CN112549846B

CN112549846B - Spoke performance improving method applied to liquid die forging hub product

Info

Publication number: CN112549846B
Application number: CN202011516844.3A
Authority: CN
Inventors: 刘忠锁
Original assignee: Liaoning Zhongxiang Aluminum Co ltd
Current assignee: Liaoning Zhongxiang Aluminum Co ltd
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2022-06-03
Anticipated expiration: 2040-12-21
Also published as: CN112549846A

Abstract

The invention belongs to the technical field of vehicle hubs, and relates to a spoke performance improving method applied to a liquid die forging hub product. The invention solves the problem that the mechanical property of the spoke part of the existing liquid die forging hub product is lower than that of the wheel rim and the wheel rim part, and improves the overall performance of the hub.

Description

Spoke performance improving method applied to liquid die forging hub product

Technical Field

The invention belongs to the technical field of vehicle hubs, and relates to a spoke performance improving method applied to a liquid die forging hub product.

Background

The hub is one of the most important safety parts on the automobile, bears the pressure of the action of the mass of the automobile and the loaded objects, is acted by the dynamic torque of the automobile during starting and braking, and also bears the irregular alternating stress generated by dynamic loads from different directions, such as turning, uneven road surface, road surface obstacle impact and the like during the running process of the automobile. The quality and reliability of the wheel hub are not only related to the safety of vehicles and personnel materials on the vehicles, but also affect the performances of the stability, maneuverability, comfort and the like of the vehicles in the running process, so that the wheel hub is required to have good dynamic balance, high fatigue strength, good rigidity and elasticity, high size and shape precision, light weight and the like, the aluminum wheel hub meets the requirements with good comprehensive performance, and the wheel hub is prominent in the aspects of safety, comfort, light weight and the like, thereby being popular in the market.

The existing molding process of the automobile aluminum hub gradually adopts liquid die forging, which is a new metal molding process which not only has the casting characteristic, but also is similar to solid die forging. A certain amount of metal liquid to be cast is directly poured into a cavity coated with a lubricant, mechanical static pressure is continuously applied, and a solidified hard shell is plastically deformed by utilizing the technology of easy flowing and forging during metal casting, solidification and forming, so that metal is crystallized and solidified under the pressure, and shrinkage cavities and shrinkage porosity formed by solidification and shrinkage are forcibly eliminated, and a liquid die forging workpiece without casting defects is obtained.

In the prior art, as disclosed in chinese patent No. CN106345984B, a liquid die forging process for a357 aluminum alloy applied to a commercial vehicle hub is disclosed, which mainly includes the following steps: optimizing alloy components, smelting, purifying melt, performing liquid die forging forming, demolding, trimming, tapping, performing heat treatment strengthening, machining, performing surface treatment, optimizing chemical components by rare earth elements, optimizing a melt purification technology, and improving the metallographic structure of the alloy; the method changes the temperature field and the flow field of forging and pressing and heat treatment strengthening, comprehensively analyzes and regulates the deformation temperature, the deformation speed and the deformation degree of the aluminum alloy, establishes a mathematical model of a short-flow and casting-forging integrated continuous liquid die forging process, and develops a new technology of the aluminum alloy wheel hub with large size and relatively complex structure, so that the mechanical property of the wheel hub is obviously improved, the tensile strength is increased by more than 42.5%, the yield strength is increased by more than 116.7%, the elongation after fracture is increased by more than 75%, and the Brinell hardness is increased by more than 61.7%. However, the method has the problem that the mechanical performance of the spoke part of the hub prepared by the method is lower than that of the wheel flange and the wheel rim part, so that the overall mechanical performance of the hub is reduced.

Disclosure of Invention

In view of the above, the present invention provides a method for improving spoke performance of a liquid die forging hub product, which is used to solve the problem that the mechanical performance of a spoke part is lower than that of a rim and a rim part.

In order to achieve the above object, the present invention provides the following method:

a spoke performance improving method applied to a liquid die forging hub product is characterized in that a hub is formed by integrating a rim and a spoke, and the spoke is extruded after liquid die forging and before heat treatment.

The principle of the basic scheme is as follows: after liquid die forging and before heat treatment, the spoke is extruded, so that the material in the spoke part is denser, and grain boundaries are microscopically reduced.

The beneficial effect of this basic scheme lies in: after liquid die forging and before heat treatment, the spoke is extruded, so that the material in the spoke part is denser, and grain boundaries are microscopically reduced, thereby improving the strength and the elongation.

