US2529718A - Broaching machine - Google Patents

Description

Nov., M, i950 B. wELTE 2,529,718

BROACHING MACHINE Filed Aug. 2l, 1944 2 Sheets-Shea?l 2 I wle auf I 40 I /gg 2&5' vane/,z l

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Patented Nov. 14, 1950 ,sais

BROACHING MACHINE Benedict Welte, Lake Orion Township, Oakland County, Mich., assigner to Colonial Broach Company, Delaware Detroit, Mich., a corporation of Application August 21, 1944, Serial No. 550,330

Claims.

The present invention relates to an automaticcontrol mechanism for operating a plurality of positive displacement hydraulic motors in a hydraulically-operated machine through a complete cycle of operations.

One object of the present invention is to provide an improved and simplified type automaticcontrol mechanism for operating a plurality of hydraulic piston and cylinder units through a desired cycle of operations, which mechanism is readily adaptable to various types of machines.

Another object of the present invention is to provide an automatic-control mechanism of the type mentioned, in which safety interlocks are provided to prevent normal operation of any motor where another of the motors is in an improper position and which will automatically restore the improperly positioned motor or motors to their proper positions and then cause a resumption of the normal cycle of operations.

Another object of the present invention is to provide an automatic-control mechanism of the type mentioned having a simple, manuallyoperated means for selectively shifting each motor in either direction to facilitate machine set-up operations.

Another object of the present invention is to provide an automatic-control mechanism of the type mentioned which is peculiarly adapted for use with an independent source of operating liquid for each motor, such as is provided when use is made of the multiple flow-control valve mechanism of applicants copending application, Serial No. 548,294, filed August 5, 1944.

A further object of the invention is to provide a control mechanism of the type described which incorporates means for independently adjusting the speed of operation of each of the motors.

Another object of the invention is to provide an automatic-control mechanism of the type mentioned, in which an improved and simplified electrical circuit is employed to control the operation of the main valves of the hydraulic system with resulting simplication of the interlocking mechanism.

Another object of the invention is to provide an automatic-control mechanism having the above mentioned advantages for cycling the cylinder and piston units of a shuttle-type pull broaching machine having a work moving cylinder which is simple in construction and positive and fool-proof in operation.

Other objects and advantages will become apparent from the following specification, the accompanying drawings, and the appended claims.

Referring to the drawing in which like numerals are applied to like parts in the several Views, Figure 1 is a diagrammatic illustration of the mechanical and hydraulic portions of a shuttle-type pull broaching machine having a moving table and incorporating a portion of the control means of the present invention.

Figure 2 is a fragmentary side elevation of a portion of one of the mechanically operated electric switches illustrated in Figure 1.

Figure 3 is a diagrammatic illustration of the electrical circuit employed to control the operation of the mechanism illustrated in Figure 1.

While the invention is applicable to various types of hydraulically operated machines the particular embodiment illustrated is specially designed and arranged to control the operation of the shuttle-type pull-down broaching machine having a work moving table or iixture which moves the workpiece into and out of broaching position. Such machines incorporate at least three positive displacement piston and cylinder units or motors. One of these units operates what is generally referred to as the broach-handling chuck; the second operates the breach-pulling chuck, and the third operates the table or fixture which moves the workpiece into and out of breaching position. These piston and cylinder units may either be of the type embodying a stationary cylinder and a movable piston or of the type embodying a stationary piston and a movable cylinder. The particular mechanism illustrated in Figure 1 is of the latter type, in which the pistons are stationary and mechanical features of the machine in general may be of the type illustrated in greater detail in'applicants copending application, Serial No. 495,856, led July 23, 1943, and now Patent No. 2,395,702, granted Feb. 26, 1946. In this connection it may be noted that the broach-handling and pulling chucks are preferably of the conventional type which contain means to positively lock the broach in the chuck and which have a release sleeve which engages a fixed abutment at the end of the inward stroke of the chuck and is thereby shifted axially to release the broach. A chuck of this type is shown in Fig. 3A of Hart Patent 2,162,814.

Referring to Figure 1 there is illustrated a movable breach-pulling cylinder I to which is secured in any desired manner, not illustrated, the broach-pulling chuck, a movable breachhandling cylinder 2, to which is secured in any desired manner the broach handling chuck and a movable worktable operating cylinder 3. Cylinder I contains a piston 4 which is secured by means of a hollow piston rod to a stationary manifold 6. The interior of the hollow piston rod 5 communicates through the manifold in the manner indicated by the dotted line 1 with a pipe 8. The hollow piston rod 5 and the manifold provide means for conducting liquid under pressure to the lower end of the cylinder I. Likewise, xed to the manifold 8 is a second pipe 9 which projects into the cylindei1 i and provides means for conducting liquid under pressure to the upper end of the cylinder I. Pipe 9 communicates through the manifold, as indicated by the dotted line I8, with a pipe II, which contains a conventional foot valve I2. The foot valve I2 serves to offer sufficient resistance to now of liquid from the upper end of the cylinder I through the pipe I I to prevent cylinder I from moving down under the influence of gravity. The foot valve offers no appreciable resistance to now in the opposite direction. The valve may he of any desired construction, such as that indicated generally by the numeral 324 in Figure 9 of applicants aforementioned copending application, Serial No. 495,856, now Patent No. 2,395,702.

While, for purposes of illustration, the pipe 9 and piston rod 5 are shown as separate pipes leading to opposite ends of the movable cylinder I, it is preferred, in the actual construction, that these two pipes be concentrically arranged in the manner shown in Hart Patent No. 2,190,667.

The handling cylinder 2 is similarly provided with a stationary piston I3 having a hollow piston rod I4 connected to a stationary manifold I5. The hollow piston rod I4 provides a path for uid communication to the upper end of the handling cylinder 2. A second pipe I6, also connected to the manifold I5, supplies uid to the lower end of cylinder 2, the arrangement of the pipes I4 and I8 being similar to that referred to above in connection with pipes 5 and 9 in cylinder I. Pipe I4 communicates through the manifold with a pipe I1 which contains a foot valve I8 similar to the foot valve I2, previously mentioned. Pipe I6 communicates through the manifold with a pipe I9. The work handling cylinder 3 is likewise provided with a stationary piston 2li having a hollow piston rod 2l which is xed to a stationary manifold 22 and supplies iiuid to the lefthand end of the cylinder 3. The cylinder also has a stationary pipe 23 xed to the manifold 22 which supplies fluid to the righthand end of the cylinder. Piston rod 2| communicates with pipe 24, and pipe 23 communicates through the manifold with the pipe 25.

It will be apparent from the above that the six pipes 8, II, I1, I9, 24, and 25 serve to conduct the operating fluid to and from the three motors, each pipe being effective when it conducts pressure fluid to effect a movement of one of the cylinders in one direction. The present invention requires that each of these pipes be provided with a valve which is effective in one position to conduct liquid under pressure to the pipe, and in the other position to connect the pipe. to aA low-pressure reservoir. In order to realize the full advantage of the improved control and mechanism, which constitutes one feature of the present invention, it is essential that these valves be provided with valve-shifting means incorporating a solenoid which, when energized, effects a shift of the valve in one direction in combination with suitable means to return the valve when the solenoid is not energized. The six lines illustrated may, if desired, be provided with individual valves of this type, but in the embodiment of the invention illustrated each pair of pipes is connected to a four-way valve having a single source of liquid under pressure, and a single pipe line leading to the low-pressure reservoir. Such four-way valves are in effect two individual three-way valves combined in a single valve.

The particular four-way valves employed in the preferred embodiment of the invention illustrated are conventional four-way valves of the type having an axially shiftable spool, a pair of solenoids each effective when energized to shift the spool in one of its two directions of movement, respectively, and a spring-centering device which is effective when neither solenoid is energized to shift the spool to a central position in which it blocks all flow through the valve. The solenoids may either act directly on the valve spool or control a pilot valve which supplies hydraulic pressure to shift the valve spool. Since such Valves are old and 'well known, they are merely vindicated. diagrammatically in the drawings. As hereinafter pointed out, the spring centering device may be omitted from valve 38, if desired, in which event the valve is preferably provided with any conventional form of spring-pressed detent which will hold the valve spool against displacement from either of its two positions of adjustment when neither solenoid is energized.

Pipe lines 8 and II for the main cylinder I are connected to a spring-centered blocking center four-way valve 26 having a pair of solenoids 21 and 28. The construction is such that when the solenoid 28 is energized the spool of the valve shifts to its lefthand position, in which it connects pipe II to the pressure supply line 2-6 and simultaneously connects pipe 8 to a pipe 3 I, which is in communication with the low-pressure reservoir 32. When solenoid 21 is energized the spool of the valve shifts to its right-hand position, in which pipe II is connected to the low-pressure pipe 3l and pipe 8 is connected to the pressuresupply line 38. When neither solenoid is energized all flow through the valve is blocked.

