US2345958A - Exhaust hood - Google Patents

Description

April 4, 1944.

s. E. wooDBuRY EXHAUST HOOD Filed May 5, 1943 2 Sheets-Sheet 1 4 INVENTOR. M... (Mm-3' April 4, 1944.

- S. E. WQODBURY -EXHAUST HOOD Filed May 5, 1943 2 sheets-sheet 2 INVENTOR. r BY 'drm E@ Patented Apr. 4, 1944 UNI-TED STATES PATENT OFFICE EXHAUST HOODA Stephen E. Woodbury, Beverly, Mass., assigner to Reid Brothers Company, Inc., Beverly,'Mass.,a corporation of Massachusetts f Application May 5, 1943, seria1.No. 485,748

r claims. (or tl-evsy This invention relates to an exhaust hood.

The invention has for an object to provide a novel and improved exhaust hood particularly adapted for use in a vacuum operated, exhaust system with a grinding wheel orl other rotating dust creatingmember for enabling the dust laden air created during the rotation of the Wheel in contact with the work to be removed,v and whose construction is such as to contribute greatly to increased efficiency in dust removal..

With this general object in review, and such others as may hereinafter appear, the invention consists in thel exhaust hood, in the. vacuum operated exhaust system,l and in the. various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

In the drawings illustrating the preferred embodiment of the invention as embodied in avacuum operated dust removal system for a grinding 'wheeL Fig. 1 is a front elevation of an exhaust hood embodying the present invention shown with the hinged front section removed; Fig. 2 is a plan View of the present exhaust hood; Figs. 3 and 4 are cross sectional views taken on the lines 3-3 and 4 4 respectively of Fig. l; Fig. 5 is an end view in vertical cross section taken n the line 5-5 of Fig. l, and Fig. 6 is a plan view in cross section taken on the line 6--6 of Fig. 1.

In general, the. present invention contemplates an improved construction of. exhaust hood particularly adapted for use with a grinding wheel for removing-the dust, grit and metal particles created during the grinding operation, and the present invention seeks particularly to counteract the eiTect of the centrifugal force of the rotating wheel which normally tends to displace the air outwardly from the hood to thereby greatly increase thev efliciency of the dust removal characteristics of the exhausting system.

In observing the behavior of the air adjacent a prior hooded grinding wheel in the operation of a vacuum dust removal system, it appears that the wheel entrains considerable air upon its rough sides, causing` a fan-like eiTect, setting up air currents resulting in a strong outward flow of air from the hood opening. Thus it will be seen that the vacuum provided in the hood by the exhaust system, to which the hood is connected, is substantially neutralized or, at least, greatly reduced in eiectiveness so that but a small part of the dust laden air enters the hood. In practice, the particles of grit and metal leave the wheel at relatively high velocity,y and this movement together with the outward. flow of theair as' above. .described causes the particles to continue'outwardly beyondk the hood, onlythose relatively heavy particles which are bodily thrust into thehood finding their way into the` exhaust system'. Thus it will be'seen that such prior exhaust: hoods are. ineffective to remove, the dust laden air efficiently.

In, accordance with. the present invention, provisionis made for reducing to aminimum the displacement of air caused by the rotationA of the wheel,. preferably' by applying a. vacuum to both sides of the Wheel whereby to set up an opposing force drawingv the air inwardly towards the center .,of, the Awheel and counteracting the outward how` of.y air caused bythe centrifugal force. As aresuitoi this neutralizing.action,..the main hood opening` isY enabled to operate with increased e-; ciency, so as. .to remove practically all the dust laden. air. adjacent: the work, being ground. It was. alsofound, inpractice, that asa result of the counteracting current of air being drawn inwardly from the sides of the wheel towards the center thereof., af relatively Weak vacuum at the main hocdeopening permits the atmospheric pressure to drive the `dust laden air` into the. hood. In other words, the velocity. of the particles leaving; thewheelis greatly reduced by this expedient soi that a relatively low degree. of vacuum is sufficient, to: draw the particles into the exhaust system. Referring now to the drawings which illustrate the preferred embodiment of the invention,y the present exhaust hood, represented generally by thenumeral lla comprises an arcuate casing l2 formed about the upper portion of a grinding wheel iii, shown in dotted lines, the bottom of the vcasing being provided with an opening I6 adjacent the work l 8 which is mounted on and movable: with the reciprocable table 20 of ar grinding machine, The arcuate casing is connected by a, laterally extending and tapering duct 22 to a cylindrical duct 2li which latter may and preferably will be connected to piping, notl shown, forming part of `anl air exhausting system. A vacuumis produced in the casing for drawing the dust laden air adjacent the work into the opening i6. 'In the. illustrated embodiment of theinvention, the tapering duct 22 extends from the left of the casing I2, as viewed in Fig. l, in apcsition to receive the grit and metal particles-being projected from the clockwise rotating; grindingwheel I4 in contact with the Work. As-shown in Fig. 5, the casing is also provided with a. rearwardly extended arcuate portion 26 having-aa flange; 2-8-.bolted` .to avertically adjpst.

