JP4611625B2 - Forging method - Google Patents

Description

  The present invention relates to a method of forming a cup-shaped or shaft-shaped component such as a constant velocity joint outer ring by cold forging.

  As a method for forging and forming parts such as cups and shafts, a method of cold forging a material at a temperature below the transformation point between a die (die) and a punch is widely used (for example, patents). Reference 1). In this method, if the material is forged, the seizure occurs unless the lubricating film is formed. Forging in the fourth step, a cylindrical workpiece having a forged surface with a Rockwell hardness B scale of around 75 is subjected to the first step, the second step, the second step, the third step, and the third step. Immediately before the cup forming process, the Rockwell hardness B scale of the forged surface of the workpiece becomes 100 or more.

  With this hardness, normal forging is impossible. Between the third and fourth steps, a process called an intermediate process, that is, a low-temperature annealing process to lower the hardness, an oxide film on the surface, that is, an oxide scale, is applied. A shot blast process for removing and a bond film forming process for forming a chemical conversion film on the work surface are performed. In some cases, a lubricating effect may be obtained by spraying lubricating oil instead of the bond film forming process.

  Among the above-mentioned lubrication means, in the case of the bonding process, the film thickness is drastically reduced by one molding, and when the molding is continuously performed and the molding ratio is large, a sufficient lubricating effect may not be obtained. Also, the means for spraying the lubricant is difficult to spray evenly on the material or mold, and if the oil film breakage occurs due to the increased molding rate, the molded product may be defective, and the working environment hygiene The above is also not preferable.

  In order to solve this problem, an oil bath molding method has been proposed in which lubricating oil is filled in a cavity in advance and a material is put into the cavity for forging molding (see, for example, Patent Document 2). However, when forging by the oil bath method, there is a case where the lubricating oil is contained between the material and the bottom surface of the cavity during the molding depending on the shape of the material. In such a case, it is necessary to open a lubricating oil discharge path at the bottom of the mold cavity and smoothly discharge the contained lubricating oil to the tank outside the mold. In this case, when the punch is raised after molding, the molded part W is hung on the punch and rises together with the punch, which causes problems such as double strikes.

  In order to solve this problem, a lubricating oil discharge path connected to the tank outside the mold is opened at the bottom of the mold cavity, and the lubricating oil sealed between the bottom of the cavity and the material is placed in the middle of the discharge path. A check valve is provided that opens the discharge passage when the pressure reaches a predetermined value and closes the discharge passage when the pressure is lower than the predetermined value (see, for example, Patent Document 3).

  In this apparatus, the lubricating oil interposed between the cavity bottom surface and the material during molding is returned to the tank through the discharge path because the check valve is opened, and after molding, the discharge path is closed and after molding. Since these parts are in close contact with the bottom surface of the cavity, they remain in the cavity without adhering to the punch side when the punch is raised.

JP 59-220243 Japanese Patent Application No. 62-324515 Japanese Patent Laid-Open No. 2-187228

In the forging method disclosed in Patent Document 2 described above, intermediate processing takes time, and the lubricating effect of the bond film is lost by the final forging, and the bond film process is performed once before the ioning and coining process of the fifth process. It is necessary to apply.
In the forging method disclosed in Patent Document 3, the adhesive force of the lubricant, which is a liquid, is weak, and it is necessary to perform the bond film treatment again before the ioning / coining step of the fifth step.
Furthermore, when performing the fourth forging by the oil bath molding method in which the raw material is put into the cavity and forging, the lubricant is ignited by the heat generated by pressurizing the workpiece. There are problems that must be overcome.

  It was made in view of the problem of lubricant deterioration and ignition in the conventional forging method described above, and a sufficient lubricating effect for forging can be obtained without making the forging time longer than before. An object of the present invention is to provide a forging method capable of performing safe forging without causing the lubricant used for forging to ignite due to heat generated by forging pressurization.

The present invention
It is a forging method of a molded product having a plurality of press steps for cold forging without heating,
A plurality of times of lubricant spraying is performed on the workpiece that has generated heat in the press process prior to the molding press process, and the plurality of lubricant sprays are performed after the previous lubricant spray is dried and after the final lubricant spray is dried. It is a forging method of a molded product characterized by performing the molding press step.

Embodiments of the present invention are as follows.
The workpiece is a constant velocity joint outer ring.
The temperature at which the workpiece is sprayed with the lubricant is 150 ° C. or more and 250 ° C. or less.
The lubricant is a water-dispersed lubricant containing a lubricant-dispersing adhesive and a wetting-water evaporation accelerator before forging, and is a solid lubricant during forging. .
The molded product is cup-shaped.
The molded product is a shaft.

