US3483781A - Shearing apparatus for rolled metal forms - Google Patents

Description

Dec. 16, 1969 c. G. cRlTlDEs ETAL 3,483,731

SHEARING APPARATUS FOR ROLLED METAL FORMS Filed April l1, 1967 4 Sheets-Sheet l INVENTORS ORDATO CHARLES G. CRI-runas EMIL A. sc JOHN d. HARTNET Dec. 16, 1969 c. G. cRmDEs ETAI- 3,483,781

SHERING APPARATUS FOR ROLLED METAL FORMS Filed April 11, 1967 4 Sheets-Sheet 2 Dec. 16, 1969 C. G. CRITIDES ET AL SHEARING APPARATUS FOR ROLLED METAL FORMS Filed April ll, 1967 4 Sheets-Sheet 5 EMM. A. SCORDATO gQHN d.

Dec. 16, 1969 c. G. cmTlDr-:s ET AL 3,483,781

SHEARING APPARATUS FOR ROLLED METAL FORMS 4 Sheets-Sheet 4 Filed April 11, 1957 3,483,781 SHEARING APPARATUS FOR RLLED METAL FURMS Charles G. Critides, Stamford, Conn., and Emil A. Scordato, Bronxville, and John J. Hartnett, Bronx, NX., assignors to Automation Technology, Inc.,

a corporation of Connecticut Filed Apr. 11, 1967, Ser. No. 630,094 Int. Cl. B26d 5/20 ILS. Cl. 83-168 8 Claims ABSTRACT F THE DISCLOSURE The invention relates to an apparatus for automatically shearing the excess width portions of the bulbous ends of a rolled bar as it emerges from a rolling mill stand.

SUMMARY OF rII-IE INVENTION The invention relates to an apparatus for cropping the protruding edges at the ends of a bar when a billet is reduced to bar size in a hot rolling mill.

In forming metals by hot rolling, the bar, as it emerges from the rolling mill, generally has a bulbous shape at its leading and trailing ends. These ends are anywhere from to 10% wider than the nominal width of the bar and protrude outwardly as ears beyond the width of the bar. The ears, moreover, are not uniform in size or configuration; some are reasonably symmetrical with respect to the longitudinal axis of the bar, and others are asymmetrical by having more material in one ear than in the other. The probable cause for such asymmetry lies in the billets not always striking the mill rolls in a perpendicular direction but rather at some slight angle to the perpendicular. The removal of the ears from the bars is highly desirable since it facilitates the subsequent scalping and re-rolling operations by obviating the need to adjust the side guides of the finishing mills to compensate for the protruding ears.

The object of the invention is to provide an improved apparatus for removing the ears from a rolled bar.

In carrying out the invention there are provided a pair of Opposed guillotine cutters that are independently movable towards and away from a bar that has been arrested in a position to have the ears cropped by the cutters. Each cutter moves transversely towards the bar until a contact block mounted on the cutter senses the bar and halts further inward movement of the cutter. The cutter then pivots in a direction depending on whether the leading or the trailing end of the bar is being cropped to present the shearing blade at a slight angle to the length of the bar to trim the end of the bar to a wedge shape. Appropriate controls are provided to sequentially arrest a longitudinally moving bar with its leading end in a trimming position, move the cutters towards the leading end of the bar where they pivot to the desired cutting angle, actuate the mechanism to effect the trim, move the cutters away from the bar, advance the bar to bring it to a position wherein the trailing end can be trimmed, move the cutters into contact with the trailing end of the bar where they pivot to the desired cutting angle for the trailing end, actuate the mechanism to effect the trim, and move the cutters away from the bar to await the presentment of a new bar while the trimmed bar is moved ahead for further processing.

Features and advantages of the invention may be gained from the foregoing and from the description `of a preferred embodiment of the invention which follows,

In the drawings:

FIG. 1 is a schematic illustration of a hot rolling mill;

'nited States Patent Patented Dec. 16, 1969 ICC FIG. 2 is an illustration of a hot rolled bar prior to a trimming operation;

FIG. 3 is an end view of the shearing apparatus of the present invention with some parts removed;

FIG. 4 is a view taken along line 4-4 of FIG. 3;

FIG. 5 is a top plan view of the turret platform of one of the guillotine cutters of the shearing apparatus;

3 FKClv. 6 is a detailed view taken along line 6-6 of FIG.

FIGS. 7 and 8 are a schematic wiring diagram of the electrical controls for the shearing apparatus.

