GB1573347A - Apparatus for making serpentiform springs - Google Patents

Description

(54) APPARATUS FOR MAKING SERPENTIFORM SPRINGS (71) WE, NAUCHNO-ISSLEDOVATELSKY INSTITUT TEKHNOLOGII TRAK TORNOGO I SELSKOKHOZYAISTVENNOGO MASHINOSTROENIA, of Marxistskaya ulitsa, 20, Moscow, Union of Soviet Socialist Republics, a Corporation organised and existing under the laws of the Union of Soviet Socialist Republics, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to apparatus for making serpentiform springs.

Known in the art is an apparatus for making serpentiform springs, comprising a drum having freely fitted pins, a ratchet mechanism, a disc cam engaging the drum pins, a carriage having bending rods and a roller for retracting the pins of the drum (cf. USSR Inventor's Certificate No. 369961, Cl. B21D 11/06 of October 2, 1970).

The disadvantages of the prior art apparatus consist in a complicated kinematic chain, cyclic movement of the tool (drum with pins and carriage with bending rods) and therefore, low productivity and insufficient accuracy of the resultant serpentiform spring since, depending on quality of the material, the stock is not uniformly urged against the drum pin about which the stock is bent. Consequently the dimensions of the serpentiform spring being made vary both in length and width.

According to the present invention, there is provided an apparatus for making serpentiform springs by bending metal strip, the apparatus comprising a cylindrical drum rotatable about its own axis, a plurality of pins arranged at pre-set spacings around the entire cylindrical surface of said drum, means for extending the pins from and retracting the pins into said drum as the drum rotates, the circumferential zone where the pins are extended forming a strip bending zone, and means arranged on either side of the strip bending zone for bending the strip about the extended pins, said bending means including bearing plates mounted for rotation in a plane parallel to a tangent to the drum in the bending zone, bending rods mounted on said plates parallel to their axes of rotation, and spring-loaded shoes located on either side of the bending zone transversely of the strip being fed, one of said shoes urging the strip against the pin about which the bending is effected at a given moment, and the other shoe urging the bent strip against the preceding pin.

This construction permits the strip to be bent at high speed about the drum pins while retaining an accurate positioning of the bent portions of the serpentiform spring being made relative to the pins leaving the bending zone.

The bearing plates preferably comprise double arm bodies having central axis of rotation, each arm supporting a bending rod, and each bending rod engaging a cam of the mechanism for retracting the pin after its participation in the bending process, the rotary drive of the plates being in a force transmitting connection with the rotary drive of the drum, the following condition being provided: nl Z2 n2 2Z1 wnerem n is the number of revolutions of the plates per minute, n2 is the number of revolutions of the drum per minute, Z1 is the number of bending rods of the plate, Z2 is the number of pins of the drum.

This construction enables a desired svnchronization of rotation of the driven drum and plates supporting the bending rods to provide for high-performance continuous bending of serpentiform spring.

The invention will now be described, by way of example, with reference to specific embodiments thereof illustrated in the accompanying drawings, in which: Figure 1 shows a kinematic chain of the apparatus according to the invention; Figure 2 shows the drum with pins and a fixed cam in the apparatus of Figure 1; Figure 3 shows the arrangement of bearing plates (sectional view taken along the line III-III in Figure 1); and Figures 4 and 5 show the position of the plate shaft depending on the shape of serpentiform spring.

A metal strip is bent in its own plane into a serpentiform shape in the apparatus for making serpentiform springs.

The apparatus shown for making serpentiform springs comprises a shaft 1 (Figure 1) having a pinion 2 and a worm 3 which are in a force transmitting connection with, respectively, gears 4,5,6 and a worm wheel 7. A worm wheel shaft 8 supports a drum 9 having pins 10 (Figure 2).