The pair of pipes I1 and I9 for the broachhandling cylinder 2 is provided with a similar four-way valve 33 having a pair of operating solenoids 34 and 35, a pressure supply line 36 and a pipe 31, which is in fluid communication, not shown, with the low-pressure reservoir. Likewise the pair of pipes 24 and 25 are provided with a similar four-way valve 38 having a pair of operating solenoids 39 and 48, a pressure-supply line 4I, and a low-pressure reservoir return line 42.

While in a broad sense the pressure-supply lines 3U, 36, and 4I may receive a suitable supply of pressure iiuid from any desired source, in accordance with one aspect of the invention these lines receive fluid from a multiple flow-control valve mechanism which may be any one of the various forms of such mechanism disclosed in applicants copending application, Serial No. 548,294, filed August 5, 1944.

The particular form of multiple flow-control mechanism illustrated includes a valve housing 43 provided with an internal cylindrical chamber 44 in which is slidable a piston 45 carrying a valve plunger 46 which controls a discharge port 41 in the housing. The chamber 44 is provided with an inlet port 48 connected by pipe 49 to a positive constant-displacement pump 50, the intake line 5| of which is connected to the low-p-ressure reservoir 32. A spring 52 acts on the piston 45 to force it in a direction to cause the plunger 46 to close the outlet port 41, which outlet is connected to the low pressure reservoir 32 by a pipe 53. The tapered end of the plunger 46 is preferably tapered at a slightly steeper angle than the tapered seat at port 41 in accordance with common practice so that the eiTective seating area is equal to the full cross-sectional area of plunger 46. The piston 45 has an upwardly projecting cylindrical plunger 54 which fits a reduced cylindrical chamber portion 55. The entire valve element including the piston 45 and the plungers 46 and 54, is provided with an axial opening indicated in dotted lines at 56, which opening extends entirely through the element.

The valve housing is provided with an outlet port 51 which is in communication with the inlet port 48 at all times, regardless of the position of the plunger 46. The outlet 51 is connected to a pipe 58, in which is positioned an adjustable throttle valve 59. The valve 59 constitutes a restriction in the line 58, which restriction can be adjusted by manipulation of the handle 6D. The degree of restriction provided by the valve 59 is preferably that required to cause a relatively small pressure drop in line 58 when the quantity of liquid passing through the valve is that required to operate the main cylinder at its desired speed. For example, in a system having a maximum operating pressure of 1000 pounds per square inch, the valve 59, when fully opened, may cause a pressure drop of approximately twenty pounds per square inch during passage of the full discharge of pump- 58. By adjusting the valve 59 to increase its restricted effect, the amount of iiow for the given pressure drop may be reduced.

The spring 52 is of such stiffness that it will just balance a pressure differential on opposite sides of the piston 45 equal to the pressure drop through valve 59, when the desired amount of liquid is owing through the latter valve. Thus, in the example given., the spring 52 would balance a pressure differential on opposite sides of the piston 45, of twenty pounds per square inch. The design and construction of the spring should be such that no material increase in pressure is exerted by it when the valve plunger 46 moves from fully closed to fully open position..

Pipe 58 is connected directly to the pipe 38 which supplies the pressure fluid to the main four-way valve 26, and it is also directly connected to a pipe 6| which in turn is connected to previously described pipes 36 and 4| through adjustable throttle valves 62 and 63 located, respectively, in the pipes 36 and 4|. The adjustable throttle valves 62 and 63 are identical in construction to the valve 59 except that in the particular embodiment of the invention they are of smaller size, being so designed as to produce the same pressure drop as the valve 59 but for the smaller quantity of liquid required to operate the smaller cylinders 2 and 3 at the desired speeds.

The space within the chamber 44 above the piston 45 is connected by means of -a port 64 and a line 65 to a low-pass valve 66, having an internal chamber 61 provided with a pair of axially spaced internal annular grooves 68 and 69 which are connected by means of a passageway 10 to each other and to the line 65. The chamber 61 contains a movable plunger or spool 1| having a pair of annular channels 12 and 13. The annular channel 12 is connected by cross passageway 14 and an axial passageway 15 to the lefthand end of the spool, while the channel 13 is connected by a cross passageway 16 and an axial passageway 11 to the righthand end of the spool. The spool is so constructed that when it is in the lefthand position illustrated, channels 12 and 68 are in communication with each other and the spool blocks channel 69. When the spool is in the righthand position, channels 13 and 69 are in communication with each other and the spool blocks channel 68. The ends of the valve housing 66 are connected by means of a pair of pipes 18 and 19, respectively, to the pipes 36 and 4| at points in the latter located beyond the adjustable throttle valves 62 and 63, respectively. As 4a result of this arrangement, the upper end of chamber 44 and pipe 65 are in fluid communication with and subject to the pressure in that one of the two pipes 18 and 19 which is at the lowest pressure. Thus, when the pressure in line 18 is less than the pressure in line 19, the spool 1| will be forced to the left into the position shown in which it connects pipes 65 and 18. When pipe 19 is subject to a lower pressure than pipe 18, the spool will shift to the right and connect lines 65 and 19. As shown in the drawing, the end closure plates 66a and 66h of the housing 66 are recessed and each recess is provided with an inwardly projecting lug 66e and 66d, respectively, for limiting endwise movement of the spool 1l.

l The lugs are of limited radial and circumferential extent in order that substantially the entire end areas of the spool will be subject to the pressure from lines 18 and 19. If desired, a spring may be provided for normally holding the spool 1| in its lefthand position illustrated when the pressures in the lines 18 and 19 are equal. The spring 88 preferably exerts suilicient force on the spool 1| to overcome a pressure differential between the lines 18 and 19 equal to approximately half of the pressure differential Awhich would be balanced by the spring 52 of valve 43.

Valve chamber 43 contains a countersunk passageway 8| in communication with the port 64. The passageway 8| contains a spring-pressed ball check valve 82 which normally closes communication between the passageway 8| and a line 83 which is connected to the low-pressure reservoir 32 in any desired manner, not illustrated. The spring 84 of the ball check valve is of such stiiT- ness as to permit opening of the check valve 8| only when the pressure in line 65 exceeds the safe operating pressure for the system. The check valve thus limits the pressure which can act on the upper side of piston 45 to a safe maximum with the result that the valve plunger 46 will move upwardly and discharge oil from the pump 50 to the reservoir through line 53 when the pressure below the piston 45 exceeds that maximum plus the small additional pressure necessary to overcome spring 52. The existence of a pressure drop necessary to overcome spring 52 is insured by the bleed restriction 85 provided in the line 65. This mechanism, therefore, provides a safety over-pressure relief for the system.

The space within the chamber 44 above piston 45 is also connected by means of a port 86 and 4a line 8l to a blocking valve 8S which is operated by means of a solenoid 33. The blocking valve 88 may be of any desired or conventional construction, it being sufcient only that it block now through line 8l except when the solenoid 89 is energized. The valve 88, when opened, permits unrestricted ow through the line 81 to a line 90 which is connected to the low pressure reservoir. Consequently, the valve 88 serves as means for venting the space above the piston 45 and thereby entirely relieving the pressure on the system when desired.

The mechanism so far described operates in th following manner. If it be assumed that the pump 59 is running and that none of the solenoids 2l, 28, 34, 35, 39, or 40 is energized, the lines 35, 36, and 4l will be blocked by the blocking four- way valves 25, 33, and 38, and there will be no outlet for the uid delivered to the valve housing 43 except through the outlet port 4l. The pressure in line i3 will be transmitted without change through the valve 43 and through lines 58, El, 36, 18, the low-pass valve G5, line 55, and port G4 to the upper end of the valve chamber 44. There being no outlet for the uid delivered, the pressure will immediately build up to open the ball check valve 82, thus venting the uid in the valve chamber above piston 65 and causing the valve plunger 46 to open fully and discharge all of the fluid delivered by the pump to the reservoir through the line 53 at the maximum safe operating pressure of the system. Under these circumstances the pressure drop through the bleed restriction 85 will be sufficient to overcome the action of spring 52 and, consequently1 the pump discharge pressure will exceed the pressure in the ball check valve line SI by the relatively small pressure drop required to overcome spring 52. f it is desired to relieve the pressure upon the pump this may be done by energizing solenoid 89 and thus opening valve 88. This mediately connects the upper end of chamber @Il directly to the low-pressure reservoir and, consequently, the pressure above the piston 45 will be substantially zero. Under these circumstances the valve plunger 4'! Will open fully and discharge all the iluid delivered by the pump to the reservoir through line 53 at the relatively low pressure required to overcome spring 52. Under these circumstances the bleed restriction 85 prevents the flow of liquid to the upper end of the valve chamber as rapidly as it can be Withdrawn through the line 87, and consequently prevents transmission of the pressure existing in the lower end of the chamber i4 to the upper end of the chamber 44. Means hereinafter described for automatically controlling the cycle of operation of the inachine, incorporates means to energize the solenoid 83 when the machine is stopped and means or de-energizing the solenoid 89 when any motor of the machine is in operation. r'hus there is no idle period during which the pump is required to act against a high pressure.

