US2223638A - Buffing head - Google Patents

Description

- Dec. 3, 1940. E. G. PETERSON BUFFING HEAD Filed Oct. 5, 1936 2 Sheets-Sheet l 2 Sheets-Sheet 2 Dec. 3, 1940. E. e. PETERSON BUFFING HEAD Filed 001;. 5, 1936 Ill/I/I/l/m Patented Dec. 3, 1940 UNITED STATES PATENT OFFICE BUFFING HEAD Edward G. Peterson, Rockford, Ill. Application October 5, 1936, Serial No. 103,997

' 3 Claims. (c|. 15-230) This invention relates to bufllng devices, and has special reference to a bufllng head of improved characteristics. 7

An object of the invention is the provision of a bufling head having a highly resilient face capable of readily taking the surface configuration of the work, having shape characteristics adapting the head for a wide variety of work, and capable of giving the work a substantially straight line wiping or bufllng movement.

Another object of the invention is the provision of a pneumatic bufling head having improved means for inflating and driving the same.

A further object of the invention is the provision of a bufllng head adapted to be used with portable driving means for use in the bufllng of automobile bodies and similar surfaces.

A still further object of the invention is the provision of an improved buffing cover.

Other objects and advantages will become apparent to those skilled in the art from the following description and the accompanying drawings, in which- Figure l is a section through an inflated buffing head and cover embodying my invention;

Fig. 2 is a perspective view of an inflated buffing head embodying the invention;

Fig. 3 is a perspective of a bufl'ing cover;

Fig. 4 is asection through a modified form of the device, uninflated;

18. 5 is a view of the bottom end of the drive shaft shown in Fig. 4;

Fig. 6 is a section on the line 6-6 of Fig. 4, and

' Fig. 7 is a section through a modified form of the device, uninflated.

The invention contemplates the provision of a gascell in the form of a right cone having a base 1 and conical side walls 8, the cell being adapted to be inflated to give the side walls I a desired resiliency. The side walls I are formed of a resilient substantially gas-tight material such as sheet rubber, and should berelatively thin so as to be capable of ready flection so that the side of the gas cell may take the configuration of the surface against which it is being pressed.

Referring to Figure l, the base 1 is formed of a plurality of fabric layers impregnated or covered with rubber so that it is relatively stiff and will remain substantially plane when the gas cell is inflated. In this instance, the thickness of the base is decreased toward the annulus as shown at I so that the junction between the base and the side wall will become rounded as shown at H under the inflation pressure. A valve stem I! 'of inflating the cone. The opposite end of the having a head II is positioned at the center of the base and projects perpendicularly therefrom throiuh the gas cell, the stem being attached to the base by means of the head I! and a nut I 4 between which the base is clamped. The op- 6 posite end of the valve stem passes through an opening at the point of the cone, the side walls of which are clamped between washers II and il by'means of nuts I! and II threaded onto the valve stem, thereby sealing the gas cell at the 10 point at which the stem passes through. When the cone or cell is inflated the side walls curve upwardly as shown at ll around the projecting end if of the valve stem to form a pocket within which the projecting end of the valve stem is 16 recessed. This projecting end of the valve stem has the conventional air valve 22 communicating with a longitudinal bore 23 and a lateral opening 24 through which air may pass for the purpose 20 bore 23 is closed by a pin 2! which projects perpendicularly from the center of the base and serves as a means for driving the head. This pin is received in a conventional hand motor 1mit such as used in portable buiilng operations which may be a portable motor, a flexible shaft, or other driving means. The outer surface of the gas cell is covered by a layer of fabric 20 which serves to prevent distortion of the rubber side walls I away from a fairly true conical shape. I have found that the results of the invention are best obtained when the cone is so shaped that. the walls lie at an angle of about 20 to about with respect to the base depending upon the particular type of work. 35

In service the 89s cell or cone is provided with a cover carrying the abrasive, a preferred form being shown in Figs. 1 and 3. In this instance the abrasive is a sheep's wool buillng element which consists of a leather sheet 21 upon which the wool still remains, as shown at 28. This bumng element is cut and sewed in the form of a cone of the same slope as the buillng head leaving a small opening at the point of the cone as shown at 29. This opening is such as to permit '45 access to the projecting end if of the valve stem so that the cone may be inflated with the cover in position. .At the base of the conical cover a disk ll of flexible rubber is attached; for example, by vulcanizing the rubber to a piece of fabric 32 extending along the annulus of the disk which is in turn sewed to the sheep's wool portion of the cover as shown at 88. The center of the rubber disk ll is cut outas shown at 34 so that. the gas cell may be inserted into the cover as through this opening or conversely so that the cover may be drawn over the gas cell, the rubber ring 3| stretching out for the passage of the cell. When the cell is accurately positioned within the cover, the rubber disk or ring 3| seats against the base I so as to firmly retain the cover in the position shown in Figure 1. The cover cooperates in the same way with those forms. of the invention shown in Figs. 4 and 5, and presently to be described.

