CN104249090B - A kind of superhigh intensity precision rectangular tube forming method and device - Google Patents

Abstract

The present invention provides a method and device for forming an ultra-high-strength precision rectangular tube. The method includes the following steps in sequence: Step 1: Take a preformed rectangular tube with a large fillet radius, and perform local heating on the four fillet parts by a heating fixture. Heating to a preset temperature; Step 2, the preformed rectangular tube heated to a preset temperature is rolled into a pre-finished rectangular tube with a small fillet radius in the first finishing pass roll bending process; Step 3, the pre-formed rectangular tube is rolled into a small fillet radius; The finishing rectangular tube is rolled into a precision rectangular tube with a near-sharp angle in the second finishing pass roll bending process. Compared with the traditional roll forming process, the hot roll forming technology of the present invention focuses on the application of high-strength steel or ultra-high-strength steel, and has obvious technical advantages and a wide range of applications; compared with hot stamping, hot roll The bending forming process has fast forming speed, high material utilization rate and good forming performance; this process can produce near-sharp rectangular tubes with good performance.

Description

A method and device for forming an ultra-high-strength precision rectangular tube

technical field

The invention relates to the technical field of local heating roll bending, in particular to a method and device for forming an ultra-high-strength precision rectangular tube.

Background technique

In order to meet the increasingly stringent requirements for automobile lightweight, crash safety performance and exhaust emission, in addition to the use of lightweight materials such as Al, Mg and polymers, ultra-high-strength steels are increasingly used in the automotive industry. In the manufacture of foreign mainstream automobile bodies, replacing ordinary strength steel with ultra-high-strength steel is a direction for the development of modern auto parts.

Taking the rectangular tube, the main structural part of the automobile, as an example, in its main preparation process, the roll forming process has higher forming ability and advantages, its production speed is fast, the cost is low, and the material utilization rate is high. For structural parts, the roll forming process has irreplaceable advantages of other processes. However, ultra-high-strength steel has high yield strength at room temperature, and requires a large roll forming force, which requires high forming ability of roll bending equipment; its springback is large, and the dimensional accuracy of the product is difficult to guarantee; at the same time, its yield ratio High, that is, the forming interval is relatively small, especially the forming of precision rectangular tubes with small fillet radii, which is prone to cracking. Therefore, it is almost impossible to produce ultra-high-strength precision rectangular tubes by traditional roll forming technology.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and device for forming an ultra-high-strength precision rectangular tube to solve the problem that the roll-forming process in the prior art cannot produce ultra-high-strength precision rectangular tubes.

In order to solve the above problems, an embodiment of the present invention proposes a method for forming an ultra-high-strength precision rectangular tube, which includes the following steps in sequence:

Step 1, take a preformed rectangular tube with a large fillet radius, and locally heat its four fillet parts to a preset temperature through a heating fixture;

Step 2, the preformed rectangular tube heated to a preset temperature is rolled into a prefinished rectangular tube with a small fillet radius in the first finishing pass roll bending process;

Step 3, the pre-finishing rectangular tube is subjected to the second finishing pass roll bending process and rolled into a precision rectangular tube with a near-sharp angle.

Wherein, in step 1, the preset temperature is 600°C-950°C.

Wherein, the roll diameter of the first roll bender is 1-5 mm larger than that of the second roll bender.

Wherein, in step 1, the heating fixture includes an induction heating coil, the induction coil is ring-shaped and arranged on the outer circumference of the rectangular tube, and four rounded corners corresponding to the rectangular tube are provided with rounded corners. close proximity structure.

In order to solve the above-mentioned technical problems, an embodiment of the present invention also provides an ultra-high-strength precision rectangular tube forming device, including a first roll bender and a second roll bender arranged at intervals, the first roll bender is equipped with a temperature measuring instrument and an automatic feedback system, the first roll bender is provided with an induction coil, and the induction coil is respectively connected to the induction heating control cabinet and the automatic feedback system, and the automatic feedback system compares the preset temperature with the temperature of the thermometer and The induction coil is automatically controlled by the induction heating control cabinet to heat the rectangular tube.

Wherein, the induction coil is arranged in a ring shape on the outer circumference of the rectangular tube, and an approaching structure is provided at the four rounded corners corresponding to the rectangular tube to approach the rounded corners.

Among them, a plurality of guide rollers are also included to guide the rectangular pipe.

Among them, a cooling device is also included, which is installed after the second roll bender to cool the rectangular tube.

The beneficial effects of above-mentioned technical scheme of the present invention are as follows:

(1) Compared with the traditional roll forming process, the hot roll forming technology of the present invention focuses on the application of high-strength steel or ultra-high-strength steel, and has obvious technical advantages and a wide range of applications; compared with hot stamping , The hot roll forming process has fast forming speed, high material utilization rate and good forming performance; the hot roll forming process reduces the requirements for equipment and prolongs the life of the equipment.

