US 3917233 A
A pneumatic vibrator for foundry molding machines and the like has a plunger reciprocable in a bore between striking and exhaust positions. The plunger has exhaust passage means therethrough for exhausting air from an inlet port to an exhaust port in its exhaust position. A striker insert of low sound transmitting material is positioned adjacent the inlet port. Inlet passage means passes air from the inlet port to the vibrator bore through the insert for cooling the same. Noise muffler means covers the exhaust port for reducing noise and preventing entry of foreign material into the vibrator bore.
Claims available in
Description (OCR text may contain errors)
Umted States Patent 1191 1111 3,917,233
Blower Nov. 4, 1975 VIBRATOR 3,132,704 5/1964 Bassinger 91/234 x  Inventor: warren A. Blower, Brecksvine, 3,718,318 2/1973 Blower 259/1310. 43 x Ohlo Primary Examiner-Harvey C. Homsby  Assignee: The Sherwin-Williams Company, Assi nt Examiner-Alan Cantor Cleveland, Ohio Attorney, Agent, or Firm-Donnelly, Maky, Renner & Otto  ABSTRACT A pneumatic vibrator for foundry molding machines and the like has a plunger reciprocable in a bore between striking and exhaust positions. The plunger has exhaust passage means therethrough for exhausting air I from an inlet port to an exhaust port in its exhaust po- 7 11 Claims, 3 Drawing Figures c A I 50 56 12 2s 16 as 411K416 52 so 54 14 54 70 18 U.S. Patent Nov. 4, 1975 A 50 Th W VIBRATOR BACKGROUND OF THE INVENTION This application relates to vibrators, and more particularly to pneumatic vibrators for use on foundry molding machines and the like.
Vibrators are commonly used in foundry molding for enhancing sand flow or assisting removal of molds from patterns or flasks. Such vibrators may be used on foundry molding tables, pattern stools, match plates, hoppers and like parts. The vibrators are usually double-acting and have a sleeve member. A plunger reciprocates within the sleeve between opposite striker plugs. In vibrators of this type, extensive machining of circumferential grooves and ports is required in the sleeve member and plunger. This makes thevibrator costly to manufacture.
Vibrators of the type described are also very noisy. Attempts to reduce the noise level have included the use of elastomeric striker inserts. Repeated striking of the plunger against such striker inserts produces internal friction in the striker insert and they become extremely hot. The inserts then soften and deteriorate very rapidly requiring frequent replacement or reconditioning of the vibrator.
With vibrators of the type described, the exhaust ports are normally open directly to atmosphere. Particles of sand or other foreign material often enter the sleeve through these open exhaust ports and interfere with movement of the plunger. The exhaust ports are also a source of considerable noise. The present invention thus includes several improvements over prior vibrators such as shown in US. Pat No. 3,718,318 dated Feb. 27, 1973 to Warren A. Blower and Emil P. Jerse.
SUMMARY OF THE INVENTION A pneumatic vibrator of the type described includes a housing or sleeve having a cylindrical bore therein. A
as long as air pressure is supplied to produce high frequency impacts.
In accordance with an important aspect of the invention, the exhaust passage is formed in the plunger itself. In one arrangement, the bore has a circumferential groove therein located intermediate the inlet and exhaust ports. The groove is covered by the plunger in its striking position. Movement of the plunger away from its striking position opens the groove to communication with the inlet port. The exhaust passage in the plunger is also opened to communication with the groove. Thus, air is exhausted from the inlet port to the exhaust port through the groove in the bore and through the ex haust passage in the plunger. The exhaust passage may include a plurality of radially extending bores in the plunger communicating with an axial plunger bore which also communicates with the exhaust port.
In accordance with another aspect of the invention, the vibrator includes a striker insert positioned adjacent the inlet port. Inlet passageway means passes air from the inlet port to the bore in contact with the striker insert for carrying heat away from the striker insert. With such an arrangement, the striker insert does not become overheated and rapid deterioration does not occur.
In accordance with another aspect of the invention, the inlet and exhaust ports are formed in end caps closing the opposite ends of the bore. The end cap in which the exhaust port is formed also includes an enlarged flared recess having noise muffler means therein covering the exhaust port. The muffler means may comprise metal mesh or wool-like material. A fine screen is positioned in the recess to hold the muffler over the exhaust port. The muffler and screen prevent foreign particles from entering the bore through the exhaust port. The muffler also substantially reduces the noise of air escaping through the exhaust port. The noise produced by the plunger acting against the striker insert is also muffled.
