APPARATUS FOR BENDING METAL
United States Patent 3583199
Metal bending apparatus is provided for progressively bending metal products such as sheets, strips, flat bars, and the like, to a predetermined angle by simple hand pressure, by pivotally moving a bending lever or arm into a wedge-shaped upper surface of a supporting bed. The pivotal mounting of the forward end of the bending arm is made resilient so that the pivoting portion of the bending arm automatically elevates in response to the thickness of the material being bent to minimize the variation which occurs in the angle of the bend along the length thereof.
Application Number:
04/828595
Publication Date:
06/08/1971
Filing Date:
05/28/1969
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Export Citation:
Assignee:
Josephson, Speiser & Ives (New York, NY)
Primary Class:
Other Classes:
72/466.900, 72/346
International Classes:
B21D5/02; B21D5/01
Field of Search:
72/446,465,387,310,319,380
Primary Examiner:
Herbst, Richard J.
Assistant Examiner:
Crosby, Gene P.
Claims:
I claim
1. In apparatus for bending metal comprising a bed having a wedge-shaped upper surface and a bending arm having its forward end pivotally secured to the forward portion of the bed above said wedge so that the bending arm enters said wedge progressively from front to rear as the bending arm is pivoted to lower said arm, the improvement comprising a resilient pivotal interconnection between the forward end of said bending arm and the forward end of said bed and means biasing the forward end of said bending arm downwardly toward said bed.
2. The improvement recited in claim 1 in which said resilient pivotal interconnection includes a compensating aperture in the forward end of said bending arm and a pivot pin carried by the forward end of said bed and extending through said aperture, said aperture being vertically elongated to permit the forward end of the bending arm to rise with respect to said pivot pin.
3. The improvement recited in claim 2 in which a yoke carried by said pivot pin extends across the top of the forward end of said bending arm and a compensating spring is interposed between the top of said yoke and the forward end of the bending arm overlying said pivot pin.
4. The improvement recited in claim 3 in which said yoke and said bending arm are locked together so that the two will swing in unison to maintain said compensating spring at a right angle to the length of the bending arm.
5. The improvement recited in claim 4 in which said yoke is locked to said bending arm by means of a threaded retaining bolt which extends through the top of the yoke into a tapped hole in the forward end of said bending arm.
6. The improvement recited in claim 1 in which said bed includes a measuring ledge which extends sidewardly from the upper surface of said bed.
1. In apparatus for bending metal comprising a bed having a wedge-shaped upper surface and a bending arm having its forward end pivotally secured to the forward portion of the bed above said wedge so that the bending arm enters said wedge progressively from front to rear as the bending arm is pivoted to lower said arm, the improvement comprising a resilient pivotal interconnection between the forward end of said bending arm and the forward end of said bed and means biasing the forward end of said bending arm downwardly toward said bed.
2. The improvement recited in claim 1 in which said resilient pivotal interconnection includes a compensating aperture in the forward end of said bending arm and a pivot pin carried by the forward end of said bed and extending through said aperture, said aperture being vertically elongated to permit the forward end of the bending arm to rise with respect to said pivot pin.
3. The improvement recited in claim 2 in which a yoke carried by said pivot pin extends across the top of the forward end of said bending arm and a compensating spring is interposed between the top of said yoke and the forward end of the bending arm overlying said pivot pin.
4. The improvement recited in claim 3 in which said yoke and said bending arm are locked together so that the two will swing in unison to maintain said compensating spring at a right angle to the length of the bending arm.
5. The improvement recited in claim 4 in which said yoke is locked to said bending arm by means of a threaded retaining bolt which extends through the top of the yoke into a tapped hole in the forward end of said bending arm.
6. The improvement recited in claim 1 in which said bed includes a measuring ledge which extends sidewardly from the upper surface of said bed.