  According to the present invention, the lubrication effect sufficient for forging can be obtained without making the forging processing time longer than before, and the lubricant used for forging can be ignited by heat generated by forging pressurization. There is an effect that safe forging can be performed.

  Hereinafter, a forging apparatus that performs a forging method according to an embodiment of the present invention will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, the forging apparatus 10 includes a workpiece supply unit 12, a press device 14, and an ioning / coining unit 15.
The workpiece supply unit 12 holds billets that are continuously supplied, that is, workpieces W, aligned at predetermined positions so that they can be sequentially taken out.
As shown in FIG. 1, the press device 14 includes a first press 20 that performs an axising process that is forward forging, a second press 22 that performs preliminary upsetting, a third press 24 that performs upsetting, and a cup that is backward forging. The fourth presses 26 for forming are arranged in a line at equal intervals.

  As shown in FIGS. 1 and 2, a pair of first feed bar 30 and second feed bar 32 extending in the length direction are arranged on both sides of the first press 20 to the fourth press 26. Eight grip control units 36 having grip claws 38 are attached to the first feed bar 30 and the second feed bar 32. The eight gripping claws 32 and the grip control unit 30 are disposed to face each other so as to grip the workpiece W disposed on the first press 20 to the fourth press 26.

  The first feed bar 30 and the second feed bar 32 are moved up and down to a height at which they can move horizontally without being interfered by the presses 20 to 26 by lifting the workpiece W by a feed bar control system (not shown). The reciprocating motion and the longitudinal reciprocating motion of two adjacent intervals of the first press 20 to the fourth press 26 are driven.

  The first nozzle holding frame 42 and the second nozzle holding frame 43 are attached to the outside of the grip control unit 36 corresponding to the third press 24 of the first feed bar 30 and the second feed bar 32 via the nozzle control unit 40. The first lubricant nozzle N1 and the second lubricant nozzle N2 are attached to the front end of the nozzle holding frame 42 obliquely downward on the inside. The first lubricant nozzle N1 and the second lubricant nozzle N2 are two-fluid nozzles that atomize the lubricant with high-pressure air. In order to avoid interference between the first lubricant nozzle N1 and the second lubricant nozzle N2, and the first feed bar 30 and the second feed bar 32, the nozzle control unit 40 includes the first feed bar 30 and the second feed bar 32. The first lubricant nozzle N1 and the second lubricant nozzle N2 are moved to the spray position at the top dead center only when there is a top dead center.

(Control system)
As shown in FIG. 4, the control system 100 of the nozzle control unit 40 has a line L1 from the compressed air source 102 through the first air pressure reducing valve 104 and further through the first 5 port pilot switching valve 106. It is connected to the air cylinder 108 of one feed bar 30, and is connected to the pilot air port 111 of the first lubricant nozzle N1 via a second fifth port pilot switching valve 110.

The line L2 from the compressed air source 102 is connected to the air cylinder 116 of the second feed bar 32 via the first air pressure reducing valve 104 and further via the third fifth port pilot switching valve 114, while the second fifth The port pilot switching valve 120 is connected to the pilot air port 121 of the second lubricant nozzle N2.
A line L3 from the compressed air source 102 is connected to the spray air inlets 130 and 132 of the first lubricant nozzle N1 and the second lubricant nozzle N2 via the second air pressure reducing valve 122.

  The lubricant vessel 140 that hermetically contains the lubricant LU is provided with a stirrer 142 that is driven by compressed air supplied from the compressed air source 102 via the first air pressure reducing valve 104. The lubricant LU is, for example, a water-dispersed lubricant in which a solid lubricant is blended with an adhesive having lubrication and dispersibility and a wetting and water evaporation accelerator. The lubricant vessel 140 is also supplied with compressed air via a third air pressure reducing valve 144. The lubricant LU accommodated in the lubricant vessel 140 is supplied to the lubricant port 145 of the first lubricant nozzle N1 and the lubricant port 146 of the second lubricant nozzle N2 via a line L5 connected to the bottom thereof. The Each solenoid valve 148 of the first 5 port pilot switching valve 110 to the fourth 5 port pilot switching valve 120 is connected to the control panel 150.

(Operation)
For example, the gripping control unit 36 and the gripping claws 38 placed on the first feed bar 30 and the second feed bar 32 sequentially take out the workpiece W in a cycle of 20 spm from the workpiece supply unit 12 and perform the first press 20 to the fourth press. Advance to the press 26. The first press 20 performs an axising process that is forward forging. The second press 22 performs preliminary upsetting by forward forging. The third press 24 performs an upsetting process that is forward forging.

