US2065144A - Timing mechanism - Google Patents

Description

Dec, 22, 1936.

L. F. MILLER ET AL.

TIMING MECHANISM Filed April 25, 1935 2 sheets-sheet 1 ATTORNEY@l Dec. 22, 1936. L. F. MILLER x-:T Al.

TIMING' MECHANISM 2 sheets-sheet 2 Filed April 26, 1935 mw 4 7 5 ww Mw 55 Il @Wm @im MMWMA if@ y @MW Rnd Patented Dec. 22, 1936 UNITED 'STATES PATENT OFFICE TIMING MECHANI SM corporation of Ohio Application April 26, 1935, Serial N0. 18,393

3 Claims. (Cl. 121-164) This invention is directed to a timing moldmaking method and mechanism particularly adapted for use with fluid-pressure machinery, and especially intended to govern automatically 5 the time of action of jolt machines and squeeze machines, whether separate or combined, for the making of sand molds in foundry work.

In the making of sand molds, it is customary to jolt the mold after iilling in order to compact the sand and a common practice is also to squeeze the mold for the same purpose. Machinery is well known in the trade either for jolting, or for squeezing, and very frequently the two functions are combined in a single machine which is generally made with one cylinder for jolting and another for squeezing, the two cylinders being nested. Compressed air is almost universally used as a motive power for these mechanisms. Inasmuch as it is highly advantageous for the operator to keep his hands free to handle the molds, the supply of air to the machine either for jolting or for squeezing is usually controlled by a valve which the operator opens by knee pressure and holds open as long as he wishes the jolting or the squeezing, as the case may be, to continue.

The present invention is of a character to govern the supply of compressed air or other uid pressure to such machinery so that all the operator need do is open the valve, whereafter the pressure will remain on for a predetermined period and then automatically shut itself oi, thus controlling the number of jolting strokes or the time the squeeze is held.

The purposes of this invention include adding to the art a timing mechanism which will allow operation as indicated for a definite time and stop it at the end of that time, the timing mechanism being of a construction which is accurate, reliable, positive, compact, rugged, which can be easily and accurately regulated and which is relatively simple to manufacture.

ToI the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and the following description set forthV in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In the accompanying drawings:

Fig. 1 is apartly diagrammatic elevation illustrating the piping and valve lay-out and the ap- .55 plication of the timing mechanism;

Fig. 2 is a transverse vertical section through an automatic valve associated with the timing mechanism;

Fig. 3 is a longitudinal mid-section through the timing mechanism;

Fig. 4 is a section on the plane indicated at 4-4, Fig. 3; and

Fig. 5 is a section on the plane indicated at 5-5, Fig. 4.

The fluid for operating such mechanisms is 10 usually compressed air, and this specication is accordingly written designating compressed air, although it will be understood that the apparatus is of general application with any fluid under pressure. l5

In the general lay-out, Fig. 1, the timing mechanism as a whole, indicated by the reference character I, is shown as bolted or otherwise secured to part of the frame or cylinder 2 of a jolt or squeeze or jolt-squeeze machine, although for sim- 20 plicity the invention will hereafter be referred to in its application to a jolt machine.

A valve 4 herein shown as having a knee-actuated operating lever 6 is illustrated as attached to another portion 2 of the machine conveniently 25 accessible to the operator. Air reaches this valve through a branch I from an air main III. Beyond the valve 4, the branch 'I is continued as at 'I' to the valve cage 8 of the timer I, and another branch, 9, runs from the timer to a diaphragm 30 Valve II on the air main I0. The diaphragm valve Il controls flow of air to the jolt cylinder, being connected thereto by a continuation III of the main. Part of the piston P of the jolt or squeeze mechanism (as the case may be) is shown 35 in Fig. l. A cut-off valve I2, ordinarily left open, is illustrated as applied to the continuation I0.

Before proceeding to the description of the timing mechanism, the operation of the valve Il, which is shown in detail in Fig. 2, will be eX- 40 plained as an aid to understanding the use of the timing mechanism.

