US3361020A

US3361020A - Cable-cutting apparatus

Info

Publication number: US3361020A
Authority: US
Inventors: Robert S Baker
Original assignee: American Concrete Crosstie Corp
Current assignee: American Concrete Crosstie Corp
Priority date: 1964-02-11
Filing date: 1967-02-27
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02
Also published as: US3504066A; GB977175A; US3305907A

Description

R. S. BAKER Jan. 2, 1968 CABLE-CUTTING APPARATUS 4 Sheets-Sheet 1 Original Filed Feb. 11, 1964 iil R. S. BAKER CABLECUTTING APPARATUS Jan. 2, 1968 Original Filed Feb. 11. 1964 4 Sheets-Sheet 2 'iililililil i'lilflililili Ell illlilllillli Jan. 2, 1968 R. s. BAKER 3,361,020

CABLECUTTING APPARATUS Original Filed Feb. 11, 1964 4 Sheets-Sheet INVENT OR 'RQBEQT SBQKE ma wmgfmww ATTORNEYS f s Q Jan. 2, 1968 R. s. BAKER 3,361,020

CABLE-(BUTT ING APPARATUS Original Filed Feb. 11, 1964 4 Sheets-Sheet 4 INVENTOR ROBERT S. Bm ER mailk iwicsw will ma ATTORNEYS United States Patent 3,361,020 CABLE-CUTTING APPARATUS Robert S. Baker, Tampa, Fla., assignor to American Concrete Crosstie Corporation, Tampa, a corporation of Florida Original application Feb. 11, 1964, Ser. No. 344,095, now Patent No. 3,305,907, dated Feb. 28, 1967. Divided and this application Feb. 27, 1967, Ser. No. 618,742

6 Claims. (Cl. 83-214) ABSTRACT OF THE DISCLOSURE Cable-cutting apparatus which utilizes spaced power saws, each vertically slidable, with a control system including a counter, the counter being operable in response to saw motor load to cause sequential movement of the saws into cutting position.

Cross-reference to related application This application is a division of co-pending application of Robert S. Baker, Serial No. 344,095, filed Feb. 11, 1964, now Patent No. 3,305,907, for Machine for Making Prestressed Concrete Members.

Background of the invention This invention relates to apparatus for cutting the cables of prestressed concrete members to free the members from their molding pallets after the concrete members are cured, and particularly to such apparatus for use in connection with machines for automatically making prestressed concrete articles.

In the above mentioned co-pending application, a machine is disclosed for automatically making prestressed concrete members. The machine includes a platform along which pallets are advanced to stations for inserting stressing cables in the pallets and anchoring them therein, for stressing the cables, for pouring and molding the concrete member, for transferring the molded member on its pallet to a transporting car for passage through a curing tunnel, for loading the cured pallet back onto the platform, for cutting the cables to free the cured member from the pallet, and for removing the cured member from the pallet. The operation is continuous and automatic.

The present invention is concerned only with the apparatus for cutting the stressing cables to free the concrete member from its connection to the pallet. Reference may be had to the co-pending application for a complete disclosure of the machine for forming prestressed concrete members.

Summary of the invention The principal object of the present invention is to provide means for cutting stressing cables which are embedded in a concrete member and anchored to a pallet to release the tension of the cables to the concrete member, and to free the member from the pallet so that it can be removed.

Another object of the invention is to provide means to cut cables at the opposite ends of a prestressed concrete member in such manner that there will be no possibility of the concrete member jumping to one end of the pallet and jamming the saw at that end.

A still further object of the invention is to provide cable-cutting apparatus which will cut several cables sequentially at one end of a prestressed concrete member, then cut the cables sequentially at the opposite end of the concrete member. 1

Yet another object of the invention is to provide cable- 3,361,020 Patented Jan. 2, 1968 cutting apparatus wherein motor load is used as a control for the cutting operation.

Other objects of the invention will become apparent from the following description of one practical embodiment thereof, when taken in conjunction with the drawings which accompany, and form part of, this specification.

Brief description of the drawings Description of the preferred embodiment Referring first to FIGURE 1, there is shown diagrammatically a plan of the entire apparatus with which the cable-cutting mechanism of the present invention is particularly designed for use. It consists of a rectangular orbit, or path, 1 for a pallet transporting means. The transporting path includes a leg 2 along and above which a concrete member forming machine 3 is located, and a parallel leg 4 substantially the whole length of which is enclosed by a curing tunnel 5. Connecting the ends of the legs 2 and 4, and completing the orbit are transfer pits 6 and 7 along which transporting cars 8 are shifted from the forming machine leg 2 of the orbit to the tunnel leg 4, and from the tunnel leg to the forming machine leg.

The concrete member forming machine has a base 9 ;forming a bridge over the leg 2 of the transport path, and

a platform upon which various stations, where the several required operations are performed, are located. These include (starting at the right end of the machine as shown in FIGURE 1) a pallet receiving station 10, the cable cutting station 11, a concrete member removal station 12, a pallet header cleaning station 13, a pallet cleaning station 14, an anchor inserting station 15, a cable laying station 16, a cable stressing station 17, a molding and vibrating station 18, and a loaded pallet delivery station 19.

