US1763662A - Pneumatic jar-ramming molding machine - Google Patents

Description

w. LEWIS 1,763,662

June 17, 1930.

PNEUMATIC JAR RAMMING MOLDING MACHINE 3 Sheets- Sheet 1 Filed June 15, 1927 IN VEN TOR wing? v BY W rag FORNEY June 17, 1930. w. LEWIS 1,763,662

PNEUMATIC JAR RAMMING MOLDING MACHINE Filed June 15, 1927 3 Sheets-Sheet 2 WITNESSES:

a-"4:1 QSQWW June 17, 1930. w. LEWIS 1,763,662

PNEUMATIC JAR RAMMING MOLDING MACHINE Filed June 15, 1927 3 Sheets-Sheet 3 coo I O ff w-e g lewdi ATTORNEY.

.7 .40 valve shown in Fig. 2.

Patented June 17, 1930 WiLFRED Lewis, or, navamoee, rennsewiimi enema-m me-eanivnaenbtbise Machine appnaadn ties has '15,

This application is a continuation'in part of my application S. No. 141,090 filed 12 October, 1926. g

Objects of the present invention are to prea vent an excessive overrun of thetable; to avoid material variations in the length of the stroke of the table; to provide for shifting the jarring valve at veryslow speeds'so that the exli'aust will always be wide open when it opens at all; to avoid destructive effects in the nature of hammer blows and to cushion the valve stem; to give the exhaust valve a lead in closing so as to retard the table and insure proper contact of the mold with it; to adapt the operation of the machine to and make it equally efiective under diiferent loads imposed by different flasks; and, in the case of shocklessmachines, to keep the anvil and the table in step. I

Other obj ects of the invention willappear from the'following description and the invention will be claimed at the end of the description and the description will begiven with reference to i the accompanying drawings forming part hereof and illustrating anembodiment of the invention and in which drawings V Figure l'is a sectional view ofa shockless jarring machine embodying all the features of the invention. 7

, Figure 21s a view oflthe operating valve in section drawn to an enlarged scale showing one of the machine parts to which the improvements apply. i a

Figure 3 is a view in section on the line MN Fig. 2 showing the air passages leading from the operating valve to the jarring cylinder.

Figure at is a top view of the operating Figure 5 is a view in cross section correspohding to Figure 2 showing the piston J in raised position with the exhaust valve"D open. 1 y

Figure 6 is a similar view in cross section showing the inlet ports H closed owing to the raised postion of the piston J. a 1

In the drawings, 1 is a jarring cylinder having an exhaust valve seat 2. J is a jarring plunger having an airchamber C provided 1ee-"7.' steam. ease.

with an air inlet I and with an'admission" valve seat 0 Bis a hollow valve body movable in the air chamber O, having twointernal diameters, 6 and i, with choke holes, E, inthe wall of 6, at its lowerend. There is provided at diameter 6 a cylinder space,.an'd ,1, at the A lbWl end of the body, B, is an admission v'alve of diameter, 7 to seat upon G K is a spring arranged between the choke sleeve, S, (adapted to seat on a shoulder at the lower end of the casing C) and the valve body B ahd tendingto open the admission valve. B is a bushing of diameters b and 4 centered in the valve body and firmly secured thereto. This formsa stop for the piston V on the valve stem, V, beneath, and acts as a guide for its upper end, V The hollow valve,sten1,V, has three external cylindrical surfaces, V at the top, of diameter 3, in sliding relation with the bushing B .V beneath, of diameter '6, moving between stops in the valve body, and V at the lower end, of diameter 4, bothV and V, are in packed sliding relation with B, and

V is carried downto exhaust. The portion of diameter V constitues a piston element in j the cylinder space at diameter 6. Immediately below the piston V for a length about equal to the travel of the valve stem in the valve body, the diameter 4 is reduced to provide clearance, Y, in Whi'c'h'air' can-be stored a when the piston, V is down against the shoulder on valve body at E, for a, purpose .to be disclosed. vPressur'e' is admitted tothe interior of the valve stem thru ports H, ar-

ranged below the admission valve and carried thru ports, X, in the wall of V into the annularcylinder space above the piston V D is a double faced hollow exhaust valve of' which one face, D cooperates with the valve seat, 2, and of which theother face-,D' ,-coopcrates with the seat, 11, provided in a contractionatthe lower end, V of thestem V.

