SU1754289A1 - Method to fabricate hollow articles from tubular workpieces - Google Patents

Abstract

The use of metal forming, for example, when hydrostatic distribution of tubular blanks The essence of the invention is to expand technological capabilities by ensuring the manufacture of products from low carbon low alloy steels with a ratio of length to diameter in the range 2.5-3.5 at ratios of wall thickness to diameter within 0.04-0.1 and diameters at the ends and in the middle within 1.5-2 and improving quality by eliminating corrugation. In the method for producing hollow articles from tubular blanks, including mechanical distribution with mandrels calibrating the mandrels of the end sections of tubular blanks With a degree of deformation t / K), 5-5% with sealing of the preform cavity, crimping the middle part of the workpiece is performed on the mandrel by pressurized liquid with the external part applied to the middle part of the blank. The radial overpressure, the distribution of the pipe is carried out by inputting a double taper guide with angles of 15-25 ° & and ar 2-3 & the degree of deformation at the ends of the lip is 15–20%. Then, the mandrels are removed and cylindrical mandrels with calibrating angles from –90 ° C are inserted into the cavity of the conical billet. after that, a high-pressure liquid is crimped with a degree of deformation of t / 15-20% 17 sludge (L C

Description

The invention relates to the processing of metals by pressure, in particular to methods for the hydrostatic pressing of hollow articles from tubular blanks, for example motorcycle steering columns.

In practice, motorcycle steering columns are made from welded blanks. In this case, steering column cups having a maximum diameter size are made by casting or stamping and the middle part of the part is made from a pipe. Then, two cups with a pipe are welded and the welded billet is machined.

This technology is characterized by high labor intensity, considerable metal consumption and the presence of casting (stamping) operations, welding and several machining transitions. To reduce the complexity of manufacturing parts of this type, it is advisable to use deformation processes using a hydrostatic compressed medium.

The closest in technical essence to the present invention is a method for producing hollow articles from tubular blanks, according to which after installing the tubular billet in the container, the end sections of the pipe are distributed and then

Xi

ate

4 S 00 S

crimping the middle part on the mandrels with high-pressure liquid, while the product is performed with the perimeter of the inner longitudinal part 0.5-2% less than the perimeter of the inner surface of the workpiece with the ratio of wall thickness to the diameter of the workpiece, 035-0.044, At the initial moment of crimping to the middle part the workpiece is applied external radial mechanical support. Crushing the cut in processing with this method favorably affects the uniformity of filling of all the cavities of the profile and the decrease in the required pressure of the liquid. This method makes it possible to manufacture products of a complex profile (slotted and hexagonal, etc.).

However, in a known manner, it is possible to make products from pipes with only a small difference in cross-sectional area, since the process of good filling of the profile or a predetermined shape of the mandrel is ensured only if the perimeters of the inner surface of the product and the inner surface are equal or insignificant (0.5-2%). billets, so products with a large difference in the perimeters of the type of motorcycle steering columns, which are characterized by significant differences in diameter in length, and the ratio of the length of the middle part of the part and to its diameter, 5-3,5 not receive the desired shape after processing in this way.

The application at the initial moment of crimping to the middle part of the workpiece of an external radial mechanical support influences the crushing of the faceting during deformation and allows controlling the process of lateral stability within certain limits, but does not prevent the formation of longitudinal waves, due to which the product with an I / D0 ratio within 2.5-3.5 bend and their shape does not meet the geometrical requirements.

The purpose of the invention is the expansion of technological capabilities by ensuring the manufacture of products from low-carbon low alloy steels with a ratio of length to diameter in the range 2.5-3.5 with ratios of wall thickness to diameter in the range 0.04-0.1, and diameters at the ends and in the middle, within 1.5-2 and quality improvement by eliminating corrugation.

The goal is achieved by the fact that according to the method of obtaining hollow articles from tubular blanks, including mechanical distribution by calibrating the mandrels of the end sections of tubular blanks with a degree of radial deformation of 0.5-5% and subsequent crimping

with high pressure liquid on cylindrical mandrels with mechanical radial support of the middle part of the workpiece at the initial moment, the distribution of the pipe is carried out in two stages with double taper mandrels with angles of 2-3 ° in the lead-in area and angles of 15-20 ° in the section following it, the degree of radial deformation at the ends of the pipe is 15–20% at the first stage and cylindrical mandrels with calibrating pieces perpendicular to the axes of the mandrels at the second stage, and crimping is carried out with a degree of radial deformation of 15–20%.