Referring to FIG. 1, a hot rolled bar mill is shown schematically. A billet 10 is received from the billet furnace 11 and conveyed to the hot rolling mill 12 where it is reduced to the desired size by several passes through the mill. The reduced billet, now a bar 13, is next conveyed to the quenching tank 14 to be cooled and then to the attener 1S to remove any longitudinal curvature that might have been produced in the rolling operation.

The bar will have bulbuous ends such as illustrated in FIG. 2 which naturally occur due to the metal deformation resulting when the billet strikes the mill rolls. The bulbous ends may be symmetrical as shown at the right end of the illustrated bar or the ends may be asymmetrical as shown at the other end of the bar. The degree of symmetry is caused by the angle at which the billet strikes the mill rolls. Those bars having a symmetrical bulbous end being those which approach and strike the mill rolls perpendicularly, while those which are; asymmetrical probably struck the rolls at a slight angle to the perpendicular.

Again referring to FIG. 1, the bar, after leaving flattener 15 is next edge cropped to remove the bulbous proturberances called ears in the shearing apparatus of the present invention. After cropping, the bar is carried by a conveyor 17 to a slab miller 20 where it is finished to the desired dimensions. As will later be seen, the cropping of the bar in shearing apparatus 16 effects a tapered end to the bar to facilitate its enry into miller 20 and through the subsequent milling operations to which the bar might be subjected.

The shearing apparatus comprises generally a hydraulic control unit, a base structure or bed frame secured to a concrete foundation and two guillotine cutters mounted on the bed frame for movement towards and away from each other. The guillotine cutters have been made movable as indicated to obviate the need for a guide mechanism to direct the bars to the blades of the cutters. Also, by making the cutters thus movable, bars of different widths can be accommodated without any prior adjustment of the apparatus since the guillotine cutters move towards each other until they strike a bar positioned between them.

T he bed frame 21 of the shearing apparatus includes two parallel spaced apart channel beams 22 and 23 (see FIG. 3). The beams are placed on their edges and secured to a concrete floor, either directly or to cross beams which in turn are secured to or in the concrete tioor. On the upper edge of each beam rails 24 and 25 are fastened. The rails project outwardly from the beams as shown in FIG. 4 for a reason which will soon be apparent.

On the bed frame two guillotine cutters 26 and 27 are mounted for movement towards and away from each other. Since `both guillotine cutters are identical, only one will be described in detail. Cutter 26 includes a carriage 30 comprising a steel plate 31 having two parallel rail engaging bars 32 and 33 fastened to the underside thereof. The bars are adapted to ride on the rails 24 and 25 of bed frame 21. A side guide member 34 is bolted to bar 32 and it engages the edge of rail 24 while a further member 35 engages the underside of the projecting lip of the rail. Similar members are provided on bar 33. It is thus apparent that carriage 30 can slide along the bed frame beams, but any sideways or upward movement with respect thereto is prevented.

lThe longitudinal movement of the guillotine cutter carriage is effected by means of a hydraulic cylinder assembly 36 mounted beneath the carriage and between the bed frame beams 22 and 23. The hydraulic cylinder is pivotally mounted on a pin supporting member 37 secured to an end beam 40 of the bed frame. The piston 41 of assembly 36 is likewise pivotally connected to the plate 42 depending from carriage plate 31. The control of movement of the guillotine cutter carriage which depends on the ow of hydraulic fluid to assembly 36 will 4be hereinafter considered.

The carriage 30 supports the turret assembly 43 of guillotine cutter 26 through a trunnion which permits the turret to rotate about a vertical axis. The rotation of the turret will be limited in both directions of rotation but it will be sufficient to provide the desirable tapered cut to the ends of the bar.

The turret platform 44 includes a bearing 45 to which is welded an upper plate 46 and a lower plate 47. See FIGS. 3 and 5. The plates 46 and 47 are formed into a structural unit by cross `beams 50 and 51 and four lengthwise beams 52. A ship channel 53 is secured to the forward end of platform 44 adjacent cross beam 50 and it extends upwardly above the upper plate. A stationary knife blade 54 of the cutter 26 is bolted to channel 53 by bolts and nuts 55; bolting facilitates removal and replacement of blade 54 when required.

The turret platform 44 is tted over the post or trunnion 56 which is secured to the guillotine cutter carriage 30. A cover plate 57 that overlays bearing 45 and is secured to trunnion 56 prevents any upward movement of platform 44 and the shearing mechanism carried thereon which might otherwise occur during a shearing operation.

