Patent Application
20240216975
The present invention relates to the field of plastic forming process of mechanical engineering, in particular to a current-assisted composite spinning forming device and method for deep cup-shaped thin-walled parts.
A deep cup-shaped thin-walled part is a thin-walled complex component with a bottom and a large length-diameter ratio. Due to its large length-diameter ratio, it can be formed by a spinning process. Generally, it is necessary to first obtain a shallow cup-shaped part through multi-pass deep drawing spinning, and then obtain a deep cup-shaped thin-walled part by reducing the wall thickness through multi-pass flow spinning.
The above processes mainly have the following problems:
1. The two spinning processes of deep drawing spinning and flow spinning are completely separated from each other, which makes the forming process and time of the workpiece too long; moreover, after the deep drawing spinning, it is necessary to replace and adjust the tooling before the flow spinning, which not only delays the forming but also affects the accuracy of parts.
2. In the process of deep drawing spinning, a single roller is used for multi-pass forming, or double (or more) rollers with the same geometric parameters are used for repeated multi-pass forming; because the geometric parameters of the rollers are the same, the pass reduction is limited, and the number of passes has to be increased at this time, which will also lead to extension of the forming time; more importantly, even due to the extension of the forming time of the workpiece and extension of the time for replacing and adjusting the tooling, the production process of the workpiece is discontinuous, resulting in hardening of the workpiece and thus fracture of the material.
3. In some cases, current-assisted spinning forming is used, but one of the electrodes is applied to the surface of the workpiece (i.e. the blank); due to the electric spark generated by the dynamic contact during spinning, the surface of the blank is ablated, resulting in serious damage to the surface of the formed part, which affects the product quality.
The present invention provides a current-assisted composite spinning forming device and method for deep cup-shaped thin-walled parts. Therefore, the present invention solves the problems in the prior art, such as the fracture of the material due to the hardening of the workpiece resulted from the discontinuous forming process of deep drawing spinning and flow spinning (or shaping spinning) in the production of the workpiece, the readjustment of tooling during the process replacement, and the long production cycle.
A current-assisted composite spinning forming device for deep cup-shaped thin-walled parts is provided, comprising a spinning mandrel 4, a tailstock 6, and a plurality of rollers 3 evenly distributed on the circumference of the spinning mandrel 4; the rollers 3 are arranged in a staggered manner in the axial and radial directions of the spinning mandrel 4, and the roller surface of each roller 3 comprises a deep drawing roller surface 1, a flow spinning section, and a shaping roller surface 2, wherein the staggered arrangement means that the deep drawing roller surfaces 1, the flow spinning sections and the shaping roller surfaces 2 of the rollers 3 are distributed in a staggered manner in the axial and radial directions of the spinning mandrel 4.
The number of the rollers 3 is at least three, with the staggered distribution specifically as follows:
The section line of the deep drawing roller surface 1 of each roller 3 is an arc line, with the arc radii of the deep drawing roller surfaces 1 gradually decreasing in turn;
The inclination angles of the first two adjacent rollers 3 are the same in the range of 2° to 3°, or decrease in turn in the range of 2° to 3°, while the inclination angle of the third roller 3 is in the range of 0.5° to 1°.
The device also includes a reverse thrust plate 5 against the edge of a blank 7; two electrodes are provided respectively at the reverse thrust plate 5 and the tailstock 6, the one on the reverse thrust plate 5 being the negative electrode and the other one on the tailstock 6 the positive electrode; and in the spinning process, a pulse current is applied to the tailstock 6 and the reverse thrust plate 5, and flows from the central area of the blank 7 to the edge to act as the current-assisted spinning.
When there are three rollers 3, they are evenly distributed on the circumference of the spinning mandrel 4 at an interval of 120°.
A current-assisted composite spinning forming method for deep cup-shaped thin-walled parts is provided, comprising the following steps:
The tailstock 6 is used to center the round plate-shaped blank 7 against the spinning mandrel 4;
The final wall thickness of the formed deep cup-shaped part is determined by the roller 3 with the smallest gap between the tip fillet of the flow spinning section and the axial surface of the spinning mandrel 4.
The current-assisted composite spinning forming method for deep cup-shaped thin-walled parts also includes a step for cutting off the excess edge of the mouth of the deep cup-shaped part.
(1) In the present invention, the functions of deep drawing spinning and flow spinning (or shaping spinning) are skillfully integrated into one roller in a staggered arrangement, thereby saving the time for tooling replacement, process switching and adjustment between multiple spinning processes such as deep drawing spinning and flow spinning (or shaping spinning), and effectively eliminating the tedious process of readjusting the tooling every time the tooling is replaced.
