Method and Apparatus for Manufacturing Asymmetrical Roll-Formed Sections

Abstract

A roll-forming station for forming asymmetrical sheet metal beams with unequal flanges, where both of the unequal flanges contact the rolls simultaneously and where the diameters of the rolls are such that the bending moments applied to the unequal flanges are identical in magnitude. This prevents lateral displacement of the workpiece during forming.

Description

FIELD OF THE INVENTION

The present invention relates to roll-forming, and more specifically to roll-forming asymmetrical sheet metal sections.

BACKGROUND

Roll-forming is a continuous bending operation in which a long flat strip of sheet metal is passed through several sets of rolls mounted on roll stands, each set of rolls bending the strip incrementally further and further until the desired profile is obtained. Typically, the process is used for manufacturing constant-section beams.

While the e are many possible cross-sections that can be manufactured this way, when a cross-section is asymmetrical (such as an unequal-flange U-section), the rolls may not contact the workpiece simultaneously, or the points of contact may not be equidistant from the axial plane of the rolls. This results in lateral displacement of the workpiece, which can cause twisting, bowing, and other defects, as the workpiece passes through the subsequent roll stands.

A need therefore exists for a reliable method of centering an asymmetrical section as it passes through a roll stand, and of ensuring simultaneous contact and equal torque on either side of an asymmetrical section.

SUMMARY OF THE INVENTION

The object of the present invention is to develop a method for the manufacture of asymmetrical angles, channels, and other asymmetrical profiles that includes additional technical steps for centering the workpiece during bending by means of the simultaneous application of opposite moments of the forming forces, and to develop a machine for implementing this method, as well as to improve the structure of the roll stand and the rolls by changing their location and the interaction of the forming elements, as well as introducing a certain relationship between their sizes.

While the below disclosure focuses on the method and machine for manufacturing an unequal-flange channel section, the invention is not limited to the formation of such sections, but may also be used to form other asymmetrical section roll-formed sheetmetal sections, as a person of reasonable skill in the art shall find readily apparent. Nothing in the below disclosure shall be understood to limit the invention to the manufacture of the roll-formed channel sections with unequal flanges.

One embodiment of the present invention comprises a roll stand intended for the manufacture of asymmetrical profile beams (with a longer flange and a shorter flange) in which the dimensions of the rolls are such that the longer flange contacts its forming roll at the same time as the shorter flange contacts its forming roll, and the shape of the rolls are such that the bending moment applied to the longer flange by its corresponding roll is nearly equal and opposite to the bending moment applied to the shorter flange by its corresponding roll. Furthermore, the point of contact between the longer flange and its corresponding roll, and the point of contact between the shorter flange and its corresponding roll, are equidistant from the central plane of the rolls. This prevents lateral displacement of the workpiece and the resulting twisting and bowing defects in its manufacture. Due to the prevention of lateral displacement, it is possible to apply higher forces to the workpiece, meaning that fewer roll stations are needed to achieve the desired bending angles.

The rolls may be kinematically coupled or freely rotating. Also, one or more of the rolls may be spring-loaded to ensure good contact with the workpiece.

The present invention thus broadens the industrial possibilities for the manufacture of asymmetrical section roll-formed beams from coiled sheet metal workpieces, due to the possibility of piecework manufacture and the resulting simplification of the manufacturing process.

LIST OF FIGURES

FIG. 1 shows the moment at which the workpiece enters the rolls of an intermediate roll stand and the beginning of the simultaneous bending of the longer and shorter flanges of the channel section in accordance with the present invention;

FIG. 2 shows a schematic illustration of a roll-forming machine for implementing the claimed method;

FIG. 3 shows a schematic illustration of the coupled rolls in an intermediate roll stand, designed and installed in accordance with the present invention;

FIG. 4 shows a schematic illustration of the coupled rolls in a roll stand with the vertical roll driven by the horizontal roll by means of linked conical gears;

FIG. 5 shows a schematic illustration of a non-driven disc-shaped forming element on the driven roll for bending the shorter flange of the channel section.

On the drawings are shown:

FIG. 1: 1—the longer flange of the channel section; 2—the shorter flange of the channel section; 3—the workpiece at the moment it enters the rolls of an intermediate roll stand and the roll-formed section begins to be formed; 4—the central region of the section; 5—the calibration plane (axial plane of the rolls); 6—the female side roll of the roll stand for bending the longer flange of the section; 7—the vertical axis of rotation of the roll for bending the longer flange of the section; 8—the female lower roll for bending the shorter flange of the section; 9—the horizontal axis of rotation for the roll for bending the shorter flange of the section; 10—the spacing between the rolls; 11—the male upper roll with a horizontal axis of rotation.