As was indicated earlier, the turret assembly of the guillotine cutter is capable of rotation, and in fact rotates during shearing operations. The rotation, or more precisely pivoting, of the turret assembly takes place about trunnion 56. The turret assembly 43 is supported by bearing blocks 60 which ride on rails 61 secured to the top surface of steel plate 31 of the carriage 30. A stop member 62 depending from the underside of lower plate 47 engagesl either of two abutments 63 and 64 secured to plate 31 and in this way limits the pivoting motion of the turret assembly and the taper that is given to the sheared end of the bar. See FIG. 5. Stop member 62 is provided with an elongated slot 65 so that its position can be adjusted on platform 44 and either faces 66 or faces 67 aligned with abutments 63 or 64 respectively. In this way the degree of pivot allowed turret assembly 43 can be controlled to provide the desired angle of cut to the ends of bar 13.

The direction in which the turret pivots is determined by the contact blocks 70 and 71 provided on the turret. In operation the bar will be arrested for a trimming cut with an end positioned longitudinally between the two blocks on each turret. Thus, with the -bar supported on flattener 15 with its leading end in the shearing apparatus, when the guillotine cutters move in on the bar, the rear blocks 71 will strike the bar and pivot turret asssembly 43 clockwise and turret assembly 72 counterclockwise. It is clear that when the trailing end of the bar is positioned within the shearing apparatus, the turret assemblies will be pivoted in the opposite directions.

The turret platform 44 supports a guillotine cutter frame 73 comprising two upright spaced apart channel shaped standards 74 and 75 that are connected at their upper ends by a cross beam 76 that is in the form of an I-beam having a number of strengthening plates 77 to add rigidity to the structure. A rocker shaft S is supported in frame 73 by two spaced bearings 81 and 82 bolted to the lower flange of beam 76. A walking beam 83 is journaled on shaft 80 between bearings 81 and 82 and it extends fore and aft of frame 73. The rear end of walking beam 83 is pivotally connected to the piston of a hydraulic mechanism 84. The lower end of the hydraulic cylinder 85 is pivotally connected to the turret platform 44. A pin 86 extending between the clevis arms S7 of cylinder 85 passes through the upstanding support 88 which is bolted to plate 46.

The forward end of walking beam 83 is provided with a cross shaft 90 that extends the width of the guillotine cutter. 'The ends of shaft 90 are journaled in two links 91 and 92 that are pivotally supported on rocker shaft 80. In this way shaft 90 which will Ibe seen to carry the movable knife of the guillotine cutter can be moved upwardly and downwardly by the action of the centrally located walking beam and yet be well supported throughout its length. A pair of `connecting links 93 and 94 are pivotally supported on shaft 90 in spaced apart positions on either side of walking beam 83. The links are in the form of stub I-beams with bearing hubs formed at both ends thereof. The lower hubs of links 93 and 94 support another shaft 95.

The shaft 95 in turn supports the guillotine cutter knife holder 96. rl`his part is a large casting having three spaced apart bearing arms 97 formed at its upper edge; shaft 95 passes through the bearing apertures. The vertical edges of the knife holder are provided with V-shaped grooves 100 (see FIG. 6) so that the vertical movement of holder 96 can be guided.

A bar 101 having a triangularly shaped edge is bolted to the forward edge of upright channels 74 by bolts 102 passing through bar 101 and channel 74 and threaded into a so-called nut bar 103 which is welded into channel 74. A pair of hardened steel rails 104 are fastened to the triangular edge of bar 101 by bolts 105 and it is these rails which engage the V-grooves of knife holder 96. A second bar like 101 is similarly provided on channel 75 to engage a V-groove on the other vertical edge of knife holder 96. It is thus apparent that the knife holder is constrained to move in a well defined vertical plane.

A knife 106 is bolted to the lower end of holder 96 by bolts and nuts 107. The knife is designed for progressive shearing action when cropping the ears of the rolled bar being trimmed.

The knife holder 96 also carries a hold down clamp 110 that engages a bar prior to the knife beginning its shearing action. The clamp 110 comprises an elongated clamping shoe 111 which, through a ball joint, is connected to the piston 112 of a hydraulic mechanism 113. The cylinder 114 is provided with a clevis and pin 115 to pivotally connect to knife holder 96. The action of the mechanism is such that when the knife holder descends, clamping shoe 111 comes into contact with the work first thereby compressing hydraulic mechanism 113. The fluid displaced from the cylinder passes through a how control valve which can be adjusted to obtain any hold down pressure desired.

