KR20100114632A - Forged product with hollow body and terminal flan ges and manufacturing method thereof - Google Patents

Abstract

PURPOSE: An hourglass drum-shaped forged product and a manufacturing method thereof are provided to reduce the loss of material and enhance the internal tempering and densifying effects at the flanges of the product. CONSTITUTION: An hourglass drum-shaped forged product comprises a first flange(3), a hollow body(1), and a second flange(5). The first flange is formed by compression-expanding a round rod to have semi-elliptical grain flow. The body is formed by longitudinally punching the center of the first flange and the round rod below the first flange to form a non-through hollow and then extending the round rod below the first flange to the length corresponding to the volume of the non-through hollow. The second flange is formed by compression-expanding the rest part of the round rod below the first flange to have semi-elliptical grain flow and then punching the central portion to be connected to the non-through hollow.

Description

Long-form hollow forging and its manufacturing method {FORGED PRODUCT WITH HOLLOW BODY AND TERMINAL FLANGES AND MANUFACTURING METHOD THEREOF}

The present invention relates to an elongated hollow forged product and a method for manufacturing the same. More specifically, the material loss rate is very low, the product yield is high, the internal annealing and densification effect on the flange is large, It is formed continuously without boiling, especially the long flow hollow forging and its manufacturing method which improve the durability (life), crack resistance and impact resistance of the forged product by overlapping the semi-elliptic grain flow and tissue arrangement of both flanges It is about.

The long hollow hollow forging has a form in which circular flanges extending in a direction perpendicular to the longitudinal direction of the trunk are formed at both ends of the hollow circular trunk. Gears are formed on this flange by post-processing. When cutting this type of product, it takes much time to process a single product. Therefore, when producing a large amount of this type of product, it is necessary to perform forging to save the material quickly.

As such, the long hollow hollow forgings used as the base material for forming a gear are required to have high mechanical properties (structure density, durability, impact resistance, and abrasion resistance) of the flange after forging because the gear teeth are radially formed at both ends of the flange. In particular, since the gear teeth formed on the flange are subjected to circumferential forces and impacts during power transmission, it is preferable in terms of durability, impact resistance and wear resistance that the gear arrangements of the gear teeth and the gear arrangement are continuously connected.

Conventionally, two methods have been mainly used for forming a long hollow hollow forging.

One method is shown in FIGS. 5A and 5B. The method shown in FIGS. 5A and 5B is a die forging method, in which a cavity capable of compressing the outer shape of an elongated hollow forging into an upper mold and a lower mold is halved, and a cavity of 1250 ° C. After inserting the round bar heated in and out and pressurizing the body (1a) and the flanges (3a, 5a) on both ends at the same time and a burr (11a) to come out to the mating surface. This method is a method of simultaneously molding each part of the long hollow forging by hot die forging. According to this method, the hollow inside the trunk 1a is separately formed by a cutting machine such as a drill after the burr is pulled out.

Another method of forming a long hollow hollow forging is shown in FIG. 3. The forging method shown in FIG. 3 is called a forging method by cross rolling. In the outer roller having an inner diameter, an inner roller having an outer diameter smaller than the inner diameter of the outer roller is provided, and an outer roller inner diameter surface and an inner roller outer diameter surface are provided with protrusions capable of compression molding the outer shape of the long-form hollow forging. A cylindrical rod heated at about 1250 ° C. is inserted between the two rollers, and the trunk 1b and the flanges 3b and 5b at both ends are simultaneously crimped while rolling in the circumferential direction, and the burrs 11b are placed on both sides of the flange. It is a way to generate. This method is similar to the die forging method in that each part of the long hollow hollow forging is simultaneously molded. Even in this method, the hollow is formed separately by a cutting machine such as a drill after the burr is pulled out.

However, the above two methods have the following disadvantages and need improvement.

First of all, the die forging method and the cross rolling method simultaneously form the trunk and both flanges at a high temperature, so that a large amount of burrs must be generated to increase the dimensional accuracy, and the hollow is forged. Since it must be drilled separately by a cutting machine such as a post drill, there is a problem in that the material corresponding to the volume of the burr and the hollow is lost. Therefore, the loss rate of the material is very large, there is a problem that the product yield for the put round bar is too low.

In addition, in the case of the die forging method and the cross rolling method, it takes a lot of time to extract the burrs and hollow drilling, and thus the product productivity is low.

In addition, since the outer diameter difference between the body portion and the flange portion is relatively large, the mold is easily damaged when the body and the flange are simultaneously forged, and thus the life of the mold is short.

In addition, the above die forging method and cross rolling method uses a bulky material than the final forging to temporarily form the trunk and both flanges, the diameter of the flange (3, 5) Since it is larger than the diameter of the trunk (1), the internal annealing effect on the flanges (3, 5) is less, discontinuity occurs in the root tooth and the tooth tissue of the gear teeth formed on the flange, hot forging at high temperature (about 1250 ℃) Therefore, there is a problem that not only a short flow line is formed but also a blending ratio of the forging material component elements is different.

