US3651774A

US3651774A - Method of continuous feed of separate straps in process of blanking

Info

Publication number: US3651774A
Authority: US
Inventors: Vitaly Konstantinovich Gilev; Volf Nakhimevich Evzlin; Tofik Kudrat Ogly Idayatov; Nea Eachievna Proshian; Rafael Tevosovich Sarkisov; Ernst Arakelovich Stepanian
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-10-13
Filing date: 1969-10-13
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28

Abstract

The invention relates to a method of continuous feed of separate straps during the blanking, comprising the following operations: the strap of sheet material to be blanked is fed into a die, the end of the blanked strap during the movement for a feed pitch prior to the last blanking operation is deflected aside with simultaneous movement of the next strap so that the beginning of the latter overlaps the deflected end of the blanked strap, in which case the last blanking operation is effected on the blanked strap, thereafter, both straps are moved simultaneously and at the same speed for a feed pitch; at the end of this movement, prior to the first blanking operation on the next strap, the end of the blanked strap is withdrawn from the blanking zone at a speed exceeding the rate of feeding the strap into the blanking zone.

Description

llnite Gilev et a1.

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[ 51 Mar. 2, 11972 22 Filed: Oct. 13,1969

21 Appl.No.: 872,890

[52] U.S.Cl. ..1l3/1l3 1R, 83/250,83/418,

83/446 [51] lint. C1 ..B21d 43/00 [58] Field oiSearclh ..72/338, 339,420, 421,425;

References Cited 7 UNITED STATES PATENTS Primary Examiner-Richard J. l-lerbst Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT The invention relates to a method of continuous feed of separate straps during the blanking, comprising the following operations: the strap of sheet material to be blanked is fed into a die, the end of the blanked strap during the movement for a feed pitch prior to the last blanking operation is deflected aside with simultaneous movement of the next strap so that the beginning of the latter overlaps the deflected end of the blanked strap, in which case the last blanking operation is effected on the blanked strap, thereafter, both straps are moved simultaneously and at the same speed for a feed pitch; at the end of this movement, prior to the first blanking operation on the next strap, the end of the blanked strap is withdrawn from the blanking zone at a speed exceeding the rate of feeding the strap into the blanking zone.

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METHOD OF CONTINUOUS FEED OF SEPARATE SlPS llN PROCESS OF BLANKING thickness higher than 1 mm.).

Known in the art is a method of continuous feed of separate straps during the blanking. In this case the straps are used having different lengths, and each strap pushed the preceding strap so that the straps form a continuous band of the material to be blanked.

This method is suitable for blanking members of plate steel (having a thickness higher than 1 mm.).

However, this method of continuous feed of separate straps by means of pushing one strap by the other, while reducing rejection of the straps due to the fact that the straps form a continuous hand, does not eliminate the possibility of making rejected articles when the overlapping joint of the straps occurs in the blanking zone. In this case, the more articles are blanked from one strap the less is the quantity of the rejects. In order to reduce the number of rejected articles, it is necessary to out off the ends of the strap, by setting the length of the straps multiple to the pitch of feed used during the making specific articles. This requires additional equipment and extra consumption of time.

In addition, it should be noted that the known method has a limited application and cannot be used for making of rotor and stator laminations from sheet electrical steel, as it is rather difficult to feed the straps of sheet steel (less than 1 mm. thick) by pushing one strap by the other. Furthermore, when only a few stator and rotor laminations (from 4 to 8) are punched from a single strap, the application of the above method to straps which are not calibrated by length results in a high percentage of rejected articles (laminations).

Therefore, for the purposeof punching stator and rotor laminations from sheet electrical steel, the other method of feed is employed, in which the use is made of calibrated straps whose length is multiple to the pitch of feed. These straps are fed to the blanking zone by means of rollers and other driving and pulling mechanisms providing for continuous movement of the straps, one after another, at a constant speed. As said above, the calibration of the straps by length requires additional equipment and extra consumption of time.

An object of the present invention is to provide such a method of continuous feed of separate straps during the blanking, which would make it possible to use the straps which are not calibrated by length, in particular the straps having a positive tolerance.

This and other objects are attained due to the fact, that prior to the last bending operation, the end of the blanked strap during the movement for a feed pitch is bent with simultaneously movement of the next strap, the beginning of which overlaps the bent end of the blanked strap, in which case the last blanking operation is effected on this particular strap, thereafter, both straps are moved simultaneously and at the same speed for a feed pitch. At the end of this movement, prior to the first blanking operation on the next strap, the end of the blanked strap is being withdrawn from the blanking zone at a speed exceeding the rate of feeding the strap to the blanking zone.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 11 is a conventional diagrammic view of the process of blanking circular members (stator and rotor laminations) from a strap of sheet steel;

FIG. 2 is a diagram of bending the end of the blanked strap and overlapping of two straps (blanked strap and the next one) prior to feeding the next strap to the blanking zone;

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FIG. 3 is a conventional diagrammic view of the position of two straps prior to the blanking operation on the strap and prior to feeding the next strap to the blanking zone;

FIG. 4 shows the withdrawal of the reject of the blanked strap from the blanking zone.