(2) The local induction heating technology of the present invention can not only accurately realize the heating of the rounded corners, reduce the residual stress, prevent work hardening, but also have almost no effect on the rest of the base material, ensuring the strength of the raw material; compared with the overall heating, the local The heating technology has fast heating speed, high thermal efficiency and low cost.

(3) The present invention introduces a thermal straightening system, rationally utilizes waste heat, reduces straightening tension, omits the Turkish head in the traditional roll forming process, reduces costs, and improves product dimensional accuracy.

Description of drawings

Fig. 1 is the structural representation of the ultra-high-strength precision rectangular tube forming device of the embodiment of the present invention;

Fig. 2 is a comparison diagram of preformed rectangular tubes, prefinished rectangular tubes and precision rectangular tubes according to an embodiment of the present invention;

Fig. 3 is the schematic diagram of the thermal finishing straightening principle of the embodiment of the present invention;

Fig. 4a is a structural schematic diagram 1 of a heating fixture according to an embodiment of the present invention;

Fig. 4b is a second structural schematic diagram of the heating fixture according to the embodiment of the present invention.

[Description of main component symbols]

1: Induction heating control cabinet;

2: The first roll bending machine;

3: rectangular tube;

4: Upper and lower rolls and side rolls;

5: The second roll bender;

6: guide roller;

7: cooling device;

8: Automatic feedback system;

9: Induction coil.

detailed description:

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

The invention aims at the problem that the roll forming process in the prior art cannot produce ultra-high-strength precision rectangular tubes, and provides an ultra-high-strength precision rectangular tube forming method and device.

As shown in Figure 2, a method for forming an ultra-high-strength precision rectangular tube provided by an embodiment of the present invention includes the following steps in sequence:

Step 1: Pre-bend the ultra-high steel sheet into a rectangular tube with a large fillet radius by the traditional cold bending process, take the preformed rectangular tube with a large fillet radius, and locally heat the four fillet parts to Preset temperature, the preset temperature is 600°C-950°C, the heating fixture includes an induction heating coil, the induction coil is set in the outer circumference of the rectangular tube in the form of a ring, and on the four sides of the corresponding rectangular tube The rounded corner is provided with an approaching structure approaching the rounded corner;

Step 2, the preformed rectangular tube heated to a preset temperature is rolled into a prefinished rectangular tube with a small fillet radius in the first finishing pass roll bending process;

Step 3, the pre-finishing rectangular tube is rolled into a precision rectangular tube with a near-sharp angle in the second finishing pass roll bending process;

The first roll bender of the first finishing pass roll bending process and the second roll bender of the second finishing pass roll bending process are arranged at intervals, and the first roll bender is more than the The roll diameter of the second roll bender is 1-5mm larger.

As shown in Figure 1, in order to solve the above technical problems, the embodiment of the present invention also provides an ultra-high-strength precision rectangular tube forming device, including a first roll bender 2 and a second roll bender 5 arranged at intervals, the first roll bender 5 The first roll bender 2 is provided with a temperature measuring instrument and an automatic feedback system 8, and the front of the first roll bender 2 is provided with an induction coil 9, and the induction coil 9 is respectively connected to the induction heating control cabinet 1 and the automatic feedback system, so The automatic feedback system compares the preset temperature with the temperature of the thermometer and automatically controls the induction coil 9 to heat the rectangular tube 3 through the induction heating control cabinet 1; it also includes a plurality of guide rollers 6 for guiding the rectangular tube 3; It also includes a cooling device 7, which is arranged after the second roll bender 5, and is used for cooling the rectangular tube 3.

Both the first roll bender and the second roll bender are composed of upper and lower rolls and side rolls 4 .

As shown in Fig. 4a and Fig. 4b, the induction coil 9 is arranged in a ring shape on the outer circumference of the rectangular tube 3, and an approaching structure is provided at the four rounded corners of the corresponding rectangular tube 3 to approach the rounded corners.

The first frame of the present invention is to transport the preformed rectangular tube into the induction coil stably to prevent the preformed rectangular tube from contacting the induction coil to form a short circuit; then enter the special induction coil, and the four rounded corners of the rectangular tube are heated When the temperature reaches the predetermined temperature, the temperature measuring instrument and automatic feedback system ensure the constant heating temperature; then enter the finishing roll, the rectangular tube is subjected to four-way extrusion force, and because the rounded corner is affected by the temperature, the yield strength is lower than that not affected by the temperature The base material, the extrusion force is transmitted to the corner, plastic deformation occurs, and the radius of the fillet is reduced; after the fillet undergoes large deformation, it is often subject to non-uniform residual stress, resulting in distortion, side bending, longitudinal bending, etc. Redundant deformation. As shown in Figure 3, the present invention provides a thermal tension straightening system, the principle of which is to use the speed difference caused by the roller diameter difference between the two passes to generate a certain tension between the two passes, and then combine the heat The residual heat after finishing makes the two ends of the rectangular tube subjected to thermal tension that is higher than the yield strength of the material and lower than the tensile strength of the material, thereby eliminating redundant deformations such as twisting and warping after thermal finishing.

