JPH0669587B2 - Cold roll forming method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cold roll forming method and apparatus for pressing a strip-shaped material with a forming roll to form a set shape, and particularly to a wide material with high dimensional accuracy. The present invention relates to a cold roll forming method and apparatus capable of forming.

[Conventional technology]

Conventionally, as a cold roll forming method in which a strip-shaped material is pressed by forming rolls to form a set shape, Jitsuko Sho 54-25250
Publication, "Plasticity and Processing" (Vol. 18, No. 202, 892-900)
P., Published in November 1977) and Japanese Patent Publication No. 43-28307.

The first method is to improve the strength by giving a small corrugation having unevenness of a plate thickness or less to the band-shaped material, and to make this material into a U-shaped or angle-shaped structural profile by an ordinary cold roll molding method. It is what is molded. The second method is to form a final shape trapezoidal cross-section material from a flat plate at once by using one forming roll stand. Furthermore, the third
Method is to form a corrugated sheet at a stretch by engaging a thin plate between gears, in which case a rubber tire-like back-up ring is used to correct axial flexural deformation of the gear shaft in the middle between the gear bearings. .

[Problems to be solved by the invention]

The first of the above-mentioned conventional techniques is a technique for forming a material to be formed into a U-shaped or angle-shaped structural profile, which is an ordinary cold roll forming method, and includes a large number of forming roll stands and a large number of sets. The equipment cost is high because the molding rolls are required.

The second method is to form the final shape at once by one forming roll stand. However, it is also possible that the gap between the rolls formed by the pair of forming rolls is equal to the plate thickness over the entire width. In addition, since the back-up roll is not used, it is difficult to apply a rolling force enough to apply a compressive stress equal to or higher than the yield stress in the wide material.

The third method is to use a gear-shaped forming roll to correct axial flexural deformation of the gear shaft while rolling-supporting the tip of the tooth tip with a rubber tire-like backing ring. The back-up force that the appling can apply cannot generate compressive stress higher than the yield stress in the material to be molded.

An object of the present invention is to provide a cold roll forming method and device that can simplify the structure of a cold roll forming apparatus and reduce the equipment cost, and can apply a sufficient and uniform forming force to a forming roll. It is in.

[Means for solving problems]

The above-mentioned object is to support a pair of forming rolls in which backup rolls are arranged in parallel to each other, and to apply a load for continuously applying a compressive force to a forming material made of a strip-shaped material between the forming rolls. In the cold roll forming method, in which the material to be molded inserted into the gap is clamped, and the material to be molded is molded into a set shape by the projection row provided on the outer peripheral surface of the molding roll, the material to be molded is deformed in the first molding process. Then, it bites with the forming roll while forming the set shape, and as the molding progresses, the load remains such that the film stress between the biting parts becomes a tensile stress equal to or higher than the yield stress (σ _Y ). After being roughly deformed into a set shape with elongation deformation, the material to be molded between the biting parts is clamped in the second molding process to yield stress (σ _Y )
This is achieved by applying the above compressive stress and compressively deforming this part.

Further, the material to be molded formed in the second molding step may be pulled with a tensile force equal to or lower than the yield stress (σ _Y ) of the material to be molded by the tension applying means arranged in front of the discharging method of the molding roll.

Further, the above-mentioned object is a pair of forming rolls composed of a forming roll having a plurality of protrusion rows on the surface of a cylindrical roll, and a forming roll having a groove row engaging with the forming roll on the surface of the cylindrical roll. A roll, a backup means for maintaining a gap between the forming rolls at a set dimension, and a pair of clamp rolls having a shape capable of pressing the forming shape on the discharge side of the material to be formed are provided in the discharging direction. Tensioning means capable of rotating in the same direction as the above and applying a tensile force equal to or lower than the yield stress (σ _Y ) to the material to be molded,
This is achieved by providing a cold roll forming apparatus that includes an up-down position guide that can adjust the up-down position of the material to be formed between the forming roll and the tension applying means.

