KR20110064791A - A production equipment of titanium alloy bolt - Google Patents

Abstract

PURPOSE: A facility for manufacturing a titanium alloy bolt is provided to enhance mechanical strength by manufacturing of the titanium alloy bolt using warm forging and to prevent failure including cracks. CONSTITUTION: A facility for manufacturing a titanium alloy bolt comprises a material feeder(100), a loader(200), a heater(300), a forging unit(400), a material inserting unit, a heat treatment device, an oxide film remover, a processing unit, a rolling unit and a washing unit. The material feeder feeds raw materials, which are cut rods formed from titanium alloy. The loader transfers the raw material. The heater heats the raw material transferring along the loader. The forging unit comprises a forging mold to mold the heated raw material to a forged product. The material inserting unit guides the heated raw-material to the forging mold. The heat treatment device heat-treats the forged product.

Description

Titanium Alloy Bolts {A production equipment of titanium alloy bolt}

1 is a schematic view showing the external configuration of a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 2 is a perspective view showing the external configuration of a material input device and a heating device which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 3 is a perspective view showing a schematic configuration of a forging die which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 4a is a perspective view showing a state in which the raw material is supplied to the forging die which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 4b is a perspective view showing a state in which the raw material is seated in the forging die which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 4c is a perspective view showing a state in which the raw material is inserted into the forging die which is one component of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 5 is an enlarged view showing a part of the material supply apparatus which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 6a is a process flow chart showing a titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 6b is a flow chart showing in detail the surface treatment step as a step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 6c is a flow chart showing in detail the material heating step of one step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 7 is a photograph of the specimen forging the forging formability according to the temperature conditions of the surface treatment step, which is one step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

8 is experimental data for selecting a temperature condition of the material heating step, which is one step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

9 is a sample photograph of the embodiment of FIG. 8;

10 is a real picture showing the change in shape of the raw material in the preferred embodiment of the forging step is a one step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

11 is a real picture showing the shape change of the forging when the heating temperature or the holding time of the raw material for the forging step is a step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 12a is a table showing the mechanical strength change according to the heat treatment conditions of the forging product heat treatment step is a step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 12b is an enlarged photograph comparing the structure before and after the forging heat treatment step of the first step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 13 is a real picture showing the appearance of the forging appearance before / after the oxide film removal step is a step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 14 is a sample photograph after the implementation of the first step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

Figure 15 is a sample photograph showing a change in the outer diameter according to the change in the time of the surface washing step, which is one step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention.

Figure 16 is an ASTM picture showing the microstructure of the titanium alloy bolt prepared according to a preferred embodiment of the present invention.

Figure 17 is a photograph measuring the thickness of the α-case of the titanium alloy bolt surface prepared according to a preferred embodiment of the present invention.

18A is an experimental data of measuring the tensile strength of the Tatinium alloy bolt prepared according to a preferred embodiment of the present invention.

FIG. 18B is a photograph of the specimen of FIG. 18A; FIG.

Explanation of symbols on the main parts of the drawings

100. Material supply device 120. Supply pipe

140. Stopper 142. Sensor

144.Cylinder 146.Interference Plate

200. Loader 220. Opening

240. Discharge pipe 300. Heating device

320. Heater 340. Furnace

360. Auxiliary heating furnace 400. Forging molding equipment

420. Forging molds 422. Material injection parts

440. Punch 460. Ejector

500. Material input device F. Forging

S100. Surface treatment step S120. Lubricating Process

S140. Oxide film formation process S200. Material supply stage

S300. Material transfer step S400. Material heating stage

S420. Primary heating process S440. Secondary heating process

S500. Forging step S600. Forging Heat Treatment Step

S700. Oxide removal step S800. Forging Process

S900. Rolling step S1000. Surface cleaning step

 W. Raw materials

The present invention relates to a titanium alloy bolt manufacturing equipment that enables the production of titanium alloy bolts in a warm forging process.

Titanium alloy has higher strength, corrosion resistance and light weight than ordinary carbon steel, stainless steel and special alloy steel, and is the second most abundant metal after aluminum, iron and magnesium among the various metals that can be mined on the earth.

Therefore, the existing materials as structural materials and functional materials are being replaced with titanium, and the demand for military equipment and civil industry is rapidly increasing, and is being actively used for aircraft and ships.