The essence of the proposed method consists in the followmg.

An uncalibrated-by-length strap of sheet material (FIG. 1) devised for making blanking members therefrom is fed into a die of an automatic press.

By means of a mechanism 2 (FIG. 2) for feeding the strap, e.g. by means of feeding rollers, a stick-slip motion is imparted to the strap 1. In this case, the strap during each stroke is displaced for a feed pitch t.

The punched members may have any prescribed shape, in particular a circular shape for stator and rotor laminations.

After the blanking, the round holes 3 remain in the strap 1 as shown in FIG. 1.

Owing to the fact that the strap 1 fed to the die is not calibrated by length, after the blanking it has a remnant end 4 (FIG. 1) due to the positive tolerance, the length a" of this end being less than the prescribed size of the punched member.

To provide a continuous feed of separate straps in the process of blanking, before the last operation on the blanked strap 1, it is necessary to set the beginning 5 (FIG. 2) of the next strap 6 to the initial position prior to the first blanking operation on this strap, i.e. before introducing the strap 6 into the blanking zone. This operation is hindered by the unsized end 4 of the blanked strap 1 remaining after the last blanking operation.

According to the proposed method, the end 4 of the blanked strap 1 is bent aside by means of an attachment '7 intended for this purpose. It is most expedient to bend this end 4 to the die 8 (FIG. 3). At the same time the next strap 6 is moved by means of the feed rollers 2 which move the next strap 6 at a speed V in the direction shown by the arrow A. The next strap 6 is set to the initial position, prior to introducing it into the blanking zone, by compressing the spring 9 of the attachment 7.

As a result, the beginning 5 of the next strap 6 overlaps the end 4 of the blanked strap 1. At the same time, the last operation of the blanked strap 1 is being effected. Due to the overlapping, the end 4 of the strap 1 is pressed against the lifter It) and the face of the die 8, and this makes it possible to avoid an occasional catch of the punched members by the blanked strap 1.

After the last operation on the blanked strap I, both overlapped straps 1 and 6 are moved simultaneously and at the same speed for a feed pitch t.

At the end of the movement, when the beginning 5 of the next strap 6 moves to the initial position, as shown in FIG. 41, before effecting the first blanking operation on this strap, it is necessary to remove the remnant end 4 of the strap ll from the blanking zone, otherwise the die can be broken due to the nonuniform load caused by the fact that the blanking material of a double thickness is placedat one side of the die.

In order to eliminate the breakdown of the die and to provide for the removal of the rejects of the blanked strap during the period employed for effecting a feed pitch, an increased rotational speed V is given to the pull rollers Ill. In this case the blanked strap moves from the blanking zone at a speed V which exceeds the speed V Owing to this fact, the rithm of the blanking process is not disturbed, and the next blow of the punch 12 makes it possible to punch out a new member from the blank which is already on the die face.

The application of the proposed method allowed to use a strap of electrical steel, which is not sized by length, for blanking laminations for magnetic circuits of electric motors. The operation of sizing the straps is excluded from the process of making the above-said laminations and this increases the efficiency of the process of making the laminations for magnetic circuits of electric motors.

What is claimed is:

fecting the final blanking operation on said first strap; simultaneously advancing both straps at equal speeds through the open die zone whereby the overlapped portions of said straps are passed therethrough; and withdrawing the trailing edge of said first strap from said die zone at a rate of speed exceeding the rate of the movement of said simultaneously advanced straps.

Claims

1. A method of continuously step-feeding separate sheet material straps in sequential order into a die for manufacturing blanks, comprising; advancing into said die a first strap to be blended; bending the trailing edge of said strap prior to the final blanking operation thereon; simultaneously feeding a successive strap into said die toward an initial blending position, the leading edge of said successive strap overlapping the trailing edge of said first strap when the length thereof exceeds the multiple of the length of the feed pitch toward said die; effecting the final blanking operation on said first strap; simultaneously advancing both straps at equal speeds through the open die zone whereby the overlapped portions of said straps are passed therethrough; and withdrawing the trailing edge of said first strap from said die zone at a rate of speed exceeding the rate of the movement of said simultaneously advanced straps.