It will be apparent that to cause any desired cylinder of the three cylinders l, and 3 to move in either of its two directions of movement it is only necessary to energize one of the solenoids 2l, 28, 34, 35, 39, and 40. Consequently, any desired sequence of operations of the three cylinders may be accomplished by simply energizing the solenoids in the proper sequence.

If it is desired to have the table cylinder 3 move the workpiece into broaching position, which is accomplished by moving the cylinder to the left, as viewed in the drawing, solenoid 39 is energized, thus connecting the line 4| to line Z4 and at the same time connecting line 25 to the low-pressure discharge line 42. Under these conditions a portion of the huid from the pump will pass through valve 43, pipe 58 containing valve 59 and pipe 6I to the line 4I, during which flow it will pass through the adjustable throttle valve 63 in line 4|. The throttle valve 63 will cause a pressure drop which will result in a lower pressure in line 'I9 than that existing in line TS, due to the fact that no now is occurring in pipe 36 and, consequently, there is no pressure drop through valve 52. The high pressure in line 18 will shift the spool of the low-pass valve to the right, thereby connecting line 'i9 to line 65 and subjecting the upper end of the valve chamber 44 to the pressure existing in the pipe 4I below the valve 63. As a result of these connections piston 45 with the plunger i5 will automatically adjust itself to by-pass to the low-pressure reservoir through line 53 all of the fluid delivered by the pump except that amount which will produce the predetermined pressure drop through valve S3 required to overcome the spring 52. Since the mechanism maintains a uniform pressure drop through a Xed opening the rate of ow of liquid through the line 4I will remain constant, independent of variations in the resistance to movement of cylinder 3. The total pressure against which the pump discharges under these circumstances will be the pressure required to move the cylinder 3 at its desired speed plus the relatively small pressure drop through valve 83. lf it is desired to adjust the speed of movement of the cylinder 3 it is only necessary to adjust the degree of opening of the throttle valve 63. If the opening is reduced a smaller quantity of the liquid will pass for the given pressure drop maintained by spring 52 and, consequently, the speed of the cylinder will be reduced and vice versa. It is apparent that the mechanism will operate in a similar manner to cause reverse or return movement of the cylinder 3 when solenoid 4G is energized in place of solenoid 39.

When it is desired to effect movement of the broach-handling cylinder 2 in downward direction, solenoid 35 is energized, thus connecting lines 3G and I9 and at the same time connecting lines 3l and Il. The valve mechanism previously described will, under these circumstances, maintain the speed of cylinder 2 at a uniform rate in exactly the manner described in connection with the cylinder 3, except that in this case the pressure in line 'I8 will be lower than that in line 7S, and the low-pass valve will assume the position illustrated in the drawings in which it connects the upper end of valve chamber 44 with the pipe at a point below the adjustable restriction 62. A5 in the previous case, the rate of flow through the line 36 may be adjusted by adjusting the degree of opening of the throttle valve 62.

Return or forward movement of the cylinder' 2 is effective in the same manner by energizing the solenoid 34 instead or" the solenoid 35.

When it is desired to cause the downward movement of the main cylinder I, solenoid 2l is energized, thus connecting pipe 30 to pipe 8 and at the same time connecting pipe Il to pipe 3l. Under these circumstances, the liquid from the pump will pass through valve 4.3 and the adjustable throttle valve 59 to line 3U, and thus causing a downward movement of the cylinder l; and the mechanism in valve housing 43 will serve to maintain the now in pipes 58 and 30 at the uniform rate required to maintain thek pressure drop across Valve 59 equal to the differential pressure required to overcome spring 52. Since under these circumstances no liquid will be flowing in lines 36 or 4I, the low pass valve 66 will, under the influence of spring 89, assume the position illustrated in the drawings in which it connects line I8 to line 95. Thus, the upper end of valve chamber M will be subject to the pressure in pipe 58 beyond the adjustable throttle valve 59. As in previous instances, the quantity of liquid supplied through the main cylinder I may be adjusted by adjusting the degree of opening of the throttle valve 59 since for the iixed pressure dro-p maintained by the mechanism in valve 43 the quantity of liquid which will pass valve 59 is a function of the size of the opening provided therein.

Reverse or upward movement of the cylinder I is eiective in the sam-e manner by `energizing solenoid 28 in place of the solenoid 21.

It will be noted that successful operation of the flow control mechanism depends upon the fact that flow occurs in only one of the lines 39, 36, and 4I at a time. This requires the presence of some means to block flow in the lines to the cylinders which are not operating at any given time, or at least so reduce flow that no appreciable pressure drop will occur through the throttle valves of the inoperative cylinders. In certain machines, such as broaching machines, it is possible to prevent such flow by moving each operating cylinder lunit against a mechanical abutment in each direction to stop the movement and consequently the flow of liquid to the unit upon completion of its stroke even though the position of the four-way valve leading to the cylinder does not change. In that case, it is unnecessary to employ a blocking valve in the fluid line to the cylinder. In broaching machines of the type herein disclosed, it is a common practice to limit the stroke of the table cylinder in both directions by positive abutments and consequently the spring centering device may be omitted from valve 33 if such an arrangement is employed without affecting the mode of operation of the machine. While the same practice may be employed with the cylinders I and 2, it is preferred to employ a blocking valve in lines 39 and 36 to facilitate adjustments in the stroke of the cylinders. As previously indicated, the four-way valves 29 and 94 perform the necessary blocking function when neither solenoid is energized by reason of the action of the spring centering device.

It will be observed that the adjustable throttle valve 59 is connected in series with the adjustable throttle valves 62 or 63, the latter being connected in parallel with respect to each other. Consequently, when liquid is supplied to either the broach-handling cylinder 2 or the tablemoving cylinder 3, it will also ow through the adjustable throttle valve 59. In the particular embodiment of the invention illustrated and described, it is assumed that the quantity of liquid required to operate the cylinders 2 and 3 at their desired speeds is so much smaller than that required to operate the larger broach pulling cylinder I that the ilow required to operate the cylinders 2 and 3 will cause no appreciable pressure drop on passage through valve 99. Consequently,r adjustment of valve 59 made for the purpose of adjusting the speed of operation of the cylinder I will not appreciably affect the speed of operation of the cylinders 2 and 3. The valves 62 and ,portion of the machine.

reciprocating plunger IOS which is depressed by i9 63 are connected in parallel because of the fact that the amount of fluid required to operate the cylinders 2 and 3 is more nearly in the same order and, consequently, a parallel connection is desirable to enable adjustments of the speed of one of these two cylinders to be made without affecting the speed of the other. It is apparent that, if desired, all three of the restriction valves may be connected in parallel in a manner more fully disclosed in applicants copending application, Serial No. 548,294, filed August 5, 1944. Reference may be had to that application for more detailed description of the multiple flow control mechanism and the preferred form of adjustable throttle valve employed therein.

The cycle of operation of the three cylinders is controlled by means of an electrical circuit, hereinafter described in combination with a plurality of limit switches operated by the three cylinders. As best shown in Figure l, the limit switches include a switch 96 having a pair of operating arms 9'I and 98 xed to a rotatably mounted switch contact operating shaft 99. The contacts and internal mechanism of the switch,

being conventional, are not illustrated or described, it being suflicient to note only that the switch incorporates a pair of contacts which, in one rotative position of the shaft 99, are electrically connected together and in another rotative position are disconnected. As best shown in the fragmentary side elevation of Figure 2, the arms 97 and 98 are axially offset with respect to each other and are provided, respectively, with flanges |99 and IOI adapted to engage, respectively, lugs |92 and |93 which are iiXed to the broaching cylinder I. The housing of the switch 96 is fixed in any suitable manner to a stationary portion of the machine in such position that the flanges IBB and IUI will be engaged by the lugs I92 and i433. Lug I92 is displaced downwardly from the plane of Figure 1 with respect to lug |93, with the result that lug |93 will not engage flange i799 of the arm 91, while lug I92 will not engage flange IBI of arm 98, the latter flange being engaged by the lug I93. The construction and arrangement of the lugs and the limit switch 96 are such that when the ram I approaches its upper position illustrated, lug |92 will engage the flange I9!) of arm 97 and rotate the shaft 99 with its attached arms 9'I and 9B into the position illustrated in Figure l in which position the contacts of the switch are broken. When the ram approaches its lower position, the lug I 93 will engage the ilange I9! of arm 98 and rotate the `shaft 99 counterclockwise approximately 99 to close the electrical circuit between the two contacts of the switch. The switch 96 and the operating means therefor are indicated diagrammatically in Figure 3 in which the double arms 97 and 98 are represented as a single arm engaged alternately by the lugs |92 and |99 for the sake of simplicity. The switch is of the snapacting type so that it will be held in each of its two positions of adjustment. This is represented 'diagrammatically in Figure 3, by the spring pressed detent E94.