The base 9 is formed of a tending, horizontally spaced, vertical walls or legs 20, with a flat platform 21 resting upon the tops of the legs. The legs, and the portion of the platform which bridges the legs, forms a tunnel 22 through which the transporting kiln cars 8 move. The platform is sufficiently broad to project some distance beyond the legs on either side of the tunnel. It is upon this platform that the various operating stations, including the cable-cutting station, are mounted.

Pallet tracks 23 are mounted on the platform 21, and extend the full length of the platform. The track, and the means for moving pallets along the track, can be any appropriate type, and one specific track and pallet moving means is described in detail in the above mentioned 00- pending application.

The pallet 24, in which the concrete member is formed, and which forms a transporting receptacle for the member, is an elongated, trough-shaped member having a fiat bottom 25 and upwardly diverging side walls 26. The ends are formed by

headers

27 and 28 which span the ends of the trough-shaped member. Header 27 is rigidly fixed to the trough end, While header 28 is a movable one having no permanent connection to the trough. The movable header is moved outwardly and held in its moved popair of longitudinally exsition to stress the cables as described in detail in the co-pending application. Each header has a plurality of cable openings 29, and a cable anchor is attached to the header in alignment with each of the openings. When the cables are inserted in the openings they will be held by the anchors during stressing and throughout the concrete member forming and curing operations. Although the cable openings may have any desired pattern, each header is shown as having four openings as seen in FIGURE 2.

After the concrete members are formed on the pallets, they are moved to, and through, the curing tunnel 5 and then transferred back to the machine leg of the apparatus. The pallets, with the cured concrete members, are unloaded from the cars and onto the pallet track at the pallet receiving station, and then moved along the pallet track until they arrive at the cable-cutting station 11. Here, the cables 31 are cut free from the headers, so that the cable tension is released to the cured concrete member, and the member is free to be removed from the pallet.

At the cable-cutting station, there is a frame 32 supported upon the machine platform 21. The frame includes a standard 33 at one side of the pallet track 23, and a standard 34 at the other side. The two standards are connected at their tops by a bridge beam 35 which extends across the pallet track. Standard 33 is composed of two legs 36, spaced apart transversely of the machine platform and interconnected by vertically spaced, horizontal base plates 37. One of the plates is at the tops of the legs and the other is at a level below the tops of pallets on the pallet track. Brackets 38 are mounted at the ends of the base plates and form supports for vertical guide rods 39. Rods 39 slidably receive bushings 40 at the rear of a saw motor bed 41. A saw motor 42 is fixed to the bed, and carries an abrasive saw 43 upon its shaft 44. The vertical plane of the saw will pass through the exposed cables between the end of the cast members and the pallet headers of pallets on the pallet track. The exposed cables span the spaces at the pallet ends occupied by the mold box ends during the casting operation. A cylinder assembly 45 has its cylinder 46 mounted upon the upper base plate 37, and its piston rod 47 fixed to the motor bed 41. Operation of the cylinder will cause the bed to lower and rise on the guide rods 39.

Standard 34 is identical to standard 33 and has a similar motor and saw mounted upon it. The parts of the standard and saw are given the same reference numerals with a prime afiixed.

It is necessary in operating the cable-cutting saws to cut the cables at one side of the pallet and then those at the other side. This will prevent jamming and breaking the saws in the event one saw should cut through the cables before the other, thus allowing the concrete member to jump to the opposite side of the cable tension. Therefore, it is dseirable to cut through the upper cables at one side, then the lower ones, and then repeat this procedure on the opposite side.

The controls to accomplish the above stated operation are timed from a cam shaft 48 by means of a cam 49. The cam has a notch 50 into which switch arm 51 will fall to start operation of the saw cycle.

The

saw motors

42 and 42 are connected to heavy duty power lines of the system. A common wire 52 of the motor circuits is connected to the primary winding of a transformer 53. The motors run continuously during machine operation, and increases in motor load will cause the motors to draw more current, and therefore increase the current induced in the secondary winding of the transformer 53. This permits motor load to be used to control the cutting operation as will be described.

The step-by-step operation of the motors is achieved by means of a step counter 54 which has a hand 55, a series of counter contacts 56, a counter coil 57 and a release coil 58. The counter coil is energized upon increases in load on the motors to cause the hand to move step-by-step, and the release coil is energized by closing switch 51 by rotation of cam 49. Switch 51 is connected to power line 59 by line 60, and to release coil 58 by line 61. The opposite side of coil 58 is connected to a return line 62 by line 63. Therefore, closing switch 51 will energize coil 57 and cause counter hand 55 to move back to the No. 1 contact of the series 56. This will complete a circuit from power source 59 through line 64 to solenoid coil 65, controlling the operation of cylinder assembly 45 to start the saw 43 moving downwardly toward the pallet. A line 66 connects the coil 65 with contacts No. 1 and No. 2 of the counter. As the counter hand is at contact No. 1, the circuit is completed through the hand and line 67 to line 62.