[Action]

The cold roll forming method of the present invention realizes a sufficient and uniform forming force distribution by pressing the forming roll at an appropriate position between the bearing supports via the back up roll, and A cold roll forming method capable of reducing deformation after forming and stabilizing the shape by balancing residual stress and strain distributions.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 illustrates the structure of a forming apparatus in one embodiment of the cold roll forming method of the present invention. As shown in FIG. 1, the cold roll forming apparatus of the present invention sandwiches a strip-shaped flat plate between forming rolls having a row of protrusions on a cylindrical surface,
A flat plate is formed into a corrugated plate by applying a forming force to a forming roll through a back-up mechanism. The pair of corrugated sheet forming rolls 1a and 1b are rotatably supported by a bearing 5 held by a bearing support frame 4 in parallel with their axes, with their projection rows meshing with each other. The corrugated sheet forming force applies the pressing force of the hydraulic cylinder 9 attached to the upper base 7 to the forming rolls via the back-up mechanism installed above and below the forming rolls 1a and 1b. Also, forming rolls 1a, 1b
The rotational driving force of the motor 11 is converted into a biaxial output in which the rotating force of the motor 11 is counter-rotated by the synchronizing gear 12 at the same speed and then transmitted to the forming roll via the universal joints 10a and 10b. The magnitude of the forming force applied to the forming rolls 1a and 1b and the distribution state thereof can be appropriately set by controlling the arrangement state of the upper and lower back-up mechanisms and the pressing force of the hydraulic cylinder 9. Spring 6 interposed in the gap of bearing 5 of forming roll
For easy insertion of the flat plate at the start of molding,
This is for expanding the gap between the forming rolls 1a and 1b by the spring force. FIG. 2 shows a forming roll for forming a corrugated sheet.
The shapes of 1a and 1b are shown. While providing a row of annular protrusions 14 and groove portions 15 on the surface of the molding roll 1a in parallel with the roll axis,
A protrusion 16 and a groove portion 17 are similarly provided on the surface of the forming roll 1b so that the protrusion row and the groove row of these two forming rolls mesh with each other and are held parallel to the roll axis. This forming roll 1
The corrugated sheet 18 can be formed by inserting a flat plate into the gap between a and 1b and rotating the roll shaft while sandwiching the flat plate with a forming roll. FIG. 3 illustrates the forming process of the material to be formed in the cold roll forming method of the present invention, and shows the relationship between the cross-sectional shape of the formed product and the gap (G) between the forming rolls 1a and 1b. 4 (a) and 4 (b) show changes in the film stress and film strain of the bead portion 19 and the flange portion 20 of the material to be formed in the cold roll forming method of the present invention. The strip-shaped flat plate of the material to be molded is fed into the gap between the molding rolls 1a and 1b and is pinched by the projection rows 14 and 16 of the molding rolls to be molded into the corrugated plate having the final shape at once. FIG. 3 (a) shows a situation in which the strip-shaped flat plate is being bitten into the forming roll, and the flat plate is pushed halfway into the groove portions 15 and 17 by the protrusions 14 and 16 and is moved in the plate width direction. The movement (that is, the width-shifting operation) is restricted. The film stress and film strain of the material to be molded at this time correspond to portions A to B on the curves of FIGS. 4 (a) and 4 (b). Then, with the molding roll 1a
When the gap of 1b becomes narrow, the material to be molded is completely caught in the molding roll as shown in FIG. 3 (b), and
The film stress of the bead portion and the flange portion that has been bitten is plastically deformed by the tensile stress equal to or higher than the yield stress (σ _Y ) and stretches and is shaped along the shape of the protrusion of the shaping rolls 1a and 1b. The film stress and film strain at this time are shown in Fig. 4 (a),
It corresponds to the portion before B to C on the curve of (b). FIG. 3 (c) shows the situation when the gap between the forming rolls 1a and 1b is minimized, and the flange portion of the material to be formed is shown.
20 is crushed between the protrusion 14 and the bottom surface of the groove portion 17, and the material of the sandwiched portion plastically flows in the plate width direction and the longitudinal direction. The film stress and film strain of the bead portion 19 at this time correspond to the portions B, C to D in FIG. 4 (a). Also, the flange part 2
The film stress and film strain of 0 correspond to portions B, C, E to F in FIG. 4 (b). Here, if a tension applying means is provided on the discharge side of the material to be molded and a tensile stress is applied in the longitudinal direction of the bead portion and the flange portion, the film stress and the film strain of each part are as shown in FIG. It changes from C of b) to H and I. As shown in FIGS. 4 (a) and 4 (b), in the cold roll forming method of the present invention, plastic deformation, that is, residual strain ε ₁ occurs during the process of being caught in the forming roll. Furthermore, residual strain ε ₂ is generated only in the flange portion during the process of compression and crushing with the forming roll. Here, if tension is applied from the discharge side, the residual strains of the bead portion and the flange portion will be ε ₃ and ε ₄ , which will cause a larger residual strain than if no tension is applied and the residual stress as described later. Non-uniformity is eliminated.