S is a bypass choke sleeve, sli'dably mounted on the valvesteln at V It is'tr'aversed on -V in one direction by a "shoulder on the ,3 lower end of the chamber C and in the other directionby the spring, K, under the valve body, B, and in its highest'position it covers the ports, H. The diameter of the air inlet, I, is somewhat greater than that of the valve stem V to provide clearance when the latter is raised to open the exhaust. The stops, 1?), on B are arranged to keep open air passages Z Fig. 4 to the chamber C. The valve D has pin and slot or lost motion connection 12 with the stem V.

In its initial position, as shown in Fig. 2, the valve body, B, is in the condition of immersed equilibrium. The pressure in the chamber, C, surrounds it on all sides and its weight only rests upon the sprin K. In this position, also, the valve stem, T7, is held down on its seat, D by the air pressure above it, which is not balanced on the diameter of D, beneath, an amount substantially equivalent to the air pressure on the diameter 3 of V plus the weight of the valve stem. \Vhen pressure enters the chamber, C, it passes thru the passages 15 in the choke sleeve S, under the plunger, J, and causes it to rise carrying with it the sleeve, S, and the valve. body, B, on sprin K, until the valve body stops against the piston V after which the continued upward movement of J compresses the spring, K, until C meets B and cuts off the air supply. At this point the additional lifting force of the spring, K, must be less than the load carried on the valve seat, 11, by a liberal margin, to insure a tightly closed exhaust as the plunger continues to rise by momentum and lifts the valve stem, V at its seat, 11, away from the valve face, D At this time the ports H are closed by the sleeve, S, and the air within the valve stem immediately escapes reducing the pressure in the annular space above V to that of the exhaust, without affecting the pressure beneath the plunger, J. The way is thus prepared for quick and positive action in the opening of the jarring cylinder to exhaust. The air trapped in the clearance space, Y, immediately expands lifting D, away from its seat 2 while air entering thru the choke holes, E, carries the valve stem up at apredetermined rate faster than the table can fall by gravity, but under control, to minimize the velocity of impact between the valve stem V and the cushion sleeve C. Hitherto in air thrown valves for a like purpose, the valve stem, V has struck the cap on the valve body above it at such high velocities as to be very destructive. The cap bolts have frequently been broken and the valve parts have been upset in a way to prevent their proper action. Here the velocity of the valve stem, V, is further reduced as V approaches B by the increasing resistance of the outlets, X, for the air trapped around them to which the normal leakage around the unpacked stem, V contributes. It may here be remarked that more or less leakage 1s unavoidable even when packing rings are employed and since some air will escape from the jarring cylinder in action when it should be confined, a corresponding input can do no harm. Good sliding fits without packing are therefore contemplated for the valve stem at V and V where the sleeve, S, covers the port holes H. In this way, also, full holding down pressure is assured 011 V after the ports, H, have been covered by the sleeve, S, on the rising stroke of the jarring plunger. Then, when the valve stem seat, 11, is lifted from its face, D the air within the valve stem escapes to exhaust, and the valve stem rises picking up the exhaust valve, D, and separating the face, D from its seat 2 for a wide open exhaust from the jarring cylinder, J. This upward movement of the valve stem is made as rapid as need be to exceed the downward velocity of the falling plunger, slowing down toward the end of its travel to cushion the impact between V and B \Vhen this contact has been made the valve, D, rests upon the cross pin, 12, and the face D is ad vanced by the lost motion in the slot for the pin 12 to close the seat 2 before the plunger J, strikes the plate 10 in the bottom of the jarring cylinder. hen this lost motion has been taken up, the valve face D closes against its seat 11 and stops the downward movement of the valve stem and valve body, while the jarring plunger continues to fall opening a space between B, and C known as the valve lead, after which the body B is raised further by the spring, K, while air flows thru the choke holes, 15, to lift the arring plunger, J. In this way air is trapped in the jarring cylinder before the jarring blow is struck, thus saving in air consumption while reducing the objectionable rebound, which tends to laminate the sand and prevent the uniform adhesion desired.

