CN111014531A

CN111014531A - Cold forging lubricating method based on net-shaped storage structure

Info

Publication number: CN111014531A
Application number: CN201911227296.XA
Authority: CN
Inventors: 李子博; 胡成亮; 赵震
Original assignee: Shanghai Jiao Tong University
Current assignee: Shanghai Jiao Tong University
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2020-04-17
Anticipated expiration: 2039-12-04
Also published as: CN111014531B

Abstract

A lubricating method in the field of cold forging of metal materials is a cold forging lubricating method based on a net-shaped storage structure, and the surface lubricating treatment is realized by preparing a multi-layer net-shaped storage structure, fully soaking the multi-layer net-shaped storage structure by a thermosetting lubricating medium, adhering the net-shaped storage structure soaked with the lubricating medium to a cold forging blank subjected to surface treatment, heating and curing the cold forging blank to form a composite lubricating layer. The invention can quickly realize the lubrication treatment of the blank, is used for the subsequent cold forging processing, greatly reduces the harm to the environment, and does not need to continuously add the lubricant in the subsequent use process.

Description

Cold forging lubricating method based on net-shaped storage structure

Technical Field

The invention relates to a technology in the field of cold forging processing, in particular to a cold forging lubricating method based on a net-shaped storage structure.

Background

In the cold forging process, the friction is generated between the die and the blank on a contact interface, the surface of the die is easily damaged under the condition of no lubrication, and the batch production cannot be realized. Therefore, the cold forging process must be well lubricated to improve the surface quality of the forging and the service life of the die. The phosphorization and saponification treatment is a classic lubrication treatment mode in cold forging processing, and a porous phosphate coating is formed on the surface of the treated metal and is used for storing saponified fat to play a role in lubrication. However, the process has many steps and long flow, and is accompanied with the problem of environmental pollution such as heavy metal ions, acid mist, wastewater and the like, and the application of the process is restricted by strict laws at present. Meanwhile, many products after cold forging processing need to be continuously added with lubricant to ensure normal use, and the subsequent operation is relatively complex. Therefore, it is urgently required to develop a new cold forging lubrication method which can solve the above-mentioned problems.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the cold forging lubricating method based on the net-shaped storage structure, which can quickly realize the lubricating treatment of the blank, and does not need to supplement additional lubricant during the subsequent cold forging and use, thereby greatly reducing the harm to the environment and simplifying the lubricating treatment process.

The invention is realized by the following technical scheme:

the invention realizes the surface lubrication treatment by preparing a multi-layer reticular storage structure, fully impregnating the reticular storage structure with the thermosetting lubricating medium, adhering the reticular storage structure impregnated with the lubricating medium on the cold forging blank subjected to the surface treatment, heating and curing the reticular storage structure to form a composite lubricating layer.

The multilayer mesh storage structure is formed by stacking a plurality of single-layer mesh storage structures, warp-wise fiber bundles and weft-wise fiber bundles are staggered between adjacent single layers and are stacked, and the multiple layers are connected by using an orthogonal interlocking structure.

The multilayer mesh memory structure is preferably three layers.

The multilayer reticular storage structure is made of fiber materials, and the material parameters preferably meet the following requirements: elongation at break delta_g>18% initial modulus E_g>20cN/dtex, fiber diameter

And surface expansion ratio η when the blank is cold forged_s>Time 2 (η)_s＝S_{After forging}/S_{Before forging}) Elongation at break delta_g>41 percent; further preferred is polytetrafluoroethylene or polyacrylonitrile in a cylindrical shape.

Each layer of the multi-layer mesh storage structure is woven by warp-wise and weft-wise fiber bundles to obtain weaving units, and the weaving units repeatedly extend in the warp direction and the weft direction to form the multi-layer mesh storage structure, wherein the warp-wise and weft-wise fiber bundles are respectively formed by n_gAnd n_wRoot cylindrical fibers and satisfies n_g＝n_wThe cross section of the weaving unit is in a fan blade shape, and the weaving unit is 80-120.

The weaving unit obtained by the weaving satisfies

Wherein:

every n warp yarns for a weft yarn are interwoven,

for one warp yarn to interlace every n weft yarns α_gTo weave corners, 0<α_g≤90°。

The material parameters of the thermosetting lubricating medium preferably satisfy the following conditions: curing temperature T_s80-130 ℃ and average particle diameter

The solution viscosity η is 0.015 to 0.020Pa · s, and the pH is 9 to 10, and further preferably a PTFE concentrated solution or a nylon 6 fiber concentrated solution.