When corrugated sheet is formed by one forming roll stand,
As shown in Reference 1, non-uniform residual stress and residual strain occur in the material to be molded, resulting in defective molding. Further, the residual strain is complicated and changes greatly in the vicinity of the forming roll, and also changes greatly under the forming conditions, so that it is difficult to appropriately adjust. for that reason,
In the conventional cold roll forming method, the residual film strain is not generated in the material to be formed by forming the final shape while gradually approaching the width with a large number of forming roll stands. Unlike the conventional cold roll forming method, the cold roll forming method of the present invention attempts to form a final shape while positively generating residual film strain, and in principle, one forming roll is used. Depending on the stand and the shape, the flat plate is formed into the final shape by several forming roll stands. A measure to eliminate molding defects while positively generating residual film strain is to apply molding force that is significantly larger than the molding force of the conventional cold roll forming method (that is, reduction force). This is to balance the residual film strain generated in the material to be molded. The yield condition when the stresses σ ₁ , σ ₂ and σ ₃ of the three orthogonal axis components are applied to the rectangular parallelepiped is
There is a Mises yield condition in material mechanics. This yield condition is σ _{S of the} following equation. Exceeds the yield stress (σ _Y ), it means that the rectangular parallelepiped is plastically deformed. From this equation, it is understood that if a large stress is applied from one direction, the other two axes will be plastically deformed even if the stress is small. That is, the molding method of the present invention,
By utilizing this principle, a sufficiently large compressive stress is applied to the flange portion to cause plastic deformation, whereby the residual film stress is made extremely small and the defective molding is eliminated.
In addition, the adverse effect of the complicated and greatly changing residual strain generated in the vicinity of the forming roll as shown in the above-mentioned reference document 1 can be reduced by forming while applying a sufficiently large compressive stress. Furthermore, if a tensile stress equal to or lower than the yield stress (this is the longitudinal stress, σ ₂ ) is applied to the discharge side of the material to be molded, compressive stress (this is the plate thickness direction force, σ ₃ ) and tensile stress Due to the effect of (σ ₂ ), the stress in the plate width direction (this is referred to as the plate width direction stress, σ ₁ ) can be made extremely small, and the imbalance of the stress distribution in the material to be molded can be reduced. it can.

FIG. 5 is an explanatory view for explaining the configuration of the cold roll forming apparatus of the present invention, which is viewed from the side of the forming apparatus. In FIG. 5, 21 is a flat plate, 22 is a molded product, and 23, 24.
Is a forming roll, 25 and 26 are backup rolls, 27 and 28 are tension applying rolls, and 29 and 30 are vertical guide rolls. The cold roll forming apparatus of the present invention is a cold roll forming apparatus for forming the flat plate 21 into the final-shape formed product 22 at a stretch. It is possible to reduce the number of forming roll stands and apply a sufficiently large forming force (straightening, rolling down force) to form a molded product of a set shape with one or several roll stands. This is a feature of the molding method of the present invention. In order to apply a sufficient forming force, the back-up rolls 25 and 26 are installed above and below the forming rolls 23 and 24, and the forming force is applied to appropriate positions between the bearings of the forming roll via the back-up rolls. Furthermore, in order to improve the stability of the shape of the molded product 22 after molding and eliminate molding defects, tension-applying rolls 27, 28 are provided on the discharge side of the molded product, and the molded product has a yield stress or less and a good molded shape, for example. It is desirable to form while applying a tension of about 1/5 to 1/3 of the yield stress. As a result, of the film stress in the material to be molded, σ _1, that is, the stress in the plate width direction becomes small, and σ _2, that is, the stress in the longitudinal direction becomes a stress corresponding to the tension over the entire plate width. Further, in order to eliminate molding defects in the out-of-plane direction, that is, vertical direction due to residual stress imbalance, vertical guide rollers 29, 30 are provided, and vertical guides are provided to eliminate vertical molding defects of the molded product 22. Adjust the vertical position of the rollers 29, 30.