The breaching ram I is also provided with a limit switch Ill'l, which is xed to a stationary Switch I9? contains a and III.` When the plunger |99 is depressed,v

contacts are electrically connected, and contacts are disconnected When, on downward movement of the ram, the cam lug |09 is withdrawn from contact with the plunger |08, a spring |2 forces the plunger outwardly disconnecting contacts H0 and making an electrical connection between the contacts The handling cylinder 2 is provided with a limit switch H3 which is identical in construction and operation to the limit switch 96 previously described and which is operated by a pair of lugs ||4 and ||5 carried by the handling cylinder 2. As best shown diagrammatically in Figure 3, when the handling cylinder is up, lug ||4 operates the switch to break electrical communication between the two contacts of the switch. When the handling cylinder reaches the bottom of its downward stroke, the lug |5 operates the switch in the opposite direction to make an electrical connection between the contacts. The switch H3 is also snap acting as indicated diagrammatically by a spring-pressed detent ||6 in Fig. 3.

The handling cylinder 2 is also provided with a limit switch ||8 having a plunger ||9 adapted to be depressed by a cam lug on the handling cylinder-when the cylinder reaches the upper end of its stroke. The switch ||8 is similar in construction and mode of operation to the switch |01 previously described and contains two pairs of contacts |24 and |22, as indicated diagrammatically in Figure 3.

For reasonsv which will appear more fully hereinafter, the handling cylinder 2 is also provided with a solenoid operated latch mechanism indicated generally at |24 which serves, when the machine is idle, to prevent the handling cylinder, if it should sink by gravity, from completing the last few inches of its downward stroke. The latch mechanism includes a housing containing a solenoid |25 and a latch plunger |26 adapted to engage a lug |21 on the handling cylinder to limit downward movement of the cylinder when the plunger is in its outermost position illustrated in Figure l. The plunger is normally held in its outermost position by means of a spring |28 and is retracted on energization of the solenoid |25. The arrangement of the lug |21 is such that when the cylinder 2 is in its lower-most position the lug prevents latch plunger |26 from projecting outwardly under the iniluence of spring |28.

The table cylinder 3 is provided with a pair of limit switches |30 and |3| which are identical in construction and mode of operation to limit switch |01, except that they incorporate only one pair of contacts, as best shown diagram,- matically in Figure 3. The limit switch |30 is mounted in such a position that when the table cylinder reaches the end of its stroke in the direction in which it moves the table into broaching position and engages (or the table engages) a xed abutment |32, the plunger |33 of the switch |30 will be depressed by any suitable means xed to the cylinder or table, such as the projection |34. Such depression closes the circuit between th'e pair of contacts of the switch |30, as indicated diagrammatically in Figure 3. The switch |30 is of the type which will close upon a very minute inward movement of the plunger |33 and in which the closing position can be set with great accuracy to coincide with the point at which the cylinder or table engages the fixed abutment. The limit switch |3| contains a simi- 12 lar plunger |35 which is depressed by means of a cam lug |36 on the cylinder 3 when the cylinder reaches the opposite end of its stroke, as indicated diagrammatically in Figure 3. Both are opened by constantly acting springs.

Figure 3 is a diagrammatic illustration of the circuit employed to control the operation of the cylinders of the machine. As there shown, the circuit comprises a pair of main line conductors |40 and |4| connected to any suitable source of electrical power. The line |4| is divided into two lines, |42 and |43, which are connected, respectively, to one contact of the two pairs of contacts in a double pole, double throw switch |44. When the switch |44 is in the position illustrated, line |42 is connected to line |45 and the circuit is broken between line |43 and a line |46. The electrical connection of line |45 with a line |41 is controlled by means of the normally open contact |48 of a relay |40, the coil of which is connected between the line |40 and |4| by means is provided with a holding circuit |54 connected in parallel with the line |5| and containing a normally open contact of the relay |49. When the relay |49 is energized, contacts |48 and |55 close. If switch |46 is in the position illustrated, closing of contact |48 connects line I4! with the line |41, and closing ofcontact |55 closes the parallel holding circuit |54 which maintains the energization of the relay |49 until such time as the emergency stop button |52 is depressed.

The connection of line |41 with line |4| places the circuit in a condition to start the normal cycle of operation of the machine, since all of the control switches andy relays and the valveoperating solenoids are connected in parallel between the lines. |40. and |41. Thus, there are provided the following lines connected in parallel between the. lines |40 and |41; lines |60, |6|, |62, |53, |64, |65 (the latter being divided i into a pair of parallel lines |55a and |65b), |66,

|61, |63, |69. (the latter having a parallel branch |6Sa), |10 (the latter being divided into a pair ci parallel lines |.10a and |1019), and line |1.|. Line |50, contains the coil of a relay |16 having three normally Open contacts |11, |18, and |19,

and also contains a normally open starting switch button |52, and the normally closed contact |83 of a relay |84. The coil of relay |84 is connected in line |63. Thecontact |11 of relay |15 ,controls a relay holding circuit |05 connected in parallel across the contacts of the starting switch |82, as a result of which, on depression o the starting button, the relay |16. will be energized, thus closing all of its` contacts, and the .contact |11 will maintain the relay |16 ener.-

gizedafterV thestarting buttonis released. Contact |18 of the relay |16 islocated in the line IE5-a, and contact |10 is located. inthe line |61. Line |6| contains the limit switch 3| and also the coil of a relay |85, having a normally open contact |31 located, in line |10b. Line |62 containsrthe limit switch |33 and also the coil of a relay |68, having three normally open contacts |80, |90, and |9|, and a normally closedvcontact |92. Contact |89 is in line |69; contact |90 is in line |10a; contact |9| is in line |1; and contact |92 is in line |68. Line |63 contains the limit switch |3 and also the coil of the aforementioned relay |8,4. Relay |84 has two normally closed contacts, namely, contact |83 in line |69 and H93 in line l 10a, and three normally open contacts, namely, contact |94 in line |64, l95 in line 199D, and |98 in line |1|. Line |84 contains the limit switch 96 and also the coil of a relay l9`i' having two normally open contacts, namely, contact |95 in line ii and |99 in line Hilo, and two normally closed contacts, namely, contact ili in line |98, and 292 in line Ill,

Line E55 contains the solenoid 89 of the pressure control valve S3 shown in Figure l. As previously indicated, the line |95 is connected to the line lill' through the two parallel lines |6511 and S9517. Line E89 contains the solenoid i9 of valve 98. Line |91 contains the solenoid 39 of Valve 39 and also contains the contacts 52| of switch H9. The line |58 contains the solenoid 3d of valve 33 and also the contacts |22 of switch H8. Line |99 contains the solenoid 35 of valve es and also the contacts H9 of switch |91, and the parallel branch |99@ contains the latch solenoid i255. Line |18 contains the solenoid 28 of valve l@ and is connected to the line |41 by a pair of branch lines Illia and |1919, the former branch line containing the contacts iii of the switch |91.

The electrical circuit so far described constitutes the complete circuit necessary to operate the broaching machine through its normal cycle. It also serves to interlock the position of the various cylinders to prevent the operation ci any cylinder when the cooperating cylinders are in an improper position, and it further operates to automatically correct any improper positioning of the cylinders, and thereafter permit automatic resumption of the cycle of operation,

The operation of the circuit is as follows: In Figure 3, all of the relays are illustrated in the position they assume when the cylinders of the machine are in their starting positions and no power is supplied tothe lines Idil and |4|. rhis will be the theoretical position assumed when the power supply is cut off after the inachinc has stopped at the end of its cycle of operation. Actually, as hereinafter pointed out, if the machine is left idle for any appreciable period of timeI one or more of the vertically positioned cylinders may sink down by gravity and assume an improper position. While the foot valves I2 and i9 serves to hold the cylinders in their upper positions, unavoidable leakage will often permit a gradual sinking of the cylinders during long idle periods. The result of such occurrences will be dealt with hereinafter.

If the lines E49 and lill are energized when the parts are in the position illustrated, no power will be supplied to the line |46 because the jogging switch llt is in the position it assumes when the machine is set for normal operation. Likewise, no power will be supplied to the line |41 because of the open contact |48 of relay |49. Consequently, no power is supplied to any of the parallel lines connecting lines |49 and |551, and none of the valve solenoids will be energized.