Gusset plates 116 and 117 are provided on upright standards 74 and 75 to add to the rigidity of the structure.

A conveyor mechanism 120 is also mounted on turret platform 44. It is located directly under the knife holder 96 and it is intended to carry the cropped ears of a bar away from the guillotine cutter and to a waste bin. It is not believed necessary to described the conveyor in detail other than to say it includes an endless procession of conveyor pads carried by endless chains that are driven from a hydraulic motor 121. A sweeper member 122 is carried by the conveyor and it insures that any trimmed metal that falls onto the conveyor is removed to the waste bin. The conveyor is only intermittently operated and then at the completion of a trimming operation. In fact, the sweeper mechanism is operated only after the leading end of a bar is trimmed thus sweeping the cropped ears from the trailing end of the preceding bar and the cropped ears from the leading end of the bar in process of being trimmed. The reason for this is that the sweeper is operated only when it would not slow down the entire operation of the shearing apparatus. This time is when the length of the bar is passing through the shearing apparatus. i.e., after the leading end but before the trailing end of a bar is trimmed. There is insucient time between the trailing end of one bar and the leading end of the closely following bar.

The electrical circuitry, as will later be explained, controls the energization of motor 121. When the sweeper member traverses the width of the shearing apparatus it strikes a limit switch 123 which reverses the motor and restores the sweeper member to its initial position. Another limit swtch 124 signals this occurrance and deenergizes hydraulic motor 121.

The compiete shear apparatus includes two guillotine cutters of the type just described. As previously mentioned they are mounted on the bed frame for movement towards and away from each other so that both sides of a bar can be trimmed simultaneously. Also, since a bar to be trimmed must be stopped in position to be sheared, a stopping mechanism must be provided. The sidewise position of the bar need not be controlled since the guillotine cutters independently move towards each other so that their travel need not be equal to clamp the bar. However, the longitudinal travel of the bar has to be controlled so that the end of the bar stops precisely in position to be trimmed.

Mechanical stops can be provided, but it has been preferred to utilize a photo-cell system to detect the end of a bar and then to apply a brake to the moving bar. When trimming the leading end of a bar, the brake can be part of the attener since the bar will be in the attener when the leading end is trimmed. However, when the trailing end of the bar is trimmed, the bar will be on conveyor 17, and consequently, a brake is provided with the shearing apparatus. FIG. l schematically shows a hydraulically actuated clamp 125 or brake which arrests travel of a bar when it is actuated. The brake comprises a fixed brake shoe over which the bar passes supported on a frame located lat the exit end of the shearing apparatus. A movable shoe which is actuated by a hydraulic cylinder mechanism is mounted to engage the upper surface of a bar. Logic circuitry, as will later be seen, distinguishes between the leading and the trailing ends of a bar.

Before describing an operation of the shearing apparatus, it should be borne in mind that all of the movements of the apparatus, eg., the knife and the turrets, are effected by hydraulic pressure. Consequently, a hydraulic system is provided in which a continuously running pump supplies fluid under pressure to the various hydraulic cylinders used. The flow of fluid to actuate the apparatus is controlled by solenoid operated valves while relief valves are provided to maintain the desired pressure in the hydraulic lines. Thus a fluid pressure is maintained to keep the turret carriages in their retracted positions and the knives in their raised positions. A fluid circuit diagram has not been illustrated because it is believed obvious to those skilled in the art, particularly in view of the description of the apparatus and its operation.

A simplified electrical wiring diagram is included to facilitate a description of the apparatus in operation. However, it should be understood that a more complicated circuit, including start and end of cycle circuits, safeties and push button controls for manual operaion of the apparatus, would be provided in an actual installation. Again, though, such circuits would suggest themselves to those skilled in the art.

A series of photocell actuated switches is provided to detect the entrance of a bar into the shearing apparatus and initiate operation thereof. Referring to FIG. 1 as a bar enters the shearing apparatus from flattener 15, it will first interrupt the light beam of photocell device 3PC,

and then with further travel the light beam of photocell device 2PC, and nally the light beam of photocell device 1PC By circuitry later to be described, the switches controlled by the photocell devices will determine whether a leading or trailing end of a bar is in position to be trimmed. The term photocell device is used herein to include a light source for projecting a beam of light across the path traveled by a bar to a light response element and a switch operated according to whether or not the light beam is interrupted.

ln operation, it will be assumed that the attener 15 iS being driven by a motor and the llattener is propelling a bar toward the shearing apparatus 16. Before the bar reaches apparatus 16, each of the light beams of photocell devices IPC, 2PC, and 3PC are uninterrupted, and the switch contacts of the photocell devices are in the condition shown in FIG. 7 with the movable contact in engagement with the upper stationary contact. If the light beam of any photocell device is interrupted, the movable contact of the associated switch will pivot downwardly into contact with the lower stationary contact. It will be noted that devices 2PC and SPC include double pole switches, while device 1PC includes a single pole switch.