Since the cold roll forming apparatus of the present invention performs forming while applying a compressive stress equal to or higher than the yield stress to a part of the material to be formed, like a normal cold roll forming apparatus, both shaft ends of the forming roll are formed. Good forming cannot be achieved simply by applying a pressing force, and the intermediate part between the bearings of the forming roll is arranged to be pressed down via the back-up roll. By pressing the forming roll through the back-up roll, it was not necessary to correct the axial bending deformation of the forming roll, and the forming force applied to the forming roll could be evenly distributed.

FIG. 6 and FIG. 7 are explanatory diagrams for explaining the relationship between the distribution state of the forming force and the load point, and show the case of a smooth roll for simplification. When an equal pressing force W is applied to both shaft ends of a forming roll that has been generally used,
Due to the difference in the amount of flexural deformation of the roll shaft, a concave forming pressure distribution is shown in which the center is small and both ends are large, as shown in FIG. When the corrugated sheet is formed under such a load condition, defects such as pocket waves and wrinkles are likely to occur because the shape and stress state of the center and both ends are different. Therefore, when the pressing force is dividedly applied to the central portion of the forming roll as shown in FIG. 7, the forming pressure distribution of the flat plate becomes substantially uniform in the plate width direction. If the corrugated sheet is formed under such a load condition, the formed shape and the stress state in the sheet width direction become substantially equal to each other, so that the above-mentioned defects can be eliminated and a satisfactory corrugated sheet can be formed. Further, it is desirable that the magnitude of the pressing force and the load position can be appropriately set according to the conditions of the corrugated sheet to be formed. Also, the magnitude of the pressing force, the load position and its distribution state are controlled by means for detecting the shape of the corrugated sheet after forming, means for calculating the detection signal, and control signals obtained by the calculation processing means. The addition of the pressing force control means further improves the molding shape and dimensional accuracy.

The following is a comparison of the molding force, that is, the rolling force, between the molding method of the present invention and the conventional molding method.
As for the forming force in the single roll stand similar to the forming method of the present invention, when forming a material having a plate width of 77 mm and a plate thickness of 1 mm, a force of 400 kg to 1000 kg is required depending on the forming shape. On the other hand, as in the present invention, if a compressive stress equal to or higher than the yield stress is applied for forming, the forming force can be obtained as the rolling force of the rolling theory, and the rolling force (P) is Can be expressed as Where p _S = 1.5, σ _Y = 45 kg / m
Assuming m ² , b = 77mm, R = 50mm, Δh = 0.2mm, P
= 10,957 kg. That is, the molding force of the molding method of the present invention needs to be 11 to 27 times larger than the molding force of the conventional molding method. However, since there is a portion such as the bead portion in FIG. 3 in which the compression pressure does not have to be applied, the molding force is slightly smaller than the above molding force. Like the molding method of the present invention, in order to mold while applying a large compressive stress to the material to be molded,
It is not enough to apply a force at the shaft end of the forming roll as in the conventional cold roll forming method, and the forming force distribution becomes non-uniform due to the axial bending deformation of the forming roll.
Therefore, in the present invention, in order to be able to push the middle of the forming roll shaft with a force of an appropriate magnitude, a plurality of back-up rolls are installed, and a structure for pushing the forming roll through the back-up rolls is used. did. In addition, a part of the back-up roll is a roll crown (a drum-shaped outer diameter shape) for correcting the axial deflection deformation of the back-up roll itself.
Is used, a back-up roll having a projection row that meshes with the projection row of the molding roll is used, and the shape of the projection row of the back-up rolls only in contact with the groove bottom between the projection rows of the molding roll. , The tip of the protrusion of the forming roll does not contact the groove bottom between the protrusion rows of the backup roll,
That is, the groove portion of the back-up roll is formed to escape. The forming roll abuts only on the outer peripheral portion of the tip end of the projection row of the backup roll, and the contact state between the forming roll and the backup roll can be adjusted by this outer peripheral shape. Moreover, the outer periphery of the back-up roll is
Since it is easy to process, has good dimensional accuracy, and can be processed into an appropriate shape, it is also easy to provide an appropriate roll crown. Therefore, if the back roll having this structure is used, an appropriate forming force and forming force distribution can be realized, and cold roll forming with a good forming shape can be performed.