FIG. 2: 12—uncoiler for the coiled sheetmetal workpiece; 13—straightening machine; 14—shears; 15—welding machine; 16—the feed rolls; 17—workpiece holder; 18—straightening machine; 19—flying cutter; 20—roll-forming machine; 21—intermediate roll stand; 22—roller conveyor.

FIG. 3: 23—forming (and calibrating) region of the roll 6 for bending the longer flange of the section; 24—calibrating section of the roll 8 for bending the shorter flange; 25—directing surface for entry of the shorter flange of the roll-formed section into the working groove of the roll for bending; 26—working shaft of the female roll with a horizontal axis of rotation; 27—cylindrical forming element of the roll; 28—disc-shaped forming element with a conical calibrating region; 29—spacer; 30—nut; 31—disc element of the frictional transmission.

FIG. 4: 32—conical gear of the vertical roll; 33—conical gear of the horizontal roll; 34—roll spacer.

FIG. 5: 35—disc-shaped freely rotating forming element; 36—bearing for mounting the disc-shaped freely rotating forming element on the shaft; 37—spacer for mounting the bearing on the shaft; 38—spacer for mounting the bearing on the shaft.

K—the point of contact between the longer flange of the roll-formed section and the vertical roll; *K—the location of point K on the roll-formed section in the rolls; M—the point of contact between the shorter flange of the roll-formed section and the horizontal roll; *M—the location of point M on the roll-formed section in the rolls; Z_k—the distance between point K and the center plane of the rolls, m; Z_M—the distance between point M and the center plane of the rolls; D_d.k and D_d.f—main diameters of, respectively, the vertical female roll used for bending the longer flange of the channel section and the horizontal female roll used for bending the shorter flange of the channel section; D_d.m—main diameter of the male rolls; (D_d.k, D_d.f, and D_d.m—the diameters, respectively, of the vertical female roll, the horizontal female roll, and the horizontal male roll); b_s and b_b—respectively, the width of the shorter and longer flange of the section; h_s and h_b—respectively, the height of the section measured from the shorter and longer flange of the section; α and Δα—respectively, the total bending angle of the longer flange of the roll-formed section in the preceding roll stands and the bending angle in the current roll stands; β and Δβ—respectively, the total bending angle of the shorter flange of the roll-formed section in the preceding roll stands and the bending angle in the current roll stands; δ—difference between the cross-sectional radius (d_M/2) of the horizontal female roll and its nominal radius at the entry point of the shorter flange of the working groove of the roll at point M (where the edge of the profile contacts the roll); T—the region of contact between the two female rolls; P—force applied to create frictional forces between the side roll and the bottom driven roll, H; D_T.h and D_T.K—the diameters of the ring-shaped contact regions including point T on the horizontal and vertical rolls, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A method of manufacturing an unequal-flange channel section profile is described below as the preferred embodiment. It is to be understood that the invention is not limited to that particular profile, but is applicable to any other asymmetrical profile. FIG. 1 shows an intermediate stage in roll-forming an unequal-flange channel section profile 3. The longer flange 1 and the shorter flange 2 are bent in relation to the central region 4. The contact between the longer flange 1 and its forming roll is simultaneous with the contact between the shorter flange 2 and its forming roll. Also, the point of initial contact between the longer flange 1 and its forming roll is equidistant from plane 5 to the point of initial contact between the shorter flange 2 and its forming roll. The roll used to bend the longer flange 1 is the vertical female roll 6 (its vertical axis of rotation is 7), and the roll used to bend the shorter flange 2 is the horizontal female roll 8 (its horizontal axis of rotation is 9). Thus, the rolls used to form the unequal-flange channel section are the two female rolls 6 and 7 and the horizontal male roll 11.

As an example of this embodiment of the present invention, suppose an intermediate roll stand is bending the flanges of the roll-formed section that are 70 mm and 25 mm in width, with a 50 mm central wall. The bending angles for the longer flange of the roll-formed section are α=60° and Δα=15°; those for the shorter flange are β=60° and Δβ=15°. The analysis that has been performed on the initial stage of forming the profile with the above parameters has shown that the simultaneous contact between both flanges of the roll-formed section and the corresponding rolls happens at equidistant points K and M from the cross-sectional plane of the rolls in the roll stand, i.e. when Z_k=Z_M. If distance Z_k exceeds distance Z_M, the longer flange 1 will contact roll 6 before the shorter flange 2 contacts roll 8. This will result in lateral displacement, bowing, and twisting of the section in the direction of the longer flange. If distance Z_k is smaller than distance Z_M, the shorter flange 2 will contact roll 8 before of the longer flange 1 contacts the vertical roll 6. This will result in lateral displacement, bowing, and twisting of the section in the direction of the shorter flange.

