US2857715A

US2857715A - Means for abrasive blast cleaning edges of surfaces

Info

Publication number: US2857715A
Application number: US609388A
Authority: US
Inventors: Hastrup Herman; Rolf C Hastrup
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-09-12
Filing date: 1956-09-12
Publication date: 1958-10-28
Anticipated expiration: 1975-10-28

Description

H HASTRUP EIAL ms FOR ABRASIVE BLAST CLEANING EDGES or SURFACES Filed Sept. 12, 1956 2 Sheets-Sheet 1 14 TOR/VI) Oct. 28, 1958 H. HASTRUP ETAL MEANS FOR ABRASIVE BLAST CLEANING EDGES OF SURFACES 2 Sheets-Sheet 2 Filed Sept. 12, 1956 lm I am FIG. 37

R mm H N W M eou c warm/p MEANS FORABRASIVE BLAST CLEANING EDGES 0F; SURFACES Ihis invention relates to abrasive blasting machines for cleaning surfaces, in. which machines there is directed toward said surface a blast str m air andabrasive material and from which surface spent abrasive and debris are withdrawn in a suction air stream, the said two streams passing through a housing generally termed the operating head of the machine, said operating head generally being provided with what is sometimes called the surface contacting rnember, which member, during operation of themachine is held in contact with the surface being blast cleaned and surrounds and encloses the space between an area of said surface andthe outer end of the operating head of the machine More particularly the inyentipr relates to apparatus by which the surface conas in ms sb i Q Such mena e b a p to clean the surface which lies at the edge of ,an' object.

in abrasive blasting machines of the aforesaid type an object sought is .to' conduct the blast cleaning operation while keeping all abrasive, dust and debris confined so that there is no spatteiing of dirt and dust and the surrounding fixtures and the clothes of the operator are kept clean. The operation is adapted for indoor work and to the surfaces of objects of varying size and shapes.

The said surfacecontacting member of such machines general-1y .comprises' a skirt-like element the length of which varies with the nature of the skirt and the material of which it is made. In certain of the machines the operation is c onducted so that the spent air from the blast stream constitutes substantially the entire amount of air of thesuction stream, there being no dependence upon airlbeing drawn through the skirt oir under the edge thereqf to constitute a part ofthe suction stream which carries the spent abrasive and debrisaway from the area of surface undergoing treatment. In such machines the skirt element isnon-air pervious, which also helps to'assure against theescape of spent abrasive and debris tofth surroundingenvironment.

Abrasive blasting machines which do not depend upon theintake of air throughthe surface contacting element, and therefore operate with substantially non-air pervious surface contactors, are described in ,U. S. Patent 2,133,493 to .Hastrup and.Pink ertorijand in our co-pending application Serial. No. 52'1,7l9, .filed July13f'l955. In, our co pending application .Serial. No. 555,495, filed December27, 1955, there isdescribed a surface eontac ting. element for use with such machines and adapted to he. used over rough and irregular surfaces while still rernainingsubstantially impervious to the entrance of'air from ,theoutside into the area undergoing cleaning, the skirt of such surface contactor being comprised of laminate of rubber or like material with the said laminae 'sli'tted. aiiially fromthe outer edge of the skirt.

In another type of grit blasting machine, the skirt of -,the gara e contactor is air'pervious and dependence is i d upon air entering therethrough from the'outside to ls'titjutela part of the suction stream which carries spent asive and debris awayfrom the surface being cleaned. Machinesof'this type are described in the U. 8. Patent United States Patent 9 lce No. 2,455,514 to Mead and in Reissue No. 23,186 thereof.