FIG. 8 and FIG. 9 show another embodiment of forming rolls 1a and 1b used in the cold roll forming method of the present invention. FIG. 8 is an example of a forming roll for forming a large-width formed product of a wide width and a thick plate used for a deck plate and a structural profile. When the strip-shaped material is continuously formed into the final shape by the projection rows 14 and 16 and the groove rows 15 and 17 provided on the cylindrical surface of the forming rolls 1a and 1b, the bead portion 19 and the flange portion are also formed in the large forming product. As in the case of 20, it is difficult to obtain a good bead shape unless molding is performed by applying compressive stress. Therefore, the forming rolls 1a and 1b of FIG. 8 are configured so that compressive stress can be applied not only to the flange portion 20 but also to the bead portion 19, and the gap between the protrusion 16 and the groove portion 15 in FIG. Is approximately equal to the gap between the protrusion 14 and the groove portion 17. However, the inclined portion 33 of the bead portion 19 is provided with a sufficient gap in this portion of the forming rolls 1a and 1b so that plastic flow easily occurs from the portion to which the material to be molded having compressive stress is applied. FIG. 9 is an example of a forming roll for forming an uneven plate having button-shaped protrusions. The cylindrical recesses 34 and the cylindrical protrusions 35 provided on the cylindrical surface of the forming rolls 1a and 1b allow the button-shaped protrusions 36 to be formed on a flat plate.
Mold a large number of. Moreover, since the button-like protrusion 36 is formed by plastically deforming a flat plate, uneven residual stress is generated around the overhang forming portion. Therefore, in the molding method of the present invention, a large compressive stress equal to or higher than the yield stress (σ _Y ) is applied to the periphery of the button-shaped protrusion 36 to redistribute the film stress in the periphery of the button-shaped protrusion 36, so that the film stress of this portion is reduced. In addition to eliminating the non-uniformity, the residual film stress is reduced to improve the stability of the molding shape and eliminate molding defects.

FIG. 10 illustrates a method for detecting axial flexural deformation of the forming roll shaft used in the cold roll forming apparatus of the present invention. When the Gap sensor 37 is attached to the upper portion of one of the pair of forming rolls 36a and 36b and the gap between the outer periphery of the forming roll 36A and the sensor 37 is continuously detected, the output of the curve A is obtained. On the other hand, when the rotational position detector is attached to the shaft end of the forming roll 36a and the rotational position of the forming roll 36a is detected, the output of the curve B is obtained. Appropriate level on curve B,
That is, when the signal level of the curve A is taken out at an appropriate rotational position and compared with the signal level at the same position last time, the axial bending deformation of the forming roll can be detected. The example of FIG. 10 shows a case in which the flexural deformation of the forming roll shaft is detected only four times per rotation. The Gap sensor must be attached so that the holding position does not change even when a forming force is applied to the forming roll. As in the present embodiment, if the same position of the molding roll 36a is detected by the Gap sensor 37, the molding rolls 36a and 36b are not affected by the dimensional error and the roundness error of the molding roll 36a. The gap can be detected accurately. In the cold roll forming apparatus of the present invention, as shown in FIG. 1, the forming roll is backed up by a plurality of backing up rolls and a forming force is applied.
A sensor can be attached, and the axial flexural deformation of the forming roll shaft can be directly detected.