In addition, many studies have been conducted on the manufacture of bolts using titanium alloys.

That is, since the titanium alloy bolt is generally poor formability, the cold forging process is required to be carried out a number of times, and the productivity is lowered, so that mass production is difficult.

In addition, the titanium alloy bolt manufactured by hot forging has a problem in that the cracking occurs frequently as the surface oxide layer and the machinability is inferior.

Therefore, much research is being conducted to improve the formability and machinability of the titanium alloy bolts.

However, the titanium alloy bolts formed by a plurality of cold and hot forgings have the following problems.

That is, defects such as cracks are frequently generated during forging molding, which causes difficulty in mass production.

In addition, since the forging die is caused due to friction with the inside of the mold and the characteristic of the material during the forging using the forging die, there is a problem in that the management cost due to the forging die is rapidly increased.

In addition, the forged-molded titanium alloy has a high hardness, and the amount of tool wear of the molding machine is rapidly increased during the post-processing, and often need to be replaced, there is a problem that eventually increases the manufacturing cost of the titanium alloy bolt.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a titanium alloy bolt manufacturing equipment that allows for the continuous production of titanium alloy bolts by using warm forging.

It is another object of the present invention to provide a titanium alloy bolt manufacturing facility capable of producing titanium alloy bolts having improved mechanical properties by performing surface lubrication on raw materials to prevent sintering in the forging mold and performing heat treatment under optimum conditions. Is in.

The titanium alloy bolt manufacturing equipment according to the present invention includes a material supply device for supplying raw materials obtained by cutting a bar material formed of titanium alloy to a predetermined length, a loader for receiving and transporting raw materials from the material supply device, and the loader. A forging molding apparatus having a heating device for heating the raw material to be transported along with it, a forging mold for molding the heated raw material into a forging product, and a material feeding device for guiding the raw material heated by the heating device to the forging mold. And a heat treatment device for heat treating the forged product, an oxide film removal device for removing an oxide film on the surface of the heat treated forged product, a processing device for processing one side of the forged product from which the oxide film has been removed, and a thread on the outer surface of the forged product on which one side is processed. Comprising a rolling device for forming a, and a cleaning device for washing the surface of the titanium alloy bolt formed with the thread do.

The loader is characterized in that the closed curve movement so as to circulate through the inside of the heating device.

The said heating apparatus is comprised including the heating furnace which heats the said raw material primarily, and the auxiliary heating furnace which auxiliary-heats the raw material which exited the said heating furnace.

One side of the auxiliary heating furnace, characterized in that the vibration generator for generating a vibration to enable the smooth transfer of the raw material.

The material supply apparatus includes a supply pipe for guiding a supply direction of the raw material and a stopper for restricting movement by selectively interfering with one side of the raw material moving along the internal space of the supply pipe.

The stopper is characterized in that it is provided with a plurality.

One side of the material input device, characterized in that the insulating material for insulating the raw material to move to the forging die is provided.

According to the present invention as described above, the productivity is maximized, there is an advantage that the dimensional accuracy, strength and fatigue resistance of the titanium alloy bolt is improved.

Hereinafter, a configuration of a titanium alloy bolt manufacturing facility according to the present invention will be described with reference to FIGS. 1 to 3.

Figure 1 is a schematic view showing the external configuration of the titanium alloy bolt manufacturing equipment according to the present invention, Figure 2 shows the external configuration of a material input device and a heating device which is one configuration of the titanium alloy bolt manufacturing equipment according to the present invention A perspective view is shown, and FIG. 3 is a perspective view showing a schematic configuration of a forging die, which is one configuration of a titanium alloy bolt manufacturing facility according to the present invention.

As shown in these drawings, the titanium alloy bolt manufacturing facility according to the present invention (hereinafter referred to as a 'manufacturing facility'), transfer and heating the raw material cut to a predetermined length of the bar material formed of titanium alloy, and forged to form a heat treatment and a machine It is configured to perform the processing and the like sequentially.

