US2706368A

US2706368A - Reciprocator sanding head

Info

Publication number: US2706368A
Application number: US101023A
Authority: US
Inventors: Chalmers H Randolph
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1949-06-24
Filing date: 1949-06-24
Publication date: 1955-04-19
Anticipated expiration: 1972-04-19

Description

April 19, 1955 c. H. RANDOLPH RECIPROCATOR` SANDING HEAD 2 Sheets-Sheet l Filed June 24, 1949 |||||IIlllllIIIlIIIIIlIlIII'Ill ,4 wl f .il-.Q u.

April 19, 1955 c. H. RANDOLPH RECIPROCATOR SANDING HEAD 2 Sheets-Sheet 2 Filed June 24, 1949 MMX! 4% United States Patent O RECIPROCATOR SAN DING HEAD Chalmers H. Randolph, Manhattan Beach, Calif., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware Application June 24, 1949, Serial No.101,023

1 Claim. (Cl. 51-170) This invention relates to abrading or sanding machines which comprise a movable head powered by a flexible shaft, the head carrying a plurality of abrading lfnads that reciprocate in the plane of their working suraces.

Objects include the provision of improved driving means for reciprocating the pads, and improved lubricating means.

The invention provides a plurality of eccentric discs fixed to a centrally located power shaft and a corresponding number of driving arms extending outwardly from the shaft strapped to the discs at their inner ends and pivoted to reciprocating pads or pad mounts at their outer ends.

It also provides means for directing a lubricant through an abrading machine into contact with the surface of a work piece to which the abrasive is being applied, to serve as an abrading lubricant, and means for diverting some of the lubricant into contact with moving parts of the machine.

Advantages of such constructions include decreased vibration and increased lubrication efficiency.

An illustrative embodiment is described below and illustrated in the accompanying drawings inwhich:

Figure 1 is a perspective view;

Figure 2 is a bottom elevation with the pads, pad shoes and the bottom plate of the casing removedj Figure 3 is a vertical longitudinal section on the line 3 3 in Figure 2; and

Figure 4 is a vertical cross section on the line 4--4 in Figure 3.

An elongate, rectangular, relatively flat frame or casing 11 forms a chamber 12.

For convenience, the said casing, as well as the entire machine will be described herein as normally horizontally disposed, although it is to be understood that it can be used in any and all other positions, as well as in a horizontal position.

A short vertical power shaft 13 extendsdownwardly into the chamber from the center of the top of the casing. It is an extension of a shaft 113 lthat is rotatably supported by well known conventional bearing means that are not here shown, in a power head 14. The shaft 13-113 is rotated through conventional gearing by a rotating flexible driving shaft 15.,` The power head assembly, which includes the said gearing, flexible shaft, etc., is lubricated by well known conventional means, separately from the system hereinafter described for lubricating the abrading operation andthe reciprocator assembly.

Two proximate (closely adjacent to each other) eccentric discs 20 and 20' are fixed on the vertical power shaft 13 with their respective lobes spaced 180 from each other. Two links or driving arms 21 and 21' which extend outwardly in either direction from the shaft 13 towards the ends of the frame 11, are connected or strapped at their inner ends by straps 22 and 22' to the discs 20 and 20', respectively. At their outer ends the

arms

21 and 21 are pivoted at 23 and 23' to two cross heads 24 and 24', respectively. The cross heads reciprocate in

lower ways

25 and 25 and

upper ways

25a and 25a', both respectively, alternately toward and away from each other.

Two

shoe blocks

26 and 26 are held by screws to the cross heads 24 and 24', respectively. The blocks, in turn, hold (by screws) two pad shoes 27 and 27', and the two shoes hold two abrading

pads

28 and 28.

rice

The shaft 13 is axially bored throughout its length with a bore 33. A lubricating material is conducted from a source (not shown) through a supply tube 34 into the upper end of a bore 133 that extends through the previously identified shaft 113, and thence into the bore 33 from whence it is free to discharge downwardly through a hole or aperture 35 in the bottom plate 36 of the casing 11 onto the surface 37 of a work piece to which the pads 28-28' are being applied, thus serving as an abrading lubricant.