able spindle bearing 30 of the grinding machine.

As herein illustrated, the arcuate casing, indicated generally at I2, is provided with an inner chamber 32 formed by an inner arcuate wall 34 and side walls 36, 38 having the opening I6 at the bottom and communicating directly with the tapering duct 22. The arcuate casing l2 is also provided with an outer chamber 40 formed about the walls or the inner chamber by an arcuate wall 42 and side walls M, 46. The outer chamber lo communicates with the inner chamber 32 through openings Q8, 50 formed in the side Walls 3S, 38 respectively, adjacent the central portion of the wheel ils', and is provided with a separate air withdrawal duct 52 opening into the rear of the casing i2 and leading to lthe duct 24 connected to the exhaust system, as clearly shown in Fig. 6. The front portion 54 of the casing I2 is preferably hinged as at 56, see Fig. 5, in order to permit such portion to be rocked up out ci the way for convenience in assembling or replacing a grinding wheel upon the spindle 3l. As herein shown, the inner and .outer side walls 36, "i4 respectively, form part of the hinged cover portion 5d and when the latter is closed into assembled relation with the main or body portion of the casing, a continuous duct or chamber 4l] is for-med around the top and sides of the wheel, the bottom portion being closed by integral bottom walls 58, and 60.

In the operation of the device as thus constructed and as above described, it will be seen that any air pressure built up within the hooded portion of the exhaust hood by the rotation of the wheel or any air currents created thereby tending to force the air outwardly from the hood are eiiectively counteracted and substantially neutralized by the novel application of the vacuum to the Wheel. It will be observed that a vacuum is applied toboth sides of the wheel, and as indicated by the arrows in Fig. 5, the air currents set up in the open chamber 32 by the rotation oi the wheel are diverted from their travel in an outward direction and caused to turn about and enter either side of the chamber 40 through the openings 48 and 55 adjacent the center of the wheel, or, more correctly, the air pressure is substantially neutralized to render inelective the outward flow of air. As shown in Fig. 5, the air passing through the opening 50 in the side wall 38 passes almost directly itno the duct 52, and the air passing through the opening A8 in the opposite wall 36 is directed outwardly and around the inner wall 3i into the duct 52, which, as above stated, communicates with the duct 24 and theexhausting system.

From the description thus far it will be seen that with the air movement within the hood thus substantially neutralized, the suction opening I6 in the bottom of the hood is enabled to operate with maximuml efficiency since the vacuum applied at this opening is not required to overcome the outward iow of air as was formerly necessary and thus is enabled to more readily pick up the dust, grit and metal particles created during the grinding operation and to carry them away through the duct 22 and into the exhaust system, In practice it was found that a relatively slight reduction in pressure at the opening i6 is eiective to cause the dust laden air to enterthe hood. Thus, the amount of vacuum required to neutralize or substantially nullify the outward iiow of air and to also draw the dust laden air into the hood, need not exceed the amount of vacuum normally applied at the opening I6 alone in prior exhaust hoods, the present invention effecting a more efiicient distribution thereof. l l

While the preferred embodiment of the present invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the folowing claims. Y i

Having thus described the invention, what is claimed is:

