CN107199443A - A kind of autoform combination technological method of non-hardened and tempered steel connecting rod blank - Google Patents

Abstract

The invention belongs to the field of engine connecting rods, and in particular relates to a casting and forging composite forming process suitable for forging blanks of non-quenched and tempered steel connecting rods of automobile engines; comprising the following steps: a) smelting non-quenched and tempered steel; b) casting and forming connecting rod castings Billet: pour the smelted non-quenched and tempered steel molten metal into the casting mold through the gating system, fill the mold and solidify, and cast the casting billet; c) Cool the casting billet and shake out: air cool to normal temperature and then shake out; d) Surface cleaning: Clean up the sand on the surface of the riser, burr and casting billet; e) heating the casting billet; f) die forging: put the heated casting billet into the forging mold for final forming; g) trim the forging billet; h) The forging billet is regulated and cooled; the casting and forging forming composite process adopted in the present invention can obtain the connecting rod of the near-end product at one time, which can effectively reduce energy consumption and improve production efficiency; the present invention uses non-quenched and tempered steel, eliminating the need for subsequent Quenching and tempering treatment, so it has the advantages of energy saving and environmental protection.

Description

A composite process method for casting and forging forming of non-quenched and tempered steel connecting rod blank

technical field

The invention belongs to the field of engine connecting rods, and in particular relates to a casting and forging composite forming process suitable for forging blanks of non-quenched and tempered steel connecting rods of automobile engines.

Background technique

The connecting rod is a key part of the engine, which works under high-frequency loads and has high requirements for strength. Its processing technology level directly affects the manufacturing level and product quality of the complete engine. The forming process of engine connecting rod mainly includes squeeze casting, cross wedge rolling, roll forging, die forging, powder metallurgy forging, etc. At present, the connecting rod forming mainly adopts the production process of cross wedge rolling or roll forging billet + die forging precision forming. Cross wedge rolling and roll forging have high requirements on the service life of the mold and the tonnage of the equipment, and the connecting rods produced by casting have casting defects such as shrinkage and shrinkage.

In recent years, non-quenched and tempered steel has been widely used in the production of connecting rods. This kind of steel is based on low alloy steel or medium carbon structural steel, adding trace elements such as vanadium, titanium, niobium, etc., by controlling the heating temperature and heating speed. , cooling speed, etc., so that the material can obtain better comprehensive mechanical properties and uniform microstructure after forging or rolling, without the need for quenching and tempering heat treatment.

Contents of the invention

The technical problem to be solved by the present invention is to propose a casting and forging composite process for forming the non-quenched and tempered steel connecting rod blank in view of some shortcomings of the above-mentioned prior art, that is, first casting the casting blank of the connecting rod, and then further It is forged and formed to eliminate defects such as casting looseness and pores and refine grains to obtain a connecting rod blank that meets the surface accuracy and size requirements and has good performance. The casting and forging compound forming of engine connecting rod forming is not just a superposition of the two in a simple sense, but complements each other's advantages and disadvantages, thereby improving product performance, increasing the service life of connecting rods, and reducing production costs. .

In order to solve the shortcoming of above-mentioned technical existence, the present invention adopts following specific scheme to realize, and in conjunction with accompanying drawing, description is as follows:

A composite process method for casting and forging forming of a non-quenched and tempered steel automobile connecting rod blank, comprising the following steps:

a) Smelting non-quenched and tempered steel;

b) Pouring forming connecting rod casting billet: inject the smelted non-quenched and tempered steel metal liquid into the casting mold through the pouring system, fill the mold and solidify, and cast the casting billet;

c) Cool the casting billet and shake out: air cool to normal temperature and then shake out;

d) Surface cleaning: clean up the sand on the surface of the riser, burr and casting blank;

e) heating the casting billet;

f) Die forging forming: put the heated casting billet into the forging mold for final forming;

g) Trimming the forging billet;

h) Regulating and cooling the forging billet.

The casting mold described in the step b) of the technical solution is composed of an upper mold, a lower mold, a gating system and a riser. There are four pieces in one mold. The liquid flows smoothly when filling the mold, the casting billet is placed horizontally, and the center top is used for casting. The casting billet cavity is evenly distributed around the gating system. The molten metal enters the sprue directly from the sprue cup, and a direct pouring The channel nest fully buffers the flow rate of the molten metal. The ingate cuts into the bulk of the casting billet horizontally, and the risers are distributed at the cut-in place of the ingate for feeding.