(2) In the process of deep drawing spinning in the prior art, a single roller is used for multi-pass forming, or double (or more) rollers with the same geometric parameters are used for repeated multi-pass forming; because the geometric parameters of the rollers are the same, the pass reduction is limited, and the number of passes has to be increased at this time, which will also lead to extension of the forming time; more importantly, even due to the extension of the forming time of the workpiece and extension of the time for replacing and adjusting the tooling, the production process of the workpiece is discontinuous, resulting in hardening of the workpiece and thus fracture of the material.
The present invention distributes the rollers in a staggered manner, that is, the radii of the arc surfaces of the deep drawing roller surfaces 1 of the rollers are different, the inclination angles of the shaping roller surfaces 2 are different, and the positions of the tip fillets of the conical structures of the flow spinning sections are different. Therefore, with different arc-shaped profile shapes and structures of the rollers for deep drawing spinning, the rollers focus on applying pressure to different portions of a blank in the period of each revolution of the spinning mandrel, which is beneficial to increase the pass reduction and reduce the spinning pass. This can not only improve the production efficiency, but also contribute to reducing defects such as material rupture and unusability due to hardening of the workpiece that is caused by the discontinuous material forming process.
(3) The present invention adopts staggered spinning, and enables each pass of spinning to complete part of the deep drawing spinning, flow spinning and shaping spinning processes, which not only makes the forming process continuous, thus effectively preventing material hardening, but also maximizes the production efficiency.
(4) By applying a pulsed current to the tailstock and the reverse thrust plate and making it flow to the central area and edge of the blank, the spark ablation due to the dynamic contact between the useful surface of the blank and the electrode can be avoided, so that the surface smoothness of the part can be ensured and the accuracy requirements can be met. Finally, the excess ablated edges can be removed through a trimming process to obtain the high-quality spun parts.
The plasticity of the material is further improved by current-assisted forming.
In addition to the above-mentioned functions, the reverse thrust plate can also be used to improve the stability of deep drawing spinning to avoid material instability and wrinkling.
The present invention will be further described in detail below with reference to specific examples.
As shown in
As shown in
The number of the rollers 3 is at least three, with the staggered distribution specifically as follows:
The section line of the deep drawing roller surface 1 of each roller 3 is an arc line, with the arc radii of the deep drawing roller surfaces 1 gradually decreasing in turn; and the section shape of the shaping roller surface 2 of each roller 3 is a straight line; according to the spinning sequence, the inclination angles of the shaping roller surfaces 2 of the first two adjacent rollers 3 relative to the axis of the spinning mandrel 4 are the same or decrease in turn, and the inclination angle of the shaping roller surface 2 of the third roller 3 relative to the axis of the spinning mandrel 4 is smaller than that of the first two rollers 3.
In
Each flow spinning section is of a conical structure, which refers to the tip fillet at the connection between the arc line of the deep drawing roller surface 1 and the straight line of the shaping roller surface 2, with the tip fillets of the flow spinning sections gradually staggered in turn.
As can be seen from the above technical features, the staggered distribution in the present invention means that the radii of the arc surfaces of the deep drawing roller surfaces 1 of the rollers are different, the inclination angles of the shaping roller surfaces 2 are different, and the positions of the tip fillets of the conical structures of the flow spinning sections are different. With these differences, the functions of deep drawing spinning and flow spinning (or shaping spinning) are skillfully integrated into one roller in a staggered arrangement, thereby saving the time for tooling replacement, process switching and adjustment between multiple spinning processes such as deep drawing spinning and flow spinning (or shaping spinning).
In the process of deep drawing spinning in the prior art, a single roller is used for multi-pass forming, or double (or more) rollers with the same geometric parameters are used for repeated multi-pass forming; because the geometric parameters of the rollers are the same, the pass reduction is limited, and the number of passes has to be increased at this time, which will also lead to extension of the forming time; more importantly, even due to the extension of the forming time of the workpiece and extension of the time for replacing and adjusting the tooling, the production process of the workpiece is discontinuous, resulting in hardening of the workpiece and thus fracture of the material.
As described above, in the present invention, with different arc-shaped profile shapes and structures of the rollers for deep drawing spinning, the rollers focus on applying pressure to different portions of a blank in the period of each revolution of the spinning mandrel, which is beneficial to increase the pass reduction and reduce the spinning pass. This can not only improve the production efficiency, but also contribute to reducing defects such as material rupture and unusability due to hardening of the workpiece that is caused by the discontinuous material forming process.
