Redressing of laps in lapping or honing machines

[57] ABSTRACT

The annular working surfaces of cast-iron laps in a two-lap lapping or honing machine are redressed by three or more redressing units each having an abrading ring surrounded by and secured to a gear which constitutes the planet pinion of a planetary transmission. The redressing units can be used interchangeably with gear-shaped workholders and their rings remove material from the working surfaces when the gears are rotated about their respective axes while the laps rotate in opposite directions.

Claims, 4 Drawing Figures

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PATENTEDMAY 16 1972

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PATENTED HAY 16 1972

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The redressing unit can be used interchangeably with gearshaped workholders for workpieces, i.e., the drive means may form that part of a lapping or honing machine which is provided mainly for the purpose of rotating the workholders.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanvine drawing. ^}

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic vertical sectional view of a vertical lapping machine which embodies the invention;

FIG. 2 is an enlarged horizontal sectional view taken along the line 11—11 of FIG. 1 and showing three gear-shaped workholders;

FIG. 3 is a similar horizontal sectional view but showing three redressing units; and

FIG. 4 is a vertical sectional view taken alone the line IV— IV of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1, there is shown a vertical lapping machine with annular cast-iron laps 1 and 11. The lower lap 1 is attached to a coaxial disk-shaped carrier 2 which is rigid with a hollow vertical shaft 3. The latter is connected with a pulley 4 which is driven by a pulley 6 by way of an endless belt 5. The pulley 6 is driven by a transmission 7 which receives torque from the output member of an electric motor 8 mounted in the frame 22 of the lapping machine. The transmission 7 comprises two mating gears.

The upper lap 11 is affixed to a coaxial disk-shaped carrier 12 which is connected with a vertical shaft 13. The latter is driven by a pulley 14 which is rotated by a pulley 16 by way of an endless belt 15.The pulley 16is driven by a transmission 17 which also receives torque from the motor 8. The transmission 17 includes three mating gears so that the shafts 3, 13 (and hence the laps 1, 11) rotate in opposite directions when the circuit of the motor 8 is completed.

A vertical drive shaft 9 extends axially through the hollow shaft 3 and its lower end carries a pulley driven by a second pulley on the output shaft of a reversible variable-speed electric motor 18. The two pulleys are connected to each other by means of an endless belt 10. Theupper end of the shaft 9 carries a disk 19 which is provided with an annulus of equidistant upwardly extending vertical pins 20 (see also FIG. 2) so that the parts 19,20 together form a gear which is the sun gear of a planetary transmission further including a stationary ring gear ₅₅ having a ring 21 fixedly mounted in the frame 22 and an annulus of pins 23 which extend upwardly from the ring 21. The distance between the pins 23 is the same as that between the pins 20. The ring 21 surrounds the lower lap 1 and the diameter of the disk 19 is less than the internal diameters of annular

FIG. 2 shows several workpieces 24 which can be treated by the working surfaces of the laps 1 and 11 when the machine of FIG. 1 is in use. These workpieces are inserted into holes 25 provided in gear-shaped workholders or adaptors 26 whose 65 teeth 27 mate with the pins 20 and 23. Thus, the workholders 26 constitute the planet pinions of the planetary transmission and are set in rotary motion about their own axes as well as in orbital motion about the axis of the shaft 9 when the motor 8 drives the shafts 3,13 while the motor 18 drives the shaft 9. In 70 FIG. 2, the workpieces 24 are of prismatic shape and the configuration of holes 25 in the workholders 26 is of similar outline.

When the motor 8 is on to rotate the laps 1, 11 in opposite directions and the workholders 26 are located between the 75 two laps, the motor 18 is started to rotate the shaft 9 and the

REDRESSING OF LAPS IN LAPPING OR HONING MACHINES

BACKGROUND OF THE INVENTION

The present invention relates to lapping or honing machines in general, and more particularly to improvements in preparation and redressing of laps in two-lap lapping or honing machines. Still more particularly, the invention relates to improvements in devices which can be utilized for redressing of flat, concave, convex and/or otherwise configurated working surfaces of laps consisting of cast-iron or the like and serving for forming lapping or equalizing lapping of flat, rounded and/or other surfaces of workpieces.

It is known to redress the working surfaces of cast-iron laps in lapping or honing machines by resorting to turning or analogous tools including diamonds, steel bits or the like. It is also known to redress by “lapping the laps”, i.e., by offsetting the upper spindle from the lower and by driving one of the laps while its working surface engages the working surface of the other lap which is free to rotate. A drawback of the first method is that the redressing consumes much time and that, subsequent to material removal by means of a bit or diamond, the thus treated working surfaces must be subjected to a further treatment (such as superfinishing) in order to remove tool marks which develop during turning. Furthermore, turning of the upper lap (which is normally mounted in such a way that it can perform wobbling movements) necessitates the provision of special bearings which hold it against all other but rotary movements during removal of material from its working 30 surface.

Lapping of the laps can be resorted to only when the working surfaces should be flat and when the wear on the working surfaces prior to redressing is such that one surface resembles a funnel and the other surface resembles a roof or cone.

