US2247994A - Lapping machine - Google Patents

Description

July 1, 1941.

v v i 1 mm I M. e. FI EDLER LAPPING MACHINE P Filed June 15, 1940 l'mm rum [7 .c--.

Patented July 1, 1941 PTEN LFE'EQE.

LAPPING MACHINE Application June 13, 1940, Serial No. 340.353

2 Glaims. (Cl. 51-429) This invention relates to lapping machines and, more particularly, to a means for lapping the conical or frusto-conical faces of articles which have cylindrical body portions as, for example, the valve elements of the fuel injection nozzles of solid fuel injection apparatus for internal combustion engines.

Many such articles include both a cylindrical portion which must be kept within very close tolerances and an angular face or seat-engaging element which must be as accurately surfaced due to the extremely high pressures at which the finished product must seal against the fluids with which it is employed.

An important object of this invention is the provision of an apparatus for lapping the angular faces of such articles without damage to the cylindrical surface and which at the same time employs a lapping element the angle of which may be very rapidly and accurately adjusted.

Another object of the invention is the provision of apparatus of this character in which the insertion and removal of thearticles to be lapped is facilitated, and in which the type of drive employed is such that the article itself becomes an element therein.

These and other objects I attain by the construction shown in the accompanying drawing wherein, for the purpose of illustration, I have shown a preferred embodiment of my invention and wherein:

Fig. 1 is a side elevation of lapping apparatus constructed in accordance with my invention, the dotted lines indicating an adjustment of the lapping tool; and

Fig. 2 is a section on line 2--2 of Fig. 1.

Referring now more particularly to the drawing, the numeral It] indicates a base adapted to be rigidly secured to a structure II which is preferably smooth-surfaced throughout. Arising from the base is a support comprising a pair of spaced standards I2 and I3 between which a rotatable unit [4 is mounted and is at present shown as including a pair of pulleys l5 and it. One of the standards, at present shown as the standard l3, has its upper end formed with an upwardly opening V groove ll of sufficient length to adequately support the cylindrical portion iii of the article to be lapped. In alignment with the pulley IS the upper portion of the standard I3 is slotted as at l9 to permit a belt to be passed about pulley l6 and the cylindrical portion l8 of the article. This belt can be, and preferably is, resilient and may constitute simply a rubber band in the case of light articles such as the valve stems hereinbefore specifically referred to. The other of the standards, I2, has a T to be lapped opposite that at which the conical face 23, which is to be the actual subject of the lapping operation, is disposed. The standard [3 preferably mounts a pivoted arm 24 which, through a spring 25 engages the article and constantly maintains engagement between bearing 22 and the seat 25.

Pivoted to the base ii! as at 25 is a leaf 2'! having a bearing support 28. This bearing support guides a rotatable shaft 29 the lower end of which mounts the lapping element 36. Secured to the upper end of shaft 29 is a pulley 3| the lower surface of which is abutted by a thrust bearing 32. A spring 33 surrounds the shaft between thrust bearing 1-52 and the upper surface of standard 28 and serves to urge the shaft upwardly and to tend to move lapping element toward the shoulder 34 on the under surface of the bearing support. This movement is limited in any suitable manner, as by means of a ring 35 secured to the shaft. The upper end of the shaft mounts a ball 36, and projecting upwardly from the bearing support is an arm 3'! the upper end of which has directed therethrough a screw 38 which is in axial alignment with the ball and the inner end of which engages the ball. Shaft 29 is rotated through the pulley 3| in any suitable manner. as by means of motor 39, while the unit M is driven through its pulley 15 as indicated by belt 49.

In use of the apparatus the article is disposed in the V notch with its cylindrical portion engaging therein, and its surface 23 which is to be ground in opposition to the surface of lapping element 36 which at that time will be withdrawn through retraction of the shaft by spring 33. The belt 20 is placed in position together with bearing 22 and the pressure-applying arm 24. Shaft 29 is then adjusted downwardly through screw 38 until the lapping device 39 comes into proper engagement with the surface 23. When, due to service, the lapping device becomes worn, or when, for any reason, it is desirable to change the angle of the working surface of the lapping device to that of the axis of the cylindrical portion ill of the article being lapped, this may be readily accomplished by means of adjusting screw M extending through the free end of leaf 2'! and engaging the supporting surface ll. After the adjustment has been perfected, it may be secured very readily removed and replaced and that a. very accurate adjustment of the lapping may be had while at the same time employing an eX-.

tremely simple and durable apparatus.

Since the construction is capable of considerable modification Without departing from the spirit of my invention, I do not wish to be understood as limiting myself thereto: except as hereinafter claimed.

I claim:

1. Means for lapping the conical faces of valve members having cylindrical. shanks, comprising a rest having a \f-shaped notch for the reception of the cylindrical shank of. the member, a bearing to engage the end of" the shank, a. shaft paralleling the notch, a standard. pivoted. to the rest in opposition to. the conical end. of a supported valve element, means to adiust: the standard about the pivot thereof, a second shaft rotat ably andv longitudinally adjustabl-y' mounted in.

the standard and bearing a lapping tool to en.-

gage said conical end, a spring to shift the sec- 0nd shaft in a direction withdrawing the lapping tool from the conical member, an adjustable stop engaging the shaft to determine the operative position thereof, means (to rotate said shafts and a frictional driving connection between the first-named shaft and the cylindrical portion of the valve member.

2. Means for lapping the conical faces of valve members having cylindrical shanks, comprising a..rest having a V-shaped notch for the reception of the cylindrical shank of the member, a bearing to engage the end of the shank, a shaft paralleling the notch, a standard pivoted to the rest in opposition to the conical end of a supported valve element, means to adjust the standard about the pivot thereof, a second shaft rotatably and longitudinally adjustably mounted in the standard and bearing a lapping tool to engage said conical end, a spring to shift the second shaft in a direction Withdrawing the lapping tool from the conical member, an adjustablestop engaging the shaft to determine the operative position thereof, means to rotate said shafts and a frictional driving connection between the firstnamed shaft and the cylindrical portion of the valve member, said driving connection including an elastic member under tension whereby to maintain the cylindrical portion of the member in position Within the notch.

MAX GEORGE FIEDLER.

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