As the bare interrupts the light beam of photocell device SPC, contacts SPCa and SPCb pivot downwardly into engagement with contact 3PCc. As the bar continues its forward movement it interrupts the light beam of photocell device 2PC and contacts ZPCa and 2PCb thereupon pivot downwardly into engagement with contacts 2PCc and ZPCd. Contacts 2PCa and 2PCc complete a circuit to energize relay SRL through contacts 9RL1 and the contacts of switches of photocell devices 1PC, 2PC, and 3PC. Relay 3RL becomes self holding through contacts 3RL1.

Energization of relay SRL causes contacts SRLZ to separate and thereby deenergize the flattener drive clutch solenoid FCS. This disconnects the driving power from the attener; at the same time engagement of contacts 3RL3 complete a circuit to energize the flattener brake solenoid FBS which sets the attener brake and brings the bar to a halt with the leading end between the guillotine cutters 26 and 27.

The energization of relay SRL also engages contacts SRL-4 and completed a circuit through contacts 5RL1 for energization of the turret in solenoid TIS. This causes fluid under pressure to be delivered to hydraulic cylinders 36 and 126 to move carriages 30 and 127 towards each other. The carriages move towards each other until the contact block of one or both of the turrets strike the bar which is positioned between them. If one turret strikes the bar it pivots to the angle determined by the engagement of member 62 and abutment 63 or 64 at which time further movement of that turret halts. A pressure switch PS1 is actuated. A relief valve prevents further build up of pressure in the associated hydraulic mechanism, eg., 84, but the other carriage continues to move inwardly until the contact block of its turret strikes the bar and its movement is halted. At such time pressure switch PS2 is actuated, thus completing a circuit to energize relay SRL. The resultant separation of contacts 5RL1 interrupts the circuit for the turret in solenoid TIS while the engagement of contacts 5RL2 provides a self holding circuit for the relay.

The engagement of contacts 5RL3 completes a circuit for the energization of the lower blade solenoid LBS. This opens the appropriate valve to cause uid to ow to hydraulic mechanisms 84 and 130 and thereby lower knives to trim the ears off the leading end of the bar. When both knives reach the lower extremity of their travel, switches LKSI and LKSZ will engage to complete a circuit for relay 6RL which immediately becomes self holding by the engagement of contacts 46RL2. The engagement of contacts 6RL3 complete a circuit for the raise blade solenoid RBS. When the solenoid is energized, it operates a valve to feed uid to hydraulic mechanisms 84 and 130 to raise the knives. When both knives reach their upper positions as indicated by the engagement of switches lHKS (for cutter 26) and ZHKS (for cutter 27), relay SRL will be energized, and the consequent engagement of contacts 8RL2 completes a circuit for the energization of turret out solenoid TOS. This operates a valve causing fluid to flow to hydraulic cylinders 36 and 126 and the the guillotine cutters to move to their farthest spaced apart positions. When they reach these positions, switches lTOPS (for cutter 26) and ZTOPS (for cutter 27) will engage to complete a circuit for relay 12RL. The energization of relay 12RL causes contacts 12RL1 to engage to energize relay 9RL and contacts 12RL2 to separate shortly thereafter to deenergize relay 9RL. The momentary energization of relay 9RL signals the completion of a shearing operation.

The separation of contacts 9RL1 interrupts the circuit for relay SRL thereby causing the engagement of contacts 3RL2 to energize the attener clutch solenoid FCS and permit the flattener to drive the bar in a forward direction; attener brake solenoid FBS was deenergized to release the brake when contacts 3RL3 separated. Separation of contacts 9RL1 also deenergized those remaining circuits that were not previously deenergized as is apparent from the circuit diagram.