To this end, the manufacturing facility includes a material supply device 100 for supplying raw materials (reference numeral W in FIG. 4A), a loader 200 for receiving and transporting raw materials W from the material supply apparatus 100; , A heating apparatus 300 for heating the raw material W to be transported along the loader 200 and a forging die for molding the heated raw material W into a forged product (reference numeral F in FIG. 10) (FIG. 3, the forging molding apparatus 400 is provided, the material input device 500 for guiding the heated raw material (W) to the forging mold 420, and the heat treatment for heat-treating the forging (F) An apparatus, an oxide film removing device for removing an oxide film on the surface of the heat-treated forged product (F), a processing device for processing one side of the forged product (F) from which the oxide film has been removed, and a screw thread on the outer surface of the processed forging (F) And a cleaning device for cleaning the surface of the threaded titanium alloy bolts. It is.

The heat treatment device, the oxide film removing device, the processing device, the precursor and the cleaning device are not shown as a generally used device, the process conditions using each device will be described in detail below.

First, the material supply device 100 is to supply the raw material (W) to be seated on the upper surface of the loader 200 for supplying the raw material (W) to the heating device 300, as shown in Figure 5, It restricts the movement by selectively interfering a supply pipe 120 having a tubular shape and guiding a supply direction of the raw material W in the longitudinal direction, and one side of the raw material W moving along the inner space of the supply pipe 120. It is configured to include a stopper 140.

The supply pipe 120 is made using a cylindrical hollow rod having an inner diameter larger than the outer diameter of the raw material (W), the raw material (W) is introduced into the upper portion and the lower portion is disposed so as to be located above the loader 200 do.

Therefore, the raw material (W) is guided in the longitudinal direction of the supply pipe 120 through the inside of the supply pipe 120 is able to be seated on the upper surface of the loader 200.

A stopper 140 is provided below the supply pipe 120. The stopper 140 is configured to selectively supply a plurality of raw materials (W) moving along the inside of the supply pipe 120 to stop and to be supplied to the loader 200 by maintaining a predetermined interval and time.

Looking at it in more detail, the stopper 140, a pair of sensors 142 fixed to penetrate through the inside of the supply pipe 120, the cylinder 144 linearly reciprocating in conjunction with the sensor 142 and It is configured to include an interference plate 146 coupled to the end of the cylinder 144, one end of which is selectively inserted into the supply pipe 120.

Accordingly, when the sensor 142 detects the raw material W moving along the inside of the supply pipe 120, the cylinder 144 interlocking with the sensor 142 is linearly stretched to extend and contract the length of the interference plate 146. One end is inserted into the supply pipe 120 to prevent the movement of the raw material (W).

In addition, the sensor 142, the cylinder 144, and the interference plate 146 are configured in two pairs to control the pair of interference plates 146 to move in different directions.

That is, if any one of the pair of interference plate 146 is inserted into the supply pipe 120 to interfere with the movement of the raw material (W), the remaining interference plate 146 exits the supply pipe 120 outside It is possible to move the other raw material W which has been interfered in advance.

Therefore, the stopper 140 can continuously supply the raw materials (W) one by one at regular time intervals.

The loader 200 is provided below the front end of the supply pipe 120. The loader 200 is configured to circulate while drawing a closed curve via the inside of the heating apparatus 300. That is, the loader 200 is provided with a material seating portion having a large area, such as a conveyor belt, both ends of the material seating portion is connected to each other to form a closed curve, the material seating portion is rotated by the rotational power supplied by the motor.

And, the lower end of the material seating portion is located below the lower side of the heating device 300 is possible to supply the raw material (W) from the material supply device 100, the upper end of the material seating portion of the heating device 300 It is located at.

Accordingly, the raw material W seated on the material seating portion moves along the direction in which the material seating portion travels, and then falls at an end portion of the material seating portion, that is, the direction is changed.

In addition, the material seating part may be made of various materials within a range where thermal deformation does not occur since the heating device 300 generates heat at a high temperature.

The heater 300 is provided above the loader 200. The heating device 300 is a device for heating the raw material (W) moving along the loader 200 to a predetermined temperature to improve the formability during forging molding.

To this end, the heater 300 is provided with a plurality of heaters 320 for heating the raw material (W) by heating by the electric heating method, an infrared thermocouple (not shown) for measuring the temperature inside the heating device (300) Is not installed).