It is a principal object of the present invention to provide an improved pneumatic vibrator.
It is another object of the present invention to provide a pneumatic vibrator having a very low noise level.
It is a furtherobject of the present invention to pro vide a pneumatic vibrator having a cooling arrangement for preventing deterioration of a striker insert.
It is an additional object of the present invention to provide a pneumatic vibrator with a muffler for reducing noise and preventing entry of foreign particles into the vibrator bore.
It is also an object of the present invention to provide an improved single-acting pneumatic vibrator.
It is a further object of the present invention to provide a pneumatic vibrator 'having exhaust passage means in the vibrator plunger itself.
BRIEF DESCRIPTION OF THE DRAWING The invention may take form in certain parts and arrangements of parts, certain preferred embodiments of which will be-described in detail in this specification and illustrated in the accompanying drawing which forms a part hereof.
FIG. 1 is a cross-sectional elevational view of an improved vibrator constructed in accordance with the present invention;
FIG. 2 is a cross-sectional elevational view of another improved vibrator constructed in accordance with the present invention; and
FIG. 3 is a cross-sectional elevational view of still another improved vibrator constructed in accordance with the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawing, wherein the showings are for purposes of illustrating preferred embodiments of the invention only and not for purposes of limiting same, FIG. 1 shows a pneumatically operated vibrator A including a part 12 having a cylindrical bore 14 therethrough. A generally cylindrical plunger B is reciprocatingly positioned within bore 14. The opposite end portions of the internal peripheral wall forming bore 14 are internally threaded as at 16 and 18 for threadably receiving threaded portions 20 and 22 of end caps C and D. End cap C has a hole 24 thereother device. This is an end mounting type of mounting for vibrator A.
In accordance with one arrangement, an air inlet port 26 is formed in end cap C and communicates with bore 14 on one side of plunger B. Air inlet port 26 is preferably substantially coincidental with the longitudinal axis of bore 14. Inlet port 26 communicates with an air inlet bore 28 adapted to be connected with a source of pressurized air.
Threaded portion of end cap C has an enlarged cylindrical recess 30 therein substantially coincidental with air inlet port 26. A cylindrical striker insert E is tightly fitted within cylindrical recess 30. Striker insert E is made of a material having very low sound transmitting characteristicsSriker insert'E may be formed of urethane, rubber, or similar materials. Obviously, natural rubber or other materials could also be used for striker insert E. Preferably, striker insert E is relatively soft as compared with steel and has the desirable characteristicof low sound transmission. At the same time, striker insert E is relatively hard so that it will not be compressed too much and absorb the force of plunger B. Such action would reduce the action of the vibrator.
In one arragement, striker insert E is made of urethane rubber having a durometer hardness on the shore-A scale of around 80 to 100. A durometer hardness of 90 or above is preferred. Striker insert E may be molded to have an exterior diameter slightly larger than the diameter of cylindrical recess 30 and have a longitudinal slit therethrough. The longitudinal slit makes it possible to squeeze striker insert E to reduce its diameter for insertion within recess 30. The natural memory and resiliency of striker insert E then causes it. to expand radially outward into firm engagement with the peripheral wall of recess 30. Obviously, insert E could also be a tight fit within recess 30 without having a longitudinal slit. Insert E could also be secured in recess 30 by mechanical fastener means or adhesive.
Striker insert E has a centrally located cylindrical hole 34 therethrough substantially coincidental with air inlet port 26. Striker insert E has a length sufficient to project out beyond. the terminal end of threaded portion 20 on end cap C when it is bottomed in cylindrical recess 30.
Plunger B has a striker end 36 adapted to strike against striker insert E. Striker end 36 of plunger B preferably is circular and has a diameter substantially the same as the diameter of striker insert E. Plunger B has a generally conical portion 38 sloping outward from striker end 36 and intersecting a generally radially extending fiat circumferential surface 40. Plunger end surfaces 38 and 40 cooperate with bore 14 to define an annular space 44 at the striker end portion of plunger B.
In accordance with one arrangement, striker insert E has at least one radially extending notch 46 therethrough for allowing passage of air from hole 34 to annular space 44 so that air pressure can act upon plunger end surfaces 38 and 40, as well as against striker end 36.