1. In an exhaust system for a grinding wheel or the like, a hood enclosing the major portion of the wheel and having an opening in the bottom thereof, a main exhaust duct communicating with the hood for carrying away the dust, grit and metal particles created during the grinding operation, and means for counteracting the effect of air movement created by the rotation of the wheel comprising an auxiliary duct connected to a source of suction and communicating with openings formed in either side oi said hood adjacent the center of the wheel whereby to enable said main exhausting duct to operate with increased eliiciency. v

2. In an exhaust system for a grinding Wheel or the like, a hood enclosing the major portion of the wheel and having an opening in the bottom thereof, a main exhaust duct communicating with the hoodfor carrying away the dust, grit and metal particles created during the grinding operation, and means for reducing to a minimum the outward low of air as eiected by the rotation of the wheel comprising an auxiliary duct connected to a source of suction and communicating with openings formed in either side of said -hood adjacent the center of the wheel whereby to eiect a reduction in the velocity of the particles detached from the grinding wheel during the grinding operation and to thus enable said main exhausting duct to operate with increased eiilciency.

3. In an exhaust system for a grinding wheel or the like, a hood enclosing the major portion of the wheel and having an opening in the bottom thereof, a main exhaust duct communicating with the hood for carrying away the dust, grit and metal particles created during the grinding operation, and means for substantially equalizing the pressure built up within said hood by the rotation of the wheel comprising an auxiliary duct connected to a source of suction and communicating with openings formed in either side of said hood adjacent the center of the wheel whereby to eiect a reduction in the velocity of Ythe particles detached from and created by the wheel during the grinding operation thus permitting said main exhaust duct to operate with increased efficiency.

4. In an exhausting device for a grinding wheel o1' the like, an inner hood enclosing the major portion of the wheel and forming a chamber having an opening in the bottom thereof, a main exhausting duct communicating with said chamber and disposed to receive the dust, grit and metal particles created during the grinding operation, and means for reducing to a minimum the outward flow of air as eiected by the rotation of the wheel including an outer hood spaced from said inner hood and forming therewith a second chamber provided with openings directed toward each side of the wheel adjacent the center thereof, and an auxiliary exhausting duct comrnmu'nicating with said second chamber whereby to counteract said outward flow of air to permit said main exhausting duct to operate with increased eiciency. i f

5. In an exhausting system for a grinding wheel or the like, an inner hood extending about the major portion of the circumference of the wheel and around each side thereof forming a chamber having an opening in the bottom thereof, a main exhausting duct communicating with siad chamber and disposed to receive the dust, grit and metal particles created during the grinding operation, an outer hood spaced from said inner hood and forming therewith a second chamber comprising a continuous duct between said inner and outer hoods provided with openings directed toward each side of the wheel adjacent the center thereof, and an auxiliary eX- hausting duct communicating with said second chamber whereby to counteract the outward iiow of air as effected by the rotation of the wheel and thus permit said main exhausting duct to o operate with increased efficiency.

6. In an exhaust system for a grinding wheel or the like, a hood enclosing the major portion of the wheel and having an opening in the bottom thereof, a main exhaust duct communicating with the hood for carrying away the dust, grit and metal particles created during the grinding operation, and means for counteracting the effect of air movement created by the rotation of the wheel comprising an auxiliary duct connected to a source 0f suction and communicating with openings formed in either side of said hood 30 adjacent the center of the wheel whereby to enable said main exhausting duct to operate with increased eiiciency, one side of said hood being hinged with relation to the remainder of the hood whereby to permit replacement of a wheel without removing the hood,

7. In an exhausting system for a grinding wheel or the like, an inner hood extending about the major portion of the circumference of the wheel and around each side thereof forming a chamber having an opening in the bottom thereof, a main exhausting duct communicating with said chamber and disposed to receive the dust, grit and metal particles created during the grinding operation, anv outer hood spaced from said inner hood and forming therewith a second chamber comprising a continuous duct between said inner and outer hoods provided with openings directed toward each side of the wheel adjacent the center thereof, and an auxiliary exhausting duct communicating with said second chamber whereby to counteract the outward flow of air as eifected by the rotation of the wheel and thus permit said main exhaustingduct to operate with increased eiiiciency, one side of the combined hood being hinged and provided with duct forming portions arranged to abut with similar portions of the remainder of the hood to form said continuous duct.

STEPHEN E. WOODBURY.

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