In addition, since the heater 320 should be configured to control the heating temperature, it is preferable that a heater controller is provided at one side of the heating device 300.

In addition, the heating device 300 is configured to heat the raw material (W) at various temperatures. That is, the heating device 300 is a heating furnace 340 for heating the raw material (W) primarily, and an auxiliary heating furnace 360 for auxiliary heating of the raw material (W) exiting the heating furnace 340. It is configured to include.

" 형상을 가지며, 로더(200)를 따라 이동하는 원소재(W)를 1차로 가열하게 된다. 그리고, 상기 가열로(340)의 우측단 내측에는 도 2와 같이 로더(200)의 단부가 위치하게 된다.The furnace 340 is approximately "

"Has a shape, and the raw material (W) moving along the loader 200 is primarily heated. And, the end of the loader 200 is positioned inside the right end of the heating furnace 340 as shown in FIG. Done.

Therefore, the raw material W heated while passing through the inside of the heating furnace 340 falls down from the end of the loader 200.

An auxiliary heating furnace 360 is provided below the right end of the heating furnace 340. The auxiliary heating furnace 360 serves to guide the omnidirectional direction at the same time as the auxiliary material (W) heated in the heating furnace 340.

To this end, the auxiliary heating furnace 360 is formed to be inclined in all directions, the opening 220 is formed at the rear end of the upper surface, the opening 220 is discharge pipe 240 provided at the front end of the auxiliary heating furnace 360 In communication with.

Therefore, the raw material (W) dropped into the auxiliary heating furnace 360 through the opening 220 is discharged to the outside of the auxiliary heating furnace 360 through the discharge pipe 240, the auxiliary heating furnace 360 An auxiliary heater (not shown) is installed inside the case 260 to form an external appearance of the c) so that secondary heating of the raw material W is possible.

In addition, a vibration generator (not shown) is provided at one side of the auxiliary heating furnace 360. The vibration generator is guided to transfer the raw material (W) by the inclination of the material input device 500 to facilitate this guide, as well as the role of blocking the raw material (W) in advance. Do this.

On the other hand, the material input device 500 is connected to the tip of the auxiliary heating furnace 360, that is, the discharge pipe 240. The material input device 500 is a configuration for guiding the raw material (W) heated in the auxiliary heating furnace 360 to the forging die (420).

That is, the material input device 500 is formed by bending a hollow tube having a predetermined length and shape, the upper end of which is connected to the discharge pipe 240 and the lower end of the material input part 422 of the forging die 420. It is arranged to be located above.

In addition, the outer side of the material input device 500 is provided with a heat insulating member. The heat insulating member is to prevent the raw material (W) moving along the material input device 500 to cool.

A forging die 420 is provided below the material input device 500. The forging mold 420 is seated in the forging molding apparatus 400 and the raw material (W) is introduced into the forging molding apparatus 400 so that an approximate shape of the bolt may be formed by the pressure applied to the punch 440.

To this end, the forging die 420 is provided with a material input part 422 having an upper opening as shown in FIG. 3, and the material input part 422 is located below the left end of the material input device 500. . In addition, the right side of the forging die 420 is provided with a punch 440 for linearly moving in the left direction to push the raw material (W) to the left side, that is, the forging die 420, and then press molding. On the left side of the forging die 420, an ejector 460 is provided to push the forged article F forged in the forging die 420 toward the material input part 422.

Therefore, the raw material (W) guided to the material input portion 422 by the material input device 500 as shown in Figure 4a is dropped to the lower side of the material input portion 422, as shown in Figure 4b, the punch 440 When it is pushed in the left direction and inserted into the forging die 420, it becomes a state as shown in FIG. 4C, and the molding of the forging F is possible.

On the other hand, the heat treatment apparatus is a configuration for heat-treating the forged product (F) formed by the action of the forging mold 420, if the configuration that can heat the forging (F) within the range of conditions to be described below Various changes can be applied.

In addition, the oxide film removing device is configured to remove the oxide film on the surface of the heat-treated forging (F), and sand-blast is applied in the embodiment of the present invention.

The processing device is configured to process one side of the forged product (F) from which the oxide film is removed, and the processing device of the embodiment of the present invention is capable of cutting the end of the forging (F) and the outer peripheral surface of the lower end of the head of the forging (F). Various applications are possible within the scope.