Figures 1-3 show pipe billet, a process for dispensing a pipe with double taper mandrels and the shape of the workpiece after dispensing; in fig. 4 shows the installation of a split sleeve on a tapered billet; in fig. 5-7 - scheme

the process of hydrostatic crimping and the finished product; in fig. 8-12 - diagram of the process of hydrostatic crimping of products with a relative length of the section subjected to compression in the range of 1.5-2.0,

I / D4 with a range of radial deformations of crimp within 10-12%, and the sequence of shaping the finished product (these operations are characteristic of a known method); in fig. 13-17 - the same, but

for products with a relative length of area subjected to compression in the range of 2.5-3.5 with a range of radial deformations of 15-20%, with a sequence of operations characteristic of the known method.

The device for carrying out the method (FIGS. 1-7) consists of a blank 1, conical mandrels 2 and 3, having portions with different taper 1 1 and а a, conical billet 4 with regions of different taper and with

linear dimensions hi and h2, plug bushing 5, cylindrical mandrels 6 and 7, finished product 8, container 9, connecting pin 10. The plug bushing 5 is provided with radial holes 11 and

pins 12

According to this method, dispensing mandrels 2 and 3 with taper angles art and O2 for a given length And and 12 are inserted into the cavity of a pipe billet with a diameter of D0 and a length of 0. After distribution, the billet of the mandrel is removed and a conical billet 4 with a length of Li U is obtained, the shape and size of which is shown Fig 3 Conical billet 4

at the ends has an outer diameter DI. and in the middle - the diameter D0, equal to the diameter of the workpiece 1. The degree of distribution

y,: Dl-Do100%

Do

for billets of low carbon steels is 15-20%. The corners of the mandrels are equal respectively: "1 15-20 °," 2 2-3 °. At angles "1-15-20 °, the distribution of the pipe is carried out without disturbing its shape in the middle part (bending, draft) in the range of degrees of radial deformation t / 15-20%. Then, a plug sleeve 5 is fitted on the tapered billet 4, equipped with pins 12 and radial holes 11 (Figs. 4 and 7). After that, mandrels b and 7c angles az 90 ° were inserted into the cavity of the conical billet 4 before contact with the ends, the outer diameters of the conical billet 4 were increased to Oz. The degree of distribution is insignificant, and a pin 10 is used to center the mandrels b and 7 The mandrels 6 and 7 have rods with a diameter d4 and calibrating with a diameter of da, the corners of the mandrels are straight and rounded with a radius g. The diameter of the rod d4 is less than 10-15% of the inner diameter of tubular billet 1 after the withdrawal of the mandrels 6 and 7 with connector This sleeve 5 is installed in container 9 (Fig. 5)

The sleeve 5 is installed along the channel of the container with a small clearance (0.2-0.3 mm). There is a variable gap (3, which is smaller in the middle and increases closer to the ends of the product) (Fig. 5). The pressure of the liquid begins to compress the middle part of the conical blank 4 and fit the contour material of the contour of the closed mandrels 6 and 7 with the formation of the finished product 8 of length LI. Since the reduction rate of the middle part of the workpiece is 10-15%, the process of shaping follows the scheme shown in Fig. 11 (section A-A in Fig. 10) and the floor is reached teaching of the circular section of the finished product. The formation of longitudinal waves 14 (Fig. 15) is prevented by the fact that the length of the middle line O O of the product 8 is longer than the length of the middle line 00 of the workpiece 4, the corrugations are flattened (Fig. 6). at the ends of the workpiece 4, the gap is significant, the transverse corrugation (pos. 16 in Fig. 17) is suppressed because of the proximity of the mandrels calibrating the rims and the longitudinal

the waves (pos. 14 in Fig. 15) completely disappear when the material of the workpiece mandrel b and 7 is fitted. The difference in the lengths of the average lines of the workpiece 4 (00) and product 8 (O O) is equal to 2h, can be estimated by the formula

2n

2 d3 d4 (cos it + sinai -1).

sin "1

ABOUT)

where da is the internal diameter of the end of the conical billet after entering the cylindrical mandrels (Fig. 4);

d4 - inner diameter of the middle part of the finished product;

“1 is the angle of taper of the distribution mandrels.

Under the action of the pressure of the fluid in the material, during compression, tensile stresses arise, causing the correction of longitudinal waves, which appear at the stages of small deformation.