The impregnation is as follows: putting the multi-layer net-shaped storage structure into a thermosetting lubricating medium for soaking for a time t_s≥0.5h。

Preferably, the surface treatment is performed to satisfy Ra 5 to 7.5 μm, that is, the roughness Ra of the contact surface between the blank and the mesh-like storage structure is increased, and the surface treatment is performed by, but not limited to, sandblasting or the like.

The composite lubricating layer arranged on the surface of the blank is as follows: according to the surface area S of the composite lubricating layer contacted with the blank_nCutting the mesh storage structure into areas S using laser cutting_c＝1.1～1.15S_nAfter cutting is finished, the cutting toolAnd (4) removing burrs of the composite lubricating layer and flatly paving the composite lubricating layer on the surface of the blank.

The heating temperature T in the heating and curing_hThe corresponding relation is satisfied: when the solidification temperature of the lubricating medium meets T_sWhen the temperature is 80-10 ℃, T_h130-160 ℃; when T is_sT at 100-130 ℃_h160-190 ℃. Holding time t for solidifying lubricant_h＝1.5～2.5h。

The heating solidification is preferably carried out by clamping the net-shaped storage structure and the metal blank by using a clamping tool, and the clamping force F is further preferably selected_N＝200～400N。

The invention relates to a lubricated surface prepared by the method, wherein the shear friction factor m of the lubricated surface is 0.10-0.17, and when the fiber is polyacrylonitrile, α_g90 degrees, using PTFE concentrated solution as lubricating medium, surface treating, Ra 7 μm, F_N＝400N，T_h＝190℃，t_hWhen m is 2.5h, m is 0.10-0.13, and η follows the blank_sIncreasing the friction factor and floating the friction factor, when the fiber is polytetrafluoroethylene, α_g60 degrees, the concentrated solution of nylon 6 fiber is used as lubricating medium, Ra is 5 μm after surface treatment, F_N＝300N，T_h＝150℃，t_hWhen 2h, m is 0.17 and remains stable.

Technical effects

Compared with the prior art, the invention integrally solves the technical problems that: the traditional phosphorization saponification lubricating method which has multiple working procedures and great harm to the environment in the field of cold forging processing is replaced, and a treatment mode of continuously lubricating cold forging blanks without adding a lubricating agent is provided. The unexpected technical effects that result from this include:

the invention adopts a mode of heating and solidifying a lubricating medium to finish the lubricating treatment of the blank. The net-shaped storage structure is formed by weaving single-layer or multi-layer fiber bundles, and is fully soaked in a lubricating medium and then is adhered to the blank subjected to surface treatment. And then the cold forging blank is lubricated by the net-shaped storage structure after being heated and solidified by the lubricating medium.

Drawings

FIG. 1 is a schematic view of a multi-layered web storage structure adhered to a surface of a blank;

in the figure: a is a three-layer mesh memory structure, b is a partial enlarged schematic diagram of a, and c is an enlarged schematic diagram of part I;

FIG. 2 is a flow chart of the construction of the composite lubricating layer;

in the figure: a is surface treatment, b is clamping and adding a composite lubricating layer, and c is heating and curing treatment.

Detailed Description

Example 1

The embodiment relates to a cold forging lubricating method based on a net-shaped storage structure, wherein a PTFE concentrated solution is used for soaking a three-layer net-shaped storage structure, sand blasting is carried out on a metal blank, a clamping tool is used for clamping the net-shaped storage structure on the surface of the blank, and then the blank is placed into a high-temperature box for heating and curing, so that the lubricating treatment is completed.

This example uses a martensitic precipitation hardening stainless steel 05Cr17Ni4Cu4Nb to produce a metal blank in the form of a flanged ring having an outer diameter

Flange thickness h_b2mm, the outer diameter of the metal ring is

An inner diameter of

First step, a three-layer mesh memory structure is prepared due to target η_s>2, so delta is selected_g＝46％，E_g＝30.8cN/dtex，

The acrylic fiber (polyacrylonitrile) is formed by respectively combining a warp-wise fiber bundle and a weft-wise fiber bundle_g＝n_w100 cylindrical acrylic fibers are polymerized, and the section of the acrylic fiber is in a fan blade shape.

The single-layer storage structure is woven in a mode of three-layer, one-layer, two-layer, twill and four-layer satin, and the warp parameters and the weft parameters of each layer are respectively

α_g90 degrees, and the fiber parameters meet the following conditions:

the warp and weft fiber bundles are staggered and stacked between two single layers, and the multiple layers are connected by an orthogonal interlocking structure.

