GB2167984A - Blast-cleaning, shot-peening and peen-forming machines - Google Patents

Abstract

The machine includes a rotatable throwing wheel having a single runner disc carrying throwing blades 20 (e.g. eight in number, equally spaced from one another) on one face of the disc. Each blade is secured to the disc by (a) a boss having a neck and a head which is of greater cross-sectional area than the neck, said boss extending through an aperture 18 in the disc and the head engaging the disc, and (b) a protuberance which is accommodated in a notch in the disc periphery and is secured to the disc by a screw 60 which extends radially within the disc thickness. One side of each blade lies against said one face of the disc or is accommodated in the respective one of a number of radial grooves formed in said one face. The machine is reversible because both faces of each blade are throwing surfaces. A protective ring 70 may cover the disc periphery. <IMAGE>

Description

SPECIFICATION Blast-cleaning, shot-peening and peen-forming machines This invention relates to blast-cleaning, shot-peening and peen-forming machines; such a machine will hereinafter be called "a machine of the type described".

Wheels for machines of the type described (as defined above) are variously called centrifugal blasting (or blast) wheels, throwing wheels, blast impellor wheels and will be simply called wheels in this Specification. Similarly, the wheels with their associated blades or vanes have been either single-sided or dual-sided types; in one singlesides type, the single runner disc (variously called a side plate, side wall or side cheek) is of rather massive construction (thickness) due to the mode of connection of the radially extending blades thereto whereas, in the dual-sided types, there are spaced parallel runner discs with the radially extending blades located between and connected to said discs.All of these matters are well-known and have been widely written about in various Patent Specifications and in Volumes I and 11 of "Blast cleaning and allied processess" by H.J.Plaster, published by Industrial Newspapers Ltd.

A disadvantage of the wheel of the single-sided type mentioned above (disclosed, for example, in United States Patent Specifications No.2,869,289 and No.2,983,082 and page 13 of Volume II of the above-mentioned work by Plaster) is that the single runner disc is of great weight and this necessitates the use of special bearings when the wheels are directly coupled to the motor (often an electric motor) drive. Another disadvantage is that the particulate material which is to be thrown by the wheel (e.g. an abrasive material) usually becomes or can become packed between the tapered flange on each blade and the complementary slot in which the tapered flange is accommodated, this packing making it difficult to remove worn blades in order to replace them by new ones.In fact, the degree of packing can become such that the blade(s) need to be knocked out, in a radially outwards direction, using a hammer and this necessitates demounting the control cage and the impellor and the feed spout. This demounting of the control cage impellor and feed spout is another and concomitant disadvantage because, each time the control cage is taken off, it must be remounted and accurately reset in order to produce the desired blast pattern; this task of demounting, remounting and resetting of the control cage is very lengthy and a skilled man will normally take about 1 hour to 21 hours to carry out resetting.

In at least some dual-sided types of wheels, blades which are worn can be replaced by demounting the control cage and the impellor and the feed spout, and by thereafter removing the worn blades axially of the wheel; the full replacement procedure is described, for example, in United States Patent Specifications No.3,683,556 and No.3,785,105 and in United Kingdom Patent Specification No. 1,500,092. Such essential removal of the parts recited above is a grave disadvantage because of the long "down time" of the machine, as already explained in the preceding paragraph.

Moreover, the provision of the two runner discs instead of only one increases production cost, especially when each runner disc needs to be grooved radially to receive the flanged long edges of the blades (see, for example, the blades described and illustrated on pages 15 to 17 of Volume II of the work by Plaster).

It must be stressed that some machines are such that the blades need to be tapped out of engagement with the runner disc or runner discs either in directions radially outwardly of said disc(s) or in directions radially inwardly of said discs. In both cases, the control cage, impellor and feed spout need to be removed because either the blades have to be taken out axially of the wheel or the necessary space has to be created in order to wield the hammer.

Many machines disclosed in Patent Specifications and in the work by Plaster are not reversible, namely, they are not capable of throwing abrasive or other material equally well irrespective of the direction of rotation of the throwing wheels. Thus, for example, even though the spring clip and the simple ancillary tool shown in pages 15 to 17 of Volume II of the work by Plaster may facilitate retention of the blades, the illustrated throwing wheel is either a left-hand or a right-hand wheel because only corresponding one faces of the blades can be used to throw the material. Also, the throwing wheels disclosed in United States Patent Specification No.2,983,082 and in Figures 16 and 17 on pages 13 and 14 of Volume II of Plaster can only be used in one direction of rotation because blade retaining studs or lock pins engage corresponding one faces of the blades.