Description:
The present invention relates to improvements in apparatus for bending metal of the type in which a progressive bending pressure is applied by pivotally moving a bending lever or arm into a wedge-shaped upper surface of a supporting bed. In the prior structures of this type, the pivotal bending arm was provided with a fixed pivot which was poorly adapted for the bending of metal products of various type including sheets, strips, flat bars, and the like, because the bend made near the pivot is sharper and more angular than the bend remote from the pivot. Thus, the angle of the bend varies significantly along the length of the bend, and the longer the length of the bend, the greater the undesired variation.
The principal purpose of this invention is to vary the structure of the bending apparatus in order to minimize the variation which occurs in the angle of the bend along the length thereof so that metal products can be more efficiently and accurately bent without employing cumbersome and expensive equipment such as the brakes normally employed for the purpose.
The present invention is therefore directed to improvements in a known type of metal bending apparatus in which a bed has a wedge-shaped upper surface and a bending arm has its forward end pivotally secured to the forward end of the bed so that the bending arm enters the wedge portion of the bed from front to rear as the bending arm is pivoted. This known apparatus is useful for the bending of metal products including sheets, strips, flat bars, rods, and similar materials. The improvement in the invention relates to the pivotal mounting of the forward end of the bending arm whereby the pivoting portion of the bending arm automatically elevates as needed in response to the thickness of the product being worked upon. In this way, the bend imposed upon the product will be relatively constant along the length thereof.
The invention will be more fully understood from the accompanying drawings in which:
FIG. 1 is a perspective view of the bending apparatus of the invention;
FIG. 2 is a cross section taken through the middle of the apparatus with the bending arm in bending position and looking toward the forward end of the apparatus; and
FIG. 3 is a cross section taken on the line 3-3 of FIG. 2.
Referring to FIG. 1, the bending apparatus includes a bed 10, a bending arm 11 and pivot means 12 which generically identifies the pivotal interconnection between the forward end of the bending arm 11 and the forward end the bed 10.
The bed 10 is a single casting having sidewardly extending ears 13 which are bored at 14. It is advisable to secure the bed to a work support and this may be done using "C" clamps or, preferably, by bolts which are passed through the holes 14. The bed 10 may also include a groove G to facilitate the bending of rods and tubes.
The upper surface of the bed 10 constitutes a female die and is wedge-shaped as shown at 17. The upper corners of the wedge, identified at 15 and 16 are preferably rounded and smoothed so as not to mar the sheet being bent since this sheet slides over the upper corners 15 and 16 as the bent portion thereof is forced downwardly into the wedge portion of the bed.
The bending arm 11 has a raised handle portion 18 and a knife portion 19 which moves into the wedge portion 17 as the bending arm 11 is pivoted by lowering the handle 18.
The forward end of the bed 10 is formed with upstanding portions 21 and 22 which are formed integrally with the forward end of the bed. The forward end of the bending arm 11 is formed to fit within the upstanding portions 21 and 22 and this serves to align the knife portion 19 of the bending arm 11 with the axis of the wedge portion 17.
A pivot pin 23 is inserted through the upstanding portion 21, then through the forward end of the bending arm 11 and lastly through the upstanding portion 22 so as to pivotally mount the bending arm 11 and the forward end of the bending arm 11 which fits between the upstanding portions 21 and 22 includes a compensating aperture extending laterally therethrough in order to accommodate the pin 23. This aperture is an important feature of the present construction and can be seen in dotted lines in FIG. 2 of the drawing where it is identified by the numeral 24. The aperture 24 is approximately the same size as the pin 23 along the length of the bending arm 11 to minimize movement of the arm 11 along its own length, but the aperture 24 is oversized in the direction of the height of the knife portion 19 so that the forward end of the arm 11 can be elevated by the back pressure generated through bending contact between the knife portion 19 and the sheet or bar being bent. This elevation occurs after the metal being bent is forced to the bottom of the wedge portion 17 and serves to align the bending edge of the knife 19 with the upper surface of the sheet being bent-- which will vary with the thickness of the sheet being bent.