In the present invention, the inclination angles of the first two adjacent rollers 3 (wherein the roller with the largest arc radius of the deep drawing roller surface 1 is used as the first roller, i.e. the roller A) are the same in the range of 2° to 3°, or decrease in turn in the range of 2° to 3°, while the inclination angle of the third roller 3 (the roller with the smallest arc radius of the deep drawing roller surface 1, i.e. the roller C) is in the range of 0.5° to 1°. However, depending on the actual conditions of the workpiece, other angles may also be used.
As mentioned above, in order to increase the pass reduction in the process of each pass of deep drawing spinning, three rollers are used for deep drawing spinning at the same time, and the arc-shaped profiles of the three rollers are designed to have different arc radii R, as shown in
In
The current-assisted composite spinning forming device for deep cup-shaped thin-walled parts of the present invention also includes a reverse thrust plate 5 against the edge of a blank 7; two electrodes are provided respectively at the reverse thrust plate 5 and the tailstock 6, the one on the reverse thrust plate 5 being the negative electrode and the other one on the tailstock 6 the positive electrode; and in the spinning process, a pulse current is applied to the tailstock 6 and the reverse thrust plate 5, and flows from the central area of the blank 7 to the edge to act as the current-assisted spinning. The spark ablation due to the dynamic contact between the useful surface of the blank and the electrode can be avoided, so that the surface smoothness of the part can be ensured and the accuracy requirements can be met. Finally, the ablated edges can be removed through a trimming process to obtain the high-quality spun parts. When the blank 7 is made of alloy structural steel, the pulse current is 1100-1400 A during the current-assisted spinning. The current required for other materials depends on the actual application.
The use of current-assisted forming can also provide better material plasticity, which is required especially for the spinning forming of deep cup-shaped thin-walled parts. During the current-assisted spinning forming, the conventional electrode wiring method is to connect one of the two electrodes to the surface of the component; however, it is still difficult to solve the problem that the dynamic contact generates electric sparks to ablate the surface of the component. Therefore, the present invention proposes a current-assisted spinning method, by which a pulse current is applied to the tailstock 6 and the reverse thrust plate 5, and flows from the central area of the blank 7 to the edge.
To this end, the present invention proposes a method for applying a current to the reverse thrust plate 5 and the tailstock 6, with the principle structure shown in
In the example of the present invention, there are three rollers 3, which may be evenly distributed on the circumference of the spinning mandrel 4 at an interval of 120°. According to actual needs, there may be two or more rollers 3.
Step 1: The tailstock 6 is used to center the round plate-shaped blank 7 against the spinning mandrel 4.
Step 2: A thrust is applied to the reverse thrust plate 5 in the axial direction of the spinning mandrel 4, i.e., toward the blank 7, so as to press the reverse thrust plate 5 against the edge of the blank 7; and a pulse current is applied to the tailstock 6 and the reverse thrust plate 5, and flows from the central area of the blank 7 to the edge to act as the current-assisted spinning.
Step 3: The deep drawing roller surface 1 of the roller 3 is put in the working station; when there are three rollers 3, the arc radii of their deep drawing roller surfaces 1 and the inclination angles of their shaping roller surfaces 2 gradually decrease in turn; correspondingly, the gaps between the tip fillets of the conical structures of the flow spinning sections and the spinning mandrel 4 gradually decrease.
Step 4: The spinning mandrel 4 spins; according to the order in which the arc radii of the rollers are arranged from large to small, the deep drawing roller surfaces 1 gradually perform deep drawing spinning on the blank 7 in turn; the deep drawing spinning is carried out until the tip fillet of the flow spinning section is reached, and then the flow spinning is performed on the blank 7 to complete the deep drawing and thinning of the blank 7; then the shaping roller surface 2 is reached, and smoothing and shaping is gradually performed on the surface of the thinned blank 7; when the deep drawing spinning, flow spinning and shaping spinning processes on the blank 7 are completed, the three processes of deep drawing spinning, flow spinning and shaping spinning can then be completed through spinning of the spinning mandrel 4 and one axial feeding of the roller 3, until an entire deep cup-shaped part with a required wall thickness is obtained; and finally the excess edge of the mouth of the deep cup-shaped part is cut off.
The final wall thickness of the formed deep cup-shaped part is determined by the roller 3 with the smallest gap between the tip fillet of the flow spinning section and the axial surface of the spinning mandrel 4.
The present invention can be well implemented as described above. Three rollers are used in the above-mentioned process; in practical applications, according to specific conditions and application requirements, the structure and shape can be analogized in turn, and the number of the rollers can be one, two, three, four or more.
The embodiments of the present invention are not limited to the above-described examples, and any other alterations, modifications, substitutions, combinations and simplifications that are made without departing from the spirit and scope of the present invention shall be equivalent replacements and within the scope of protection of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010211625.8 | Mar 2020 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2020/121361 | 10/16/2020 | WO |