The principal object of the present invention is to provide a machine of the type described (as defined above) which is of the single-sided type and which does not possess the disadvantages which are inherent (a) in existing single-sided types both as regards blade demounting and as regards the massive single runner disc in which the blades are mounted, and (b) in existing dual-sided types as regards the cost and weight of two runner discs and as regards blade demounting.

It is a subsidiary object of the invention to make said machine, referred to in the preceding paragraph, reversible.

According to a first aspect, the present invention consists in a machine of the type described (as defined above) having a rotatable throwing wheel which comprises a single runner disc drivingly connected to a motor and a number of blades mounted on said runner disc in such a manner as to extend radially of the disc; a stationary control cage mounted coaxially with said throwing wheel and positioned radially inwardly of the radially inner ends of the blades;: a rotatable impellor arranged coaxially within said control cage; and means for ducting particulate material to said impellor; each blade having opposed surfaces of which at least one is a throwing surface and having flanged sides each of which extends substantially along the full length of the blade; circumferentially spaced notches in the periphery of the runner disc which extend substantially radially of the disc; tapped drillings made in the thickness of the runner disc and extending radially of the disc, each drilling opening at its radially outer end into a respective one of said notches; an aperture in said disc in radial alignment with each of said notches; first and second disc-engaging means on one flanged side of each blade, the first means engaging the disc at a respective one of said apertures and the second means engaging in the disc at the respective one of said notches which is in radial alignment with said aperture, said second means being held in engagement with said notch by screw means which extends through said second means into the tapped drilling which opens into said notch.

According to a second aspect, the present invention consists in a machine of the type described (as defined above) having means operable to duct particulate material into a rotatable impellor which is concentrically arranged within a stationary control cage which is both disposed coaxially with a single rotatable runner disc and disposed radially inwardly of the radially inner ends of throwing blades carried on one face of said disc; each blade extending radially of the disc and engaging the disc at two radially spaced locations; the engagement at the radially inner location being such as to prevent movement of the blade axially away from said one face of the disc and the engagement at the radially outer location being such as to prevent movement of the blade in directions radially of the disc; said engagement at the radially outer location including a screw extending through a part of said blade and radially into said disc.

In a machine as described in the preceding paragraph, the engagement at the radially inner location is provided by (a) a boss carried by and projecting from one of the two sides of the blade, said boss consisting of a head portion spaced from said side and connected to said side by a neck portion, the head having a cross-sectional area greater than that of the neck-portion, and (b) a through-aperture in said disc of a size and shape such as to permit said head to be moved axially of the disc until said one side of the blade is in contact with the disc and thereafter radially of the disc in order to bring the neck into contact with the wall of said through-aperture.

In a machine as described in the next but one preceding paragraph, the engagement at the radially outer location is provided by (a) a protuberance carried by and projecting from one of the two sides of the blade, said protuberance being so fashioned as to accommodate the head and a part of the threaded shank of a screw or screwed bolt, with its longitudinal axis parallel to said one side of the blade and contained in the plane which divides the thickness of the blade into two equal portions, and (b) a notch which interrupts the periphery of the disc and which extends radially of the disc and into which there debouches the open end of a tapped drilling which extends radially inwardly of the disc within the thickness of the disc, said screw or screwed bolt being screwed into said tapped drilling and maintaining not only said protuberance in said notch but also said one side of the blade in contact with the respective face of the disc.

According to a third aspect, the present invention consists in a method of assembling a throwing wheel of a machine of the type described (as defined above), said machine having means operable to duct particulate material into a rotatable impellor which is concentrically arranged within a stationary control cage which is both disposed coaxially with a single rotatable runner disc which forms part of the wheel and disposed radially inwardly of the radially inner ends of throwing blades which also form part of the wheel and which are carried on one face of said disc, said method comprising the following steps, namely, (1) inserting the protuberance of a throwing blade, which has a protuberance and a boss which are carried by and project from one of the two sides of the blade and which are spaced from one another along said side, into a notch of a series of circumferentially spaced notches formed in the periphery of said runner disc whist simultaneously disposing the throwing blade in such a manner as to extend substantially radially of said runner disc and in such a manner that said boss is in contact with one face of the runner disc radially inwardly of the protuberance; (2) sliding said boss along said one face in a radially inwards direction in order to bring said boss into register with an aperture which extends in an axial direction through said runner disc and in order to cause the protuberance to move farther into said notch;; (3) moving the radially inner end of the blade in such a manner as to move said boss in a direction axially of said runner disc in order to cause a neck portion and an enlarged head portion, which together constitute said boss, to extend into said aperture and in order simultaneously to bring the major proportion of said one side of the blade into contact with said one face of the disc; (4) moving the blade in a direction radially inwards of the runner disc in order to complete the insertion of said protuberance into said notch and in order to position the enlarged head portion of said boss in such a manner that said head portion is out of axial alignment with said aperture and consequently inhibits retraction of said boss through said aperture; and (5) connecting said protuberance to said disc in a secure manner by screwing a screw or screwer bolt into the thickness of said disc in such a manner that said screw or bolt extends substantially radially inwardly towards said aperture.