Further, adopt the press of 5000 tons or more to punch to the spoke through the mould, blank temperature control is at 380 ± 10 ℃, beneficial effect: the large-tonnage press machine is adopted to lead the tissue of the spoke part to be more compact, and the hot pressing is beneficial to releasing the stress.

Further, treat the blank cooling back, extrude the spoke once more, beneficial effect: and extruding after cooling to make the spoke generate cold deformation and further improve the strength.

Furthermore, a female die and a lower die for supporting the wheel hub are arranged in the die and are used for extruding a molding pressure plate of the spoke; will the surface that shaping pressure flitch, die, lower mould and spoke contact all sets up to unsmooth form, beneficial effect: the concave-convex surface enables redundant materials to flow into the groove during extrusion, so that the deformation of the hub caused by extrusion is reduced, and the spoke structure can be extruded more tightly.

Further, will set up a drift in the middle of the shaping swage plate, the drift end face is higher than the shaping swage plate terminal surface, and the difference in height is greater than spoke thickness, beneficial effect: realize punching a hole earlier, extrude the spoke again, promote production efficiency, avoid punching a hole simultaneously and make the spoke warp.

Further, adopt the press more than 5000 tons to extrude the spoke, beneficial effect: the large-tonnage press machine provides larger pressure, so that the spoke extrusion is more sufficient, and the mechanical performance improving effect is better.

Further, the wheel hub is made of aluminum alloy or magnesium alloy, and has the advantages that: the hub is lighter in weight while achieving high mechanical properties.

The invention has the beneficial effects that: hot pressing the spoke by using a large-tonnage press machine with the weight of more than 5000 tons so that the material in the spoke is more compact, the grain boundary of crystal grains is microscopically reduced, and cold pressing is carried out after the blank is cooled so that the spoke is subjected to cold deformation, thereby improving the strength and the elongation; set up in the mould concave convex surface can make during the extrusion unnecessary material flow direction recess, reduce the wheel hub deflection that the extrusion caused, add the drift in the mould, punch a hole and extrude the spoke and go on in step, improved production efficiency.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic structural diagram of a mold according to an embodiment of the present invention;

FIG. 2 is an enlarged view of a portion A of FIG. 1;

reference numerals: 1. mounting a template; 2. a lower template; 3. an upper die pressing plate; 4. an upper die base plate; 5. a support block; 6. a female die; 7. a punch; 8. forming a material pressing plate; 9. a lower die; 10. a lower die connecting plate; 11. and (4) a hub blank.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

Examples

This embodiment is based on the liquid die forging process method disclosed in publication No. CN106345984B, and is different in that the step E of adding extrusion to the spoke includes the following steps:

A. optimizing alloy components;

B. smelting: melting an A357 aluminum ingot in a rapid melting furnace, and preserving heat;

C. deslagging and degassing: b, degassing and deslagging the melt obtained in the step A in a furnace by using an efficient refining agent to ensure that the melt is clean and free of impurities; impurities and gas in the aluminum alloy melt are removed, so that the alloy purity can be further improved, the metallographic structure of the alloy is improved, the internal defects of shrinkage cavities, looseness, air holes, cracks and the like in the product are eliminated, and the surface quality of the workpiece is improved;

D. liquid die forging: preparing a hub blank 11, wherein the hub blank 11 comprises a rim and a spoke, and the thickness of the spoke is 26 mm;

E. trimming and tapping: punching a hub blank 11 and hot-pressing the wheel spoke by a die arranged on the press by adopting a 6000-ton press, wherein the temperature of the hub blank 11 is controlled at 380 ℃; after the hub blank 11 is cooled, the spoke is cold pressed again by using the die.

F. Heat treatment strengthening: carrying out solution quenching treatment on the workpiece, and artificially aging;

G. and (4) detecting mechanical properties and processing a dimension surface.

Referring to fig. 1-2, the die used in step E includes an upper die plate 1, a lower die plate 2, a female die 6, a punch 7, a forming material pressing plate 8, and a lower die 9; an upper die base plate 4 is arranged below the upper die plate 1 through bolts, an upper die pressing plate 3 is arranged below the upper die base plate 4, and a forming material pressing plate 8 is arranged below the upper die pressing plate 3; a punch 7 is arranged in the middle of the forming material pressing plate 8, the end face of the punch 7 is 36mm higher than the end face of the forming material pressing plate 8, a support block 5 is arranged on the lower die plate 2, a lower die connecting plate 10 is arranged above the support block 5, a lower die 9 is arranged on the lower die connecting plate 10, and a female die 6 is arranged in the middle of the lower die 9; the surface shapes of the female die 6, the molding pressure plate 8 and the lower die 9 which are contacted with the spoke are all sawtooth-shaped.