The machine is placed in condition to be started by connecting lines |49 and 4| to a suitable source of electrical power and by depressing the reset button i555, which establishes a circuit through the coil of relay |49, thus causing contacts 955 and llil of that relay to close. Contact |55 establishes a holding circuit through line 655-3 for maintenanceY of the energization of the relay M9 and contact |43 closes communication from line Uli through branch line |42, switch |44, andline .E45 to the line |41. As the result of this operation, the opposite ends of all the'parallel lines |99 and |1'|, inclusive, are subject/toV ai' voltage differential which will cause a current iiow through any parallel line which forms a closed path for the iiow of the electric current. After the reset button is depressed to energize line lill, the only one of the parallel lines which is closed to the passage of electric current is the line |6| which contains the coil of relay |86. Consequently, as soonas the reset button is depressed relay !88 is energized and closes its contact |81. rihe contact |81 is in line |1011 which contains the open contact 99, and thus the closure of contact |81 does not aifect line |191) when the parts are in the position illustrated in the drawing. Since none of the remaining parallel lines |69 and iGZ to lll, inclusive, provide a closed circuit, it is necessary to depress the starting button |82 to start the machine.

As soon as the starting button is depressed, a circuit is established through the coil of relay |16 causing that relay to close its contacts |11, |18, and |19. The contact |11 establishes a holding circuit for the relay |16 through the branch line |85 and, consequently, the relay remains ener-l gized after the starting button is released. Contact |18, on closing, establishes a current flow through line |95a, line |85, the pressure control solenoid 89, thus establishing pressure in the hydraulic system in the manner previously described in connection with the mechanism illustrated in Figure 1. At the same time, current flow is established through line |61 by reason of the closure of relay conta-ct H9. yThis energizes the solenoid 3S of the table control Valve 38, and shifts the valve to the position in which it effects inward movement of the table. Such movement shifts the workpiece into broaching position.

In this connection, it will be observed that injury to the broach or to the work would result if,

' on inward movement of the table, the handling cylinder had sunk down during a previous idle period to a point in which the lower end of the broach was below the top of the workpiece. It is for this reason that the switch i8 is provided. It will be noted that, as long as the handling cylinder is in its up-permost postion, the switch |18 will be in a position in which its upper contact closes communication between the contacts |2I in line |61. If, however, the handling cylinder is not at the top of its stroke, communication between the contacts I2| will be broken and noV current will be supplied to the solenoid 39. When this state of affairs exists, the switch ||8 closes communication between contacts |22 in line |88, thus energizing solenoid 34 of the handling cylinder valve 33. This energization of solenoid 34 causes the valve to shift to a position in which the handling cylinder 2 is returned to its uppermost starting position. This energization of solenoid 94 is possible because relay |88 is de-energized and, therefore, its contact |92 is closed. As soon as the handling cylinder reaches the top of its stroke, switch H8 returns to the position illustrated iin Figure 3, in which it closes the circuit through line 291 to effect the aforementioned inward movement of the worktable.

As soon as the table begins to move in, switch |3| is opened, breaking the circuit through line |6| and de-energizing relay |86, with the result that the previously closed contact |81 is then opened. When the table reaches its innermost position,

switch iS is closed, establishing a circuit through tact |92. If at this time the breaching cylinder 1S is in its uppermost position, as it should be, switch |01 will be in the position illustrated in which it opens the connection between contacts I in line |10a, and, consequently, the closure of contact |99 will have no effect. Similarly, the closure of contact |9| will have ne effect because contact |96 in line |1| is open. However, the closure of contact |89 closes the circuit through line |69 to energize solenoid 35 of valve 33, thus causing the handling cylinder to move downwardly. At the same time, the parallel branch line |69a is energized, thus causing retraction of the latch |26.

In this connection, it will be noted that it is undesirable to have the handling cylinder move downwardly unless the breaching cylinder is in its uppermost position, since otherwise the automatic chuck on the breaching cylinder will not be open to receive the breach when it is released by the handling chuck, and in the subsequent step in the cycle the breaching cylinder will move downwardly without the breach. This in turn would result in breaking the breach when the table moved outwardly at the end of the downward movement of the breaching cylinder. It is for this reason that the switch |01 is provided. It will be noted that if the breaching cylinder is not at the top of its stroke, the switch will be in its lowermost position, in which it breaks the circuit between contacts H in line |69 and thus prevents energization of the solenoid 35. At the same time, the switch |01 connects contacts of line |10a (thus completing the circuit through line Illia and the solenoid 28, which in turn shifts the main valve 25 i-nto a position in which it returns the breaching cylinder to the top of its stroke. As soon as the cylinder reaches the top of its stroke, switch |01 returns to the position illustrated in Figure 3, thus permitting energization of solenoid 35 and downward movement of the breach-handling cylinder.

Since the switch |30 is of the type which can be very accurately adjusted to close only when the werktable is in its extreme innermost position against abutment |32, ne downward movement of the breach-handling cylinder` can occur unless the table is in its full inwardposition because as soon as it leaves that position, switch |30 deenergizes solenoid |88 and opens contact |89 in line |69. This insures that the workpiece will be in the proper position te receive the breaching tool.

During the downward stroke of the breachhandling cylinder, the switch H8 shifts downwardly from the position shown in Figure 3, breaking the circuit through line |61 and connesting contacts |22 of line |68. No current will flow through line |68 at this time, due to the fact that the table is in, and consequently relay |88 is energized, thus opening contact |92.

When the handling cylinder reaches the end of its downward stroke, switch H3 is closed by lug H5 on the cylinder, thus energizing relay |88. Enger-ization of relay |86 closes contacts |99, |95, and |98, and opens contacts |93 and |83. The closing of contact |96 has no effect because line |64 is open at switch 96. The closing of contact |95 completes a circuit through the branch |651) of the pressure control solenoid line |65. The opening of contact |93 does not aiect the circuit through line |a because that circuit is already opened by the switch |01. The opening of contact |83 breaks the circuit through the starting button line |60, thus de-energizing relay |16 anf` opening its contacts |11, |18, and |19. The open'- ing of contact |18 dos not interrupt the current through the pressure control solenoid 89 because of the simultaneous closing of Contact |95, which closes the circuit through the branch line |6512, thus maintaining the pressure control solenoid energized. The opening of contact |11 breaks the holding circuit for relay |16. The opening of contact |19 has ne effect because line |61 is open at contacts |2|. However, the closing of contact |96 completes the circuit through line |1| and energizes solenoid 21 of the main valve 26, thus shifting the valve to a position in which it causes downward movement of the breaching cylinder to eiect the breaching stroke of the machine. During this state in the cycle of operation, line |66 is open at contact |98; line |61 is open at contact |19 and contacts |2| line |68 is open at contact |92; line |69 is open at contacts ||0 as seen as the breaching cylinder starts down; line |10a is open at contact |93; and line |101) is open at contacts |81 and |99. As a result of these conditions, none of the other cylinders of the machine can move during the breaching stroke.

When the breaching cylinder reaches the end of its downward breaching stroke, lug |03 closes switch 96, thus energizing relay |91 (contact |94 having previously closed). This opens contacts 20| and 202 and closes contacts |98 and |99. At this point, line |61 is open at contacts |19 and |2|; line |68 is open at contacts |92 and 20|; lines |69 and |69a are open at contact I0; line |10a is open at contact |93; line |101) is open at contact |81; and line |1| is open at Contact 202. Line |66, however, is then closed, thus energizing solenoid 40 ef valve 38 and shifting the valve to a position in which it causes an outward movement of the worktable. It will be observed that such outward movement occurs after the breaching cylinder has reached the end of its downward stroke. As soon as the table leaves its innermost position, switch |30 is opened, de-energizing relay |88, thus opening contacts |89, |96, and |9i, and closing contact |92. The opening of contacts |89, |90, and |9| does not aiect` the lines in which they are located because at this stage in the cycle 'i those lines are opened at contacts ||0, |93, and

202, respectively. Closing of contact |92 does not aiect line |68 because that line is open at contact 29|. When the table reaches the end of its outward stroke, switch |3| is closed, thus energizing relay |86 and closing its contact |81. The closing of Contact |81 closes the circuit through line |1012 and line |10, thus energizing solenoid 28 of valve 26 and shifting that valve inte the position in which it causes upward or return movement of the breaching cylinder. During the return movement of the breaching cylinder, switch 96 is held in its closed position by the detent |86. This insures that the relay |91 will remain energized and that, therefore, the table cannot move in or the breach handling cylinder up. When the breaching cylinder reaches the upper end of its stroke, switch |01 is shifted into the position illustrated in the drawing, and switch 98 is opened by lug |02. This shift of the microswitch |91 opens the circuit between contacts of line |1011, which line is already open at contacts and |93, and connects contacts |I0 in line |69 which is already open at contact |89. The opening of switch 96 de-energizes relay |91, thus breaking contacts |98 and |99 and closing contacts 20| and 202. The opening of contact |98 de-energizes solenoid 40. The opening of contact |99 completes the de-energization of the solenoid 28 and thus relieves the breaching cylinder of operating pressure. The closing of contact 202 has no eiect on line |1| because that line is open at contact |9|. However, the closing of contact 20| completes the circuit through line |68 and energizes solenoid 34 of valve 33, thus shifting the valve to a position in which it effects upward movement of the broach handling cylinder 2. As soon as the cylinder 2 leaves its lower position, latch |26 is projected by spring |28 because line 69a is broken at contact |89.