The present invention also consists in a machine of the type described (as defined above) and as described below with reference to the accompanying drawings in which: Figure 1 is a general arrangement showing such a machine; Figure 2 is a plan view of one face of a runner disc; Figure 3 is a section on the line Ill of Figure 2; Figure 4 is a plan view of a throwing blade; Figure 5 is a side view of the throwing blade shown in Figure 4; Figure 6 is a section through the throwing blade of Figure 4 on the line A-A; Figure 7 is a view of the throwing blade shown in Figure 4, looking in the direction of the arrow X; Figure 8 is a section along the line B-B in Figure 4 of the boss which forms part of said throwing blade; Figure 9 is a view similar to that of Figure 4 but of an alternative blade; and Figures 10 to 14 are views of a runner disc edge guard.

Referring to the drawings there is a runner disc 10 connected to the hub 11 which is secured to a shaft 12 of a motor 13. The runner disc 10 has its periphery so formed as to provide a series of notches 14 (8 notches are shown in the drawing, equally spaced from one another circumferentially of the disc) and the runner disc is drilled and tapped at 15 radially of the runner disc at the bottom of each notch 14. The runner disc is provided with apertures 16 for the bolts by means of which it is secured to the hub 11 and is also provided with through-apertures 17 which are in alignment radially with the disc with the longitudinal axes of the various tapped drillings 15.

It will be seen from Figure 3 that each of the through-apertures 17 consist of a drilling 18 which has been counter-bored at 19; the function intended to be performed by the through-apertures will be explained below.

Referring to Figures 4 to 8, and also to Figure 9, there is shown a reversible throwing blade 20 which has opposed faces 21, 22 which are bound longitudinally of the blade, by opposed flanges or sides 23,24. In use of the blade, as herinafter explained, the end 25 will be the radially inner end and the end 26 will be the radially outer end. The side 24 of the blade carries a protuberance 27 and a boss 28, the boss 28 being positioned quite near to the end 25 and the protuberance being spaced apart from said boss.

The boss 28 consists of a neck portion 29 and an enlarged head portion 30; in the particular embodiment illustrated the neck portion and the head portion are circular in cross-sectional shape but are eccentric with respect to one another. This eccentricity provides the boss with a portion which has been indicated by the reference numberal 31 in Figures 4 and 9.

The protuberance 27 is drilled and countersunk at 32 for a purpose hereinafter described.

Assuming that the runner disc 10 has been mounted on the hub 11 and also assuming that the duct means 40, rotatable impellor 41, control cage 42 are in their customary positions as illustrated, the throwing wheel can be made up, with those parts in situ, by adopting the following procedure: A throwing blade 20 is placed against the outer surface of the runner disc 10 in such a manner that the protuberance 27 will extend partially into the respective notch 14 and in such a manner that the boss 28 is in contact with that outer face near to the respective through-aperture 17. The blade 20 is then slid radially inwardly until the enlarged head 30 of the boss can drop into and through the portion 18 of the aperture 17; in that condition, the enlarged head will have become positioned in the counterbored portion 19 and the neck portion 29 will have become positioned in the portion 18.The flat surface of the side 24 of the blade 29 will now be lying against the flat outer face of the runner disc 10 and the blade can, therefore, be slid further radially inwardly of the runner disc in order to cause the portion 31 of the boss 28 to lodge behind the ledge or shoulder 50 of the counterbore 19; thus positioned, the radially inner end of the blade 20 cannot be moved to the left as seen in Figure 3 because said portion 31 engages the ledge or shoulder 50. During these successive radially inwards movement of the throwing blade 20, the protuberance 27 has moved further into the notch 14, finally moving into contact with the bottom of said notch.