Further than this, the double seated valve, D, acts in effect like a pilot to prepare the way for a wide open exhaust with the least possible overrun in the rising table beyond its position when exhaust begins. This is advantageous in plain machines because it makes substantial uniformity in length of stroke possible, and it is especially desirable in shockless machines where an overrun of the table tends to put the table and anvil out of step with each other, causing the machine to run more or less wild, striking blows at irregular intervals which vary in intensity and sometimes miss altogether as the table rides on air. V'Vhen the valve, D, steps against its seat, 2, and the plunger, J, continues to fall, the air trapped in the jarring cylinder will be compressed until D seats against 11, and begins to lift B away from C to admit live air. The amount of this compression is determined by the clearance space when D is closed and the reduced space when the inlet valve opens, the difference being the volume represented by the plunger area times the movement of D between its stops, which can be varied as desired for different conditions. In general, however,

the pressure attained by compression should not exceed the minimum live air pressure in the valve body, C, for which the spring, K, is adjusted. More compression will open the inlet valve, prematurely and less compresvalve thru which it passes to the tank, T, from which air is admitted to the valve body, G, thru the admission or starting valve A. G is a pressure gauge on the tank, T, by means of whichthe balancing pressure required to support the loaded table and the working pressure can be observed. To read the pressure on the gauge G required to support or balance the loaded table, the clamp for the spring 18 maybe released and air is admitted to the tank by partially opening the valve L, and just as the table begins to rise the pressure on the gauge G is noted, atthe same time air enters the cylinder 22 and acts upon the piston 27 which is slightly larger than the valve stem 25 beneath, thus the spring compressed and then the crosshead 19 1s-clamped in that position. Now when the valve L is open wide the pressure in the tank will increase, say about 15%, and close the reducing valve towards its seat compressing the spring 18. The gauge G now reads tie working pressure. As air is used in jarring, the valve .17 will automaticallyopen to mamtam tank pressure in excess of balancing; pressure. The latter must always exceed the former by an amount required to give the desired speed which can be regulated by the reducing valve, R, in which the check valve 17 is held open by the'load spring 18 and closed by the tank pressure on the area of its lower face. The

load spring, 18, acting upon the check valve,

17, carries at its upper end a crosshead, 19, adapted to slide on the standards, 20, and be firmly secured thereto by the clamping bolt, 21. These standards are attached as shown to the reducing valve body, R, and carry at their upper ends the cylinder, 22, in communication with the tank, T, thru the pipe 23. This cylinder is bored to a diameter, 26, slightly greater than the diameter,

25 of the valve stem, 17, and the crosshead, 19, is carried up into the cylinder, 22, to form the piston head, 27, in elastic connection therewith. The piston 27 is packed in its cylinder 22 and the pressure in the tank T, acts upon its area to compress the spring 18 when the starting valve, A, is opened and air is admitted slowly thru the globe valve L, The

same pressure acts upon the check valve, 17, on its diameter, 25, which is also packed in the valve body, R, but the area of 26 being greater than that of 25 and the weight of the movmg parts, acting in the same direction, the pressure on 27 will overcome the opposing pressure on 17 and hold the latter wide open. Under the above conditions the pressure in the tank T as indicated by the gauge G will be the balancing pressure on the plunger, J, requiredto support the jarring table and its load, whatever that may be, and if we now clamp the orosshead 19 to its standards, 20, we may follow this immediately by setting L wide open to operate the machine. The pressure in the tank T will then rise automat ically'to give a certain limiting speed asdesired for the loaded table and the length of stroke will be kept within'the limit required for shockless machines to keep the table and anvil in step- 28 is a flexible hose connection between the starting valve, A, and the jarring table, and 24 1s a drip cock for drawing oii the water of condensation in the tank,

T,'but of course the outlet to the machine can be arranged as desired to carry off all liquid deposits thru the exhaust from the jarring cylinder.