The valve II comprises a two-piece casing, namely a body I3 and cover I4 having a flexible diaphragm I5 secured therebetween. A disk I6, 45 carried by the upper side of the diaphragm, is downwardly urged by its own Weight and by a spring I'I. The valve body I3 includes an annular air chamber I8 into which the main III leads, and a central outlet I9 from which the continuation 50 IB goes to the jolt cylinder.

The valve cover I4 is hollowed, forming an air chamber 2I of somewhat irregular shape, and a central space receiving the spring II and a stem 0f the disk I6, the stem being within the spring. I55

- chine.

Air under pressure is applied by the branch 9 to the upper surface of the diaphragm I5 and of the disk I6. The air chambers I8 and 2| are connected by a bleed passage 22, constantly open, which passage includes a perforation in the diaphragm I5.

When the branch 9 is closed, leakage of air through the bleed passage 22 builds up pressure in the upper chamber 2 I with the result that when the pressure in the upper and lower chambers 2l and I8 is equalized there is a greater area exposed to air pressure above the diaphragm than below it, so that the diaphragm descends. The descending action is also aided by the weight of the disk I8 and the pressure of the spring I1. The diaphragm in descending seats on the top of the outlet I9, thus cutting off I8 from I9 and stopping flow of .air through the main I9, I 6.-

Relief of pressure in the upper chamber 2I through opening the branch 9 by the timer, as described hereafter, allows the pressure beneath, in chamber I8, to raise the diaphragm, thus opening the main and supplying air to the jolt ma- It is thus .apparent that the immediate function of the timing mechanism in the illustrated preferred embodiment is to cause the opening or closing of the upper air chamber 2 I.

The timing mechanism per se is illustrated in Fig. 3 in its normal position, not under air pressure, ready but not operating. It comprises a cylinder 23 having the valve cage 8 secured to one side. A piston reciprocates in the cylinder and by its motion releases or sets a trigger mechanism protruding into the cylinder through a side opening 24. The cylinder 23 is closed and domed at the upper end by a cap 25 into one side of the top of which an air pipe 1, which is a continuation of 1, enters. The trigger mechanism actuates plunger valves 26 and 21 which open or close the air branches 1 and 9. In Fig. 3 the valve 26 is 'open connecting the branch 1 through the pipe 1 to the cap 25, but there is no pressure above the piston, because the valve 4 is closed. A bleed valve 28, preferably a needle valve, is placed in the top of the cap. An intermediate horizontal baiile 29 extends somewhat more than half way .across the dome to protect the needle valve 28 from oil, dirt, moisture, and foreign matter generally, which would tend to clog it and so stop the action of the timer or decrease its accuracy. A plug 36 closes the cylinder bottom. In the preferred form shown this plug is centrally hollowed as at 3| to receive a spring 32, normallyA holding the piston in the upper position shown.

In the illustrative embodiment the piston is double headed, the upper head 33 being thick and solid, and the lower head 34 thinner and perforated as at 35 for air escape. The two heads are connected by a sleeve 36 of less diameter, also perforated, as at 31, for air escape. A leather packing 38 at the upper end of the piston is secured by the usual means such as a washer and cap screw. The space below the piston head 33 is vented to the atmosphere through the openings 35, 31, 24, and nally out through a passage 39, Fig. 4, in the upper part of the valve cage 8.

The valve cage 8 houses the trigger mechanism in its upper part and its lower part forms` the body of both valves 26 and 21. Removable plugs 40 anda removable side plate 4I give access to the cage interior.