The rolling device is a device for forming a screw thread on the outer surface of the forged product (F), the one side is processed by a processing device, any device as long as it can form a screw thread on the outer surface of the body portion of the forged product (F) formed with a head Of course, it is applicable.

Finally, the cleaning device is a device for cleaning the surface of the threaded titanium alloy bolt, in the embodiment of the present invention, by weight solution containing 15% HNO ₃ , 3% HF, 82% H ₂ O The surface of the titanium alloy bolt was prepared and pickled.

Hereinafter, a method of manufacturing a titanium alloy bolt using a manufacturing facility configured as described above with reference to FIGS. 6A to 6C will be described.

Method for manufacturing a titanium alloy bolt according to the present invention, the surface treatment step (S100) for lubricating the surface of the raw material (W) and the raw material (W) using the material supply device 100 loader 200 ) Material supply step (S200) for supplying, the material conveyance step (S300) for transporting the element ash (W) seated in the loader 200, and the raw material (W) transported by the loader 200 The forging step (S400) and heating the raw material (W) into the forging die (420) to form the forging (F) in the warm (F) by heating the gas inside the heating apparatus (300). S500), the forging product heat treatment step (S600) of heat treating the forging (F) using a heat treatment apparatus, an oxide film removing step (S700) of removing the oxide film on the surface of the heat treatment forging (F), and the oxide film is removed Forging part processing step (S800) for processing one side of the forged product (F), and the screw thread on the outer surface of the forged product (F) And preceding step (S900) of forming, made of a surface cleaning step (S1000) to clean the surface of the titanium alloy, which the threaded bolt is formed.

Looking at the manufacturing method in order, the surface treatment step (S100), to increase the dimensional precision of the forged product (F) to be molded in the forging molding step (S500), and the sintering with the inside of the forging mold 420 during forging molding This step can be prevented.

To this end, the surface treatment step (S100), to form a groove on the surface of the raw material (W), the lubrication process (S120) for remaining the lubricant in the yaw foam and the raw material (W) by heating the raw material ( W) is an oxide film forming process (S140) to form an oxide film on the surface.

The lubrication process (S120) is to insert a plurality of raw materials (W) in a predetermined container and then vibrate to form grooves by the impact between the raw materials (W), and then the lubricant on the surface of the raw materials (W) It is a process to fill the grooves with lubricant by applying.

In the embodiment of the present invention, forging with three lubricants (OilDag, MoO ₂ , Boron-Nitride), MoO ₂ showed the best lubricating properties.

However, through the lubrication process (S120) it was possible to improve the surface properties of the raw material (W) and reduce the quenching in the forging mold 420, but it is sufficient to perform the lubrication process (S120) alone Did not show effect.

In order to solve this problem, an oxide film forming process (S140) of forming an oxide film on the surface of the raw material (W) was performed. The oxide film forming process (S140) has been selected because it can be easily implemented and has a high economic efficiency.

In addition, an oxide film was formed at various temperatures as shown in FIG. 7 to find a preferable temperature at which the raw material W should be heated during the oxide film forming process (S140).

Figure 7 (a) is a sample that has not been subjected to the oxide film forming process (S140), (b) is a sample formed by heating the raw material (W) at 927 ℃, (c) is a circle at 850 ℃ It is the sample which heated the raw material W, and formed the oxide film, (d) is the sample photograph performed at 750 degreeC.

As shown in the figure, a significant level of sintering occurred on the surface of the sample (a) that was not subjected to the oxide film forming process (S140), and it was confirmed that a crack occurred partially on the surface of the sample (a).

It was confirmed that the sample (b) had a very thick yellow oxide film formed on its surface. As a result of forging the sample (b), a phenomenon occurs in which the operation of the forging die 420 is stopped several times.

This is because the material strength rapidly increased as the initial isotropic structure of the raw material W was changed to a bi-model, and it was judged to be due to the formation of cracks from the thick brittle oxide film and propagation inside.

Sample (c) had a relatively good formability and significantly improved quenching. However, as shown in the enlarged picture, a shear band was formed in the stress concentration region inside the raw material W, and the shear band is expected to adversely affect the fatigue life and strength of the bolt in the future.