During upward movement of the broach-handling cylinder, switch ||3 is held closed by the detent ||6, but when the handling cylinder reaches the end of its upward stroke, switch ||3 is opened by lug I 4, thus de-energizing relay |84. This opens contacts |94, |95, and |96, and closes contacts |83 and |93. In addition, when the handling cylinder reaches the upper end of its stroke, the switch |8 shifts to the position illustrated in the drawings, in which it closes communication between contacts |2| and breaks the connection between contacts |22. These changes complete the cycle of operation and bring the machine to a stop, inasmuch as line |66 is open at contact |98; line |6'| is open at contact |19; line |68 is open at contact |22; lines |69 and |69a are open at contact |89; line l10n is open at contacts |90 and line |1017 is open at contact |99; and line |1| is open at contacts |9| and |96. It will be noted also that the pressure on the machine is relieved by reason of the breaking of both branches |65a and |65b of the pressure control line |65.

It will be observed that throughout the cycle described above, the latch solenoid |25 was retracted only when the handling cylinder was caused to move down. At all other times, including the stop position, the latch solenoid is deenergized and the latch advances under the influence of spring |28 into retaining position. The object of the latch |26 is to prevent the handling cylinder from moving downwardly under the influence of gravity during idle periods to such a point that the automatic broach handling chuck secured to the broach handling cylinder will release the broach. In this connection, it will be understood that the latch is so positioned as to stop the cylinder just before the chuck release mechanism contacts the release abutment.

The latch also prevents the handling cylinder from falling by gravity during idle periods suciently far to insert the broach, if carried by the handling cylinder chuck, into the chuck carried by the broaching cylinder l or to prevent the broach, if carried by the broaching cylinder chuck, from being projected into the broachhandling chuck. It further prevents downward movement of the cylinder during idle period from closing switch I3 since such closure would result in injury to the broach if the machine was started following an emergency stop after the worktable moves in, if, during the idle period, the handling cylinder sank all the way to the end of its stroke and the broaching cylinder also sank all or part way down.

It will be understood that in accordance with the conventional practice the downward stroke 01 the broach-handling cylinder,`the inward stroke of the work iixture cylinder, and the upward stroke of the broach cylinder are limited by fixed abutments in all cases, with the result that it is immaterial whether the operating pressure is maintained after the cylinders reach the positive abutment. The length of the upward stroke of the broach-handling cylinder may be readily adlOf ` adjustments are desirable in order to adjust the stroke of the two cylinders to correspond to the length of the broach employed.

If, after the machine is automatically stopped in the above described manner at the end of the broaching cycle, the broach handling cylinder should sink down by gravity, the switch |8 will shift to its lower position, thus closing the circuit through line |59 and energizing the solenoid 34 of valve 33 to shift that valve to a position in which it returns the broach-handling cylinder to its uppermost position as soon as the machine is restarted. The worktable cannot move in until the handling cylinder returns to its uppermost position and shifts the switch ||8 to the position illustrated in Figure 3. As a result there is no possibility, on restarting the machine, that the work moving table will collide with the broach.

It will be noted that if, during the idle period following an automatic stop at the end of a cycle,

ity, switch |01 will be shifted downwardly closing the circuit between contacts and opening the circuit between contacts ||0. These changes do f not have any immediate effect because line |69 is already open at contact |89, and line |10a is already open at contact |96. However, when, during the subsequent cycle, the table moves inwardly to broachingI position, it will close switch |30, thereby energizing relay |88 and closing contacts |89, |90, and |9|. Consequently, line |10a will be energizedand line |69 will be disconnected at contacts I0, with the result that the broaching cylinder will return to its upper position and the handling cylinder will not move down. As soon as the broaching cylinder reaches its upper position, the switch |01 is returned to the position illustrated, and the cycle is resumed by downward movement of the handling cylinder.

To restart the machine following an automatic stop, it is only necessary to depress the starting button |82, thus energizing relay |16 to initiate a repetition of the previously described cycle of 0peration.

At anytime during a cycle of operation, the machine can be stopped by depressing the emergency stop button |52. This de-energizes relay |49 and opens contacts |48 and |55, thereby disconnecting line |41 from the source of electrical energy. To reinstate the machine in condition to operate following an emergency stop, it is necessary to depress the cycle reset button |53, which re-energizes relay |49 and returns the contacts |48 and |55 to a position in which line |41 is connected to the electrical source. If the machine were stopped during a portion of the cycle subsequent to the end of the downward movement of the broach handling cylinder, the cycle will resume a depression of the reset button 53. If the machine was stopped at an earlier portion of the cycle, it is necessary to depress rst the reset button |53 and then the starting button |82 to restart the machine. If, during the intervening idle period, the positions of the remaining switches and relays remained unchanged the machine, on restarting, will resume its cycle where it left off. Z

It will be appreciated that by reason of the possibility of stopping the machine at any point during its 'cycle by the emergency stop button and by reason of the possible sinking by gravity of the cylinders I and 2 during idle periods, the three moving cylinders may assume a wide variety of relative positions when the machine is restarted. The control circuit provided in accordance with the present invention automatically prevents any movement of any of the-three cylinders which will result in injury to the broach, work iixture, or machine when the machine is restarted, regardless of the relative positions of the three cylinders at the time of starting. A few possible relative positions of the cylinders and the means by which they were cured during the cycle have been described above. However, many other relative positions are possible. For example, if the machine is stopped while the worktable is part way in during the beginning of the cycle and thereafter the broach-handling cylinder, which is then carrying the breach, sinks down by gravity before the machine is restarted, then, on restarting, the handling cylinder will return to its upper position and the movement of the worktable will not be resumed until after the work handling cylinder reaches its upper position. This result is achieved by reason of the fact that downward movement of the broachhandling cylinder shifts the switch ||8 downwardly, thus breaking the circuit through line |61 and closing the circuit through line |68. As soon as the handling cylinder is fully returned, switch I l 8 returns to the position illustrated and inward movement of the table resumes.

Another possibility is that the machine may be left idle following an automatic stop at the end of the cycle and that during the idle period the breaching cylinder will sink to the extreme lower end of its stroke, thus closing switch 9B. However, closure of switch 96 cannot energize relay |91 because relay |84 is de-energized thereby breaking the circuit of relay |91 at contact |94. Relay |84 is energized only when the handling cylinder is at the lower end of its stroke and the latch prevents the handling cylinder` from reaching that position during idle periods. Therefore, under the conditions stated, when the machine is started, the handling cylinder will move up if it is not at the top of its stroke and then the table will move in. At the end of the inward table stroke, the handling cylinder cannot move down because contacts |||J are open; but the circuit through line lilla is closed and, therefore, the breaching cylinder is returned to its upper position. From that point, the normal cycle resumes with a downward movement of the handling cylinder.

If the machine is stopped during the breaching stroke, it will, on restarting, resume the broaching stroke where it left off, since there is no possibility of a change of position of the work handling cylinder or table under those circumstances during the idle period. The same thing is true if the machine is stopped during the return movement of the breaching ram; that is to say, on restarting under these circumstances, the upward movement of the ram will resume.

A complete tabulation of all improper positions which may result, and the way they are automatically corrected before the normal cycle resumes, is given below. Each improper position assumed prior to restarting is indicated in the lefthand column, while in the right-hand column are listed the various cylinder movements which occur automatically in the order given when the machine is restarted and before the normal cycle is automatically resumed.