Step two, lubricating treatment: and selecting a PTFE concentrated solution as a thermosetting lubricating medium for impregnating the three-layer mesh storage structure. Curing temperature T of PTFE concentrate_s130 ℃ C, average particle diameter of

The viscosity of the colloidal solution η is 0.019 Pa.s, the pH value is 9.8, and when the three-layer net-shaped storage structure is impregnated with the PTFE concentrated solution, the impregnation time t is_s＝1h。

Step three, blank surface treatment: as shown in fig. 1, the blank is surface-treated by sandblasting, and then a mesh-like storage structure is attached, specifically: setting the target surface as the upper and lower end surfaces of a circular ring and the diameter of sand grains

Water content less than 2%, hard particles with edges and corners, and air pressure P of air machine_a＝6.0～6.5X10⁵Pa, air pressure amplitude Delta P is 0.5-1.0X 10⁵Pa, the distance L between the nozzle and the metal surface is 100-300 mm, and the included angle between the sand blasting direction and the surface normal line is α_s15 ~ 30 degrees, the cyclic annular removes the shower nozzle and slowly sandblasts 3 ~ 7 circles, shields the protection to the non-sandblast position before the sandblast. In this embodiment, the values of the parameters are

P_a＝6.5X10⁵Pa，L＝200mm，α_s22.5. The surface roughness Ra of the sand blasted was 7 μm.

The reticular storage structure adhered to the blank surface is obtained by laser cutting, and the surface area S is obtained after cutting_c＝1.15S_n，S_nIs the surface area of the web-like storage structure in contact with the web. After cutting, the burrs are removed and laid flat on the target surface of the blank.

Step four, heating and curing: as shown in FIG. 2, a clamping tool is used, as F_NA clamping force of 400N clamps the web storage structure to the blank and the whole is placed in a high temperature oven for heat curing. Heating temperature T_h190 deg.C, holding time t_h＝2.5h。

After all the lubrication treatment steps are finished, the lubrication method is evaluated by using a ring upsetting method to evaluate the lubrication conditions, wherein the deformation speed is 20mm/s, and the result shows that the shear friction factor m is 0.10-0.13 in the embodiment and is η along with the blank_sIncreasing the friction factor, and floating the friction factor until the height variation of the ring reaches 54.5 percent and the surface expansion ratio of the blank reaches η_sWhen 2.26, the net-like storage structure may not completely cover the blank.

Example 2

The cold-forged blank of this example was the same as example 1.

First step, preparation of a three-layer mesh memory Structure, unlike example 1, due to object η_s<1.5, therefore, delta is selected_g＝19％，E_g＝106.3cN/dtex，

The warp and weft fiber bundles are respectively composed of n_g＝n_w116 cylindrical teflon fibers are polymerized, and the section of the fiber is in a fan blade shape.

α_g60 degrees, and the fiber parameters meet the following conditions:

staggered warp and weft fiber bundle stacking between two monolayersThe layers are joined using an orthogonal interlocking structure.

Step two, lubricating treatment: unlike example 1, a nylon 6 fiber concentrate was chosen as the thermosetting lubricating medium for impregnating the three-layer reticulated storage structure. Curing temperature T of nylon 6 fiber concentrated solution_s90 ℃ and an average particle diameter of

The viscosity of the colloidal solution η is 0.015 Pa.s, the pH value is 9.2, and when the three-layer net-shaped storage structure is soaked by using nylon 6 fiber concentrated solution, the soaking time t is_s＝0.5h。

Step three, blank surface treatment: the method comprises the following steps of carrying out surface treatment on a blank by using a sand blasting method, and then pasting a net-shaped storage structure, wherein the method specifically comprises the following steps: setting the target surface as the upper and lower end surfaces of a circular ring and the diameter of sand grains

Water content less than 2%, hard particles with edges and corners, and air pressure P of air machine_a＝6.0～6.5×10⁵Pa, air pressure amplitude Delta P is 0.5-1.0 x10⁵Pa, the distance L between the nozzle and the metal surface is 100-300 mm, and the included angle between the sand blasting direction and the surface normal line is α_s15 ~ 30 degrees, the cyclic annular removes the shower nozzle and slowly sandblasts 3 ~ 7 circles, shields the protection to the non-sandblast position before the sandblast. Different from the embodiment 1, the values of the parameters are

P_a＝6.0×10⁵Pa，L＝200mm，α_s27.5 °; the surface roughness Ra of the sand blasted was 5 μm.