In the form shown in Figs. 4 to 6, inclusive, is

shown a structure wherein the driving means does not pass through the gas chambers and the only opening into the gas chambers is that necessary for the insertion of the air valve. This materially reduces the opportunity for leakage. In this form the. side walls 8 of the gas cell are carried downward from a point adjacent the apex of the cone as shown at 35 to form a central bore perpendicular to the centerof the base I, the walls of the bore being attached to the base. The top of the bore is closed by a wall 36 which is spaced inward from the end of the bore to form a recess having an annular soft edge 31 which permits the side of the cell in contact with the work to flatten without the exertion of undue pressure at the end of the cell. A shaft 38 is received in the bore and is of such size as to flt tightly therein. The shaft has annularly spaced longitudinally extending ribs 39 which terminate 'short of the ends of the shaft. These ribs normally prevent movement of' the shaft with respect to the bore either longitudinally or rotatively. Preferably the shaft is placed in position in the bore prior to the time the raw rubber is vulcanized so that the bore is caused to seat against the shaft intermediate the ribs as shown in Fig. 6. Furthermore, when the cell is inflated the walls 35 are pressed against the shaft. The upper end of the shaft substantially abuts against the wall 36 while the lower end of the shaft is flanged as shown at 40, the flange being of the general shape shown in Fig. 5. This flange is seated in a recess 4| in the base! formed by inserting the drive shaft in place prior to the vulcanization of the raw rubber so that the rubber takes a form complemental to the flange during the vulcanizing operations. Further driving connection between the gas cell and the shaft is therefore established through the complemental relationship of the flange and the base, the general rectangular form of the flange preventing slippage of the base with respect thereto. The driving pin is threaded into the lower end of the shaft for attachment of the bufling device to suitable driving mechanism. A valve stem 42 passes through the base I and is secured therein against leakage by the customary washers 43 and nuts 44. A counterbalancing weight 45 is positioned on the base I within the cell, this weight constituting a piece of lead or other material embedded directly within.

this form the central form 38 serves to lend stability and balance to the bufllng head for high speed operation. The walls of the cell are in this form formed of molded rubber, the thickness being gradually increased at the junction between the base I and side walls 8 as shown at 46 so that when the cell is inflated some additional curvature will be taken on in this area due to the air truncated as shown at 49 partly due to the efiective inflating of the cell.v In this form a circular plate 5| is positioned against the inner side of the base I and a plate 52 is positioned against the outer side, the base being gripped between these two plates. At the center of the base is a sleeve 53 having a head 54 which abuts against the plate 5|. A nut 55 on the sleeve abuts against the plate 52 and is threaded onto the sleeve to an extent suflicient to firmly grip the base 1. A valve stem 58 is threaded into the head 54 and projects longitudinally in the bore 51 of the sleeve 53, the bore being considerably larger than the stem. The bore 51 is threaded as shown at 58 for the reception of a driving element 59 which is provided with a bore 6| for the reception of the outwardly projecting end of the valve stem 56. The driving member 59 carries the pin 25 through which driving connection is established with a motor or other driving element as heretofore described. It will be seen that the gas cell is in this instance inflated by threading the driving element 59 out of the bore 51, leaving the free end of the valve stem 56 exposed. Likewise, it will be noted that this driving element protects the valve stem during the use of the bufling head.

