US2180646A - Cutting machine - Google Patents

Description

Nov. 21, 1939.

D. L. SMITH CUTTING MACHINE Filed July 14, 1936 4 Sheets-Sheet l lbiVENTOR #414, A M BY v ATTORNEY Nov. 21, 1939. I s rr 2,180,646 I CUTTING MACHINE Filed July 14, 1936 4 Sheets-Sheet 2 INVENTO R fi A l'TORNEY D. L.'SM|TH CUTTING MACHINE Nov. 21, 1939.

Filed July 14, 1936 4 Sheets-Sheet 3 a IIFVENTOB 6 ATTORN EY Nov. 21, 1939.

7 D. L. SMITH CUTTING MACHINE 4 Sheets-Sheet 4 Filed July 14, 1936 INVENTOR B-Y ATTORN-EY Patented Nov. 21, 1939 UNITED STATES CUTTING MACHINE Donald L. Smith, Dunellen, N. J., assignor to Air Reduction Company,

Incorporated, New York,

N. Y., a corporation of New York Application July 14,

6 Claims.

This invention relates to machines for cutting by means of a gas torch. The invention is particularly intended for cutting risers from castings, but some features of the invention are not limited to such machines.

When making castings, it is common practice to have an upwardly extending recess in the mold into which excess metal is poured when the mold is filled. This metal, which is called the riser,

allows for contraction of the casting and prevents cracks or weak places in the casting after it has cooled.

The riser must be removed from the finished casting, however, and various efforts have been made to remove these risers as economically as possible. Gas cutting torches are commonly used for the work, but it is essential that no part of the casting should be removed, and it has been necessary to allow a margin of safety by cutting the riser a slight distance away from its juncture with the casting. The end portion of the riser which remains on the casting after the cut is then ground away to make the final surface as accurate as necessary for the use for which the casting is intended.

With cutting machines of the prior art, the time required to square up a casting in all directions, with respect to the plane of movement of the gas stream, with sufiicient accuracy to cut .30 the riser close to the casting took so much time that it more than offset the economy which resulted from the elimination of the grinding at the other end of the operation. It is an object of this invention to pfovide a unitary structure that its on the casting and can be immediately clamped in position to move a torch across a riser and cut the riser close to its juncture with the casting. The cutting machine of this invention clamps on a cast work-piece which has a riser extending transversely with respect to the casting so that the work-piece is of different crosssection at spaced points along its length.

A more general object of the invention is to provide an improved, self-contained cutting machine for moving a torch along a definite course,

and especially along a straight line. One feature of the machine relates to movable supports for the pivots of'torch-supporting links. These supports shift the centers about which the links swing so that the torch-supporting portions of the links can move in a straight line instead of along arcuate paths;

While machines made in accordance with this invention are primarily" intended for cutting,

; they can on: occasions be utilized for welding 1936, Serial No. 90,471

by substituting a welding torch or other instrumentality in place of the cutting torch.

Other features, objects and advantages of the invention will appear or be pointed out as the specification proceeds.

In the accompanying drawings, forming part hereof:

Fig. 1 is an end view of a riser cutting machine embodying the invention, the machine "being shown clamped on a casting in position to cut a user;

Fig. 2 is a front view of the structure shown in Fig. 1; v

Fig. 3 is a top planview, partly in section, showing the operating mechanism within the machine of' Figs. 1 and 2. The torch and clamp handle are omitted in Fig. 3;

Fig. 4 is a front view of the machine, mostly in section, along the line 44 of Fig. 1;

Fig. 5 is a sectional view taken on the line 5--5 of Fig. 2, but showing the torch and its holder in elevation; and

Fig. 6 is a wiring diagram for the machine.

The machine illustrated includes a frame or housing H with two shafts I2 (Fig. 2) extending through its front wall. Two outside parallel arms I4 are secured to the shafts l2. The up per ends of the arms l4 are connected by a link I5. A- torch-holder I6 is connected to the link i5, and a torch ll held in the torch-holder can be moved up and down in the torch-holder by conventional rack and pinion adjusting mean operated by a hand-wheel I9.

The machine has clamping means for connecting it to the casting from which a riser is to be cut. The clamping means includes a frame 2| to which the-housing I I is connected. Two-downward extensions- 22, 23 of the clamp frame-have buttons 24 (Figs. 1 and 5) which contact with the outside of a casting 25-, one of the- extensions 22, 23 being located oneach side of a riser 26 extending from the casting. The Weight of the machineis supported on the casting by arms 28 having buttons 29 in contact with the top surface of the casting 25. A pivot connection 30. joins the mid-portion of each of the arms 28 to the frame 2!.

The extension 23 is wide enoughto cover a portion of the end of the casting 25. Buttons- 32 on the extensions 23 contact with the end face of the casting 25, and a part of the extension 23 protrudes into the casting to provide a bearing 34 for a shaft 35, the axis of which extends substantially parallel to the inside Wall of the casting. An eccentric 36 on one end of the shaft 35 is turned by the shaft 35 until the eccentric bears against the casting and clamps it against the buttons 24 of the extensions 22 and 23. In order to clamp the casting against both extensions with substantially equal force, the eccentric is preferably located midway between the two extensions 22, 23 of the clamp frame.