Thus, when the pressure of the fluid P2, the value of which is during the crimping of billets from low-carbon steels of 400-500 MPa, the manufacture of finished products 8 of a given shape is ensured. Then the pressure is discharged, the product 8 with the mandrels and the sleeve 5 is removed from the container 9 and the mandrels 6 and 7 are removed from the cavity of the part.

As a result of the described operations, the finished product has cups with a diameter Oz in the ends, diameter 04 in the middle, although a reduction rate of 15-20 °, with no folds and waves in the middle part of the product (Fig. 6). The ratio of the diameters Oz / O4 is provided in the range of 1.5-2. and the ratio of the length of the middle part of the product to the diameter, 5-3.5 with a relative wall thickness S / D0 in the range of 0.04-0.1 Experiments performed in obtaining high-quality hollow products using the method described showed that it is necessary to provide a gap of 5 variables over length Achieving a variable gap b over the length is achieved by using mandrels with an angle a, r (the smaller the ar, the smoother the change is τ To p M & KnN I and the right angles on the transitions from diameters da to d4 are better ( Fig. 6). The best results in the experiments were obtained at angles a.2 2-3 °. At O2 3 °, right angles are not obtained at the transitions from diameters da to d4, and when “2 2 °, difficulties arise in removing mandrels from the finished product.

An angle of 15-20 ° is selected from several mutually complementary conditions:

From the condition of dispensing the ends of a billet of low carbon steel to a diameter bz (Fig. 6) with a degree of radial deformation of M5-20% without cracking and disrupting the shape of the billet in the middle part (bending, draft);

from the condition of creating tensile stresses when the material of the workpiece mandrels 6 and 7 (Fig. 5) are fitted with during deformation; in this case, the longitudinal waves are eliminated; the angle a - for a given difference in the diameters d3 and d4 depends on the value of 2h (cm, formula 1), which determines the difference in the lengths of the middle line 00 of the workpiece 4 (Fig. 3) and the center line of the product 8 O (fig. b); Since the length OO is longer than 00 by 2h, this value determines the values of tensile deformations and the quality of the product;

angles "1 15-20 ° and CKi 2-3 ° together determine the amount of material elongation when the mandrel contour is attached to it, and consequently, the final shape of the finished product; Since it is theoretically very difficult to describe shaping upon the onset of loss of stability at the initial moment of hydro-pressing and in the process of its development, the combination of the values of the angles cn and CC2, together with the above factors, is optimized experimentally.

Experimentally, the best results were obtained at a 15-20 ° and 2 2-3 °. Therefore, performing distribution operations with double taper mandrels and subsequent distribution on cylindrical mandrels in combination with crimping on these mandrels with Oz 90 ° provides products with, 5-3.5, 04-0.1 and Oz / 04 1.5 -2 specified quality.

If one makes parts such as a steering column using the modes used in the prototype, it is impossible to obtain products of a given quality.

The following describes the features of deforming parts with different relative heights of the middle section and ranges of reductions.

FIG. 8-12 shows the deformation scheme of the billet with a diameter of 00 and a length of LO on mandrels 2 and 3 with a reduction range of 10-12%. In this case, the gap is small (2-3 mm), and the products have a slight relative height of the middle section (, 5-2.0). The plug sleeve 5 is installed in the channel of the container 9 with a small gap (0.2-0.3 mm), and its inner surface fits snugly to the workpiece after the ends are distributed. In the experiments used tubular blanks with chikos tennbste, 04-0.1, Distribution

pipe ends is 0.5-5%. mandrels 2 and 3 have angles close to straight. After installing the workpiece with the mandrels and sleeve 5 in the container 9 and the pressure rise process

deformations are carried out according to the following scheme:

in small deformation stages, a rhombus 13 is formed with rounded corners and a maximum size H, which is determined by the internal diameter of sleeve 5 (position 13 in Fig. 11), up to the value of fluid pressure PI;

as the strain develops, the size H decreases, the rhombus changes its shape,

its inner surface touches the surface of the mandrel;

with a further increase in pressure to P2, the material slides along the surface of the mandrel, and the product

8 acquires a round shape, therefore, obtaining a part of a given contour is achieved.