Step four, heating and curing: using a clamping tool with F_N300N clamping force clamps the web storage structure to the blankAnd tightly tightening, and putting the whole into a high-temperature box for heating and curing. Heating temperature T_hKeeping the temperature at 150 ℃ for t_h＝2h。

The lubrication process was evaluated after completion of all steps of lubrication treatment by using ring upsetting method to evaluate the lubrication conditions and the deformation speed v was 20mm/s, and the results showed that the shear friction factor in this example was stably maintained at m 0.17 until the amount of change in the height of the ring reached 28.5% and the surface expansion ratio of the billet reached η_sWhen the thickness is 1.441, the net-shaped storage structure cannot completely cover the blank.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A lubricating method in the field of cold forging of metal materials, characterized in that, by preparing a multi-layer mesh storage structure and fully impregnating it with a thermosetting lubricating medium, the mesh storage structure impregnated with the lubricating medium is then pasted on the surface-treated The composite lubricating layer is formed on the cold forging billet and heated and solidified to realize the surface lubricating treatment;

The multi-layer mesh storage structure is formed by stacking a plurality of single-layer mesh storage structures, adjacent single layers are stacked with staggered warp and weft fiber bundles, and the multiple layers are connected by an orthogonal interlocking structure.

2. The method according to claim 1, wherein the multi-layer network storage structure is made of fiber material, and its material parameters satisfy: elongation at break δ _g >18%, initial modulus E _g >20cN/dtex, fiber diameter

And when the billet is cold forged, when the surface expansion ratio η _s >2 (η _s = _after S forging/ _{before S forging} ), the elongation at break δ _g >41%.

3. The method according to claim 1 or 2, wherein the multi-layer mesh storage structure is made of cylindrical polytetrafluoroethylene or polyacrylonitrile.

4. The method according to claim 1 or 2, wherein each layer of the mesh storage structure in the multi-layer mesh storage structure is woven by warp and weft fiber bundles to obtain a weaving unit, and then weaving The unit is repeatedly extended in the warp and weft directions, wherein the warp and weft fiber bundles are polymerized by n _g and n _w cylindrical fibers respectively and satisfy n _g =n _w =80～120, and the cross section of the weaving unit Fan-shaped.

5. method according to claim 4 is characterized in that, described weaving obtains weaving unit and satisfies

in:

Interlace every n warp yarns for a weft yarn,

is a warp yarn interlaced every n weft yarns, α _g is the weaving angle, 0<α _g ≤90°.

6 . The method according to claim 1 , wherein the material parameters of the thermosetting lubricating medium satisfy: curing temperature T _s =80-130° C., average particle size

Solution viscosity η=0.015～0.020Pa·s, pH=9～10.

7. The method according to claim 1 or 6, wherein the thermosetting lubricating medium is a PTFE concentrate or a nylon 6 fiber concentrate.

8 . The method according to claim 1 , wherein the dipping refers to: putting all the multi-layer mesh storage structures into a thermosetting lubricating medium for an dipping time t _s ≥ 0.5 h. 9 .

9 . The method according to claim 1 , wherein the arrangement of the composite lubricating layer on the surface of the blank means: according to the surface area _Sn of the composite lubricating layer in contact with the blank, using laser cutting to cut the mesh storage structure into The area S _c =1.1～1.15S _n , after the cutting is completed, the burrs of the composite lubricating layer are removed and laid flat on the surface of the blank.

10 . The method according to claim 1 , wherein the heating temperature _Th in the heating and curing satisfies a corresponding relationship: when the curing temperature of the lubricating medium satisfies T _s =80～10℃, _Th =130～10 . 160°C; when T _s =100-130°C, _Th =160-190°C, and the holding time for lubricant curing _th =1.5-2.5h.

11. A lubricated surface prepared according to the above method, characterized in that the shear friction factor m=0.10-0.17. When the fiber is polyacrylonitrile, α _g = 90°, PTFE concentrate is the lubricating medium, Ra = 7μm after surface treatment, F _N = 400N, _Th = 190°C, _th = 2.5h, m = 0.10 ~ 0.13 , and as the η _s of the blank increases, the friction factor fluctuates; when the fiber is PTFE, α _g = 60°, nylon 6 fiber concentrate is the lubricating medium, Ra = 5μm after surface treatment, F _N = 300N, _Th =150°C, m=0.17 and stable at _th =2h.