Referring again to FIG. 2, the pivot pin 23 is constituted by a bolt which extends laterally through the entire structure which is held together by the bolt head at one side and, at the other side, by means of a nut 25 threaded on the free threaded end of the bolt. A yoke 26 extends across the upstanding portions 21 and 22 with its opposite ends 27 and 28 being pivoted to the opposite ends of the pin 23. Washers 29 and 30 are desirably interposed between the upstanding portions 21 and 22 and the head of the pin 23 on one side and the nut 25 on the other side to permit the yoke 26 to swing with the bending arm 11 as said arm is pivoted. While any form of shaft may be used to form the pivot pin, a bolt and nut as described are particularly convenient.
A retaining bolt 31 extends through the upper portion of the yoke 26 and is threaded into a tapped hole 32 in the forward end of the bending arm 11 immediately above the compensating aperture 24. The bolt 31 ties the yoke 26 to the pivoted end of the arm 11 so that the two will swing together. Lastly, a compression spring 33 is mounted on the retaining bolt 31 to bear downwardly against the forward pivoted end of the bending arm 11 to force the same as far down as possible. It is the spring 33 which resiliently resists the upward movement of the pivoted end of the bending arm 11 and which enables the pivoted end of arm 31 to rise and adjust for the thickness of the product being bent.
The action will be more clearly seen in FIG. 3 in which the bending of a sheet is illustrated.
As the knife portion 19 contacts the sheet to be bent at its forward end and moves this sheet to the bottom of the wedge 17, downward pivotal pressure applied to the handle 18 tends to cause the forward end of the bending arm 11 to rise as indicated by arrow A against the pressure of spring 33. The fulcrum for this pivotal movement is at F. As a result, the effective pivot point provided by pin 23 is automatically shifted to position the bending edge of the knife portion 19 at the level of the upper surface of the sheet to be bent. This enables full entry of the knife 19 into the wedge 17 along its entire length and, thus, the angle of bend at the rear of the sheet is substantially the same as the angle of bend at the forward end of the sheet to provide the uniform bend angle desired.
When contact is initially made with the sheet being bent, the leverage is great and is effective to overcome the pressure of spring 33. On the other hand, the leverage decreases as the knife 19 contacts the metal sheet to be bent further and further away from the pin 23. Moreover, when the rear of the sheet being bent reaches the bottom of wedge portion 17, the bend is complete and further heavy pressure has no purpose. As a result, after the compensating action has taken place, further elevation of the forward end of the bending arm 11 does not take place.
While the novel feature of the invention is particularly adapted to facilitate the bending of sheets, with the advantage of the invention increasing with bends of increasing length, the apparatus of the invention is nonetheless useful for bending flat bars and rods, though the automatic compensating feature is less significant in such other utilities. Similarly, while metal products are particularly contemplated, plastic and other materials can also be worked upon.
It will now be apparent that the present development is founded on employing a resilient pivotal interconnection between the forward end of the bending arm 11 and the forward end of the supporting bed with means to bias the forward end of the bending arm downwardly toward the bed. This resilient pivotal interconnection is preferably provided by employing a vertical elongated aperture in the forward end of the bending arm to receive the pivot pin with the downward resilient bias being preferably provided by means of a yoke carried by said pivot pin and which extends across the top of the forward end of the bending arm. A compression spring is interposed between the top of the yoke and the forward end of the bending arm overlying the pivot and with the yoke and bending arm being locked together so that the two will swing together and maintain the compression spring at a right angle to the length of the bending arm.
It is also desirable to be able to accurately position an edge of the metal sheet to be bent at a predetermined distance from the line of bend and this is achieved in the invention utilizing a measuring ledge 34 which extends sidewardly from the upper surface of the bed 10. As will be evident, a sheet is rested flat on the bed 10 with its edge appropriately positioned on the measuring ledge 34. When the bending arm 11 descends into the wedge 17, the portions of the metal being bent on opposite sides of the line of bend shift upwardly until, when the knife portion 19 has descended fully into wedge 17, the metal will substantially conform to the shape of the wedge which usually is formed to a 90° angle, but which may be formed to other angles if desired.