The blade 20 is now firmly secured to the runner disc 10 by inserting a screw or screwed bolt 60 into the drilling and counterbore 32 and screwing that screw or bolt into the tapped drilling 15.

This procedure will obviously be repeated until there are 8 blades mounted on the runner disc.

It will be obvious that, when any blade needs to be replaced because it has become unacceptably worn, the above procedure is reversed. It will also be readily understood that a blade can be removed and replaced by a new blade without in any way having to disturb the assembly consisting of the duct, impellor and control cage.

It is also an important feature of the invention that wheels of two standard sizes can be made by using two different sizes of throwing blade; thus Figures 4 to 8 disclose a blade for an assembly which is of 192" diameter whereas the blade illustrated in Figure 9 is for an assembly of 15" in diameter.

Another important feature of the machine according to the present invention is that the screws or screwed bolts 60 can be protected from the particulate material which is being thrown by the wheel in a neat manner. Figure 10 discloses a ring 70 which may be made of rubber or of a plastics material such for example as polyurethane. The ring 70 may have any of the cross-sections shown in Figures 11 to 14; it will be noted from the crosssections of Figures 12 to 14 that there is a boss 71 which is intended to seat in the counterbore in the radially outermost faces of each protuberance 27.

The engagement of that boss 71 in each counterbore, or even in the head of the screw or bolt, will serve to keep the ring 70 in its proper position.

The weight of the runner disc is considerably less than the weight of the massive runner disc disclosed in United States Patent Specifications No. 2,869,289 and No. 2,983,082 and on page 13 of volume II of the work by Plaster. The runner disc in the machine according to the invention may be, for example, 1" thick and 14" in diameter and this disc, together with the mounted throwing blades, will considerably reduce the overhung weight on the bearings in which the shaft rotates.

Another advantage of a machine according to the invention is that blade removal and blade fixing can be achieved by the use of a simple screwdriver and, particularly if the ring 70 is employed, there will be little if any lodgement of particulate material which would otherwise complicate replacement of the blades.

It may prove to be desirable to provide the runner disc 10 with shallow radially extending grooves (not illustrated) in one face thereof, each groove being for the accommodation of a part of the side 24 of the respective blade; in other words, each groove will accommodate a part of the thickness of said side 24, this thickness being measured in a direction which extends transversely of the blade normal to the longitudinal axis of said blade. It is hoped that the provision of said radially extending grooves will not prove to be necessary because of the cost of machining but, until tests have been run (using a wheel constructed as shown in the accompanying drawings) under conditions which will be encountered in normal practical use, it will not be known if said side 24 will lie sufficiently closely to the respective face of the runner disc 10 to prevent particulate material from travelling between said side 24 and said face. It will be apparent to those skilled in this art that if the dust, which is inevitably formed from the use of the particulate material, is able to travel between the opposed surfaces of said side 24 and the runner disc 10, wear of the runner disc will result; this wear might shorten the service life of the runner disc to an unacceptable degree.

Claims (14)

1. A machine of the type described (as defined above) having a rotatable throwing wheel which comprises a single runner disc drivingly connected to a motor and a number of blades mounted on said runner disc in such a manner as to extend radially of the disc; a stationary control cage mounted coaxially with said throwing wheel and positioned radially inwardly of the radially inner ends of the blades; a rotatable impellor arranged coaxially within said control cage; and means for ducting particulate material to said impellor; each blade having opposed surfaces of which at least one is a throwing surface and having flanged sides each of which extends substantially along the full length of the blade; circumferentially spaced notches in the periphery of the runner disc which extend substantially radially of the disc; tapped drillings made in the thickness of the runner disc and extending radially of the disc, each drilling opening at its radially outer end into a respective one of said notches; an aperture in said disc in radial alignment with each of said notches; first and second disc-engaging means on one flanged side of each blade, said first disc-engaging means engaging the disc at a respective one of said apertures and said second disc-engaging means engaging the disc at the respective one of said notches which is in radial alignment with said aperture; and said second disc-engaging means being held in engagement with said notch by screw means which extends through said second disc-engaging means into the tapped drilling which opens into said notch.

2. A machine of the type described (as defined above) having means operable to duct particulate material into a rotatable impellor which is concentrically arranged within a stationary control cage which is both disposed coaxially with a single rotatable runner disc and disposed radially inwardly of the radially inner ends of throwing blades carried on one face of said disc; each blade extending radially of the disc and engaging the disc at two radially spaced locations; the engagement at the radially inner location being such as to prevent movement of the blade axially away from said one face of the disc and the engagement at the radially outer location being such as to prevent movement of the blade at least in directions radially of the disc; and said engagement at the radially outer location including a screw extending through a part of said blade and radially into said disc.