Bore 1 4 hasa longitudinally elongated circumferential groove 50 formed therein generally intermediate its opposite end portions. Groove 50 has opposite terminal ends 52 and 54. Plunger B includes a rear end 56. An axial bore 58 extends into plunger B from rear end 56 to communication with a plurality of radially extending plunger bores 60. Radially extending plunger bores 60 also communicate with groove 50. A coil spring 64 bears against bottom end 66 of axial plunger bore 58 An exhaust port 72 extends through threaded portion 22 of end cap D and is substantially coincidental with the longitudinal axis of bore 14. An enlarged outwardly opening flared recess 74 is formed in end cap D substantially coincidental with exhaust port 72. .A noise muffler is positioned within recess 74. Recess 74 may be filled with metal wool 76 or the like to define the noise muffler. The material may also be a multilayer metal mesh. Mesh or wool-like material 76 may also be formed of natural or synthetic fibers. A fine circular screen 78 is positioned within recess 74 to hold muffler I material 76over exhaust port 72. End cap D has a circumferential groove 80 therein receiving a C-ring 82 for holding screen 78 in position. The described arrangement with screen 78 and muffler material 76 also prevents entry of foreign particles into bore 14 through exhaust port 72.
Coil spring 64 normally biases plunger B to the left toward its forward striking position as shown in FIG. 1 wherein plunger striker end 36 impacts against striker insert E. Air enters through inlet port 26, hole 34 and notch 46 to enter annular space 44. Air pressure in hole 34 also acts against plunger'striker end 36. Air pressure in annular space 44 also acts against plunger. surfaces 38 and 40 to cause shifting movement of plunger B to the right in FIG.,1 toits rearward or exhaust position. The parts are preferably dimensioned so that the spacing from plunger end 56 to end cap end is substantially greater than the distance from plunger surface 40 to circumferential groove end 52. With plunger B in its forwardmost striking position, groove 50 is covered against communication with annular space 44 and inlet port 26. As plunger B begins moving to the right in FIG. 1 toward its rearward exhaust position, plunger surface 40 will eventually move to the right of groove end 52. This will establish communication between groove 50 and annular space 44. In other words, communication is also established between groove 50 and inlet port 26. Air in annular space 44 is exhausted through radial bores 60 and axial plunger bore 58 to exhaust port 72. The exhausting action occurs before plunger end 56 makes contact with end cap surface 70.
The generally large cavity defined by plunger axial bore 58 and a portion of bore 14 allows a substantial quantity of air to accumulate under slight pressure for aiding spring 64 in shifting, plunger B back to the left in FIG. 1 for again striking against striker insert E and producing vibrations. The size of groove 50 and holes 60, and the large volume of the spring cavity defined by bore 58 and a portion of bore 14, allows rapid reduction of pressure in annular space 44. A large volume of air is exhausted at low velocity to reduce noise. Exhaust port 72 is larger than inlet port 26 so that air will be exhausted at a lower velocity than it flows through inlet port 26. This allows plunger B to return to its striking position. At the same time, exhaust port 72 is somewhat restricted so that some air pressure does build up rearwardly of plunger B to aid spring 64 in moving plunger B forwardly to its striking position. This allows exhaust air to escape relatively slowly through exhaust port 72. Such action aids in reducing the noise produced by vibrator A. The exhausted air passes through and against end 70 of threaded portion 22 on end cap r muffler 76 which also aids in building up a slight pressure rearwardly of plunger B. A substantial pressure drop occurs across muffler 76. Much of the energy and noise is absorbed and dissipated by muffler 76.
In the arrangement described, it will be recognized that hole 34 in striker insert E defines inlet passage means for passing air from inlet port 26 into bore 14 in contact with striker insert E for cooling striker insert E. The rapid repeated striking of striker insert E by plunger B produces internal friction in striker insert E and rapidly builds up heat which might cause striker insert E to deteriorate. The rapid continuous flow of cool compressed air in contact with striker insert E rapidly dissipates heat therefrom to prevent such deterioration. Expansion of air from line pressure to a lower pressure also provides cooling action.
Making the exhaust port means in plunger B itself substantially reduces the number of circumferential grooves and ports which must be formed in the vibrator bore. Such an arrangement also makes it possible to utilize some of the exhaust air pressure for aiding return of the plunger to its striking position. Passage of the exhaust air through the plunger also provides a longer exhaust path than porting directly to atmosphere. This longer exhaust path makes it possible to accumulate some of the exhaust air and relatively slowly exhaust it to atmosphere in order to reduce noise.