  When the upsetting process by the third press 24 is completed, the compressed air is supplied to the air cylinder 108 of the first nozzle holding frame 42 and the air cylinder 116 of the second nozzle holding frame 43. As a result, the air cylinder 108 and the air cylinder 116 raise the first nozzle holding frame 42 and the second nozzle holding frame 43, and the first lubricant nozzle N 1 and the second lubricant nozzle N 2 are moved to the workpiece W as shown in FIG. Move to the lubricant spray position. The spraying of the lubricant LU is performed on the single work W from the two first lubricant nozzles N1 and the second lubricant nozzle N2 alternately four times for a total of eight times, and each spraying time is 0.14 seconds. In addition, a pause of 0.01 seconds is provided between these sprays.

  These sprays are performed during conveyance of the workpiece W to the fourth press, and the gripped workpiece W and the first and second lubricant nozzles N1 are placed on the first feed bar 30 and the second feed bar 32. Therefore, the relative positional relationship between the gripped workpiece W and the first and second lubricant nozzles N1 and N2 is constant, and the same coating as that in which the lubricant is sprayed on the stationary object to be coated. This is extremely advantageous for specifying the spray area.

  The workpiece W at the time when the spraying of the lubricant starts is heated to around 200 ° C. by the forming heat of the workpiece W in the shafting process, the preliminary upsetting process, and the upsetting process. Therefore, the lubricant LU that has reached the workpiece W by each of the lubricant sprays on the workpiece W evaporates instantaneously and is completely dried before the next lubricant spray. As a result, eight strong lubricant layers are formed on the processed surface of the workpiece W, and a cup forming press that is backward forging is performed well by the fourth press 26.

  The adhesion of the water-based plastic working lubricant is affected by the lubricant temperature, spraying time, and lubricant dilution ratio. Air pressure of 0.15 MPa, lubricant from a pair of nozzles (Ikeuchi: BIMV4515) placed on a horizontal surface of carbon steel with a diameter of 80 mm, at a position 333 mm above the 45 ° direction and symmetrically on the diagonal line The results of spraying alternately at a pressure of 0.10 MPa are as shown in Table 1.

In Table 1, regarding adhesion, ◯ indicates that a uniform lubricant film was formed on the entire surface, Δ indicates that the film was formed on less than 100% of the surface over 50%, and x represents It shows that the film was deposited less than 50% of the surface. Regarding dryness, ◯ indicates that the sprayed lubricant was instantaneously dried, Δ indicates that the sprayed lubricant was dried after 1 to 2 seconds, and X indicates that the sprayed lubricant was 2 seconds. It shows that it dried after progressing above.

Table 1

  From these experimental results, it is judged that the temperature of the workpiece when spraying the lubricant is desirably 150 ° C. to 250 ° C.

  INDUSTRIAL APPLICABILITY The present invention can be used for forming a press-worked product that requires high rigidity in addition to forging a cup-shaped part such as a constant velocity joint outer ring at a temperature below the transformation point.

It is a top view of the press apparatus for enforcing the forge forming method of the embodiment of the present invention. It is sectional drawing along line II-II of FIG. It is explanatory drawing which shows the change of the workpiece | work by several press processes. It is a circuit diagram of the control system of a nozzle control part.

Explanation of symbols

W Work LU Lubricant N1 First lubricant nozzle N2 Second lubricant nozzle 10 Forging device 12 Work supply unit 14 Press device 20 First press 22 Second press 24 Third press 26 Fourth press 30 First feed bar 32 Second feed bar 36 Control unit 38 Grip claw 40 Nozzle control unit 42 First nozzle holding frame 43 Second nozzle holding frame 100 Control system 102 Compressed air source 140 Lubricant vessel

Claims (6)

A forging method for forming a molded article having a plurality of press steps for cold forging without heating ,
A plurality of lubricant sprays are performed on a workpiece that has generated heat in the press process prior to the molding press process, and the plurality of lubricant sprays are performed after the previous lubricant spray is dried, after the final lubricant spray is dried. A forging method of a molded product, wherein the molding press step is performed.   The method for forging a molded product according to claim 1, wherein the workpiece is a constant velocity joint outer ring.   2. The method for forging a molded product according to claim 1, wherein the temperature of the workpiece when the lubricant is sprayed is 150 ° C. or more and 250 ° C. or less.   Before forging, the lubricant is a water-dispersed lubricant blended with a solid lubricant, a lubricant-dispersing adhesive and a wetting-water evaporation accelerator, and is a solid lubricant during forging. The method for forging a molded product according to claim 1.   The method for forging a molded product according to claim 1, wherein the molded product is cup-shaped.   The method for forging a molded product according to claim 1, wherein the molded product is a shaft.

Images