The pins 10 are arranged in the drum 9 radially and in a staggered pattern so as to obtain the desired pitch and width of the serpentiform spring. The pins 10 are received in sockets of the drum with running fit (with a play) so as to facilitate smooth radial movement of the pins 10 in the drum 9.

The drum 9 accommodates a fixed disc cam 11. The disc cam 11 is provided to limit the stroke of the pins 10 into the interior of the drum. The disc cam 11 has a projection 1 la which causes the pins 10 to move outside the drum prior to the beginning of bending and holds the pins in the outmost position until the serpentiform spring is removed from the pins 10.

The gears 4 and 6 are fixed to shafts 12 and 13 supporting bearing plates 14 and 15 having sockets which receive bending rods 16 with a running fit, the rods being connected, by means of rollers 17, to fixed cylindrical cams 18 and 19.

The gears 2, 4, 5, 6 and the worm gear 3, 7 provide, vis the shafts 1, 12, 13 for uniform rotation of the bearing plates 14 and 15 supporting the bending rods 16 and of the drum 9 with the following ratio nl - Z2 n2 2Z1 wherein nl is the number of revolutions of the plates 14, 15 per minute, n2 is the number of revolutions of the drum 9 per minute, Z2 iS the number of the pins 10 of the drum 9, Z1 is the number of the bending rods 16 of the plate.

The axes of the plates are arranged in such a manner that at the moment when the bending rod 16 and the strip pass the rod 10 the minimum clearance between the bending rod 16 and the pin 10 is equal to the strip width, while the component of linear speed of the bending rod 16 parallel with the linear speed of the drum is at least equal to or more than the linear speed of the drum.

The plates 14 and 15 and the drum 9 define, in the bending zone, an aperture of a size of 1.05-1.1 of the strip thickness thus enabling the strip to be bent in its own plane. The cams 18 and 19 ensure, by means of the rollers 17, the engagement of the strip by the bending rods 16 before the bending zone and the travel of the rods over the strip after the strip is bent about the pin 10.

The plates 14 and 15 provide for positioning of the strip by the bending rods 16 at the pins 10 of the drum 9 and bending of the strip about the pins 10 (at 1800).

A spring-loaded roller 20 is located on the left hand side of the bending zone of the drum 9 to remove the serpentiform spring from the pins 10 and to retract the pins 10 into the sockets of the drum 9.

A stop 21 is provided on the left hand side of the bending zone and is spaced apart from the drum 9 at a distance greater than the strip thickness to retain several bent portions of the serpentiform spring on the pins 10, which is necessary to eliminate stretching of the strip in the preceding turns thus ensuring stable width of the serpentiform stock. The same function is performed by spring-loaded shoes 22 and 23 arranged on either side of the pins 10 to urge the strip against the pins 10 axially of the drum 9 at the moment of bending.

The apparatus functions in the following manner.

The strip end is passed between the two end most of the projecting pins of the drum 9 brought out by the camming surface 1 la of the cam 11.

If the pin 10, which is the endmost pin (last to be extended) is located on the left hand side of the drum 9, the strip is bent thereabout by the bending rod 16 mounted on the upper plate 14. Concurrently with bending, the bent strip is fed, together with the pins 10 of the drum 9 under the stop 21 and is urged against the pin 10 by the spring-loaded shoe 22.

After the bending of the strip about the left hand pin 10 is completed and the bending rod 16 of the plate 14 has passed over the right hand pin 10 of the drum 9, the right hand pin 10 is brought out by the camming surface 1 1a of the cam 11.

The bending rod 16 of the plate 14 continues its travel over the camming surface of the cam 18 to be spaced apart from the drum 9 and to pass over the strip. Then the strip is bent about the right hand pin 10 by the bending rod 16 of the lower plate 15. Concurrently with bending, the bent strip is fed, together with the pins 10 of the drum 9 under the stop 21 and is urged against the pin 10 by the spring-loaded shoe 23.

The serpentiform spring passes the stop 21 and leaves the pins 10 of the drum 9, while the pins 10 are retracted by the spring-loaded roller 20 located behind the stop 21.