The simultaneous contact between the unequal flanges of the roll-formed section with the forming rolls at points K and M and their simultaneous bending relative to the central region 4 of the profile in at least one roll stand is what prevents lateral displacement of the part from the central axis of the profile and thus improves the reliability of its manufacture. The application of forming forces by the rolls to the section at the places of their initial contact with both flanges of the roll-formed section at the same distance from the cross-sectional plane, with the vertical female roll used to bend the longer flange of the channel section and the horizontal female roll used to bend the shorter flange of the section, avoids bowing and twisting of the roll-formed section in the rolls. This broadens the technical applications of this method, simplifies and speeds up the forming process, and enables greater bending angles to be used. Furthermore, this increases the range of manufacturable asymmetrical channel sections (which are difficult to manufacture) and prevents manufacturing defects.

FIG. 2 shows a roll-forming machine to implement the preferred embodiment of the present invention. It comprises an uncoiler 12 for the rolled sheet metal of the workpieces, a straightening machine 13 that straightens the workpiece, a guillotine cutter 14 to cut the ends of the workpiece, a spot welding machine 15 to weld the front end of the coiled workpiece with the end of the prior roll, and feeder rollers 16 to feed the workpiece into the accumulator 17 that accumulates a sufficient length of workpiece to coordinate the workings of the different machines and mechanisms with different speeds, and to enable the continuous operation of the machine. The machine also comprises a second straightening machine 18, a flying cutter 19 for cutting the workpieces to the desired length, and the roll-forming machine 20 containing roll stands 21, including roll stands comprising coupled forming rolls with vertical and horizontal axes of rotation. A roller conveyor 22 is used to transport the finished roll-formed sections to the packer. FIG. 3 shows one of the roll stands (roll stand 21) of the roll-forming machine of the preferred embodiment of the present invention. The first calibrating region 23 of the longer flange 1 is placed in the vertical female roll 6 with axis of rotation 7, and the second calibrating region 24 of the shorter flange 2 is placed in the horizontal female roll 8 with axis of rotation 9. The working surface of the first calibrating region 24 is adjacent to a tangent surface 25, and the magnitude of the diameter D_d.k of the vertical female roll 6 is determined by the magnitude of the diameter D_d.f of the horizontal female roll 8 and the other dimensions of the profile as described in the following formula (1):

D_d.k=[D_d.f+b_s cos β tan(β+Δβ)+δ+b_s sin β] [b_s cos β tan(β+Δβ)+δ−b_s sin β]×[cos α−sin α/tan (α+Δα)]⁻¹b_b⁻¹+b_b[cos α+sin α/tan(α+Δα)],  (1)

where D_d.k and D_d.f are the main diameters of, respectively, the vertical female roll 6 and the horizontal female roll 8;

b_s and b_b are, respectively, the design widths of the shorter and longer flanges of the section: b_s=(b_s)_r+R_stan α/2, b_b=(b_b)_r+R_btan β/2;

(b_s)_r and (b_b), are, respectively, the widths of the flat region of the shorter and longer flanges of the section;

R_s and R_b are, respectively, the external radii of the transition region from the shorter and longer flanges of the roll-formed section to the central region of the section;

α and Δα are, respectively, the total bending angle of the longer flange of the roll-formed section in the prior roll stands and the bending angle in the given roll stand;

β and Δβ are, respectively, the total bending angle of the shorter flange of the roll-formed section in the prior roll stands and the bending angle in the given roll stand;

δ is the difference between the actual value of the radius of the cross-section of the horizontal roll and its nominal value at the entry of the shorter flange of the roll-formed section into the working groove of the roll, specifically at the point that the edge of the workpiece first meets the roll.