Finally, the sample (d) was subjected to the oxide film forming process (S140) at a temperature of 750 ℃, showing the smoothest surface state. After forging, most of the brittle oxide film was worn out and disappeared, and the thickness of the oxide film remaining for each part was measured within 5 μm (see FIG. 7B).

In addition, the generation amount of shear band due to plastic deformation imbalance was greatly improved. After forging molding, the microstructure maintained a fine isotropic structure, and the amount of oxide film formed on the surface of the raw material (W) was 0.2 mg / cm2 or less. appear.

After the surface treatment step (S100), the material supply step (S200) is carried out. The material supply step (S200) is a process of remaining a lubricant in the groove on the surface of the raw material (W), and supplying the raw material (W) with the oxide film formed on the loader 200 by using the material supply device (100). .

When the raw material (W) is seated on the upper surface of the loader 200, the loader 200 is rotated by drawing a closed curve is carried out material transfer step (S300) for transferring the raw material (W).

Along with the material transfer step (S300), the material heating step (S400) is also performed at the same time. The material heating step (S400) is a primary heating process (S420) for the primary heating of the raw material (W), and the secondary heating process (secondary heating for heating the primary heated raw material (W) to a different temperature ( S440).

8 and 9 will be described an experimental process for determining the heating temperature conditions in the material heating step (S400).

First, in order to investigate the deformation characteristics of titanium alloy, hot forming resistance was investigated by using Gleeble equipment. Temperature conditions are 300 ~ 700 ℃, the strain rate was variously adjusted from 0.01 / sec to 10 / sec.

The experimental results showed the general behavior of stress of Ti-6Al-4V. Especially, it showed the rapid softening behavior from 600 ℃. Therefore, it was expected to be performed at the temperature of 600 ℃ during forging.

Experimental results carried out to find specific temperature conditions of the material heating step (S400) will be described with reference to FIGS. 10 to 11G.

First, FIG. 10 is a real photograph showing the shape change of the raw material (W) in order during the preferred forging step (S500) of one step in the titanium alloy bolt manufacturing method using a titanium alloy bolt manufacturing equipment according to the present invention As an embodiment of the present invention, in the forging molding step (S500), the raw material (W) was configured to be molded little by little over three orders.

Specific temperature conditions of the material heating step (S410) to enable the molding of such a preferable forging (F) is as shown in Figure 11a to 11g.

In more detail, in FIG. 11A, the temperature of the heating furnace 340 is maintained at 800 ° C. to forge the heated raw material W, and after 20 minutes, the temperature of the auxiliary heating furnace 360 is applied to 800 ° C. Secondary forging was performed, and third round forging was performed 5 minutes after the second forging.

As a result, after the secondary forging, it was confirmed that the film residue remained inside the forging die 420, which is a result showing that the raw material (W) can be sintered in the forging die.

In FIG. 11B, the forging process was performed by setting the temperature conditions of the heating furnace and the auxiliary heating furnace 360 to 800 ° C.

As a result, the phenomenon in which the lubricant is released by the heat on the surface of the forging (F) appeared, the lubricant was released at the bottom of the forging (F) to reveal the inner layer.

In addition, on the head of the forging F, a molding trace in the direction opposite to the progression of the punch 440, which is judged to be due to frictional resistance, appeared.

Therefore, as the material waiting time increases in the heating furnace 340, the effect or workability of the lubricant is deteriorated.

In FIG. 11C, the temperature conditions of the heating furnace 340 and the auxiliary heating furnace 360 were set to 900 ° C., and the forging was performed after heating for 10 to 15 minutes.

As a result, the lubricant adhesion state of the surface was good, and the color of the lubricant appeared slightly oxidized to the head of the forging (F), but there was no sintering or molding load.

Therefore, it is considered that the waiting time of the raw material W in the heating furnace 340 should be shortened.

In FIG. 11D, the temperature conditions of the heating furnace 340 and the auxiliary heating furnace 360 were set to 840 ° C., and the forging was performed after heating for 50 minutes.

 As a result, the surface state of the forging (F) was good, and sintering did not occur even in the forging die (420). Moreover, the state of the punch 440 was also favorable.

In FIG. 11E, the temperature conditions of the heating furnace 340 and the auxiliary heating furnace 360 are set to 840 ° C., and the forging is performed after heating for 65 minutes.