In machines of'either of these types difficulty arises in attempting to clean that portion of a surface which lies at the edge of an object, such as for example at the edge of'a table top. Grit blast cleaning of surfaces is applied to many kinds of objects having iiat surfaces with an edge that presents the same situation as that of a table top. Many small machine parts have such surfaces. 'In order to have an area of surface which lies at the edge of such an object directly in the path of the blast stream from the machine, only a partof the circumferential edge of the skirt of the surface contacting member of the machine would be in contact with the object't'o be cleaned and the remaining partthereof would extend into space beyond the edge of said object and not be in contact with anything except the air in'said space. This would of"course'res ultin a part of the blast stream of air and abrasive beingshot past the edge of the object andinto open space" mere eyo a. "Even if by careful and laboriousefiort the surface contacting member were held so that its enclosed area ofjsurface were tangent to the edge of the object, inor'der to prevent the discharge of 'the blast stream past the object into open beyond, the 'cleaning of the snr'f ace at the edge of the object would'be unsatisfactory for the reason that as the machines are conventionally constructed; the blast stream impinges against thecentral portion of the area of surface enclosed by thesur flace contacting member, the space at the peripheral 'portionbf said'area being where the exhaust stream begins. the surface contacting element would be moved along in this laborious'eifort parallel to the edge of the object, there would he a narrow strip alongthe'said edge that would" not be' cleaned; In machines of'the vtype ofthe afo'resaid Mead patentwhich depends on the intake of air "through an air-pervious skirt of the surface contacting memb'en the surface "at v H i n f the obje mightpossibly to'sorrie degreeibe cleaned byipbs ng th'e surface contacting inem bei' oyeffthe surface 'wt rtio nof its encircled area eatendingbeyond the edge of the object tobe cleaned, provided that distance of such extension beyond said edge were small e' M iighthat' suction intake (if {the opening'created by such I v I 'ient to preven t' the escape therethr ughbfabr siver in t blast stream." Even 'in ri s erqn n thefulleffe' f thelblast stream would notfbe directedagainstthesufface atthl'eejdge of the object andthe bperaticinfa't bestfwouldfie unsatisfactory. in machines of the type 'of the aforesaid Hastrup' and Pinkerton patent and of our aforesaid'co pending application' where operation is; cond icte ith'out dependence upon the intake "of'air from the outside through the skirt of the surface 'contactihgmentber; it would be definitely unsatisfactory 'to try to operate the machine with the surface contacting element thus e itended beyond the edge of the object being cleaiieilinth absenceof any areaa 'ror 'clo'si offthe open' space at the edge ofthe object. I l

It'is an object of this invention to provide in abrasive blasting' macliines of the type heireinabove referred to, means lby 'which the blast stream from the machine can be directed against th'e'are a of stirface which lies at the edge'of an'obje'ct Withbut said blaststream dicharging past the said edge and on in'to space outsidethe surface contacting element of said machine.

It is another object to provide, in abrasive blast cleaning machines of the aforesaid type, when operating the machine with, the surface contacting member of, the machine positioned over and in contact with an area of surface at the .edge of an object and with a portion of the surface'contacting member extending into spaceibg.

yond the edge of said object in order that said area of surface may lie in the central portion of the enclosure surrounded by the surface contacting member and therefore be in the direct path of the blast stream, means for closing off from the space outside said surface contacting member that portion of the space within said memher which extends beyond the edge of the said object.

Other objects and advantages of the invention will appear from the ensuing description and the appended claims.

One form of the invention is illustrated by way of example in the accompanying drawings and is described in detail hereinafter. The particular constructions shown and described are to be construed as illustrative only and not as limiting the invention.

In the drawings:

Fig. 1 is a top plan view of a preferred form of the invention.

Fig. 2 is a sectional view on line-22 of Fig. 1.

Fig. 3 is a part side view and part fragmentary longitudinal sectional view of the device of Figs. 1 and 2 in I position as attached to one form of surface contacting member of an abrasive blast cleaning machine.

Fig. 4 is a view in the direction of line 44 of Fig.3.

Referring to the drawings, we will first describe briefly one form of the operating head and surface contacting member thereof to which our invention is applicable. The outer end of the operating head shown is generally designated as 10. In some machines this outer end portion is desirably, though not necessarily, detachably connected to the main part of the operating head and is sometimes called the contactor boot of 'the machine. They may vary in different machines. The form here shown is comprised of an outer casing 11 and an inner casing 12 which together form an outer channel 13 and an inner channel 14, the said inner channel being for the passage of an air and abrasive blast stream from the operating head of the machine toward the area of surface to be cleaned, and the said outer channel being for the passage of a suction air stream carrying spent abrasive and debris away from said area. The said casings are in some machines desirably made of abrasive resistant rubber and may be molded with spaced web members 15 (Fig. 4) positioned radially between said inner and outer casings and integral with the said casings to give stiffness thereto. Various forms of surface contacting members are employed with these machines, the form shown in the drawings comprising an encircling part 16 which may be fitted in various manners around the outer end of casing 11 and terminating in a skirt member, generally designated in the drawings as 17. The outer end of this skirt makes the actual contact with the surface to be cleaned and when in that position seals off the space between an area of the said surface and the end of the operating head of the machine, or of the aforesaid contactor boot thereof, in order, as hereinabove pointed out, to prevent the escape of abrasive and dust to the outside space. The skirt 17 here illustrated is made up of laminae 18 (Fig. 4), the said laminae being slitted to form a series of axially extending flaps 19 (Fig. 3) disposed so as to break the joints between fiaps of adjacent laminae, and adapted for use on rough and uneven surfaces, the said skirt thereby being substantially non-air pervious so that in the operation of the machine there is no dependence upon the entrance of air from the outside to constitute a part of the suction air stream which carries spent abrasive and debris away from the surface being cleaned.