As shown in Fig. 2 the jarring plunger is at rest above its striking plate, 10, supported by the cushion, 9, and the plate, 8, be-

neath, the admission valve, B, has been raised from its seat C by the valve stem V and carried up to wide open position by the expansion of the spring, K. g

It has been observed that the valve stem V in rising, under thepressure admitted thru the choke holes, E, will be stopped and held from a further upward movement by the bushing B and it should be pointed out that this follows from the relative areas nested and opposed to each other in sliding relation. Some latitude is permissible in these relative areas but not a great deal, and,

to illustrate suitable proportions, care has been taken to make the descriptive numbers applied to the several diameters, proportional to the actual-diameters required, beginning with 3 for the diameter of V and ending .with 7, for the diameter of the valve 13,.

In the drawing the parts are shown in the positions which they occupy when the air is turned off from the inlet, I, at some point outside of the machine, as at A or the valve L.

' The operation may be recapitulated as fol lows:

When air under pressure is turned on to lift the plunger, J,'it passes the choke holes 15 in the sleeve, S, entering the jarring cy1- inder, 1, below the plunger J, lifting the plunger and table, and the area of the holes, 15, limits the speed of the plunger and table. The reducing valve, R, performs a similar function with respect to the load on the table. If the load on the table is comparatively light,

the valve, R, may be assumed to remain in the position shown in Fig. 1 with its spring, 18, but little compressed, but if the load is comparatively heavy, the pressure under the plunger required to lift it, as shown by the gauge, G, and the spring, 18, is adjusted automatically and the crosshead, 19, is clamped in the position assumed, thus increasing the pressure in the tank, T, and adjusting the air supply to the load. In this way an abundant supply of air at proper working pressure can be held near the machine to meet any require ments and at little or no expense, because the air tank, T, now serves as a valve stand and the reducing valve, R, is a very simple and cheap device to accomplish the end in view.

Air under pressure enters not only the jarring cylinder, 1, and lifts the plunger, J, but also enters the chamber in the stem, V, by way of, H, and passes thru the ports, X, into the annular space over V The admission valve, B is held open by the spring IQ In rising, the plunger lifts the sleeve, S, covering ports, H, thus excluding the interior of stem, V, from the ingress of air under pressure. The pressure in the stem, V, acting thru the holes, X, upon the piston head of the valve stem, serves with the direct pressure on V to hold down the exhaust valve D. As the plunger rises the stem V remains stationary and the admission valve seat, 0 contacts with the valve face, B closing air admission, thereupon thru the lost motion connection the port, 11, is uncovered and the interior of the stem, V, connected to exhaust as is also the space over V The result of this is that air trapped in Y as well as air entering through holes E throws the stem upward with a quick motion at first and slower motion thereafter due to the restricted area of the holes, E, and this upward motion of the stem, V, opens the exhaust wide and quickly. The valve stem, V, is cushioned in its upward movement by the reduced outlets, X, before contact takes place between V and B and as the plunger now falls, the lost motion connection 12 causes the valve, D, to close the exhaust and to trap air under the plunger so that the fall of the plunger is checked, thus insuring that the mold or flask, which is falling with the table, is in good contact with it when the blow is struck. A short distance before impact occurs, the valve stem at V meets the bushing B and stops the valve face B while the valve seat C continues to move, thus opening the jarring cylinder to liveair followed by a wider admission. The parts thus assume the position shown in F ig. 1, the spring, K, having lifted the body, B, and opened the admission valve for a repetition of the described jarring operation. The jarring action may be stopped and started by means of the valve, A, alone, until a different load on the table requires a readjustment of the reducing valve, R.