The present invention has been made to solve the problems of the conventional long-length hollow forging and manufacturing method as described above, the first problem to be solved by the present invention, to minimize the occurrence of burrs (burr), without cutting loss of the material The present invention provides a long hollow hollow forged product and a method of manufacturing the same, which can significantly reduce material loss and increase product yield.

The second problem to be solved by the present invention is to provide a long hollow hollow forging and a method of manufacturing the same that can significantly shorten the time required for the production of the product by reducing the pulverization and hollow drilling process after forging have.

A third object of the present invention is to provide a long hollow hollow forging and a method of manufacturing the same, which can minimize mold damage and increase the life of the mold by constraining and forging the flange and the hollow body at each end in stages. .

The fourth problem to be solved by the present invention is a large internal annealing and densifying effect on the flange, the grain flow and the tissue arrangement of the flange overlap in a semi-elliptic shape around the center of the trunk, The present invention provides a long hollow hollow forged article and a method of manufacturing the same, wherein the streamline and the tissue array are continuously formed without boiling, and have excellent durability, crack resistance, and impact resistance, and prolong the life of the forged product.

The long-length hollow forging according to the present invention to solve the above problems is formed by compressing and expanding a predetermined length of one end of the round bar so that the grain flows of the compression-expanded portion overlap in a semi-elliptic shape around the inside. The length of the first flange lower round bar is formed by a length corresponding to the volume of the non-penetrating hollow while punching the first flange and the centers of the first flange and the first flange lower round bar in the longitudinal direction to form a non-penetrating hollow. The hollow body formed by stretching and compressing and expanding the remaining non-penetrating round bar under the hollow body so that the grain flows of the compression-expanded portion overlap in a semi-elliptic shape with an inner side as the center. It characterized in that it comprises a second flange formed by punching in communication with.

In addition, the method for manufacturing a long hollow hollow forging according to the present invention to solve the above problems, after opening the first flange molded part of the round bar and charged the round bar into the cavity of the mold that can restrain the rest, the opening of the round bar The first forming step of forming the first flange by pressing the formed portion, and the first flange lower round bar of the first forged product obtained in the first forming step is restrained in the mold and the first flange is in a non-constrained state to form a hollow punch. A second molding step of forming a hollow body by extending the first flange lower round bar to the first flange side by forming a non-penetrating hollow by hitting the center of the first flange in the longitudinal direction in a lengthwise direction; The first flange and the hollow body of the secondary forging obtained in the step are clamped and clamped and expanded in the cavity of the mold while the non-penetrating round bar under the hollow body is not restrained. And a third forming step of forming a second flange at the bottom of the hollow body, and forming a through hollow by drilling a central portion of the second flange of the third forged product obtained in the third forming step so as to communicate with the non-penetrating hollow. Characterized in that it comprises a four molding step.

According to the present invention, since there is little burr generation and there is no need to discard the material by separately drilling the hollow after forging, the material loss rate is low, the product yield is high, and the time required for the production of the product is dramatically shortened. , The both ends of the flange and the hollow body are stepped to restrain the mold life is increased, and above all, the internal tempering and densifying effect on the flange is large, the flow line of the entire forging is continuously formed without boiling, in the flange Since the grain flow is superimposed in a semi-ellipse shape around the root of the gear tooth to be formed on the flange, the durability, crack resistance and impact resistance of the forged product are very excellent and the life of the forged product is extended.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a front cross-sectional view showing a long hollow hollow forging according to the present invention with a flow line, Figure 2a is an external perspective view of a long hollow hollow forging according to the present invention, Figure 2b is a long hollow hollow forging shown in Figure 2a This is a perspective view of a hollow shaft both-speed gear having a gear tooth formed on a flange after post-processing.

As shown in FIG. 1, the long hollow hollow forging according to the present invention has a semi-elliptic shape around the inside of grain flows GFs formed in the first flange 3 and the second flange 5. It is formed so as to overlap, characterized in that the disconnection line (GF) formed in the flange (3, 5) and the disconnection line formed in the body (1) is connected without boiling. In order to obtain this type of streamline, one round bar must be formed by forging without removing the material. When the flow lines (GF) formed on the flanges 3 and 5 overlap in semi-elliptic shapes with respect to the inside, the gear teeth formed on the flanges also have excellent mechanical properties because the flow lines and tissue arrangements of the roots and vertebrae are connected without boiling. Properties (durability, impact resistance, wear resistance).