The size of the casting billet described in the step b) of the technical solution is based on the forging ratio of the non-quenched and tempered steel casting billet, the casting shrinkage rate of the material, the draft angle, the process correction amount and the subsequent forging process to obtain the casting billet The size; the forging ratio mainly refers to the minimum forging ratio that can effectively eliminate shrinkage porosity, shrinkage cavity and pore defects in the billet, refine the grain, and form a qualified connecting rod forging billet.

The casting blank described in step b) of the technical solution is cast by ordinary sand casting method, and multiple pieces are cast in one mold; during the casting blank casting process, the large and small end holes of the connecting rod are directly cast.

The heating mentioned in step e) of the technical solution refers to slowly heating the cast blank to 1150-1250° C. using an intermediate frequency furnace.

The forging mold described in the technical solution step f) adopts closed hot die forging, and is formed by the final forging die chamber at one time; Misshifting, the parting position is selected in the middle of the side of the forging billet; after the final forging, the continuous skin produced in the holes at both ends is removed by the punching and continuous skinning process.

The die forging is described in step f) of the technical solution, and the heating temperature of the die forging is controlled between 900-1100°C.

The casting blank described in step f) of the technical solution is put into a forging mold for forging, and the forging process adopts closed hot die forging, including two steps of final forging and punching and skinning;

The cooling mentioned in step h) of the technical solution means that the controlled cooling of the non-quenched and tempered steel connecting rod forging billet is carried out in a pass-through roller chain furnace, and the pass-through roller chain furnace is divided into three zones for temperature control. With heating and cooling functions, the three zones only have cooling, and the cooling speed can be controlled by controlling the temperature of each zone after the forging billet of the connecting rod passes through; The cooling process of high-quality steel materials is reasonably selected, and air-cooled after being released from the furnace.

The casting and forging composite process method of the non-quenched and tempered steel automobile connecting rod blank also includes the following steps:

1) Shot blasting;

2) Detection.

Compared with prior art, the beneficial effects of the present invention are:

1) The automobile engine connecting rod studied in the present invention is not only complex in geometry but also has strict requirements on performance. The casting-forging composite forming process combines the advantages of the casting process and the forging process, and is very suitable for processing parts with high performance and precision requirements and complex structures.

2) The composite casting and forging forming process adopted in the present invention can obtain a connecting rod near the final product at one time, effectively reduce energy consumption, and improve production efficiency.

3) In the present invention, the connecting rod part is obtained by casting first and then forging. Since it is formed by die forging, the metal flow line is more reasonable, and the service life of the parts is greatly improved.

4) The present invention uses a casting process instead of the pre-forging step to cast the blank of the connecting rod; and then realizes the transformation of the metal structure from the cast state to the forged state through closed hot die forging, refines the grains and improves the local casting defects of the connecting rod.

5) The present invention adopts non-quenched and tempered steel, which saves the subsequent quenched and tempered treatment, so it has the advantages of energy saving and environmental protection.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is the process flow diagram of the casting and forging composite process method of the non-quenched and tempered steel automobile connecting rod blank of the present invention;

Figure 2a is a sectional view of the engine connecting rod forging blank;

Figure 2b is a front view of the engine connecting rod forging blank;

Fig. 3 is a blank drawing of the engine connecting rod casting;

Fig. 4 is a schematic diagram of the pouring of the engine connecting rod casting billet;

Figure 5a is a hot forging die diagram of the engine connecting rod blank;

Figure 5b is a mold cavity diagram of the engine connecting rod blank.

In the figure: 1 indicates the parting surface; 2 indicates the parting surface.

detailed description

The present invention is described in detail below in conjunction with accompanying drawing:

A casting and forging composite process method for non-quenched and tempered steel connecting rod blanks, the composite process refers to casting the casting billet of the connecting rod first, and then eliminating defects such as casting looseness and pores through the forging process and refining the crystal grains, and To meet the surface accuracy and size requirements, so as to composite form the blank of the connecting rod, including the following steps:

1) Determine the casting billet size

According to the forging diagram of the connecting rod, combined with the characteristics of the casting process, the optimal forging ratio of the billet forging, and the requirements of the die forging forming process, determine the size of the casting billet, that is, the casting billet drawing.

2) Determine the casting process and design the casting mold

Determine the casting process and design the casting mold according to the determined blank drawing of the connecting rod casting.

3) Determine the forging process and design the forging die

According to the drawing of the connecting rod forging, combined with the size of the casting blank, determine the forging process of the connecting rod and design the forging die.

