Metal deforming – By deflecting successively-presented portions of work during... – By use of deflector arranged to bend work transversely of...
Reexamination Certificate
2001-02-05
2003-08-12
Crane, Daniel C. (Department: 3725)
Metal deforming
By deflecting successively-presented portions of work during...
By use of deflector arranged to bend work transversely of...
Reexamination Certificate
active
06604397
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to rollforming machines and, more particularly, to adjustable rollforming machines for forming components from materials of different thicknesses and rollforming machines having the capability to overbend the component being formed.
2. Description of the Invention Background
Rollforming is a well-know process of bending a continuous strip or cut to length strip of metal through a series of shaped rolls. Common rollforming processes gradually form a strip of metal into a predetermined shape. The shapes may include, for example, generally C-shaped cross sections or generally U-shaped cross sections, or may include relatively complex formations being formed along the length of the material.
Rollforming processes are widely used because they are regarded as being a highly efficient means for continuously forming metal strip. Any number of other operations may be performed while the metal is taking shape. These other operations may include, for example, punching, tabbing, cutting to length, perforating, drawing, lancing, embossing, knurling, edge conditioning and curving. One particular benefit of rollforming is that strength and function are added to the metal as a result of the rollforming process. Rollforming, therefore, provides for many advantages in comparison to other known processes for forming metal materials.
The marketplace for shaped, rollformed sections has expanded into virtually every field of industry thereby replacing other known processes such as extrusions, brake forming and punch press operations in the areas such as the aircraft industry and the automotive industry. Another industry that heavily relies on rollforming is the architectural industry, and more specifically, the metal frame construction industry. As an alternative to traditional wood construction components, a variety of metal frame constructions and associated components have been developed for use in the residential and/or commercial building industry. The components needed for the metal frame construction industry are greatly varied and thus can be time consuming and expensive to manufacture using conventional rollforming techniques. For example, the needed components must be manufactured in an assortment of sizes, gauges and shapes depending upon the particular need for an assortment of different residential and/or commercial structures in which the components will be utilized. In addition, such components must be manufactured to relatively close tolerances to ensure that they will fit together properly and can easily be assembled and installed.
Rollforming machines for producing components used, for example, in the metal frame construction industry, are well known and typically include a plurality of sets of forming rolls arranged in upper and lower pairs and spaced apart along the length of the rollforming machine on rollforming support stands. As is also well known, the forming rolls at one stand will produce a continuous formation in the material and the forming rolls of the next stand will produce another formation, or for example, increase the angle of the formation which has already been started at the previous stand and so on. Examples of such rollforming machines are disclosed, in U.S. Pat. Nos. 5,970,764 and 5,829,295.
When rollforming a strip of metal to produce a component, it is advantageous for the rollforming machine to be capable of working on materials of different thicknesses, also referred to as the “gauge” of the material in the metals industry. In order to achieve this flexibility of working on materials of different thicknesses, early rollforming machines required that the forming rolls be replaced entirely or substantially changed when it was desirable to form a material having a different thickness. As can be appreciated, this practice of completely replacing the forming rolls was very costly in terms of material costs to provide numerous different forming rolls, labor costs for the added time of installing and reinstalling the forming rolls, and the manufacturing costs in view of the time that the rollforming machine could not be in operation during replacement of the forming rolls. More modern rollforming machines provide for automatic adjustment of the forming rolls to accommodate the materials of different thicknesses. For example, the aforementioned U.S. Pat. No. 5,970,764 discloses a first rack and pinion arrangement in combination with an eccentrically mounted shaft for adjusting the clearance between forming rolls in a first plane and a second rack and pinion arrangement in combination with an additional eccentrically mounted shaft for adjusting the clearance between the forming rolls in a second plane. While apparently effective at adjusting the clearance between the forming rolls for materials of different thicknesses, such an arrangement still has many disadvantages and shortcomings. For example, many mechanical parts are necessary to achieve the desired adjustment resulting in increased costs for manufacturing and maintaining the rollforming machine, and also resulting in the increased likelihood of mechanical failure leading to down time and lost operating revenue for the rollforming machine. In addition, such arrangement is apparently unable to accurately and consistently maintain the required tolerances when rollforming a component.
When performing a rollforming process to produce a component of a particular shape, it is desirable for the component to maintain the desired shape after the rollforming process is completed and the component exits the rollforming machine. One problem that can occur when rollforming products is commonly referred to in the rollforming industry as “springback”. The bending process that takes place during rollforming is a complex process which seeks to avoid stress concentration at the points of bending. Because the material being rollformed has a modulus of elasticity, the material tries to assume a shape having a bend of lesser extent than was desired. Therefore, springback is generally defined as the elastic recovery of metal after a stress has been applied. Other properties of the metal which may affect and contribute to springback are, for example, tensile strength, yield strength and Rockwell hardness. As can be appreciated, the amount of springback that may occur will vary for different materials and for different shapes depending upon the degree of bending.
One solution to correcting springback is to rework the rollformed component to mitigate the effects of the springback. However, to rework the component greatly increases the unit cost for the component and, therefore, is not an effective solution. Another solution to springback is to employ additional rollforming stands on the rollforming machine that include forming rolls cut to specific angles in order to overbend the component once the desired shape has been achieved. However, this also greatly increases the costs of rollforming by requiring additional rollforming stands and increased material and labor costs to install and replace the forming rolls depending upon the particular angle that is needed in order to achieve the necessary overbend to compensate for the springback.
There is identified, therefore, a need for an improved rollforming machine that overcomes limitations, shortcomings and disadvantages of known rollforming machines.
There is also a need for an improved rollforming machine that is capable of accommodating materials of different thicknesses.
There is a further need for an improved rollforming machine that can be easily and efficiently adjusted for materials of different thicknesses and profiles.
There is a further need for an improved rollforming machine that is capable of producing a component of a desired shape or configuration wherein the component maintains the desired shape or configuration once the rollforming is completed and the component is removed from the rollform
Hedman Norman J.
Jinkens Joseph A.
Pacalo, III John M.
Patty Alfred C.
Stimpert, II Larry E.
Crane Daniel C.
Dietrich Industries, Inc.
Kirkpatrick & Lockhart LLP
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