The saw assembly will continue its downward movement until saw 43 contacts the top pair of cables. Cutting of the cables will increase the motor load and the current induced by the transformer 53 will vary depending upon whether the saw is cutting or running free. The transformer secondary winding is connected by wire 68 with a relay coil 69. When the induced current in the transformer reaches a predetermined amount, relay 69 will operate to close its contacts 70, thereby closing a circuit through the coil of a control relay 71. This circuit is from wire 59, through wire 64, wire 72, contacts 70, wire 73, coil of relay 71, and wire 74 to return wire 62. When the coil of relay 71 is energized, a capacitor 75 discharges through a circuit including the counter coil 57 to cause the counter hand 55 to move from the No. 1 to the No. 2 contact of the series 56. As these two contacts are included in the circuit through coil 65, the saw 43 will continue downwardly to contact and cut the next two cables. The capacitor is connected across the lines 59 and 62 through a rectifier bridge 76 by means of wires 77 and 78 through the normally closed contacts 79, to provide for unidirectional flow through the capacitor during its charging and dischargeing periods. The

branch lines

80 and 81 connect the capacitor to the counter coil 57 through the normally open contacts 82 of relay 71 when the relay is energized.

It will be clear from the above that the saws have a stepped movement. Saw 43 first moves down to cut the top cables at its side of the pallet. The load fluctuation on the saw motor causes the counter to move from the No. 1 to the No. 2 contact when the top cables are cut. The saw will move down and cut the second cables. The counter will operate again moving the hand to the No. 3 contact. This accomplishes two things: the circuit through coil 65 is broken and the valve of cylinder assembly 45 will shift automatically to lift the saw 43 to inoperative position; and a parallel circuit through a solenoid 83 will be made to start saw 43' on its downward movement. The movement of saw 43 is a two-step one also, with the contacts No. 3 and No. 4 of the counter being connected to the wire 84 through the coil 83 circuit. When saw 43' cuts through the lower cables at its side of the pallet, the counter hand will move to the No. 5 contact breaking the circuit through coil 83 and permitting the saw to rise. When cam 49 completes its revolution, switch arm 51 will drop into notch 50, closing the circuit through release coil 58 to return the counter hand to the No. 1 contact of the counter to restart the cycle.

With the above described control system, the saws will be operated in alternation so that the cables at one end of the cured tie will be out prior to the lowering of the other saw into cutting position. Thus, if the tie should jump lengthwise in the pallet after the cables have been cut, there will be no saw blade in the opposite end of the pallet to become jammed or broken by the impact.

While in the above, one practical embodiment of the invention has been disclosed, it will be apparent that the details of structure shown and described are merely for purposes of illustration and the invention may take other forms within the scope of the appended claims.

I claim:

1. In apparatus for making prestressed concrete members in pallets having stressing cables anchored in the ends thereof, means for cutting the cables to free the cables from pallets at a pallet position after the concrete members are cured comprising, a pair of saws located above the ends of pallets at the pallet position and movable into the pallets to cut the cables adjacent the cable ends.

2. In apparatus for making prestressed concrete members in pallets as claimed in claim 1 wherein, there is means to move the saws into pallets in sequence, the saw moving means being operative by cutting action of the first-lowered saw to raise the first lowered saw and lower the other saw.

3. In apparatus for making prestressed concrete mem bers in pallets as claimed in claim 1 wherein, there is means to move the saws into the pallets in sequence, the means including a counter operative upon completion of a predetermined number of cuts by a first lowered saw to cause the first lowered saw to move out of the pallet and the other saw to move into the pallet.

4. Apparatus for cutting cable ends at opposite ends of a prestressed concrete member comprising, a frame to straddle a prestressed member, vertical guides on the frame at opposite sides thereof, saw assemblies slidably 25 mounted on the guides, means to raise and lower the saw assemblies, and control means to operate the means to raise and lower the saws to act in sequence to cause the saw assemblies to move to and from cutting position in alternation.

5. Apparatus for cutting cable ends at opposite ends of a prestressed concrete member as claimed in claim 4 wherein, the means to operate the means to raise and lower the saw assemblies includes a counter operative upon completion of a predetermined number of cuts by a first lowered saw assembly to cause the first lowered saw assembly to raise and the other saw assembly to lower.

6. Apparatus for cutting cable ends at opposite ends of a prestressed concrete member as claimed in claim 5 wherein, the load on the saw assemblies during cutting actuates the counter.

References Cited UNITED STATES PATENTS 3,217,375 11/1965 Kinnard 1l8 3,223,379 12/1965 Erickson 25-118 WILLIAM S. LAWSON, Primary Examiner.

9/1962 Gerwick 25--l18