It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement and in matters of mere form without departing from the spirit of the invention which is not limited to such matters or otherwise than the prior art and the appended claims may requirez I claim:

1. In a ar ramming molding machine having a cylinder and a hollow plunger and a source of air supply under pressure and an exhaust port for the cylinder, and in combination a tubular air chamber and a sleeve fixed in spaced relation to the plunger to provide an air inlet passage to the cylinder, a tubular valve body spaced from the inner wall of the chamber to provide a continuation of said inlet passage, a spring interposed between the sleeve and body to support the weight of the latter, a hollow valve spindle mounted in the body and having one end closed and exposed through the top of the body and having near the other endan exhaust port, a two faced exhaust valve carried by and having lost motion in respect to the spindle and having one face for cooperation with the spindle exhaust port and the other face for cooperation with the cylinder exhaust port, admission valve elements pro vided between the air chamber and the body and which also operate to raise the body by the plunger, air admission ports arranged below the admission valve elements and in position for cooperation with the sleeve and extending from the inlet passage to the interior of the spindle, a piston element provided on the spindle, cylinder spaces pr0- vided in thebody above and below the piston element and of which the lower one is pro vided with a head adaptedto lift the spindle element by the piston element and away from the seated exhaust valve as the body is moved by the moving chamber and plunger, and ports provided from the lower cylinder space to the air inlet passage and ports provided from the upper cylinder space to the interior of the spindle whereby when the spindle uncovers the seated exhaust valve by the lifting action of the chamber and body and plunger the spindle is moved by its piston under the differential air pressure in the cylinder spaces and quickly lifts the exhaust valve to uncover the cylinder exhaust port.

2. In a jar ramming molding machine having a cylinder and a hollow plunger and a source of air suply under pressure and an exhaust port for the cylinder and in combination a tubular air chamber having an admission valve element and carried by the plunger, a spring supported tubular valve body within the chamber and having an admission valve element, a hollow valve spin-- dle having an exhaust port, a two faced exhaust valve carried by and having lost motion in respect to the spindle and of which one face cooperates with the cylinder exhaust port and of which the other face cooperates with the spindle exhaust port, pneumatic means for holding the spindle down onto the exhaust valve and the exhaust valve down onto the cylinder exhaust port as the rising plunger and chamber close the admission valve and for then lifting the spindle to uncover its exhaust port by means provided between the body and spindle, and pneumatic provisions operative in respect to the opening of the spindle exhaust port to rapidly raise the spindle and with it the exhaust valve to uncover the cylinder exhaust port.

3. I11 a jar ramming molding machine hav ing a cylinder and a hollow plunger and a a source of air supply under pressure and an exhaust port for the cylinder, and in combination an air admission valve element closed by rising movement of the plunger, a double faced exhaust valve of which one face covers the cylinder exhaust port, pneumatic mechanism for holding the exhaust valve in position to cover the cylinder exhaust port during part of the rising motion of the plunger, and pneumatic means having an exhaust port controlled by the other face of the exhaust valve and adapted for mechanical actuation by further rising movement of the plunger to uncover the last mentioned exhaust port and to thereafter lift the exhaust valve with a quick mot-ion to uncover the cylinder exhaust.

4. In a ramming molding machine having a. cylinder and a hollow plunger and a source of air supply under pressure and an exhaust port for the cylinder, and in combination an exhaust valve covering the cylinder exhaust port, pneumatic means for holding the exhaust valve in position for covering said port during a part of the rising movement of the plunger, and pneumatic means controlled by the rising motion of the plunger and adapted to move said exhaust valve quickly to uncover the cylinder exhaust during a continuation of the movement of the plunger.

5. In a jar ramming molding machine a plunger and cylinder, a pneumatic power device, admission and exhaust valves for the cylinder and for the pneumatic power device, means operated by upward movement of the plunger for closing the admission valve of the cylinder and the admission valve of the power device, means for mechanically opening the exhaust valve of the power device by further upward movement of the plunger, and connections between the exhaust valve of the cylinder and the power device whereby when the power device exhaust valve is Opened said device operates pneumatically to rapidly open the cylinder exhaust valve.

WILFRED LEWIS.

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