SUMMARY OF THE INVENTION

An object of the invention is to provide a two-lap lapping or honing machine with a novel redressing or preparing device which can impart to the working surfaces of the laps a desirable flat, concave or convex configuration and which is capable of completing the operation within a short period of time and in such a way that the laps are ready for renewed use without any additional treatment of their working surfaces.

Another object of the invention is to provide a lapping or honing machine wherein the redressing device comprises certain parts which can serve other useful purposes, particularly to engage and to move the workholders in the course of a lapping or honing operation.

A further object of the invention is to provide a device which can redress the laps irrespective of the nature of wear to which the working surfaces were subjected during the preceding use of the machine.

The invention is embodied in a lapping or honing machine of the type wherein two laps are rotatable with reference to each other and include adjacent but spaced preferably annular working surfaces. The device for preparing and redressing the working surfaces of the laps comprises at least one rotary ____________________________w , redressing unit (but preferably at least three redressing units) 60 working surfaces on the laps 1 and 11. having a pair of material removing surfaces and being insertable between the laps so that each of its surfaces engages one of the working surfaces, and drive means for rotating the redressing unit about its own axis while the laps rotate with reference to each other so that the surfaces of the redressing unit remove material from the working surfaces while the unit rotates.

The redressing unit preferably includes a gear which constitutes the planet pinion of a planetary transmission having two additional gears which form part of the drive means. One of the additional gears is preferably stationary and the other additional gear is preferably driven by a reversible variablespeed motor to constitute a sun gear which causes the gear of the redressing unit to rotate about its own axis and to simultaneously orbit about the common axis of the laps.

3,662,498 sun gear 19, 20. As a rule, the laps 1, 11 are rotated at the same speed or at substantially identical speeds. The rotating sun gear 19, 20 causes the workholders 26 to rotate about their own axes with reference to the stationary ring gear 21, 23 whereby the workholders 26 travel slowly about the sun gear and move the workpieces 24 with reference to the frame 22.

In accordance with the present invention, the redressing of laps 1,11 is carried out in a manner as shown in FIGS. 3 and 4. The workholders 26 are then replaced by at least three redressing units having rings or gears 28 which are provided with external teeth 29 mating with the pins 23 on the fixed ring 21 and with the pins 20 of the rotary disk 19. Thus, the rings 28 can be rotated and orbited in the same way as the workholders 26. Each of these rings accommodates a redressing or abrading wheel or ring 30 which is non-rotatably secured thereto by one or more keys 31 or similar coupling means. The two material removing surfaces of each abrading ring 30 abut against the adjacent working surfaces of the laps 1 and 11, i.e., all of the rings 30 have the same axial length. As shown in FIG. 4, the height of each ring 30 exceeds the height of the corresponding ring gear 28. Also, the internal diameters of the rings 30 exceed at least slightly the width (as seen in radial direction) of working surfaces on the laps 1 and 11. FIG. 4 shows clearly that the space surrounded by the cylindrical internal surface of each ring 30 extends radially inwardly as well as outwardly beyond the cylindrical internal and external surfaces of the laps 1 and 11.

The rotational speed and/or the direction of rotation of the abrading rings 30 are preferably variable (by employing a reversible motor 18) to thereby regulate the removal of material from the working surfaces of the laps 1 and 11. Such material removal in turn depends on the nature of wear on the working surfaces of the laps. The redressing operation is carried out in such a way that the relative speed between the abrading rings 30 and the lap 1 or 11 is relatively high when the rings 30 engage those portions of the working surfaces from which they should remove substantial quantities of material. When the machine is used for lapping of workpieces of the type shown in FIG. 2, the wear on the working surfaces of the laps 1, 11 is normally such that a portion of the surface on the lap 1 which was subjected to substantial wear is located opposite a portion of the surface on the lap 11 which was subjected to lesser wear, and vice versa. Analogously, when the outer zone of the working surface on the lap 1 or 11 was subjected to greater wear, the radially innermost zone of the working surface on the lap 11 or 1 was subjected to lesser wear. Since the laps 1, II rotate in opposite directions when their working surfaces undergo a redressing treatment, the relative speed between the abrading rings 30 and one of the laps 1, 11 is the sum of the speeds of a ring 30 and the one lap whereas the relative speed between the rings 30 and the other lap equals the difference of the speeds of a ring 30 and the other lap; this is obvious since the laps 1,11 rotate in opposite directions. The rate at which the abrading rings 30 remove material from the working surfaces depends on such relative speed which, in turn, can be readily varied and maintained by changing the direction of rotation and/or the speed of the motor 18. In this way, the operator can treat the working sur4 faces to a desired finish in a continuous operation without necessitating any additional treatment which is essential when the laps are redressed in accordance with certain presently known procedures. The just described mode of redressing can 5 be used to provide the laps 1,11 with flat, concave or convex working surfaces. For example, one of the working surfaces can be slightly concave and the other working surface can be of slightly convex outline.

It will be seen that the parts 9, 10, 18-20, 21 and 23 10 together constitute a drive of the redressing device which further includes the redressing units 28-31 and that such drive serves the additional (main) purpose of rotating the workholders 26 which are used interchangeably with the redressing units. Though FIG. 3 shows only three redressing units, it is 15 clear that the machine may employ four or even more such units in order to insure rapid and accurate redressing of working surfaces on the laps.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying 20 current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art.