A portion of the lubricant is diverted from the main stream that passes through the bore 33 by means of two lateral passages 38 and 38 which extend from the bore through the wall of the shaft 13 and thence radially through the bodies of the respective discs 20-20 to the peripheral surfaces of the discs on which the straps 22-22 of the driving arms bear. From thence the lubricant flows outwardly from between the straps and the peripheral bearing surfaces of the discs into the chamber 12 Where it is splashed about by the rapidly moving parts in a manner to impel a substantial quantity of it onto the Ways 25-25 and 25a-25a' on which the reciprocating cross heads 24-24 bear.

The lubricant, in addition to serving as an abrading lubricant, thus serves as a machine lubricant for the reciprocator assembly as well.

A bored screw-plug 39 in the lower end of the shaft bore 33 regulates the relative amount of lubricant that is used for the abrading lubrication and for the machine lubrication. A plug having a relatively small bore 40 permits less to pass directly through to the work surface 37 and diverts more through the passages 38-38'. A larger bore 40 passes more for abrading lubrication and diverts less for mechanical lubrication.

The use of an unbored or solid plug forces all the lubricant to go through the passages 38-38. All the lubricant supplied to the machine through 4the supply tube 34 is then first used as a machine lubricant for the reciprocator parts. The chamber 12 then acts as a collecting means and the collected lubricant flows down through the aperture 35 and through the reciprocator apertures 41-41 (through which the shoe blocks 26-26' extend) onto the work surface 37, there to serve as an abrading lubricant.

Where water is the lubricant, as it frequently is, the cross heads 24-24 and the eccentric discs 20--20 are of materials known to be adapted to serve as waterlubricated bearing surfaces, such for example as fiberor cloth-reinforced resins.

The invention thus provides reciprocator movements of novel construction which, when employed in sanding heads for lubricated abrading operations, may correctly be termed self-lubricating. The lubricating material which in prior art devices could be utilized only as an abrading lubricant, may now by this invention be used as the machine lubricant for the reciprocator as well, so that the reciprocator can be lubricated without the use of a second material. Furthermore, there is a minimum of wastage of the abrading lubricant, for after the diverted portion has served its purpose as a machine lubricant, it is directed into contact with the surface being abraded where it serves over again, this time as an abrading lubricant.

The reciprocator movement of this invention produces less vibration than those heretofore known.

I claim:

An abrading device comprising a rectangular normally horizontally disposed casing enclosing a chamber and having apertures in the bottom, an abrading pad on either side of the center of the casing beneath the casing, a water-lubricated cross head on either side of the center of the chamber within the chamber slidably mounted for reciprocal movement toward and away from the center, connecting means extending through the apertures in the bottom of the casing for fixing the two pads to the two cross heads, respectively, a hollow vertical driving shaft journaled in the center of the top of the casing and extending into the chamber, two proximate eccentric water-lubricated discs fixed to the shaft within the chamber with their respective lobes spaced apart, means for supplying water to the interior of the shaft, a passage extending radially through the wall of the shaft and radially through the body of each disc from the interior of the shaft to the periphery of each disc for conducting water to the peripheral bearing surfaces of the discs and thence into the chamber, two driving arms strapped to the discs at the inner ends of the arms and pivotally attached at the outer ends of the arms to the cross heads, respectively, and means for rotating the shaft.

1,191,981 Mattison July 25, 1916 4 MacDonald Mar. 6, 1923 Anderson May 6, 1924 Thompson June 22, 1929 Roos July 26, 1932 Mavis et al. May 8, 1934 Mall Jan. 18, 1938 Consigliere July 9, 1940 Burleigh Sept. 7, 1943 Beard July 22, 1947