The mechanical property detection results in step G are shown in table 1:

TABLE 1

Location of a body part	Tensile strength	Yield strength	Elongation percentage	Surface hardness
					Spoke for wheel	305MPa	238MPa		6％	95HB
Inner rim of wheel rim	314MPa	242MPa	7.0％	92HB
					Outer wheel rim of wheel rim	325MPa	245MPa	8.5％	92HB

Comparative examples

This comparative example completely adopts the liquid die forging process method disclosed in publication No. CN106345984B, and the difference from the examples is that: in the step D of the comparative example, the prior art means is adopted, and only trimming and punching are carried out; the rest steps are the same as the embodiment.

The results of the mechanical property measurements in step G are shown in table 2:

TABLE 2

Location of a body part	Tensile strength	Yield strength	Elongation percentage	Surface hardness
					Spoke for wheel	292MPa	238MPa		4％	92HB
Inner rim of wheel rim	316MPa	244MPa	6.5％	92HB
					Outer wheel rim of wheel rim	325MPa	241MPa	8.0％	90HB

As can be seen by comparing the table 1 with the table 2, the tensile strength, the elongation percentage and the surface hardness of the wheel spoke of the wheel hub prepared by the method are all improved, and the overall performance of the wheel hub is improved.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims

1. A spoke performance improving method applied to a liquid die forging hub product is characterized by comprising the following steps of:

A. optimizing alloy components: optimizing the Mg/Si ratio and the proportion of other alloy elements in the A357 aluminum alloy, and controlling the mass content of impurity elements, wherein the weight proportion of Si is 6.5-7.5 parts; fe is less than 0.2 part; cu is less than 0.2 part; 0.5-0.7 part of Mg0.5; 0.01 to 0.02 portion of Sr; 0.1-0.2 parts of Ti; controlling the content of Al 90-95 parts and the content of other single impurities in the A357 aluminum alloy to be less than or equal to 0.05 part, and adding 0.1-0.8 part of element Gd0.1; sm0.1-1 parts; 0.1-2.5 parts of Hf, and Sr and Ti are used for modification and refinement;

B. smelting;

C. deslagging and degassing: b, performing in-furnace degassing and deslagging on the melt obtained in the step B by using an efficient refining agent to ensure that the melt is clean and free of impurities;

D. liquid die forging: preparing a hub blank, wherein the hub blank comprises a rim and a spoke; the liquid forging molding is divided into 5 stages: the first stage is as follows: pouring the melt into a hub die: the pouring temperature is 670-680 ℃, the preheating temperature of the die is 280-320 ℃, and the single blank is precisely and quantitatively poured;

and a second stage: and (3) quick mold filling: the time for mold closing and filling pressurization is 20-30 seconds, the pressure begins to change from the moment that an upper mold punch just contacts the melt surface in a lower mold until 160-180 bar, and the speed is 1-2 mm/s;

and a third stage: and (3) pressure maintaining process: gradually reducing the pressure to 0 at a pressurizing speed of 0.1-0.3 mm/s, keeping the pressure at 200-210 bar to reach the pressure maintaining pressure, delaying for 10-20 seconds, and cooling for 120-140 seconds; the pressure remains unchanged during cooling;

a fourth stage: opening the mold: the lower die ejector rod of the die pushes a workpiece upwards, and the upper die moves upwards along with the press slide block at the same speed as the lower die ejector rod, so that the tearing force of the upper die and the lower die on the product is eliminated;

the fifth stage: taking materials: taking materials by using a mechanism clamp, putting the materials on a roller way, and turning to a next sequence;

E. trimming and tapping: punching a hub blank and hot-pressing a spoke by using a press machine with the weight of more than 5000 tons through a die arranged on the press machine, wherein the temperature of the hub blank is controlled to be 380 +/-10 ℃; after the wheel hub blank is cooled, cold pressing the wheel spoke again by using the die;

F. heat treatment strengthening: and carrying out solution quenching treatment on the workpiece, and artificially aging.

2. The method for improving the spoke performance of the liquid die forging hub product according to the claim 1, wherein the method comprises the following steps: in the step E, a female die and a lower die for supporting the wheel hub are arranged in the die and are used for extruding a molding pressure plate of the spoke; and arranging the surfaces of the molding material pressing plate, the female die, the lower die and the spoke in a concave-convex shape.

3. The method for improving the spoke performance of the liquid die forging hub product according to the claim 2, wherein the method comprises the following steps: and a punch is arranged in the middle of the forming and material-pressing plate, the end face of the punch is higher than the end face of the forming and material-pressing plate, and the height difference of the punch is greater than the thickness of the spoke.