In the local induction heating system of the present invention, the four rounded corners of the rectangular tube can be accurately heated through the self-made specific induction coil of the invention, while avoiding other plane base materials without being affected. It is also equipped with an automatic feedback temperature adjustment system, which captures the temperature before molding and feeds it back to the induction heating system through a temperature measuring instrument. If the measured temperature is within the molding temperature range, the current power will be maintained; if not, it will be rapidly increased or Reduce the power to adjust the suitable molding temperature, so as to ensure the constant heating temperature.

Embodiment one

1) Pre-bend the ultra-high-strength steel plate into a preformed rectangular tube with a fillet radius R=8, with a size of 40.0×40.0×2.0mm; 2) Rapidly heat the fillet of the preformed rectangular tube at a feed rate of 10m/min to 600°C; 3) After hot extrusion, finishing and straightening, a precision rectangular tube with a size of 38.5×38.5×2.0mm, a fillet radius R=4.0 and a dimensional accuracy of 0.1mm is obtained. After quality testing, the precision rectangular tube has less work hardening phenomenon, less residual stress and improved elongation.

Example 2

1) Pre-bend the ultra-high-strength steel plate into a preformed rectangular tube with a fillet radius R=8, with a size of 40.0×40.0×2.0mm; 2) Rapidly heat the fillet of the preformed rectangular tube at a feed rate of 15m/min to 650°C; 3) After hot extrusion, finishing and straightening, a precision rectangular tube with a size of 38.0×38.0×2.0mm, a fillet radius R=2.0 and a dimensional accuracy of 0.1mm is obtained. After quality testing, the precision rectangular tube has less work hardening phenomenon, less residual stress and improved elongation.

The beneficial effects of above-mentioned technical scheme of the present invention are as follows:

(1) Compared with the traditional roll forming process, the hot roll forming technology of the present invention focuses on the application of high-strength steel or ultra-high-strength steel, and has obvious technical advantages and a wide range of applications; compared with hot stamping , The hot roll forming process has fast forming speed, high material utilization rate and good forming performance; the hot roll forming process reduces the requirements for equipment and prolongs the life of the equipment.

(2) The local induction heating technology of the present invention can not only accurately realize the heating of the rounded corners, reduce the residual stress, prevent work hardening, but also have almost no effect on the rest of the base material, ensuring the strength of the raw material; compared with the overall heating, the local The heating technology has fast heating speed, high thermal efficiency and low cost.

(3) The present invention introduces a thermal straightening system, rationally utilizes waste heat, reduces straightening tension, omits the Turkish head in the traditional roll forming process, reduces costs, and improves product dimensional accuracy.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (1)

1. a superhigh intensity precision rectangular tube forming method, it is characterised in that comprise the following steps successively:

Step one, takes the preforming rectangular tube of Rouno Cormer Pregrinding Wheel radius, by heating tool to its four fillet positions Carry out being locally heated to preset temperature；

Step 2, the preforming rectangular tube that will warm up preset temperature carries out first final polishing pass roll bending operation It is rolled into the pre-finishing rectangular tube of small fillet radius；

Step 3, carries out pre-finishing rectangular tube second final polishing pass roll bending operation and is rolled into the essence of nearly wedge angle Close rectangular tube；

Wherein, in step one, described preset temperature is 600 DEG C-950 DEG C；

Wherein, the first roll bending machine is than the big 1-5mm in roller footpath of the second roll bending machine；

Wherein, in step one, described heating tool includes that an induction coil, described induction coil are round ring It is located at the outer border of rectangular tube, and is provided with to fillet position close at four fillet positions of corresponding rectangular tube Proximity structure；

The superhigh intensity precision rectangular tube molding used in described superhigh intensity precision rectangular tube forming method Device, described superhigh intensity precision rectangular pipe molding device of pipe, including spaced first roll bending machine and second Roll bending machine, described first roll bending machine is provided with temperature measurer and automatic feedback system, sets before described first roll bending machine Having induction coil, described induction coil connects sensing heating control cabinet and automatic feedback system respectively, described from Motional feedback system compares preset temperature and the temperature of temperature measurer and automatically controls sense by sensing heating control cabinet Answer coil that rectangular tube is heated；

Wherein, described induction coil is that round is located on the outer border of rectangular tube, and at four of corresponding rectangular tube Fillet position is provided with the proximity structure close to fillet position；

Wherein, also include multiple guide roller, in order to rectangular tube to be guided；

Wherein, also include a chiller, after being located at the second roll bending machine, in order to rectangular tube to be carried out cooling fall Temperature.