The shaft 35 is turned by a hand lever 38. A latch 39 on the hand lever engages between teeth of a gear segment 49 to hold the lever 38 and the connected shaft and eccentric in any set position. The gear segment 40 is fixed to the extension 23 of the frame 2|. The latch 39 is operated by a release lever 42 pivotally connected to the hand lever 38.

The clamping means make it possible quickly to locate the machine on the casting in the exact position for cutting the riser. The machine with such clamping means is used in shops where similar castings are turned out in quantity production. When the machine is to be used for cutting risers from castings of a different design, the old clamp frame is replaced with a new one which fits the new casting and which has abutments in position to contact with enough angularly related surfaces of the casting to locate the machine accurately in position to cut the riser. The eccentric is then operated to clamp the frame securely in position. It is the accuracy with which the machine is located by the clamping means which makes possible cuts so close to the casting that only with extremely accurate surface requirements is any subsequent guiding necessary. Ordinarilysuch cuts must be made sufiiciently far from the casting to allow for some inaccuracy in the plane of the out without destroying a part of the casting.

Each of the shafts I2 is rotatably supported in an eccentric 45 secured to a shaft 4! which turns in ball bearings 48. The axes of the shafts l2 and eccentrics 45'are parallel.

There is a recess in the side of each eccentric 45 within the casing I and an inside parallel arm 49 is secured to the portion of the shaft l2 which extends across the recess. The inside parallel arms 49 are directly behind the outside parallel arms l4 and always stay in the same relation with the outside arms because they are secured to the same shafts I2. The two arms secured to each shaft |2 form a composite link.

The inside parallel arms 49 are connected by an inside connecting link 5| which is substantially U-shaped and has three rollers 52 (Fig. 4) on studs extending from its front side. A plate 54 fitting a slot in the front wall of the housing I! has parallel tracks 55 extending above and below the rollers 52. These rollers are not in a straight line, the middle roller being a little lower than the end rollers. The distance between the tracks 55 is slightly greater than the diameter of the rollers 52, so that the middle roller runs on the lower track and the end rollers run on the upper track.

The tracks extend parallel to a line through and perpendicular to the axes of both of the shafts l2. The rollers 52 prevent the inside connecting link 5| from moving up or down and limit it to a reciprocating movement. The pivot connections 51 between the link 5| and arms 49 are limited to the same movement of translation as the link. The pivot connections 51 would ordinarily move along arcuate paths as the angular positions of the arms 49 change, but since such movement is notpossible the shafts I2 rotate the eccentrics 45 one way or the other So t at t e lower ends of the arms 49 move up or down to compensate for the constant height of the pivots 51.

The movement of the outside parallel arms l4 (Fig. 2) is exactly the same as that of the inside arms 49 (Fig. 4), and since the pivot connections between the link l5 and the arms l4 are directly in front of the pivots 5'! they have the same rectilinear motion as those pivots. Thus the link l5 (Fig. 2) and all of the structure which it supports, including the torch ll, move with straight line motion.

The inside connecting link 5| has a ridge 69 (Fig. 5) projecting from its rear face and extending parallel to the tracks 55 throughout the length of the lower portion of the link 5|. Two racks 62 and 62 bear against the ridge 69, one rack being above the ridge and the other below. Holding plates 63 fastened to the ridge extend over the rearward faces of the racks to hold them against transverse displacement on the link 5|. Tongues 64 on the rearward face of the link 5| and on the forward faces of the plates 63 extend parallel to the ridge 6!) and fit into grooves in the racks 62, 62' to hold the racks on the link, but these tongues permit the racks to move with respect to the link in the direction of their length.

The racks 52, 62' are made movable on the link 5| for purposes of adjustment, and they are held in their set positions by screws 66, shown in Figs. 3 and 4. These screws thread through end plates 61 and abut against the ends of the racks 62 and 62'. Lock nuts hold the screws 66 against displacement from vibration. The end plates 61 are fastened to the link 5| by screws 69.

Referring again to Fig. 5, a pinion ll meshes with the upper rack 62 and a similar pinion 1| meshes with the lower rack 62'. The pinions H and II are fixed on the same shafts with gears 12 and 72, respectively. The mechanism for driving the gears 12 and 12 is best shown in Figs. 3 and 4. Small gears 14 and 14' mesh with the larger gears 12 and 12', respectively.

The gears 14 and 14' are secured to the same axles as gears 15 and 15', respectively, and these latter gears are driven by pinions 16 and 16' which are rotated by shafts extending from a reduction gearing 18. An electric motor 19 is connected to and drives the reduction gearing 18.

The reduction gearing drives the pinions l6 and 16' in opposite directions so that the pinions H and H which mesh with the racks rotate in opposite directions. This difference in direction of rotation of the pinions H and 'H' is necessary because the racks are under one of the pinions and above the other.