The invention is defined in the claims which follow.
The principal purpose of this invention is to vary the structure of the bending apparatus in order to minimize the variation which occurs in the angle of the bend along the length thereof so that metal products can be more efficiently and accurately bent without employing cumbersome and expensive equipment such as the brakes normally employed for the purpose.
The present invention is therefore directed to improvements in a known type of metal bending apparatus in which a bed has a wedge-shaped upper surface and a bending arm has its forward end pivotally secured to the forward end of the bed so that the bending arm enters the wedge portion of the bed from front to rear as the bending arm is pivoted. This known apparatus is useful for the bending of metal products including sheets, strips, flat bars, rods, and similar materials. The improvement in the invention relates to the pivotal mounting of the forward end of the bending arm whereby the pivoting portion of the bending arm automatically elevates as needed in response to the thickness of the product being worked upon. In this way, the bend imposed upon the product will be relatively constant along the length thereof.
The invention will be more fully understood from the accompanying drawings in which:
FIG. 1 is a perspective view of the bending apparatus of the invention;
FIG. 2 is a cross section taken through the middle of the apparatus with the bending arm in bending position and looking toward the forward end of the apparatus; and
FIG. 3 is a cross section taken on the line 3-3 of FIG. 2.
Referring to FIG. 1, the bending apparatus includes a bed 10, a bending arm 11 and pivot means 12 which generically identifies the pivotal interconnection between the forward end of the bending arm 11 and the forward end the bed 10.
The bed 10 is a single casting having sidewardly extending ears 13 which are bored at 14. It is advisable to secure the bed to a work support and this may be done using "C" clamps or, preferably, by bolts which are passed through the holes 14. The bed 10 may also include a groove G to facilitate the bending of rods and tubes.
The upper surface of the bed 10 constitutes a female die and is wedge-shaped as shown at 17. The upper corners of the wedge, identified at 15 and 16 are preferably rounded and smoothed so as not to mar the sheet being bent since this sheet slides over the upper corners 15 and 16 as the bent portion thereof is forced downwardly into the wedge portion of the bed.
The bending arm 11 has a raised handle portion 18 and a knife portion 19 which moves into the wedge portion 17 as the bending arm 11 is pivoted by lowering the handle 18.
The forward end of the bed 10 is formed with upstanding portions 21 and 22 which are formed integrally with the forward end of the bed. The forward end of the bending arm 11 is formed to fit within the upstanding portions 21 and 22 and this serves to align the knife portion 19 of the bending arm 11 with the axis of the wedge portion 17.
A pivot pin 23 is inserted through the upstanding portion 21, then through the forward end of the bending arm 11 and lastly through the upstanding portion 22 so as to pivotally mount the bending arm 11 and the forward end of the bending arm 11 which fits between the upstanding portions 21 and 22 includes a compensating aperture extending laterally therethrough in order to accommodate the pin 23. This aperture is an important feature of the present construction and can be seen in dotted lines in FIG. 2 of the drawing where it is identified by the numeral 24. The aperture 24 is approximately the same size as the pin 23 along the length of the bending arm 11 to minimize movement of the arm 11 along its own length, but the aperture 24 is oversized in the direction of the height of the knife portion 19 so that the forward end of the arm 11 can be elevated by the back pressure generated through bending contact between the knife portion 19 and the sheet or bar being bent. This elevation occurs after the metal being bent is forced to the bottom of the wedge portion 17 and serves to align the bending edge of the knife 19 with the upper surface of the sheet being bent-- which will vary with the thickness of the sheet being bent.
