) is pressed against the inner working surface (3) of the rotating tool (1) by at least guiding the spherical surface (41) at least one direction perpendicular to the shaft axis of the spherical surface (41). Method for carrying out the method according to claim 1, which comprises a rotating tool with a rotationally symmetrical inner working surface, on which the spherical surface of a ball mounted freely rotatable on the shaft and / or freely rotatable together with said shaft bears characterized in that the ratio of the radius (r ₃ ) of this spherical surface (41) to the radius of curvature of the inner working surface (3) of the tool (1) in the plane in which the axis of the tool (1) lies is in the range 0 to 0 , 8. Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) is frustoconical. Γ f f f f · · · · f f - 10 Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) is in the form of a spherical strip. Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) is in the form of a paraboloid strip. Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) has the shape of a paraboloid canopy. Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) is in the form of a hyperbicidal web. Device according to claim 2, characterized in that the inner working surface (3) of the tool (1) is in the form of a hyperboioid canopy. Apparatus according to at least one of claims 2 to 8, characterized in that the inner working surface (3) of the tool (1) is provided at least in part with an abrasive (9) applied to the abrasive strip (91) which is arranged. on this inner work surface (3). • · ♦ r * *. _rrr f. «« · * rc _r r »♦ e ř _r - <- r- r ·· -lilo. Device according to at least one of Claims 2 to 9, characterized in that the inner working surface (3) of the tool (1) is provided, at least in part, with an abrasive (9) applied to the abrasive strip (91) disposed thereon. an inner crimping surface (3) secured by insertion into slits (10:) which are formed in the axially outer edge (11) of the tool (i).