The engagement of contacts 9RL3 completes a circuit for the sweep solenoid SWS. This solenoid causes iluid to flow to sweeper motor 121 and sweeper member 122 to ybrush the trimmed metal into the waste bin. Since relay 9RL is only momentarily actuated, as soon as member 122 moves, contacts 3SWS and 4SWS engage to maintain solenoid SWS energized. When member 122 reaches the end of its travel, switch lSWS (123) and ZSWS (not illustrated) engage to energize relay 11RL. The subsequent separation of contacts 11RL2 deenergizes solenoid SWS. Separation of contacts 11RL1 deenergizes relay RL and the consequent engagement of contacts 10RL2 energizes the sweeper return solenoid SWRS thus restoring the sweeper members to their original positions. And when they reach those positions they separate contacts SRS (124) and ZSRS (not illustrated) to deenergize the solenoid and arrest further movement of the sweeper members.

During the operations just described (which occur in a very short time interval) the bar is being driven forward by the flattener onto conveyor 17 which takes over the drive of the bar. When the trailing end of the bar passes the light beam of photocell device 3PC, the photocell controlled switch thereof is operated thus causing movable contact 3PCb to swing upwardly. In the meantime when the leading end of the bar had interrupted the light beam of photocell device IPC, movable contact lPCa had swung downwardly into contact with stationary contact 1PCe. Hence, the engagement of contacts 3PCb and SPCd completed a circuit for relay 4RL. The engagement of contacts 4RL3 completes a circuit for the shear brake solenoid SBS which applies a brake to halt the forward movement of the bar. The bar is thus arrested with its trailing end positioned between the shearing turrets ready to be trimmed. The engagement of contacts 4RL2 initiate a sequence of operations similar to that hereinabove described to trim the trailing end of the bar. However, as previously noted the sweeper mechanism is not actuated after the trailing end of the bar is trimmed. This result obtains since there is no 4RL contacts to cornplete a circuit for relay 10RL and consequently no circuit will be completed for sweeper solenoid SWS.

Having thus described the invention, it is to be understood that many changes could be made to the apparatus and circuitry disclosed without departing from the spirit and scope of the invention, and therefore the description and drawings are to be interpreted in an illustrative rather than in a limiting sense.

What is claimed is:

1. Apparatus for shearing the protruding ears of the ends of a hot rolled bar comprising, a pair of shearing heads each including a carriage movable towards and away from the other sharing head and a turret assembly that pivots about a vertical axis on the carriage, vertically movable shearing blade means mounted on each of said turrets, means for arresting a bar with the end to be sheared in position between the shearing heads, means for moving the shearing heads towards each other and into contact with a bar positioned therebetween and away from each other after a shearing operation, and means for moving the shearing blade means to effect a shearing operation.

2. Apparatus according to claim 1 wherein the turret assembly includes contact block means for contacting a bar against which the shearing head is moved and pivoting said turret assembly in one direction when one end of the bar is contacted and in a second direction when the other end of the bar is contacted so as to provide a taper cut to the trimmed end of a bar.

3. Apparatus according to claim 1 including a sweeper mechanism mounted on said carriage for removing trimmed material from said apparatus to a waste bin.

4. Apparatus according to claim 3 wherein said sweeper mechanism includes a conveyor device mounted on said turret assembly below the shearing blade means, and periodically actuated hydraulic motor means for operating said sweeper mechanism to carry trimmed material away from the apparatus.

5. Apparatus according to claim 1 wherein the shearing blade means includes a vertically movable blade holder, a blade secured to the lower end of said holder, and a clamping means compressibly mounted on said holder and positioned to engage a bar in position to be trimmed prior to said blade striking the bar.

6. Apparatus according to claim 5 wherein the means for moving the blade holder and the carriage moving means each include a hydraulic mechanism.

7. Apparatus according to claim 5 wherein the clamping means includes a hydraulic mechanism and relief valve `means for controlling the clamping force applied to a bar to be trimmed.

8. Apparatus according to claim 1 including a first braking mechanism and a second braking mechanism and wherein the means for arresting a bar with the end to be trimmed in position between the shearing heads includes a plurality of photocell devices arranged substantially in a line along the path of travel of a bar to be trimmed, circuit means for determining whether the ends of the bar positioned between the shearing heads is the leading or the trailing end of the bar, and circuit responsive means for actuating said first braking mechanism when the leading end of a bar is recognized andk for actuating sai dsecond braking mechanism when the trailing end of a bar is recognized.

References Cited UNITED STATES PATENTS 2,177,356 10/1939 Stone et al. 83-368 X 2,767,789 10/1956 Budlong et al 83-556 X 3,013,459 12/1961 Coleman 83-210 3,146,654 9/1964 Mathews et al 83-215 X 3,386,321 6/1968y Maxwell 8?: 370 X ANDREW R. IUHASZ, Primary Examiner I. F. COAN, Assistant Examiner U.S. Cl. X.R.

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