As a result, the molding appeared to have a rough temperature surface and the surface of the forging (F). In addition, sintering did not occur in the forging die 420, and the state of the punch 440 was also good.

In FIG. 11F, the temperature conditions of the heating furnace 340 and the auxiliary heating furnace 360 were set to 840 ° C., heated for 45 minutes, and then forged.

As a result, the surface roughness of the forging F increased somewhat.

In FIG. 11G, the temperature of the heating furnace 340 and the auxiliary heating furnace 360 was set to 840 ° C., heated for 55 minutes, and then forged.

As a result, although the film state of the outer surface of the forging F was not good, moldability was good.

Finally, the temperature of the inlet of the heating furnace 340 was set to a temperature of 500 ° C. or more, and the internal temperature of the heating furnace 340 was maintained at 780 ° C. to heat the raw material W for 35 minutes.

In the auxiliary heating furnace 360, 10 minutes was set at 840 ° C. for 10 minutes, followed by forging.

As a result, as shown in FIG. 10, the continuous work of the forging die was possible, and the seizure of the raw material W in the forging die 420 was prevented, and the state of the punch 440 and the forging die 420 was also good.

According to the above conditions, the material heating step S400 is performed, and the forging molding step S500 is performed after the material heating step. The forging molding step (S500) is a process for deforming the shape by pressing the heated raw material (W) at the temperature conditions proved in the material heating step (S400) is applied to the warm forging.

After the forging molding step (S500), the forging product heat treatment step (S600) is carried out. The forging product heat treatment step (S600) is a process for increasing the strength of the forging (F), to derive the experimental results as shown in Figure 12 to balance the strength and elongation and have a strength of up to 1100M㎩.

That is, six different heat treatment experiments were performed as shown in FIG. 12A, and the solution heat treatment temperature was fixed at 927 ° C. in which all the Transform-β structures were dissolved.

Thereafter, different cooling methods were tried, and aging was performed at 537 ° C and 480 ° C, respectively.

Among the various conditions of FIG. 12A, the forging F performed under the "E" heat treatment condition showed high strength and elongation, and the microstructure exhibited a double structure in which isotropic α and Transform-β were mixed.

That is, the "E" heat treatment condition is a condition in which the forged product (F) is maintained at 927 ° C. for 1 hour, heated, cooled to 850 to 900 ° C., immersed in water, and then aged at 480 ° C. for 24 hours.

The forged product (F) heat-treated according to the above conditions is subjected to the oxide film removing step (S700). The oxide film removing step (S700) is a process of removing the oxide film formed on the surface of the forging (F).

That is, the forged product (F) is a thick oxide layer is formed on the surface when exposed to high temperatures due to the nature of the titanium material and this oxide layer has a serious adverse effect on the fatigue properties, the oxide film removal step (S700) is carried out to remove it.

In the embodiment of the present invention, the oxide film removing step (S700) was sand-blasted.

13 is a real picture showing the appearance of the forged product (F) before / after the oxide film removal step (S700), the outer surface of the forged product (F) subjected to the oxide film removal step (S700) as shown in the lower photo of FIG. It can be seen that the oxide film is completely removed.

After the oxide film removing step (S700), forging processing step (S800) is performed. The forging processing step (S800) is a process of cutting the end of the forging (F) inclined, or by cutting the site where the head and the body of the forging meet.

After the forging step (S800), the forging step (S900) is carried out. The rolling step (S90) is a process of forming a screw thread on the lower outer peripheral surface except for the head portion of the forging (F), in the embodiment of the present invention by heating the forging (F) to 400 ℃ to perform a warm rolling.

Attached FIG. 14 is a sample photograph after performing a precursor step (S900) which is one step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

After the rolling step (S900), the surface washing step (S1000) is carried out. The surface washing step (S1000) is to remove the scale remaining on the outer surface of the bolt after the rolling step (S900), in the embodiment of the present invention was applied pickling treatment.

That is, in the embodiment of the present invention, the titanium alloy bolt was immersed for 5 to 10 minutes in a solution containing 15% HNO ₃ , 3% HF, and 82% H ₂ O by weight to remove the scale of oxidation.