Improper Positions Corrective Movements A. Table Out 1. Machine stopped at end of cycle a, Handling cylinder sinks l. Handling cylinder returns b. Breach cylinder sinks pnrl. Table moves in tially or fully 2. Branching cylinder returns c. Handling cylinder sinks 1. Handling cylinder returns and breaching cylinder 2. Table moves in sinks partially or fully 3. Broaching cylinder returns 2. Machinestoppedduringbroach return by breaching cylinder a. Brcaching cylinder sinks None required-cycle rc partially or fully sumes 3. Machinestoppedduringbroach return by handling cylinder a. Handling cylinder sinks None required-cycle resumes b. Broachng cylinder sinks 1. Handling cylinder returns partially 2. Machine stops 3. On restarting, table moves 1n 4. Brouching cylinder returns c. Broaching cylinder sinks 1. Broaching cylinder refully turns B. TableV Intermediate Stroke l. Machine stopped during inward movement of table a. Handling cylinder sinks l. Handling cylinder returns b. Broaching cylinder sinks l. Table moves in fully or partially 2. Broachingcylinder returns c. Handling cylinder sinks and 1. Handling cylinder returns breaching cylinder sinks 2. Table moves in fully or partially 3. Branchingcylinderrcturns 2. Machine stopped during out- None required-cycle reward movement of table sumes C. Table In 1. Machine stopped before handling cylinder moves down a. Handling cylinder sinks None required-cycle resumes b. Broaching cylinder sinks l. Broaching cylinder repartially or fully turns c. Handling cylindersinksond 1. Broaching cylinder rcbroaching cylinder sinks turns partially or fully 2. Machine stopped during down- Same as for corresponding 2. ward movement of handling positions under C-l cylinder 3. Machine stoppedduringbroach- None required-cycle reing stroke sumes It will be observed from the above table that the automatic corrective movements take place in such an order that no damage can occur to the broach, the workpiece, or the machine, and that every possible position that can result during operation or after an emergency stop at any point in the cycle is taken care of. In each case, the corrective movements listed leave the cylinders in a relative position they should assume during some point in the normal cycle. From that point on, the cycle resumes normally. It may be noted that no mention is made of the possibility of the handling cylinder sinking fully. This is due to the fact that a full sinking movement is prevented by the latch.

It should be noted that all of these functions are achieved by a very simple arrangement of parallel circuits, in which every single valve solenoid and relay operating coil is connected directly across the full line voltage. This basic arrangement insures that the full operating voltage is available to actuate each solenoid or coil at all times and greatly facilitates modification and adaption of the circuit to different types of machines.

The remaining portions of the circuit so far not mentioned, which are largely located in the lower lefthand portion of Figure 3, have no utility except for use in jogging the various cylinders during tool and xture set-up. It is highly desii-able in a machine of this type to provide manually controlled means for moving each cylinder in any desired direction to any desired extent, as such movements are required to facilitate attachment and adjustment of the tools and work holding fixtures during machine set-up opera- 21 tions. Accordingly, there is provided an auxiliary set of manual controls for use in such cases.

The jogging control circuit employs as its source of current the main conductor |40 and the branch |45 of the main conductor |4|. When it is desired to operate the manual jogging controls, the previously mentioned switch |44 is shifted to break the connection between the lines |42 and i 45 and to complete an electrical connection between the lines |43 and |45, thus energizing the latter.

In order to control movement of the table in either direction, a pair of manually operated push- button switches 204 and 205 are provided. Each of these switches has flve contacts, those of the switch 254 being indicated by the letters a, b, c, d, and e, and those for the switch 205 being indicated f, g, h, lc, and m. The contactor of switch 204 is spring-biased to a position in which it connects contacts a and b. When depressed it connects contacts c, d, and e. The contactor of switch 205 similarly connects contacts f and g in its normal position and connects contacts h, lc, and m, when depressed. Contacts c and m are connected to line |46; contacts d and f are connected together; contacts b and h are connected together; contacts e and lc are connected by lines 2 I0, 2| and 2 I2 to line |65 at a point to the right of the pressure control solenoid 89; contact a is connected by a line 2 I4 to line |61 between solenoid 39 and the contact |10; and contact g is connected by a line 2 |5 to line |66 between solenoid 40 and contact |98.

As the result of this arrangement, all of the circuits connected to switches 204 and 205 are normally open. However, when only switch 204 is depressed solenoid 40 is energized through line |46; contacts c, d, f, and g, and line 2|5, and the pressure control solenoid 39 is energized through line |46, contacts c and e and lines 2||| and 2|2. Thus depression of switch 204 causes the work table to move out, and such movement continues only so long as the switch 204 is depressed. Likewise, the pressure control solenoid is energized only so long as the switch 204 is depressed, with the result that no pressure exists in the system except when the switch is depressed. This enables the operator to leave the pump running during the set-up operations without heating the oil and yet enables him to shift the table outwardly to any desired extent by the touch of the switch button. Switch 205, when depressed alone, operates in the same manner to energize solenoids 80 and 39 to build up pressure and effect an inward movement of the worktable.

If both of the switch buttons 204 and 205 are depressed simultaneously, no movement of the worktable results, but the pressure control solenoid is energized to subject the system to operating pressure.

A pair of manually operated switches 2|8 and 2 I9 are provided for similarly energizing the solenoids and 21 respectively of the ram control valve 26 to effect any desired upward or downward movement of the ram. These switches, being identical in construction and mode of operation to switches 204 and 205, need no furthe description.

A third pair of manually operated switches 220 and 22| are provided for energizing the solenoids 34 and 35 respectively of the handling cylinder control valve 33. These switches are likewise similar in construction and operation to the switches 204 and 205. It will be noted, however, that on depression of switch 22| both the solenoid 35 and the latch solenoid |25 are energized-,1' whereas on depression of the switches 204, 205, 2|8, 2|9, and 220 the solenoids 40, 39, 28, 2l, and 24 are energized, respectively, without energizing the solenoid |25 to release the latch. Thus the latch normally operates to limit downward movement of the handling cylinder during setup operations. The only exception is when switch button 22| is depressed to cause downward movement of the handling cylinder.

It is apparent, therefore, that the hereinbefore described control circuit not only achieves an automatic positively interlocked and fool-proof control of maximum simplicity, but lends itself readily to an exceedingly simple and practical jogging control for use in tool set-up operations.

Preferably the jogging control buttons will be made inaccessible to the ordinary operator since they need be employed only by skilled machine set-up men. It is possible by manipulation of the jogging buttons to cause damage, but, as previously pointed out, it is impossible by any manipulation of the normal controls, namely, the starting button, the emergency stop button, and the cycle reset button, to cause any injury to the broach, work, or machine.

What is claimed is:

l. In a hydraulic shuttle pull-broaching machine, a double-acting positive displacement motor for operating a movable worktable between a retracted and a broaching position, a doubleacting positive displacement motor for operating a broach-handling slide between a retracted and an advanced position, a double-acting positive displacement motor for operating a broaching ram through a broaching and a broach-return stroke, a separate four-way reversing valve for controlling admission of operating liquid to each motor, separate means for shifting each fourway valve, each said means including a pairof solenoids, energization of one of which causes a shift of the valve in one direction and energization of the other causes a shift in the opposte direction, and automatic means controlled by the position of the motors for energizing said solenoids one at a time in sequence to produce a complete cycle of operations including an ad- Vance of the table to broaching position, an advance of the broach-handling slide, a broaching stroke of the ram, a retraction of the table, a broach-return stroke of the ram, and a retraction of the broach-handling slide, said lastnamed means including automatic means operable to return the broach-handling slide to its fully-returned position before any advance of the table, automatic means to return the ram to fully-returned position before any advance of the broach-handling slide, automaticv means to prevent advance movement of the broach-handling cylinder if the table is not fully advanced and automatic means to prevent a broaching stroke of the ram if the table is not fully advanced.

2. In a hydraulic shuttle pull-broaching machine, a double-acting positive displacement motor for operating a movable work table between a retracted and a broaching position, a doubleacting positive displacement motor for operating a breach-handling slide between a retracted and an advanced position, a double-acting positive displacement motor for operating a broaching ram through a broaching and a broach-return stroke, a separate four-Way reversing valve for controlling admission of operating liquid to each, motor, separate means for shifting each. four-- 23 way valve, each said means including a pair of solenoids, energization of one of which causes a shift of the valve in one direction and energiaation of the other causes a shift in the opposite direction, and automatic means controlled by the position of the motors for energizing said solenoids one at a time in sequence to produce a complete cycle of operations including an advance of the table to breaching position, an advance of the broach-handling slide, a breaching stroke of the ram, a retraction of the table, a breach-return stroke of the ram and a retraction of the broach-handlingT slide, means for rendering said automatic means inoperative, and manually controlled means efrective when said automatic means is rendered inoperative for selectively energizing any one of said solenoids.