FIG. 13-17 shows the scheme of shaping the tubular billet 1 with a relative length of the deformable section, 5-3.5 for pipes with, 04-0.1 in the range of compression of 15-20%, a gap of 5 5-7 mm. Hydrostatic crimping of such products, which are close in size to motorcycle steering columns, along with lateral buckling, leads to the formation of longitudinal waves 14. In this case, in the early stages of deformation with fluid pressure PI, the circular section of the workpiece 1

transformed into a triangular section 15 with a maximum size of N. Then, with increasing pressure, the material of the workpiece touches the surface of the mandrels, but does not become round even with

MPa. In the cross section, a rounded triangle with a size Hi and rigid corrugations 16 is obtained, and the section shape along the length I of the middle section of the product is different (at the ends it is cylindrical, and in the middle it is the most distorted). This kind of defects is shown in FIG. 15-17.

Consequently, in the manufacture of elongated products with a difference in cross sections in diameter within 1.5-2 at the ends of Oz and

In the middle of the part - 04, the implementation of the known methods of carrying out the process does not ensure the achievement of a given shape.

PRI me R. As blanks used cold-drawn pipes of steel 20

mm length with an outer diameter of 00 45 mm and an inner diameter of mm. In the cavity of the pipe billet was introduced on a hydraulic press of the mandrel with angles of taper а 2 ° and transition angles to cylindrical on a bench and 20 °. The mandrels had a rod diameter in the smallest section of mm and a diameter of cylindrical according to mm. The mandrel was introduced to a depth of mm and mm. Then the mandrel was removed from the cavity of the pipe and received a conical billet with dimensions: 1 l 175 mm; 01 53mm; mm The degree of distribution of the end sections of the pipe zagrtovki 1P 14%.

Subsequently, a detachable sleeve was installed on the overhead of the conical billet and the forming mandrels were inserted before they were touched by the ends, and the outer diameters of the ends of the conical billet were increased. The degree of distribution is 2.5%, but sealing of the cavity of the conical billet is achieved. Forming mandrels had a bar diameter of mm and diameters of mm calibrating against the bar. The corners of the mandrels are straight and rounded with a radius of mm. Then, the workpiece with forming mandrels and detachable sleeve was installed in a container with a mm channel diameter, which is mounted on a press with a force of 10,000 kN. The container was pressurized with a pressure of up to R2 of 400-500 MPa and crimped the conical billet on the mandrels. After this operation, a product with dimensions was obtained. mm; mm; mm; mm, mm Product shape and size designations are shown in FIG. 6. After relieving the pressure, the product with the detachable sleeve was removed from the container channel, the mandrels were removed from the product cavity, and the detachable sleeve was removed. The finished product had a cylindrical shape and from it in one machining operation, associated with the bore of the inner surface of the cups under the bearings, a finished part was obtained - the steering column of the IL-Planeta motorcycle41.

Thus, the use of the proposed method makes it possible to produce an exact workpiece with a large cross sectional area over the length of the tube stock in two deformation operations.

Compared with the known, the proposed method reduces the labor intensity by a factor of 3-5; reduction of metal consumption by 25-30%; improving the appearance of products by eliminating the operation of welding cups.

Claims (1)

The expected economic effect due to the use of the annual program of 400000 pcs. according to preliminary estimates will amount to 250 thousand rubles. in year. Invention Formula The method of obtaining hollow articles from tubular blanks, including mechanical dispensing by calibrating the mandrels of the end sections of tubular blanks with the degree of radial deformation 0.5-5% and subsequent crimping with high-pressure liquid on cylindrical mandrels with mechanical radial support of the middle part of the workpiece at the initial moment, characterized in that the purpose of expanding technological capabilities by ensuring the manufacture of products from low carbon low alloy steels with a ratio of length to diameter in the range of 2.5-3.5 at ratios of wall thickness to diameter in the range of 0.04–0.1, and dimeters at the ends and about the middle are within the range of 1.5–2 and improving the quality by eliminating the corrugation, the distribution of the pipe is carried out in two stage mandrels of double taper with angles of 2-3 ° in the lead-in area and angles of 15-25 ° - in the area following him, the degree of radial deformation at the ends of the pipe 15-20% at the first stage and cylindrical mandrels with calibrating edges, perpendicular pins of the mandrels, in the second stage, and crimping is carried out with a degree of radial deformation of 15-20%. Fig i five A figs N1 J ± e5 -j SP -fc. u s WITH ABOUT) with CN in g- "about Aa four( h 1 N, X UH 1 Gu & HA -Ј 1 | 1 / X Y X / D Aa B 8 FIG {2 Hhhh Х77Х71 -Ј 0/4 5 (rig f6 P2 FIG. i7