4) The composite process of casting and forging forming of non-quenched and tempered steel connecting rod is as follows:

a) Smelting: smelting non-quenched and tempered steel, increasing the nitrogen content, which is beneficial to the strength of the steel;

b) Pouring and forming the connecting rod casting billet: inject the smelted metal liquid into the casting mold through the pouring system, fill the mold and solidify, and cast the casting billet;

c) Cooling shakeout: air cooling to normal temperature and then shakeout;

d) Surface cleaning: cleaning the riser, burrs and sand on the surface of the casting blank;

e) Heating: Use an intermediate frequency furnace to slowly heat the billet to about 1150-1250 °C;

f) Die forging forming: put the heated casting billet into the forging mold for final forming, and the die forging temperature is controlled at 900-1100°C;

g) Trimming: cutting off excess flash;

h) Regulated cooling: Cooling after forging is carried out in a pass-through roller chain furnace, and the furnace temperature is not lower than 800°C.

Determine casting billet size:

First of all, the optimum forging ratio must be determined. The optimum forging ratio refers to the minimum forging required to effectively eliminate defects such as shrinkage porosity, shrinkage cavity and pores in the billet, refine the grains, and form a qualified connecting rod forging. The optimal forging ratio can be determined by experiments or finite element analysis; then according to the connecting rod forging diagram, that is, the cold forging diagram, the cold forging diagram should be thermally scaled, and the hot forging diagram is determined by the material shrinkage rate and dimensional tolerance; finally According to the external dimensions and large and small apertures at both ends of the connecting rod, the cross-sectional size and length of the rod, the casting shrinkage rate of the material, the draft angle, the process correction amount and other factors, the casting drawing is determined from the hot forging drawing.

Determine the casting process and design the casting mold:

The determination of the connecting rod casting process mainly includes: the casting billet adopts the ordinary sand casting method, subcontracted casting, and the casting billet can be formed into four pieces in one mold; the connecting rod casting billet is a symmetrical casting, and the parting surface is set at the level of the connecting rod casting billet Placed horizontally on half of the plane, the casting mold consists of an upper mold, a lower mold, a gating system and a riser. There are four pieces in one mold. In order to ensure the smooth flow of the molten metal when filling the mold, the casting billet is placed horizontally, and the center top is used for casting. The billet cavity is evenly distributed around the gating system. The molten metal enters the sprue directly from the sprue cup. A sprue nest is set at the end of the sprue to fully buffer the flow speed of the molten metal. The ingate cuts into the casting billet horizontally. For the bulk head, taking into account the feeding distance and the position of the hot spot, the risers are distributed at the cut-in of the inner runner for feeding.

Determine the forging process and design the forging die:

The determination of the forging process of the connecting rod casting blank includes: adopting closed hot die forging, forming once by the final forging die cavity; In the process of misalignment, the parting position is selected in the middle of the side of the forging; determine the shape complexity coefficient, material coefficient, forging shrinkage rate, initial forging temperature, and final forging temperature of the forging; after the final forging, the holes at both ends are removed by the punching and skinning process The skins produced in-house.

The controlled cooling of the non-quenched and tempered steel connecting rod forging billet is carried out in a pass-through roller chain furnace. The pass-through roller chain furnace is divided into three zones for temperature control. The first and second zones have heating and cooling functions, and the third zone only has cooling. After the rod forging billet passes through, the cooling rate can be controlled by controlling the temperature in each zone; the forging billet entry temperature, exit temperature and running time of the connecting rod in the furnace can be reasonably selected by the cooling process of the non-quenched and tempered steel material, and air-cooled after exiting the furnace .

The casting and forging composite process flow of the engine connecting rod blank also includes the following steps:

6) Shot peening treatment: Plastic deformation occurs on the surface of the connecting rod to form a strengthening layer to improve the fatigue strength;

7) Detection: Detect whether the size and internal structure of the connecting rod meet the requirements.

Accompanying drawing 2 is the engine connecting rod blank forging figure that certain automobile factory produces, and forging material is C70S6, and application forming process of the present invention is as follows:

1) Determine the size of the casting blank: According to the forging drawing of the connecting rod, combined with the characteristics of the casting process, the forging ratio and the requirements of the forging process, determine the size of the casting blank, that is, the casting blank drawing;

2) Determine the casting process and design the casting mold: determine the casting process and design the casting mold according to the determined drawing of the connecting rod casting;

3) According to the connecting rod forging drawing, combined with the casting blank drawing and connecting rod forging process requirements, design the forging die;

4) Smelting and pouring: sand casting process is adopted, the mass of each forging is about 0.8kg, the length of the forging is about 186.25mm, the width of the big head is 74.5mm, the diameter of the small head circle is 34.5mm, and the thickness is 24.6mm; the width of the stem is 23mm, the thickness is 14mm, Groove depth 5mm;

5) Cooling sand shakeout: Shake out sand after cooling to normal temperature in the air;