In the above description, the case where the forming roll shaft is rotationally driven as shown in FIG. 1 has been illustrated. However, in the forming method of the present invention, a part of the backup roll is rotationally driven and the forming roll is driven. May be. Further, both the forming roll and the back-up roll may not be rotationally driven, but tensile stress may be applied by the tension applying means installed on the discharge side and the material may be fed and drawn.

〔The invention's effect〕

According to the present invention, an optimum and sufficient forming force distribution can be easily realized according to the shape to be formed, the plate thickness, the plate width, and the material, so that the forming shape is good and the shape stability is good. Goods can be molded. Further, since the intermediate part between the bearings of the forming roll is pushed via the back-up roll, the shaft deflection, which is a problem with the wide material, is not deformed, and the wide material can be easily formed.

Further, according to the cold roll forming method of the present invention, the material to be formed is plastically deformed, and a compressive stress equal to or higher than the yield stress (σ _Y ) is applied in the plate thickness direction, and the material is formed while applying tension also in the longitudinal direction. Therefore, the unbalance of residual stress after molding can be minimized. Furthermore, in order to perform molding under such molding conditions, the number of molding roll stands can be significantly reduced, and it is possible to reduce equipment costs and molding roll costs, and set molding conditions and molding shapes. Can be easily changed.

[Brief description of drawings]

The drawings are explanatory views of a cold roll forming method and apparatus according to the present invention. FIG. 1 is a front view of a cold roll forming apparatus, FIG. 2 is an external view of a forming roll, and FIG. 3 is a forming process. Illustration,
FIG. 4 is an explanatory view of changes in film stress and film strain during forming, FIG. 5 is a side view illustrating the structure of the forming apparatus, and FIGS. 6 and 7 are flat plates sandwiched by smooth rolls. FIG. 8 is an explanatory view of the forming pressure distribution in the case, FIG. 8 is an explanatory view of another embodiment of the forming roll of the present invention, FIG. 9 is an explanatory view of yet another embodiment of the apparatus, and FIG. 10 is a forming roll. FIG. 6 is an explanatory diagram of a method of detecting the axial bending deformation of the. 1 …… Molding roll, 2,3 …… Back up roll, 9
...... Hydraulic cylinders, 14,16 …… Protrusions, 15,17 …… Grooves, 18
...... Corrugated plate, 19 ...... Bead part, 20 ...... Flange part, 31 ......
Flat plate, 32 ... Smooth roll.

Claims (3)

[Claims] 1. A pair of molding rolls, each having a backup roll arranged thereon, are supported in parallel with each other, and a load for continuously applying a compressive force to a material to be molded made of a band-shaped material is applied between the molding rolls. In the cold roll forming method, in which the material to be molded inserted into the gap between the rolls is clamped, and the material to be molded is formed into a set shape by the row of protrusions provided on the outer peripheral surface of the molding roll, the material to be molded in the first molding step. The material is deformed to form the set shape, and the material is bitten by the forming rolls. As the molding progresses, the film stress of the material to be formed between the biting parts becomes the yield stress (σ
_Y ) A load such that the tensile stress is equal to or more than that is applied, and the material is roughly deformed to a set shape with residual elongation deformation, and then the yield stress (σ _Y ) A cold roll forming method characterized by compressing and deforming this portion by applying a compressive stress of the above. 2. The material to be molded formed in the second molding step,
The cold roll forming method according to claim 1, wherein the tension applying means disposed in front of the forming roll in the discharge direction pulls the material to be formed with a tensile force equal to or lower than the yield stress (σ _Y ) of the material to be formed. . 3. A pair of forming rolls comprising a forming roll having a plurality of protrusion rows on the surface of a cylindrical roll and a forming roll having a groove row engaging with the forming roll on the surface of the cylindrical roll. A roll, a backup means for maintaining the gap between the forming rolls at a set dimension, and a pair of clamp rolls having a shape capable of pressing the forming shape on the discharge side of the material to be formed are provided. A tension applying means capable of rotating in the same direction as the discharging direction and applying a tensile force equal to or lower than the yield stress (σ _Y ) to the material to be molded, and a vertical position of the material to be molded are provided between the molding roll and the tension applying means. A cold roll forming apparatus comprising an adjustable vertical position guide.