The analysis of the early stages of the forming process has shown that in accordance with formula (1), the simultaneous contact between the two flanges of the roll-formed section with the rolls occurs at points K and M that are equidistant from the cross-sectional plane, i.e. when Z_k=Z_M. Also, the direction of motion of the roll-formed section through the rolls must be along a straight line, and the wall 4 of the profile must be located at the level of forming. If the distance Z_k is greater than distance Z_M, then when the roll-formed section enters the rolls, the longer flange 1 contacts vertical female roll 6 before the shorter flange 2 contacts horizontal female roll 8. This results in lateral displacement, bowing, and twisting of the section in the direction of the longer flange of the section. If the distance Z_k is less than distance Z_M, then when the roll-formed section enters the rolls, the shorter flange 2 contacts horizontal female roll 8 before the longer flange 1 contacts vertical female roll 6. This results in lateral displacement, bowing, and twisting of the roll-formed section in the direction of the shorter flange of the section.

The rolls of the roll stand should preferably be composite. For example, the composite horizontal female roll 8 contains shaft 26 that supports the disc-shaped forming elements 27 and 28, spacer 29, and nut 30 (the bushing is not shown). This type of roll is simpler to manufacture and to use.

Shaft 26 can also support a disc frictional element 31 or a conical gear for rotating the side vertical roll. The frictional transmission may be accomplished by spring-loading one of the rolls with a spring force P at the point of contact (point T in FIG. 3). The diameters D_T.h and D_T.K of the ring-shaped regions of contact that contain point T, respectively on the horizontal and vertical rolls, determine the rotation speed of the significant points of the working surface of the vertical roll.

FIG. 4 shows a roll stand of the machine, in which the vertical female roll 6 is kinematically linked with the driven horizontal shaft 26 by, for example, conical gears. The conical gears 32 and 33 are rigidly mounted to the vertical female roll 6 and the shaft 26, respectively, along with a spacer 34, the disc-shaped forming elements 27, 28, and 29, by means of a bushing and a nut 30. The recommended kinematic linkage between the rolls during forming prevents a difference in velocity between the section and the rolls at the points of contact, and thus prevents dents and edge crumpling of the longer flange of the channel section during forming as well as its lateral displacement and the resulting bowing and twisting.

In order to improve the quality of the sections and to reduce frictional losses during bending, the forming element of the roll used for bending the shorter flange of the roll-formed section may be designed to freely rotate on the shaft of the horizontal roll, for example on a bearing. FIG. 5 shows this configuration of a non-driven forming disc-shaped element 35 for bending the shorter flange of the channel section on bearing 36 on shaft 26.

The incline angle of the forming surface of the forming region of the vertical female roll 6 and the horizontal female roll 8 are identical and correspond to the bending angles of the shorter and longer flanges of the channel section. The main diameter of the vertical female roll 6 is determined by formula (2):

D_o.k=[D_o.h+b_s cos α tan(α+Δα)+δ+b_s sin α] [b_s cos α tan(α+Δα)+δ−b_s sin α]×[cos α−sin α/tan(α+Δα)]−¹b_b⁻¹+b_b[cos α+sin α/tan(α+Δα)],   (2)

where α and Δα, respectively, are the total bending angle of one of the flanges of the channel section in the prior roll stands and the bending angle in the given roll stand. Due to the shape of the rolls, the two flanges of the channel section contact the forming rolls simultaneously.

It must be noted that when the two flanges of the roll-formed section are bent at 90°, the working surface of the vertical female roll 6 is the cylindrical surface, while the working surface of the horizontal female roll 8 is the flat surface of the disc-shaped element.

Claims

1. A roll stand, comprising:

a first roll for forming a first flange of a sheetmetal beam;

a second roll for forming a second flange of a sheetmetal beam, said

second flange a different length from the first flange;

such that when the sheetmetal beam enters the roll stand, the first flange contacts the first roll at the same time as the second roll contacts the second flange.

2. The roll stand of claim 1, where the bending moment applied to the sheetmetal beam by the first roll is nearly identical in magnitude to the bending moment applied to the sheetmetal beam by the second roll.

3. The roll stand of claim 1, where the point of contact between the first flange and the first roll and the point of contact between the second flange and the second roll are equidistant from the cross-sectional plane of the rolls.

4. The roll stand of claim 1, where the sheetmetal beam is an asymmetrical channel section beam.

5. The roll stand of claim 1, where the first roll is kinematically linked to the second roll.

6. The roll stand of claim 1, where at least one of the rolls rotates freely.

7. The roll stand of claim 1, where at least one of the rolls is spring-loaded.

8. A method of manufacturing a sheetmetal beam comprising a first flange and a second flange, the first flange not equal in length to the second flange, comprising at least one roll-forming step where the first flange contacts a roll at the same time as the second flange contacts a roll, and where the bending moment applied to the first flange is identical in magnitude to the bending moment applied to the second flange.