US3540168A

US3540168A - Margin preparation method and machine

Info

Publication number: US3540168A
Application number: US708334A
Authority: US
Inventors: Walter Sawert
Original assignee: Continental Can Co Inc
Current assignee: Continental Can Co Inc
Priority date: 1968-02-26
Filing date: 1968-02-26
Publication date: 1970-11-17
Anticipated expiration: 1987-11-17

Description

Nov. 17, 1970 Q w. SAWERT 3,540,168

MARGIN PREPARATION METHOD AND MACHINE Filed Feb. 26. 1968 INVENTOR WALTER SA WERT ATT'Y.

United States Patent York Filed Feb. 26, 1968, Ser. No. 708,334 Int. Cl. 1324b 1/00, 31/00; B24c 1/00 US. Cl. 51317 3 Claims ABSTRACT OF THE DISCLOSURE This apparatus is a particle abrasion machine for can body blank margin preparation. Can body margins are abraded to fresh bare metal surface in preparation for Welding by passing the can blank edges between elastomeric rolls which rotate as they pass both sides of the blank sheet. At the same time free flowing abrasive grit is fed into the space between the rotating roll and the sheet material and is thus carried by the rolls to the sheet margin. The grit acts as many cutting edges which cut dirt and other matter from the surface on each side of the sheet. The grit and waste material fall together from the rolls into a collector through which a current of air passes. Suitable means return the grit to the hopper. The separation of grit from waste material is accomplished by a magnet, air blast, or other means.

My invention relates to an abrasion method and abrasion machine and particularly to a machine for abrading body blanks which have elastomeric rolls to control cutting pressure and an automatic grit return system for cooling and repreparation of the grit in its passage back to the hopper.

In the past abrasive wheels have been used to prepare each side of the margin of the body blank and cut the surplusage off to leave bare metal. This device is unsatisfactory due to wear of the abrasive wheels, the need to carry the heat of friction away by water or other means and the dulling of the abrasive wheels by the material of the body blank. Further, the cutting pressure with which the abrasive wheel bears against the body blank is given by the binding compound of the wheel and cannot be regulated because of the aforementioned conditions and, therefore, the abrasive wheel takes too much or too little off of the body blank margins, particularly when there are pronounced irregularities in the margins.

Another means formerly used is a rotating sharp wire brush. However, the wire ends of the brushes lose their sharpness very rapidly and quickly become inefficient. The use of sharp wire brushes produces a non-uniform result and is expensive because the sharp wire brushes wear out rapidly and must be resharpened frequently.

It is an object of my invention to provide a machine capable of dependably cleaning the margins of can body stock to the bare metal in an economical manner.

It is another object of my invention to provide a machine for cleaning the margins of the can body stock with a minimum of heat generation by the provision of many cutting edges which in their mass provide rapid heat dissipation from the margin.

In brief, my invention is a method and means for abrading the edges of a body blank in preparation for later welding. The edges of a body blank are moved between counter-rotating elastomer rolls so that the rolls press upon opposite sides of the body blank edge with a predetermined pressure. An abrasive grit is fed from a hopper into the space between the blank and the roll and is carried by the rotating roll against the margin of the body blank. After the abrasive grit has cut the margin of the body blank, a current of gas may sweep the grit and the residues into a collector and then the grit is conducted back into the hopper.

In order to enable the invention to be more fully understood, reference is made to the drawings in which the figures show an embodiment of my invention.

FIG. 1 shows a cross-section view of my apparatus.

FIG. 2 shows a side elevation of my apparatus.

FIG. 3 shows a detailed illustration of the operation of a part of my apparatus.

The machine illustrated and described shows the overall construction of a margin abrasion machine and each essential element of the machine. As shown in FIG. 1 an elastomeric surface element 1 is pressed against the margin of a body blank 2 and brushes it with a light pressure. The elastomeric surface element may be a pair of elasltomeric rolls 1 turning in counter-rotation and mounted side by side. A sheet 2 of the material to be cleaned or prepared for welding is passed between them. The elastomeric rolls 1 may be of natural rubber, properly selected synthetic rubber, polyurethane or other wear resistant material which is elastomeric and can be made harder or softer and should be of a stiffness equivalent to soft or medium hard rubber with a durometer reading of less than about 70. These rolls 1 may be made of materials such as, polyurethane; fluoro-elastomers; polybutadiene, neoprene and butyl or natural polyisoprene rubber. In this way a proper loading force can be placed upon the roll commensurate with the objectives of avoiding unnecessary heat and thus causing reoxidatiorr of the cleaned metal at a high temperature. The particle feed hopper 3 found above the rolls serves as a container for the storage of grit to be used in the abrading process. Hopper 3 may be of any size or shape and its dimensions form no critical part of this invention. In the bottom and sides of the hopper is a slot 4 through which the sheet of body blank material protrudes to pass between the elastomeric rolls. The sheet 2 is supported and positioned by guides 5 above and below it. These guides 5 and 6 may be made of steel or nylon or may be roller hearings or the like.

The body blank is moved along by means of an endless belt 7 as shown in FIGS. 1 and 2. The belt 7 presses against both sides of the blank 2 in order to form a firm contact with the blank stock 2. As feed belt 7 moves, for example, out of the plane of the paper, FIG. 1, the body blank moves with it out of the plane of the paper and passes between elastomeric rolls 1. The belt 7 passes forward out around particle feed hopper 3 and goes back along the outside of the hopper to form the return part of the endless feed belt. The endless feed belt may be actuated by a variable speed motor (not shown) so that the speed of the blank stock may be adjusted to that speed most suitable to the particular body blank material, grit and roll pressure employed in the process. In order to protect the blank stock and the inner part of the endless belt a shroud 8 (part of the feed hopper) is placed about these elements. Shroud 8 and the side wall 9 of the hopper 3 form an open slot 4 to feed the grit 10 between the elastomeric rolls 1.