WHAT WE CLAIM IS: 1. An apparatus for making serpentiform springs by bending metal strip, the apparatus comprising a cylindrical drum rotatable about its own axis, a plurality of pins arranged at pre-set spacings around the entire cylindrical surface of said drum, means for extending the pins from and retracting the pins into said drum as the drum rotates, the circumferential zone where the pins are extended forming a strip bending zone, and means arranged on either side of the strip bending zone for bending the strip about the extended pins, said bending means including bearing plates mounted for rotation in a plane parallel to a tangent to the drum in the bending zone, bending rods mounted on said plates parallel to their axes of rotation, and spring-loaded shoes located on either side of the bending zone transversely of the strip being fed, one of said shoes urging the strip against the pin about which the bending is effected at a given moment, and the other shoe urging the bent strip against the preceding pin.

2. An apparatus for making serpentiform springs as claimed in claim 1, wherein the bearing plates comprise double arm bodies with central axes of rotation, each arm supporting a bending rod, and each bending rod engaging a cam of the mechanism for retracting the rod after its participation in the bending process, the rotary drive of the plates being in a force transmitting connection with the rotary drive of the drum, the following condition being provided: nl - Z2 n2 2Z1 wherein nl is the number of revolutions of the plates per minute, n2 is the number of revolutions of the drum per minute, Z1 is the number of bending rods of the plate, Z2 iS the number of pins of the drum.

3. An apparatus as claimed in Claim 1 or 2 substantially as hereinabove described with reference to, and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. After the bending of the strip about the left hand pin 10 is completed and the bending rod 16 of the plate 14 has passed over the right hand pin 10 of the drum 9, the right hand pin 10 is brought out by the camming surface 1 1a of the cam 11. The bending rod 16 of the plate 14 continues its travel over the camming surface of the cam 18 to be spaced apart from the drum 9 and to pass over the strip. Then the strip is bent about the right hand pin 10 by the bending rod 16 of the lower plate 15. Concurrently with bending, the bent strip is fed, together with the pins 10 of the drum 9 under the stop 21 and is urged against the pin 10 by the spring-loaded shoe 23. The serpentiform spring passes the stop 21 and leaves the pins 10 of the drum 9, while the pins 10 are retracted by the spring-loaded roller 20 located behind the stop 21. WHAT WE CLAIM IS:

1. An apparatus for making serpentiform springs by bending metal strip, the apparatus comprising a cylindrical drum rotatable about its own axis, a plurality of pins arranged at pre-set spacings around the entire cylindrical surface of said drum, means for extending the pins from and retracting the pins into said drum as the drum rotates, the circumferential zone where the pins are extended forming a strip bending zone, and means arranged on either side of the strip bending zone for bending the strip about the extended pins, said bending means including bearing plates mounted for rotation in a plane parallel to a tangent to the drum in the bending zone, bending rods mounted on said plates parallel to their axes of rotation, and spring-loaded shoes located on either side of the bending zone transversely of the strip being fed, one of said shoes urging the strip against the pin about which the bending is effected at a given moment, and the other shoe urging the bent strip against the preceding pin.

2. An apparatus for making serpentiform springs as claimed in claim 1, wherein the bearing plates comprise double arm bodies with central axes of rotation, each arm supporting a bending rod, and each bending rod engaging a cam of the mechanism for retracting the rod after its participation in the bending process, the rotary drive of the plates being in a force transmitting connection with the rotary drive of the drum, the following condition being provided: nl - Z2 n2 2Z1 wherein nl is the number of revolutions of the plates per minute, n2 is the number of revolutions of the drum per minute, Z1 is the number of bending rods of the plate, Z2 iS the number of pins of the drum.

3. An apparatus as claimed in Claim 1 or 2 substantially as hereinabove described with reference to, and as shown in the accompanying drawings.