It is possible to take up the backlash and eliminate all lost motion in both of the gear trains, through which the motor drives the racks, by moving either of the racks 62, 62' with respect to the other in the direction of its length. When the motor is not running, the screws 66 of either rack are operated to cause a. relative movement of the racks in opposite directions. With the motor stationary such movement of the racks is possible only so long as there is backlash or lost motion in the gearing through which the racks are driven by the motor. When all backlash in both gear trains has been taken up, there can be no further relative movement of the racks. .The screws 65 are secured in their set positions by lock nuts.

When the machine is operated by the motor. only one of the pinions II and 1| actually transmits power to the rack, and the other pinion contacts with the faces of its rack teeth which it would touch if driving the rack in the opposite direction. If the direction of rotation of the motor is reversed, the pinion which was driving becomes the one which holds the racks back to prevent backlash and the other pinion becomes the driver.

Fig. 6 shows the electric control circuitof the machine. The motor 19 has a field coil 8! and a centrifugal governor 82 in series with the armature. A resistance 83 by-passes a part of the current around the governor. A condenser 84 is connected in parallel with the governor to prevent sparking.

A snap-switch 86 is operated by the machine so that whenever the torch reaches either end of its stroke the blade of the switch 86 is shifted from one of its contacts to the other. The snapswitch 86 is electrically connected with a manually-operated switch 88, as shown in Fig. 6, so that shifting of the position of the snapswitch 86 by the machine always opens the motor circuit and causes the motor to stop. Manual operation of the switch 88 to reverse its position, after the machine has been stopped by shifting the snap-switch 86, again closes the motor circuit, but with the field current reversed so that the motor 19 runs in the opposite direction and causes the torch to come back on its return stroke.

The snap-switch 8B is operated by a rod 98 (Figs. 3 and 4) which extends parallel to the racks of the link 5! and is supported in bearings 9! on the inside of the housing. The rod 9!! slides lengthwise in the bearings 91 and has pins 92 on opposite sides of the operating lever 93 of the switch 86 for shifting this lever when the rod 99 moves. The end plates 61 on the link 5! strike against spaced steps 95 on the rod 9|) and move the rod to operate the snap-switch 86 as the link 5| approaches the end of its stroke in either direction. The switch 86 and its operating mechanism comprise automatic means for stopping the machine at the end of each stroke of the torch.

The manually operated switch 88 is supported on the housing H within convenient reach of an attendant. The machine can be stopped at any time by reversing the position of the switch 88, or by shifting the rod by means of a handle 91 on an end of the rod which extends through the wall of the housing.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some features can be used without others.

I claim:

1. A machine of the character described, including a housing, a shaft extending through a wall of the housing, an eccentric in which the shaft turns, said eccentric being rotatable in the wall of the housing, an arm fixed on the shaft, torch-holder means supported by the arm, and guide means within the housing constructed and arranged to cause the eccentric to move into a definite angular position for each angular position of the shaft so that the torch-holder on the arm is held to a fixed course.

2. A cutting machine of the character described including a housing, two parallel shafts extending through eccentrics in the wall of the housing, an arm connected to each of the shafts inside the housing, and another arm connected in the same angular position on the shaft as the inside arm, a torch-holder carried by a link between the two outside arms, a link between the arms within the housing, and guide means in the housing holding said link against turning and limiting its movement to a predetermined path.

3. In a cutting or welding machine, a housing, two parallel, rotatable supports extending through a Wall of the housing,.a pivot shaft carried by and rotatable in each of said supports with the axis of each shaft spaced from but parallel to the axis of its associated support, an outside arm secured to the end of each shaft outside of the housing, an inside arm secured to each shaft directly behind-the outside arm but within the housing, a torch-supporting link connected to the outside arms at adistance from their connections to the pivot shafts, a driving link connected to the inside arms directly behind and in alinement with the torch-supporting link connections to the outside arms, a guide track within the housing for confining the movement of the driving link to a predetermined path, and mechanism for moving said driving link back and forth in the housing to swing the arms about the axes of the pivot shafts.

4. A riser cutting machine including a housing and means for holding the housing in position on a casting from which a riser is to be cut, a guideway on a wall of the housing, a member supported by the housing and restrained by the guideway to a reciprocating movement, a torchholder, and links supporting the torch-holder from the housing, connections between the torchholder and reciprocating member that cause the torch-holder to move along a path similar to that of the reciprocating member, and power mechanism in the housing for moving said reciprocating member including a rack connected to said member, a pinion meshing with the rack and means for rotating the pinion.

5. In a cutting machine having a torch support and. means for moving the torch support including a reciprocating member, gear teeth along the length of said member, a motor separate from the reciprocating member, two sets of gearing between the motor and the reciprocating member with the final gear of each set in mesh with different teeth of said member, and means for effecting a relative movement of the gear trains to take up the play in the'gearing and eliminate lost motion in the means for moving the torch.

6. A riser cutting machine including a housing and means for holding the housing in position on a casting, a guideway on a wall of the housing, a member supported by the housing and restrained by the guideway to a reciprocating movement, a torch-holder supported by the housing,

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