FIG. 2 shows a slightly different embodiment wherein like parts are given like reference numerals and letters. In this embodiment, part 12 comprises a cylindrical sleeve fitted within a cylindrical bore 90 on an integral 1 part 92 of a foundry molding machine or the like. Sleeve 12 has a length slightly less than the length of bore 90. End caps C and D have enlarged heads 94 and 96 which extend outward beyond sleeve 12 for engaging the ends of part 92. End caps 94 and 96 are tightened for tensioning sleeve 12. Enlarged heads 94 and 96 firmly engage against the ends of part 92 around bore 90 for securely clamping sleeve 12 within bore 90.
In the embodiment of FIG. 2, plunger B is slightly different in that axially extending plunger bore 58 is not as deep as in the embodiment of FIG. 1 and is coincidental with a somewhat smaller diameter bore 102 which communicates with radially extending bores 60. In addition, end cap D has an enlarged cylindrical recess I04 extending inward from end 70 thereof for receiving one end portion of spring 60 which bears against bottom b of recess 104. The action and advantages of the vibrator of FIG. 2 are the same as those described with respect to the embodiment of FIG. 1.
FIG. 3 shows a slightly different embodiment wherein part 12 has outwardly extending ears 108 with holes 112 therethrough for receiving bolts to clamp the vibrator to another part. This arrangement provides a side mounting vibrator. Also in this embodiment, air inlet bore 28 is formed axially in end cap C substantially coincidental with air inlet port 26 and the longitudinal axis of bore 14. This embodiment also differs from the embodiment of FIG. 2 in that axial plunger bore 58 has a length greater than the length of the corresponding bore in the embodiment of FIG. 2, and the length of bore 102 is somewhat less than the length of the corresponding bore in the embodiment of FIG. 2. In other respects, the operation and advantages of the embodiment of FIG. 3 are the same as those previously described.
Although the invention has been shown and described with respect to certain preferred embodiments, it isobvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the claims.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as fol lows:
l. A pneumatic vibrator including a part having a bore therein, a plunger reciprocatingly positioned in said bore for movement between striking and exhaust positions, air inlet and exhaust ports communicating with said bore on opposite sides of said plunger, exhaust passage means through said plunger for exhausting air from said inlet port to said exhaust port in said exhaust position thereof, opposite end caps closing said bore, said inlet port being in one of said end caps and said exhaust port being in the other of said end caps, said bore having a longitudinal axis and said inlet and exhaust ports being substantially coincidental with said axis, a striker insert of low sound transmitting material adjacent said inlet port, and inlet passage means for passing air from said inlet port to said bore in contact with said insert for cooling said insert.
2. The vibrator of claim 1 wherein said inlet passage means comprises a hole through said insert substantially coincidental with said axis.
3. A vibrator including a housing having a cylindrical bore therein, end caps secured to said housing closing the ends of said bore, a reciprocating plunger in said bore, a sound attenuating striker insert secured to the inside of one of said end caps, and an air inlet in said one end cap aligned with a hole extending through said insert for cooling saidr insert with the inlet air.
4. A vibrator as set forth in claim 3 wherein said hole through said insert and said air inlet are axially aligned and coaxial with said bore.
5. A vibrator as set forth in claim 3 wherein said insert is partially recessed in said one end cap and projects slightly therefrom.
6. A vibrator as set forth in claim 3 wherein said insert is an elastomeric material having a durometer hardness on the shore-A scale of from about to about 100.
7. A vibrator including a housing having a cylindrical bore therein, end caps closing the ends of said bore, a plunger in said bore, an air inlet in one of said end caps and an exhaust port in the other, spring means urging said plunger toward said one end cap, a relatively short by-pass groove in said bore normally closed by said plunger, a longitudinally extending exhaust passage in said plunger including a radially extending passage in said plunger communicating with said groove in all positions of said plunger to exhaust air from said one end of said plunger to the" other when said plunger moves to expose said by-pass groove to said one end.
8. A vibrator as set forth in claim 7 wherein said exhaust port is somewhat restricted to create a backpressure to assist the action of said spring means.
9. A vibrator as set forth in claim 7 wherein said spring means extends from said other end cap into said plunger through at least a portion of said exhaust passage in said plunger.
10. A vibrator as set forth in claim 7 wherein said air sound attenuating striker insert secured to said one end inlet and said exhaust port are axially aligned with each cap and having a hole therethrough aligned with said other and said bore. air inlet for cooling of said insert.
11. A vibrator as set forth in claim 7 including a