Underneath the elastomeric rolls is a collection or gathering device 11 for the abrasive grit and residues 12 from the sheet. The abrasive grit and residues 12 fall from the interface between the sheet 2 and the elastomeric roll 1 and into the collecting device 11. The mixed grit and waste material 12 is conveyed through the collection pipe 14. A suction developing pump 13 may be used to cause a fluid current to sweep the grit and grindings down through the funnel and out a collection pipe 14 to be deposited finally in the grit feed hopper '3.

While the material is being conveyed the grit and waste may be separated by air separation, magnetic separation or any other separating process before the grit is returned to the particle hopper.

Taking another view of the apparatus, FIG. 2 shows more clearly the feed hopper 3 and its relation to the elastomeric roll 1 and particle collector 11. The upper guide 5 and lower guide 6 in applicants machine are shown with the blank stock 2 sliding and held in avertical position between them. The feed belt 7 passes for some length in contact with the blank stock so as to insure a good contact and to allow space for one or more abrasive wheels at various stations to operate upon the margin of the blank stock. 9

It is contemplated that the cutting material or grit 10 can be aluminum-oxide; zirconium-oxide; diamond dust; steel grit or any of the commonly used abrasive materials. In general, the ideal shape of the grit grain should be tetrahedral for highest efficiency as opposed to. spherical, for example, because the tetrahedral shape gives an abrading or cutting action whereas the spherical shape results in primarily a sliding and burnishing action.

The composition and qualities of the elastomeric r01 1 play a critical part in this invention. This roll is made of a material having a high Wear resistance and the elasticity of the roll may be varied by varying the composition to have a firmness between medium or soft stiffness with a durometer reading of less than about 70. An adjustable spring presses the elastomeric roll against the blank stock with a predetermined force. The pressure from this elastic spring 15 and the resilience of the roll 1 presses against the grit particles in the interface between the moving blank stock and the rotating elastomeric roll (FIG. 3). The surface of the elastomeric roll holds the grit during the cutting time and assures constant pressure and seating. This pressure is sufficient to cause the grit to cut all the surface layers from the surface of the blank stock leaving fresh metal exposed after the blank stock has passed through and beyond the elastomeric roll or rolls. 1

Constant operating conditions are assured because the elastomeric roll, for example, polyurethane, or any other wear resistant elastomeric material such as those set forth above does not wear appreciably and fresh grit is continuously fed into the interface between the blank stock and the elastomeric roll. Any desired pressure is brought to bear between the blank and the roll by adjusting, the spring pressure and by using a roll of stiffness suitable to the material being abraded and the grit em-' ployed. The cutting quality of the grit is assured by continual purification of the grit and continual change of the exposed edge of the grit particle as the grit passes the blank stock in each cycle. Most of the heat generated in the process is carried away by the grit. These operating conditions are set to produce a clean fresh surface at the margins of the body blank for welding and this surface will be as cool as possible because of the coolness and sharpness of the grit, the pressure of the controlled elastomeric roll and the cooling effect of the air current on the moving parts of the machine.

If the material to be cut from the surface of the body blank is difficult to abrade in a single step or if heat generated in the body blank by the cutting step causes quick reoxidation of the surface of the body blank then a second abrasion machine using suitable material to reclean the margin may be located (or a second abrading station) further along the body blank feed line so as to provide a clean, fresh, cool uniform blank margin as an end product, i

An advantage of my machine over the prior art is that due to controlled cutting pressure the blank stock will leave the machine in a cool condition so that the fresh surface which may be exposed to air is not quickly reoxidized and the stock may be held for an interval before being welded.

Another advantage is that the fresh surface of the prepared blank stock is comparatively uniform from blank to blank in a long run since the abrasive conditions will change relatively little. r 7

Another advantage is that it is not necessary to change machine parts or settings frequently since the elastomeric roll and 'grit lasts a relatively long timewithout appreciable change of quality.

The final advantage is that the cutting pressure remains relatively constant and cutting edges remain sharp in this machine thereby assuring uniformly cleaned margin surfaces.

The foregoing is a description of an illustrative embodiment of the invention, and it is applicants intention in the appended claims to cover all forms which fall within the scope of the invention.

I claim 1. A method of preparing the margins of a body blank for welding comprising the steps of:

pressing elastomeric surface means against the margin of a body blank,

feeding grit to the interface between said body and said elastomeric surface,

moving said elastomeric body means relative to said body blank, whereby said grit abrades said body blank to produce residues, and

passing a cool current of gas adjacent to said elastomeric surface to conduct said grit and residues away from said interface and for the purpose of cooling said elastomeric surface, body blank and grit.

2. The method of preparing the margins of a body blank for Welding as set forth in claim 1 having the additional step of:

conducting the grit and residues'fallin-g from said interface to a purifying means, and I conducting the purified grit back to said interfaces whereby said grit at said interface presents a different edge to said body blank at each cycle to give a maximum cutting efficiency.

3. The method of preparing the margins of a body blank for welding as set forth in claim 2 and the additional step of: I

repeating the steps of claim 2. to cut away any foreign material left on the body blank as it passes a second abrading station.

- 1911 Great Britain. 1 3 1926 Great Britain. 9/ 19 13 France. 10/ 1911 Germany.

JAMES L. JONES, 111., Primary Examiner