15 is a sample picture showing the change in the outer diameter according to the change in the time of the surface washing step (S1000) is a step in the titanium alloy bolt manufacturing method using the titanium alloy bolt manufacturing equipment according to the present invention.

As a result of these experiments, if the time to immerse the bolt in the solution and the pickling process is less than 5 minutes, the oxidation scale remained on the surface of the bolt. Due to the increase in the etching amount of the dimensional accuracy was reduced.

Therefore, the surface cleaning step (S1000) is preferably carried out for 5 to 10 minutes in consideration of the effective removal of the oxide scale and the dimensional accuracy of the bolt.

Hereinafter, the titanium alloy bolt manufactured by the above method did not find a layered structure in all surface regions as shown in FIG. 16, and it was confirmed that the titanium alloy bolt was composed of an isotropic α phase and a double structure of Transformed-β.

In addition, as a result of examining the surface of the bolt before the surface cleaning step (S1000) as shown in Figure 17, evenly distributed α-scale of 48㎛ thickness, since the thickness is measured after the forging step (S500) surface cleaning After the step S1000, it can be determined that all α-scales are removed and do not affect the deterioration of the mechanical properties of the bolt.

Finally, Figures 18a and 18b shows the results of measuring the tensile strength of the titanium alloy bolts and a specimen picture.

Tensile tests were carried out using a total of five specimens as shown in these figures, and as shown in Figure 18b, all five specimens had fractures in the first load bearing thread, and these fracture positions indicated that the tissue uniformity of the specimens was normal. will be.

In addition, as shown in the experimental results of FIG. 18A, all five specimens showed a tensile strength of 1000 M, or more, and fractured after elongation of 3.0 mm.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

For example, in the forging mold of the embodiment of the present invention, the forging is formed by forging the raw material in three steps, but considering the productivity and manufacturing cost, it is possible to configure the molding of the forging by performing only one forging. Of course.

According to the present invention as described above, it is possible to manufacture the titanium alloy bolt in a warm forging process, it is possible to improve the mechanical strength, there is an advantage that defects such as cracks are prevented in advance.

In addition, there is an advantage that the manufacturing cost can be significantly reduced because the defect rate is minimized and the quality is improved, and the productivity is maximized.

The forming of titanium alloy using the warm forging process is not limited to bolts, but can be applied to various shapes of parts, which may bring industrial ripple effects.

Claims (7)

A material supply device for supplying a raw material obtained by cutting a bar formed of titanium alloy to a predetermined length; A loader for receiving and transferring raw materials from the material supply device; A heating device for heating the raw material conveyed along the loader; A forging molding apparatus provided with a forging mold for molding the heated raw material into a forging product; A material input device for guiding the raw material heated in the heating device to a forging die; A heat treatment apparatus for heat treating the forged product; An oxide film removing device for removing an oxide film on the surface of the heat-treated forged product; A processing apparatus for processing one side of the forged product from which the oxide film is removed, Rolling apparatus for forming a thread on the outer surface of the forged product processed on one side, Titanium alloy bolt manufacturing equipment characterized in that it comprises a washing device for cleaning the surface of the titanium alloy bolt is formed thread. The method of claim 1, wherein the loader, Titanium alloy bolt manufacturing equipment characterized in that the closed curve movement to circulate through the inside of the heating device. The method of claim 2, wherein the heating device, A heating furnace for heating the raw material primarily; Titanium alloy bolt manufacturing equipment, characterized in that it comprises a secondary heating furnace for auxiliary heating the raw material exiting the heating furnace. According to claim 3, At one side of the auxiliary heating furnace, Titanium alloy bolt manufacturing equipment, characterized in that the vibration generator for generating a vibration to enable the smooth transfer of raw materials. According to claim 1, wherein the material supply device, A supply pipe for guiding a supply direction of the raw material, Titanium alloy bolt manufacturing equipment characterized in that it comprises a stopper for restricting the movement by selectively interfering with one side of the raw material moving along the inner space of the supply pipe. 6. The apparatus of claim 5, wherein the stopper is provided in plurality. According to claim 1, At one side of the material injection device, Titanium alloy bolt manufacturing equipment, characterized in that the insulating material is provided for the insulation of the raw material moving to the forging die.

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