Coming now to the device of this invention, a'cylindrical collar 20 is adapted to be detachably mounted around the surface-contacting skirt member of the operating head, or' contactor boot, attachment thereof, of a blast-cleaning machine, such as around theaforesaid encircling member 16 shown in Fig. 3. At one side thereof,

and for a distance comprising a fractional part of its entire circumferential length, the said collar is formed into an axially extended portion 21, which said portion is in turn formed into a radially extending and segmentshaped part 22, in the terminal face of which lies the chord of the said segment. Desirably, the said radially extending portion is of such extent that its said terminal face lies'on the same side of the diameter (projected)v of said collar as the circumferential part of the collar from which the said axial part extends.

In operating the device the collar portion 20 thereof is fitted around the encircling member 16 of the surface contacting member 10 and moved upwardly thereon until the surface contacting edge of skirt 17 is in contact with the radially extending portion 22, the axially extending portion 21 being of suitable length therefor. In this position it will be seen that when the surface contacting end of skirt 17 of the blast machine is positioned on a surface at the edge of an object with the face of the said radially extending portion of the device against the edge of the object, the area of surface at the edge of the object will lie directly in the path of the abrasive blast stream of the machine and that the said radially extending portion will serve as a closure for that part of the space encircled by the skirt member 17 so that when the machine is in operation the blast stream cannot shoot past the edge of the object into the outside space.

The distance which the radially extending portion 22 may extend inwardly toward the center of the impinging area may vary, so long as when in use on the machine, the edge of the object being cleaned will suitably-lie in the path of the blast stream so as to receive satisfactory impact from said stream.

The radially extending portion 22 is preferably of increased thickness' in the area towards the axis ofthe de vice for' greater wear resistance tothe abrasive material.- In order to provide suitable fitting of the edge of skirt 17 against the radially extending part 22 the said raisedportion is formed so as to leave an arcuate shaped trough 23 in the floor or innermost surface of said radially extending part 22. The plane in which the terminal face of the radially extending portion 22 lies need not be parallel to the axis of the device and axis of the'machine' when the device is assembled thereon, but maybe varied to conform to the edge of the object against which the face fits when in use.

While we have shown a preferred form of our invention, it is to be understood that various changes may be made in its construction without departing from the spirit of the" invention as defined in the appended claims. Y

1. In an abrasive blast cleaning machine having a blast nozzle head the outer end of which is adapted toserveas a contacting member to be held against a surface to be cleaned, thereby to surround an area of said surface and enclose the space between said area and said blast nozzle head, said blast cleaning machine being of the type whereby a blast stream of air and abrasive is directed from said blast nozzle head through said space toward said area of surface and a suction air stream carrying spent abrasive and debris is withdrawn from said area of surface through said space. into and through 'said blastnozzle head, the improvement comprising the combination'with said blast nozzle head of a collar adapted to fit around the said contacting-member end of said blast nozzle head, a segment of said collar extending axially outward beyond the end of said contacting member of said blast nozzle head to form a wall arcuate in transverse section, a floor attached to the outer end of said wall and extending radially inward therefrom, said floor terminating in a face which lies in a plane parallel 'toltheaxis of said blast no -zzle head and in which plane lie both longitudinal edges or. said arcuate shaped wall whereby, in a radial cross sggjtion through said floor, said terminal face of said floor forms a chord joining the ends of the arcuate section of said wall, the length of said segment of said collar being such that said face of said floor lies in the path of the abrasive blast stream from said blast nozzle head, and the axial length of said wall being such that when the end of said contacting member of said blast head nozzle is held against a surface at the edge of an object and the said face of said floor is held against said edge of said object, the area of surface at the edge of said object which lies in the path of the blast stream from said nozzle head is closed off from the surrsunding environment.

2. In an abrasive blast cleaning machine having a. blast nozzle head the outer end of which is adapted to serve as a contacting member to be held against a surface to be cleaned, thereby to surround an area of said surface and enclose the space between said area and said blast nozzle head, said blast cleaning machine being of the type whereby a blast stream of air and abrasive is directed from said blast nozzle head through said space toward said area of surface and a suction air stream carrying spent abrasive and debris is withdrawn from said area of surface through said space into and through said blast nozzle head, the improvement comprising the combination with said blast nozzle head of a collar adapted to fit around the said contact-member end of said nozzle head, a wall of uniform arcuate cross-section attached to a segment of said collar and extending axially outward beyond the end of said contacting member of said nozzle head, a floor attached to said wall and extending radially inward therefrom and terminating in a straight face which extends from one edge of said arcuate shaped wall to the other of said edges and which lies in the path of the abrasive blast stream from said nozzle head, said floor being positioned on an approximate level with the outer end of said contacting member of said nozzle head.

References Cited in the file of this patent UNITED STATES PATENTS