3. A machine as claimed in Claim 2, wherein the engagement at the radially inner location is provided by (a) a boss carried by and projecting from one of the two sides of the blade, said boss consisting of a head portion spaced from said one side and connected to said one side by a neck portion, the head having a cross-sectional area greater than that of the neck portion, and (b) a through-aperture in said disc of a size and shape such as to permit said head to be moved axially of the disc until said one side of the blade is in contact with the disc and thereafter radially of the disc in order to bring the neck into contact with the wall of said through-aperture.

4. A machine as claimed in Claim 2, wherein the engagement at the radially outer location is provided by (a) a protuberance carried by and projecting from one of the two sides of the blade, said protuberance being so fashioned as to accommodate the head and a part of the threaded shank of a screw or screwed bolt, with its longitudinal axis parallel to said one side of the blade and contained in the plane which divides the thickness of the blade into two equal portions, and (b) a notch which interrupts the periphery of the disc and which extends radially of the disc and into which there debouches the open end of a tapped drilling which extends radially inwardly of the disc within the thickness of the disc, said screw or screwed bolt being screwed into said tapped drilling and maintaining not only said protuberance in said notch but also said one side of the blade in contact with the respective face of the disc.

5. A machine as claimed in any one of the preceding Claims, wherein each face of each blade is a throwing surface, whereby the machine is revers ible.

6. A machine as claimed in any one of the preceding Claims, wherein the runner disc is provided, in one face thereof, with spaced radially extending grooves each of which accommodates a part of one side of a respective one of the blades.

7. A machine as claimed in Claim 1 or as claimed in any preceding Claim which is appended to Claim 1, wherein a protective ring which encircles said runner disc/blades assembly covers the said several second disc-engaging means, whereby said disc-engaging means are protected from the destructive action of the particulate material during use of the machine.

8. A machine as claimed in Claim 7, wherein said protective ring is made of an elastomeric or plastics material.

9. A machine as claimed in Claim 2, wherein a protective ring which encircles said runner disc/ throwing blades assembly covers the heads of the several screws, whereby said screws are protected from the destructive action of the particulate material during use of the machine.

10. A machine as claimed in Claim 7 or Claim 9, wherein said protective ring has means adapted to provide a releasable connection between itself and runner disc/blades assembly.

11. A method of assembling a throwing wheel of a machine of the type described (as defined above), said machine having means operable to duct particulate material into a rotatable impellor which is concentrically arranged within a stationary control cage which is both disposed coaxially with a single rotatable runner disc which forms part of the wheel and disposed radially inwardly of the radially inner ends of throwing blades which also form part of the wheel and which are carried on one face of said disc, said method comprising the following steps, namely, (1) inserting the protuberance of a throwing blade, which has a protuberance and a boss which are carried by and project from one of the two sides of the blade and which are spaced from one another along said side, into a notch of a series of circumferentially spaced notches formed in the periphery of said runner disc whilst simultaneously disposing the throwing blade in such a manner as to extend substantially radially of said runner disc and in such a manner that said boss is in contact with one face of the runner disc radially inwardly of the protuberance; (2) sliding said boss along said one face in a radially inwards direction in order to bring said boss into register with an aperture which extends in an axial direction through said runner disc and in order to cause the protuberance to move farther into said notch;; (3) moving the radially inner end of the blade in such a manner as to move said boss in a direction axially of said runner disc in order to cause a neck portion and an enlarged head portion, which together constitute said boss, to extend into said aperture and in order simultaneously to bring the major proportion of said one side of the blade into contact with said one face of the disc; (4) moving the blade in a direction radially inwards of the runner disc in order to complete the insertion of said protuberance into said notch and in order to position the enlarged head portion of said boss in such a manner that said head portion is out of axial alignment with said aperture and consequently inhibits retraction of said boss through said aperture; and (5) connecting said protuberance to said disc in a secure manner by screwing a screw or screwed bolt into the thickness of said disc in such a manner that said screw or bolt extends substantially radially inwardly towards said aperture.

12. A machine of the type described (as defined above), said machine being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

13. A method of assembling a throwing wheel of a machine as claimed in Claim 6, said method being substantially as hereinbefore described with reference to the accompanying drawings.

14. Any features of novelty, taken singly or in combination, of the embodiments of the invention hereinbefore described with reference to the accompanying drawings.