6) Surface cleaning: cleaning the riser, burrs and sand on the surface of the casting billet;

7) Heating: use medium frequency induction heating furnace to heat the casting billet to the temperature required by the forging process of 1150 ~ 1250 ℃;

8) Closed hot die forging: Put the heated blank at a specific temperature into a closed die forging die for die forging. The die forging temperature is controlled at 900-1100°C, and the final simulation analysis obtains the optimal flattening amount of 3mm ;

9) Trimming: cutting off excess flash;

10) Adjustment and cooling: It is carried out in a pass-through roller chain furnace, the temperature of the furnace is not lower than 800°C, and the temperature is controlled in three zones of the equipment. The first and second zones have heating and cooling functions, and the third zone only has cooling. Celsius, the running time of the connecting rod in the furnace is 12 to 15 minutes, and it is air-cooled after it comes out of the furnace;

11) Shot peening: Shot peening is used to remove the scale, so that the surface of the connecting rod is plastically deformed to form a strengthening layer to improve the fatigue strength;

12) Testing: Check whether the size and internal organizational structure of the connecting rod meet the requirements.

Claims (10)

1. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank, it is characterised in that comprise the following steps：

A) melting non-hardened and tempered steel；

B) castable connecting rod casting base：Melted non-hardened and tempered steel molten metal is injected in casting mould by running gate system, Mold filling and solidification, casts out casting base；

C) casting base is cooled down into knockout：It is air-cooled to knockout after normal temperature；

D) removing surface：Clear up dead head, burr and the sand on casting base surface；

E) casting base is heated；

F) die-forging forming：Casting base after heating is put into forging mold and finally shaped；

G) by forging bar trimming；

H) forging bar is regulated and controled to cool down.

2. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

Casting mould described in step b), is made up of upper die and lower die, running gate system and rising head, a mould four, and die joint is arranged on In the plane of the horizontal half of connecting rod casting base level, to ensure that molten metal flows steadily when filling type, casting base horizontal positioned is adopted Cast with central term, casting base die cavity is evenly distributed on the surrounding of running gate system, molten metal is directly entered sprue from sprue cup, Sprue base is set in sprue end, and the flowing velocity of abundant buffer metal liquid, ingate level cuts the major part of casting base, Rising head, which is distributed at ingate incision, is used for feeding.

3. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

The size of casting base described in step b), is forging ratio when being forged according to casting base, the shrinkage coefficient of material, molding Gradient, molding allowance and follow-up forging technology factor obtain the size of casting base；The forging ratio, being primarily referred to as can be effective Shrinkage porosite, shrinkage cavity and the gas hole defect in strand, crystal grain thinning are eliminated, and shapes the minimum forging needed for qualified connecting rod forging bar Make ratio.

4. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

Casting base described in step b) is, using the casting of ordinary sand casting method, one-mold multiple-member to be used during strand；Casting base is cast Direct cast form goes out connecting rod size stomidium during making.

5. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

Heating refers to described in step e)：Casting base is slowly heated to 1150~1250 DEG C using intermediate frequency furnace.

6. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

Forging mold described in step f) uses enclosed hot forging, once-forming by finish impression；Die joint is selected in maximum On the position of floor projection size, for the ease of finding offsetting of the upper and lower mould in die forging process, a point mould position is selected in forging bar The middle part of side；The gross weight produced in two stomidiums is removed by punching the wad process after finish-forging.

7. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank according to claim 1, it is special Levy and be：

Die-forging forming described in step f), the heating and temperature control of die forging is between 900~1100 DEG C.

8. a kind of autoform combination technological method of non-hardened and tempered steel automobile connecting bar blank, it is characterised in that：

Casting base described in step f), which is put into forging mold, to be forged, and forging technology uses enclosed hot forging, including end Forging and the step process of punching the wad two.

9. a kind of autoform combination technological method of non-hardened and tempered steel connecting rod blank according to claim 1, its feature exists In：

Cooling refers to described in step h)：The forging bar control, which is cooled in the roller endless grate by formula, to be carried out, and passes through the roller of formula Three area's temperature controls of endless grate point, one, two have heating and refrigerating function, and 3rd area only have cooling, and forging bar can be each by control after The temperature in area, realizes the control of cooling velocity；The run time of forging bar charging temperature, tapping temperature and connecting rod in stove is by non- The cooling technique reasonable selection of quenched Steel material, air cooling after coming out of the stove.

10. a kind of autoform combination technological method of non-hardened and tempered steel connecting rod blank according to claim 1, its feature exists In：

The autoform combination technological method of the non-hardened and tempered steel automobile connecting bar blank also comprises the following steps：

1) bead；

2) detect.