Referring again to FIG. 2, the pivot pin 23 is constituted by a bolt which extends laterally through the entire structure which is held together by the bolt head at one side and, at the other side, by means of a nut 25 threaded on the free threaded end of the bolt. A yoke 26 extends across the upstanding portions 21 and 22 with its opposite ends 27 and 28 being pivoted to the opposite ends of the pin 23. Washers 29 and 30 are desirably interposed between the upstanding portions 21 and 22 and the head of the pin 23 on one side and the nut 25 on the other side to permit the yoke 26 to swing with the bending arm 11 as said arm is pivoted. While any form of shaft may be used to form the pivot pin, a bolt and nut as described are particularly convenient.
A retaining bolt 31 extends through the upper portion of the yoke 26 and is threaded into a tapped hole 32 in the forward end of the bending arm 11 immediately above the compensating aperture 24. The bolt 31 ties the yoke 26 to the pivoted end of the arm 11 so that the two will swing together. Lastly, a compression spring 33 is mounted on the retaining bolt 31 to bear downwardly against the forward pivoted end of the bending arm 11 to force the same as far down as possible. It is the spring 33 which resiliently resists the upward movement of the pivoted end of the bending arm 11 and which enables the pivoted end of arm 31 to rise and adjust for the thickness of the product being bent.
The action will be more clearly seen in FIG. 3 in which the bending of a sheet is illustrated.
As the knife portion 19 contacts the sheet to be bent at its forward end and moves this sheet to the bottom of the wedge 17, downward pivotal pressure applied to the handle 18 tends to cause the forward end of the bending arm 11 to rise as indicated by arrow A against the pressure of spring 33. The fulcrum for this pivotal movement is at F. As a result, the effective pivot point provided by pin 23 is automatically shifted to position the bending edge of the knife portion 19 at the level of the upper surface of the sheet to be bent. This enables full entry of the knife 19 into the wedge 17 along its entire length and, thus, the angle of bend at the rear of the sheet is substantially the same as the angle of bend at the forward end of the sheet to provide the uniform bend angle desired.
When contact is initially made with the sheet being bent, the leverage is great and is effective to overcome the pressure of spring 33. On the other hand, the leverage decreases as the knife 19 contacts the metal sheet to be bent further and further away from the pin 23. Moreover, when the rear of the sheet being bent reaches the bottom of wedge portion 17, the bend is complete and further heavy pressure has no purpose. As a result, after the compensating action has taken place, further elevation of the forward end of the bending arm 11 does not take place.
While the novel feature of the invention is particularly adapted to facilitate the bending of sheets, with the advantage of the invention increasing with bends of increasing length, the apparatus of the invention is nonetheless useful for bending flat bars and rods, though the automatic compensating feature is less significant in such other utilities. Similarly, while metal products are particularly contemplated, plastic and other materials can also be worked upon.
It will now be apparent that the present development is founded on employing a resilient pivotal interconnection between the forward end of the bending arm 11 and the forward end of the supporting bed with means to bias the forward end of the bending arm downwardly toward the bed. This resilient pivotal interconnection is preferably provided by employing a vertical elongated aperture in the forward end of the bending arm to receive the pivot pin with the downward resilient bias being preferably provided by means of a yoke carried by said pivot pin and which extends across the top of the forward end of the bending arm. A compression spring is interposed between the top of the yoke and the forward end of the bending arm overlying the pivot and with the yoke and bending arm being locked together so that the two will swing together and maintain the compression spring at a right angle to the length of the bending arm.
It is also desirable to be able to accurately position an edge of the metal sheet to be bent at a predetermined distance from the line of bend and this is achieved in the invention utilizing a measuring ledge 34 which extends sidewardly from the upper surface of the bed 10. As will be evident, a sheet is rested flat on the bed 10 with its edge appropriately positioned on the measuring ledge 34. When the bending arm 11 descends into the wedge 17, the portions of the metal being bent on opposite sides of the line of bend shift upwardly until, when the knife portion 19 has descended fully into wedge 17, the metal will substantially conform to the shape of the wedge which usually is formed to a 90° angle, but which may be formed to other angles if desired.
The invention is defined in the claims which follow.