An important phase of the invention is the shape of the air'cell. By forming this cell in the general or appropriate shape of a cone or a truncated cone, numerous advantages are obtained. One of these is the fact that it permits of substantially straight line buffing motion together with a relatively wide bufling area and a shape characteristic which permits of access into openings of limited size. In the past, two types of buiiing heads have been common, one comprising an arcuate pad operated with the axis of rotation perpendicular with respect to the work. This type of head gave a circular bufiing motion to the work and in fine work left circular swirls or bufling marks. The second type is in the form of a cylinder in which the axis of rotation is parallel to the work. This type of head gives a straight line bufling motion but permits of only a relatively small area of contact between the work and the abrasive. When the size becomes large it is then impossible to have access to surfaces having a limtied amount of head room or space thereabove. Onthe other hand, when the cylinders are made small it is necessary to use a rigid central shaft in order to prevent the extreme end of the cylinder from wobbling at high speed. By means of the shape characteristics herein described, the buffer produces a straight I line bufling motion, the radius of the base of the head is relatively great so that a relatively great area of contact is obtained between the work and the abrasive while the tip of the buifihg head is of such size that it may be inserted into openings of limited space. A further advantage of this shape is the fact that the head may be rotated at high speeds since the tip is held in alignment by the relatively large base.

A still further advantage of this shape is the fact that the bufling head or tool does not tend to jump or bound on the work as is comon with cylindrical bufling tools. This results from the angularity of the shaft of the tool with respect to the work and from the high degree of resiliency of the buffing head. This further eliminates any tendency of the buffing head to form butflng marks on the work.

Another feature of the invention is the fact that the walls of the air cell are relatively thin material and are backed solely by pneumatic pressure which permits of adjustment of the resiliency of the head so that the bufiing surface readily takes the shape of the work. Through this means uniform operation is obtained on work of irregular surface shape such as the curved body surfaces of automobiles and the like, or portions of automobile bodies having ribs or other abrupt changes in the otherwise plane surface.

Another feature of the invention is that when the operator forces the side of the buiiing head down against the work the cell flattens in the direction of its motion so as to give a greater flat area in contact with the work. This can be regulated to a considerable degree by the amount of pressure in the gas cell. This action is greatly facilitated by the thin side walls which flex rapidly under the rotation, the walls being backed up by gas which is sufficiently fluid to move freely ahead of the deformation in the gas cell. This is also facilitated by the semi-rigidity of the base of the cone.

Another feature of the invention is the resiliency of the head along the edges of the bufling surface, that is, at the tip of the cone and at the junction between the side walls 8 and the base I. Because of the softness, flexibility, or resiliency at these points, there is no tendency for an uneven bufling effect along the bufling surface. Furthermore, this permits of a considerable variation in the pressure within the cell so that the softness of the buiiing head may be varied within wide limits without producing an uneven buflin effect.

Another advantage of the invention is in the fact that the cover requires no fastening means for securing the same in place and may be rapidly stripped off and replaced for change in the type of abrasive as the work may require.

It will also be observed that the invention permits of a central supporting shaft through the air cell without substantially interfering with the resiliency of the working surface.

While I have thus described and illustrated specific embodiments of the invention, I do not wish to be limited except as required by the prior art and the scope of the appended claims, in which I claim:

1. The combination in a bufiing head of a gas cell of thin walled resilient material in the approximate form of a truncated right cone, said cell having a central tubular portion defining therein a bore extending perpendicular to the center of the base, said base having a recess of non-circular shape annularly of the center of said tubular portion, a shaft positioned in said bore having a plurality of circumferentially spaced longitudinal ribs intermediate its ends and an outwardly flared end 'complemental to said recess seated in the recess of the base, and a spindle on said shaft positioned perpendicularly vto the center of said base for driving the builin head.

2. The combination recited in claim 1, wherein the side walls of said cone curve inward and downward at the apex of the cone under inflation pressure to merge with the end of the tubular portion to provide an annular pneumatic ring above the end of the shaft;

3. The combination in a bufling head of an approximately conical gas cell of thin walled resilient material, said cell having a central tubular portion defining therein a bore extending therethrough perpendicular to the center of the base, a shaft positioned in said bore having an outwardly flared end seated against the base of the cone,'a spindle on said shaft projecting perpen dicularly to the center of said base for driving the bufling head, a valve stem for inflating said cell electrically positioned on said base, and means on the base for counterbalancing said valve stem.

EDWARD G. PE'rERson.

CERTIFICATE OF CO RRECTI ON.

Patent 110. 2,225,658. r December 3, 191m.

mm) G. PETERSO It is hereby certified that error agzpeare i1; the print ed specification of the abovevnumbered patent requiring correction as follows: Page 5, sec

cod column, like h1, 'claim3, for the word "electrically" read --eccentricelly -yand that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in -the Patent ofi'ice.

Signed and sealed this 114th day of January, 1\. D. 19111.

. Henry Van Arsdale,

(Seal) Acting Commissioner of Patente.

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