The trigger mechanism comprises the threefingered rocker arm 42 pivoted at 43, and a latch 44 of roughly triangular outline pivoted near one angle of its short base toa pair of upstanding fingers 45 of the rocker arm. The long forward finger 46 of the arm projects into the path of the lower piston head 34 and in down position bears n against the top of the stern 41 of the valve 21, to open that valve. The rocker arm rear finger 48, much shorter, when down contacts the top of the stem 49 of the valve 26, thus opening the Valve. A spring 5I thrusting upon the rear of the latch 44 below the pivot point, and seated in a recess in the side wall of the valve cage 8, urges the latch 44 counterclockwise and the rocker arm Yand dotted line positions, as will be described in connection with the operation of the apparatus. The details of the plunger valves 26 and 21 include the two stems 49 and 41 respectively, each suitably packed, each cone-shouldered at 54 to close on a conical seat 55. Each valve is guided by an enlargement 56 fitting the lower part of the Valve chamber, and is urged up from below by spring 51. l The course of air through the valves is apparent from Fig. 4, the valve there shown being the outer one, 26. The operation of the mechanism is as follows: Starting with the parts in the positions of the drawings, the jolt piston down, and a mold on the jolt table, the operator presses the knee valve lever 6, thereby admitting air to the branch 1. Inasmuch as the valve 26 is open, the air so admitted passes through the pipe 1" into the capl 25 thus moving the piston downward. Air will immediately begin to escape through the needle valve 28 and bleed hole, but the rate of supply l' is substantially greater than the rate of escape. As the piston moves downward, the lower edge ofthe head 33 trips the latch 44 off its shoulder 52, whereupon the rocker arm and latch are moved to the dotted line position of Fig. 3 by the spring 5I, the reduced diameter of the sleeve 36 permitting such movement.

The finger 46 thus opens the inner valve 21, which in turn vents the branch 9 to the atmosphere, relieving the pressure in the upper chamber 2I of the diaphragm valve, Fig. 2, and so opening that valve and admitting air from the main I6 through the extension I0' to the jolt cylinder.

The joltingvcontinues so long as the diaphragm valve remains open. The same movement of the rocker arm 42 to the dotted line position lifts the iinger 48 from the'stem 49, allowing the spring 51 to close the valve 26, thus stopping the supply of air through the branch 1 and pipe 1 to the cylinder 23. With the air supply oi, the pressure above the piston is relieved through the needle valve 28, Vallowing the piston to rise by the pressure of spring 32, the time of rising being regulated by the setting ofthe needle valve.

As the piston rises the lower head 34 pulls up the inner end of the finger 46, thus restoring the latch mechanism to the position of Fig. 3, allowing the valve 21 to close, and opening the valve 26. Thus the branch 9 is closed and air flow through the bleed passage 22, Fig. 2,V builds up pressure above the diaphragm, shutting the diaphragm valve and stopping the jolt action. At the same time the valve 26 is opened, but this by itself is not effective to start the jolt mechanism again be.

cause the valve 4 is now closed. The operator held his knee on the lever 6 only momentarily.

In using our timer for jolt-squeeze machines it is our preferred practice to use one timer for the jolt air supply and another for the squeeze air supply.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

We therefore particularly point out and distinctly claim as our invention:

1. In a pressure actuated timing mechanism, a piston operable by fluid pressure in one direction, means for returning said piston following release of fluid pressure, an air dome above said piston, an air supply connection to the air dome, a bleed valve from said air dome, and a baffle within said air dome shielding said bleed valve while permitting flow of air thereto.

2. An automatic timing mechanism comprising a cylinder, a piston movable in one direction therein by fluid pressure, a spring in said cylinder adapted to be compressed by said piston movement and to move said piston in the reverse direction, a valve operating unit adjacent said cylinder, said unit comprising a lever adapted to press selectively at opposite limits of its travel upon one only of two self-closing plunger valves,

a spring urging said lever to one limit of its travel, said lever protruding into the path of said piston and movable by said piston against the impulse of said spring to the other limit of its travel, admission of air to said piston being controlled by one of said plunger valves, and a bleed exhaust in said cylinder for compressed fluid above said piston.

3. An automatic timing mechanism comprising a cylinder, a piston movable in one direction therein by fluid pressure, a spring in said cylinder adapted to be compressed by said piston movement and to move said piston in the reverse direction, a valve operating unit adjacent said cylinder, said unit comprising a lever adapted to press selectively at opposite limits of its travel upon one only of two self-closing plunger valves, a spring urging said lever to one limit of its travel, said lever protruding into the path of an element of said piston and movable by said piston against the impulse of said spring to the other limit of its travel, a trip finger protruding into the path of another element of said piston, said nger being adapted to hold said lever against the pressure of its spring during part of the piston travel in one direction, admission of air to said piston being controlled by one of said plunger valves, and a bleed exhaust in said cylinder for compressed fluid above said piston.

LEON F. MILLER. ROBERT W. ELLMS.

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