3. In a hydraulic shuttle pull-breaching machinea double-acting positive displacement motor for operating a movable worktable between a retracted anda breaching position, a doubleacting positive displacement motor for operating a breach-handling slide between a retracted and an advanced position, a double-acting positive displacement motor for operating a breaching ram through a broaching and a breach-return stroke, a constant displacement pump, branch conduits for conducting liquid from the pump to both sides of each motor, a separate four- Way reversing valve for each motor associated with said branch conduits, automatic means for shifting said four-way valves one at a time in either direction to produce a complete cycle of operations including an advance oi the table to breaching position, an advance oi the broachhandling slide, a broaching stroke of the ram, a retraction of the table, a broach-return stroke of the ram and a retraction of the breach-handling slide, a by-pass valve for ley-passing to low pressure a portion of the liquid discharged by the pump, and means for automatically controlling the degree of opening of said by-pass valve to maintain the rate oi flow of liquid to each motor as that motor operates at a constant value which is different for each motor and which is independent of the resistance encountered by each motor, said last means including means in the conduits from the by-pass valve to said motors for imposing a diierent resistance to the flow to each motor, and means responsive to the pressure drop in each conduit as flow occurs therein for controlling the degree oi opening of said by-pass valve.

e. In a hydraulic shuttle pull-broaching machine, a double-acting positive displacement motor for operating a movable worktable between a retracted and a broaching position, a doubleacting positive displacement motor for operating a broach-handling slide between a retracted and an advanced position, a double-acting positive displacement motor for operating a breaching ram through a broaching and a broach-return stroke, a constant displacement pump, branch conduits for conducting liquid from the pump to both sides of each motor, a separate four-way reversing valve for each motor associated with said branch conduits, automatic means for shifting said four-way valves one at a time in either direction to produce a complete cycle of operations including an advance of the table to broaching position, an advance of the broach-handling slide, a broaching stroke of the ram, a retraction of the table, a broach-return stroke of the ram and a retraction of the broach-handling slide, a by-pass valve for by-passing to low pressure va Cgl lil

portion of the liquid discharged by the pump, and means for automatically controlling the degree of opening of said by-pass valve to maintain the rate of flow of liquid to each motor as that motor operates at a constant value which is different for each motor and which is independent of the resistance encountered by each motor, said last means including means in the conduits from the by-pass valve to said motor for mposing a different resistance to the flow to each motor and means responsive to the pressure drop in each conduit as iiow occurs therein for controlling the degree of opening or said by-pass valve, and means for independently adjusting the resistance to flow to each motor.

5. In a hydraulic broaching machine, a doubleacting positive displacement motor for operating a movable .vorktable between a retracted and a broaching position, a double-acting positive displacement motor for operating a broaching ram through a broaching and a broach-return stroke, a constant displacement pumpy branch conduits for conducting liquid from the pump to both sides of each motor, a separate four-Way reversing valve for each motor associated with said branch conduits, automatic means for shifting said four- Way valves one at a time in either direction to prod ce a complete cycle of operations including an advance of the table top breaching position, a broaching stroke of the ram, a retraction of the table, and a broach-return stroke of the ram, a by-pass valve for ley-passing to low pressure a portion ci' the liquid discharged by the pump, and means for automatically controlling the degree of opening oi said by-pass valve to maintain the rate of flow of liquid to eacn motor as that motor operates at a constant value Which is diiierent for each motor and which is independent of the resistance encountered by each motor, said last means including means in the conduits from the by-pass valve to said motors for imposing a diierent resistance to the flow to each motor and means responsive to the pressure drop in each conduit as low occurs therein for controlling the degree of opening of said by-pass valve, and means for independently adjusting the resistance to ilcw to each motor.

6. In a vertical shuttle-type pull down broaching machine having a hydraulic motor for moving a Work xture into and out of breaching position, a hydraulic motor for moving a broachhandling chuck toward and away from a broachpulling chuck, a hydraulic motor for moving a broach-pulling chuck toward and away from the broach-handling chuck, the combination of control means for automatically operating said units through a normal shuttle breaching cycle, said control means including, means operable automatically at any time during the cycle before the fixture is fully advanced to return the broachhandling motor to fully retracted position if it is not fully retracted and to prevent inward movement of the Work fixture motor unit the broachhandling motor is fully retracted, means operable automatically at any time during the cycle before the breach-handling motor is fully advanced to restore the breach-pulling motor to its fully advanced position if it is not fully advanced, and means operable during operation of said last mentioned means to prevent advance movement of the broach-handling cylinder until the broachpulling cylinder is fully advanced.

7. In a vertical shuttle-type pull down broaching machine having a hydraulic motor for mov- 75 ing a work xture into and out of breaching position, a hydraulic motor for moving a breachhandling chuck toward and away from a breachpulling chuck, a hydraulic motor for moving a breach-pulling chuck toward and away from the breach-handling chuck, the combination of control means for automatically operating said units through a normal shuttle breaching cycle, said control means including; means operable automatically at any time during the cycle before the iixture is fully advanced to return the breachhandling motor to fully retracted position if it is not fully retracted and to prevent inward movement of the work nxture motor until the breach-handling motor is fully retracted, means operable automatically at any time during the cycle before the breach-handling motor is fully advanced te restore the breach-pulling motor to its fully advanced position if it is not fully advanced and to prevent advance movement of the breach-handling cylinder until the breachpulling cylinder is fully advanced; means to prevent retraction of the work xture motor after it has fully advanced unless the breach-handling motor is in its fully advanced position and the breach-pulling motor has previously been fully retracted during the cycle, means to prevent advance movement of the breach-pulling motor after it has completed the breaching stroke until after the work fixture motor is fully retracted, and means to limit advance movement of the broachhandling motor when the machine is idle.

8. In a vertical shuttle-type pull down breaching machine having a hydraulic motor for moving a work fixture into and out of breaching position, a hydraulic motor for moving a breachhandling chuck downwardly toward and upwardly away from a breach-pulling chuck, a hydraulic motor for moving a breach-pulling chuck upwardly toward and downwardly away from the breach-handling chuck, the combination of control means for automatically operating said units through a normal shuttle breaching cycle, said control means including: means operable automatically at any time during the cycle before the fixture is fully advanced to return the breachhandling motor upwardly to fully retracted position if it is not fully retracted and to prevent inward movement of the work xture motor until the breach-handling motor is fully retracted, means operable automatically at any time during the cycle before the breach-handling motor is fully advanced downwardly to restore the breach-pulling motor to its fully advanced upward position if it is not fully advanced, and means operable during operation of said last mentioned means to prevent advance downward movement of the breach-handling cylinder until the breach-pulling cylinder is fully advanced upwardly.

9. In a vertical shuttle-type pull down breaching machine having a hydraulic motor for moving a werk fixture into and out of breaching position, a hydraulic motor for moving a breachhandling chuck downwardly toward and upwardly away from a breach-pulling chuck, a hydraulic motor for moving a breach-pulling chuck upwardly toward and downwardly away from the breach-handling chuck, the combination of control means for automatically operating said units through a normal shuttle breaching cycle, said control means including means operable automatically at any time during the cycle before the fixture is fully advanced to return the breachhandling motor upwardly to fully retracted position if it is not fully retracted and to prevent inward movement of the work xture motor until the breach-handling motor is fully retracted, means operable automatically at any time during the cycle before the breach-handling motor is fully advanced downwardly to restore the breach-pulling motor to its fully advanced upward positie-n if it is not fully advanced and to prevent advance downward movement of the breach-handling cylinder until the breach-pulling cylinder is fully advanced upwardly, means to prevent retraction of the work fixture motor after it has fullyr advanced unless the breachhandling motor is in its fully advanced de wnward position and the breach-pulling motor has previously been fully retracted downwardly during the cycle, means to prevent upward advance movement ofthe breach-pulling motor after it has completed the breaching stroke until after the work fixture motor is fully retracted, and means to limit downward advance movement of the breach-handling motor when the machine is idle.

10. In combination, a plurality of positive displacement double-acting hydraulic motors each having a movable element, a separate four-way reversing valve for controlling admission of operating liquid to each motor, separate means for shifting each four-way valve, each said means including a pair of solenoids, energization of one of which eects a shift of the valve in one direction and energization of the other of which effects shift of the valve in the other direction, automatic means controlled by the position of the movable elements of said motors for energizing said solenoid one at a time in a predetermined sequence to cause said motor elements to perform a cycle of operations, said last-named means including a switch mechanism operated by one of said motors when said motor is away from the position it should occupy when a second motor which operates immediately prior thereto in said sequence is so operating, said switch mechanism having contacts in the circuit of the solenoid which on energization elfect return of said one motor te said position and having contacts in the circuit of the solenoid which effect said prior operation of the second motor, said rstmentioned contacts being closed and the secondmentioned contacts being opened when said switch mechanism is so operated by said one meter.

BENEDIC'I WELTE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,186,379 Harrington Jan. 9, 1940 2,194,568 Romaine Mar. 26, 1940 2,209,608 Nye July 30, 1940 2,239,237 Lapointe Apr. 22, 1941 2,254,708 Nye Sept. 2, 1941 2,256,332 Welte Sept. 16, 1941 2,274,191 Davis Feb. 24, 1942 2,307,228 Monroe Jan. 5, 1943 2,317,099 Groene Apr. 20, 1943 2,374,243 Somes Apr. 24, 1945 2,395,702 Welte Feb. 26, 1946 2,429,938 Mansfield Oct. 28, 1947 2,446,397 Weite Aug. 3, 1948

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