As shown in FIG. 1, the first flange 3 is formed by compressing and expanding a predetermined length of one end of a round bar so that grain flows overlap in a semi-elliptic shape about an inner side. In addition, in order to allow the streamline lines of the body 1 and the first flange 3 to be continuously formed, the body 1 extends the central portions of the first flange 3 and the first flange lower round bar in the longitudinal direction. Punching to form a non-penetrating hollow while extending the length of the first flange lower round bar by a length corresponding to the volume of the non-penetrating hollow. Also, in the second flange 5, grain flow lines overlap semi-elliptic shapes about the inside thereof, and the stream lines connect with the flow lines of the first flange 3 and the trunk 1. In order to achieve this, the second flange 5 is formed by compressing and expanding the remaining portion of the non-penetrating round bar below the body 1 in which the non-penetrating hollow is formed.

The present invention solves the fitting defects and impact fragility resulting from the tooth dislocation and tooth discontinuity of the gears formed in the flange of the long hollow hollow forging and the resulting gear tooth wear.

FIG. 2B is a perspective view of the hollow shaft both-speed gears formed by forming gear teeth 9a and 9b on both end flanges 3 and 5 of the long hollow hollow forging shown in FIG. 2A. These gears are mainly used as power transmission parts of automobiles.

Hereinafter, a method of manufacturing a long hollow hollow forging according to the present invention described above will be described in detail.

Figure 3 is a front view of each step of the intermediate forging produced when forming an elongated hollow forging with a round bar by the method according to the invention, Figures 4a and 4b is used to form the long forging hollow forging according to the present invention This is a cross-sectional view of mold and intermediate forging parts.

4A and 4B, the first forming step loads the round bar 100 into the first dice 17a having a stepped cavity and hits the first punch 29a to hit the first flange of the torso and torso. It can be seen that (3) is the step of forming.

As shown in FIG. 4A, it can be seen that in the first molding step, a T-shaped stepped cavity 13 having a large diameter and a small diameter is formed in the first dice 17a. All. At this time, the depth of the lower cavity (small diameter portion) is a length corresponding to the volume required to form the first flange 3 at one end of the round bar when the round bar 100 is charged (hereinafter referred to as a first flange forming part). It is made into the depth which can protrude in an upper cavity (large diameter part) only. In addition, the diameter of the lower cavity is a diameter capable of restraining the lower portion of the first flange forming portion of the round bar 100 without movement, the diameter of the upper cavity is equal to the diameter of the first flange (3). Therefore, a part of the round bar 100 is inserted into the lower cavity, the rest protrudes into the upper cavity in the state in which the round bar 100 is charged in the cavity, and the protrusion amount is an amount necessary for forming the first flange 3. In the first molding step, the upper mold is provided with a first punch 29a having a sliding outer diameter in close contact with the inner wall of the upper cavity of the T-shaped cavity. The first sleeve 19a is provided around the first punch 29a. By the mold structure, in the first molding step, the body forming portion and the second flange forming portion which are the lower portion of the first flange forming portion of the round bar 100 are restrained, and the first flange forming portion of the round bar 100 is opened.

As shown in FIG. 4B, when the round rod 100 loaded in the lower mold 17a is pressed by the first punch 29a of the upper mold, the head portion of the round rod 100 in the upper cavity of the T-shaped cavity is shown. Compression expansion occurs with respect to the rest of the round bar 100, except for the first flange molded part is restrained, when the first flange molded part of the round bar 100 when the compression expansion in the cavity 13, the longitudinal direction With respect to the intermediate point of the first flange forming portion first expands outward, the upper end of the first flange forming portion is pressed downward. By this process, grain flows of the first flange are overlapped in a semi-elliptic shape with respect to the inside.

In addition, in the first molding step, the volume of the first flange forming part of the round bar 100 is precisely matched to the volume of the first flange 3 to be molded to protrude into the upper cavity, and the inner diameter of the upper cavity and the first punch ( Since the outer diameter of 29a) is matched, burrs are not generated during forging. FIG. 3B shows the primary forging product 101 thus formed.

In the second molding step, the first flange lower round bar 100a and the side surfaces of the first flange 3 of the first forging product 101 obtained in the first molding step are restrained in the second die 17b and the first flange 3 The upper surface of the) is in the open state by hitting the center of the upper surface of the first flange (3) in the longitudinal direction with the second punch (29b) to form a non-penetrating hollow (7b), the length of the round bar by the volume of the non-penetrating hollow (7b) Is extruded in a direction opposite to the advancing direction of the second punch 29b. Therefore, the second molding step may be referred to as a back extrusion step.

As shown in Fig. 4A, the second dice 17b in the second molding step has the same structure as the first dice 17a in the first molding step. However, the diameter of the second punch 29b in the second molding step is equal to the diameter of the non-penetrating hollow 7b to be formed and is smaller than the diameter of the upper cavity of the T-shaped cavity 13. That is, the second punch 29b of the upper mold in the second molding step is a non-penetrating hollow punch. Reference numeral 19b is a sleeve. When the primary forging 101 is loaded into the second die 17b, the lower flange 100a of the first flange 3 of the primary forging 101 is restrained in the lower cavity of the T-shaped cavity 13. The side surface of the first flange 3 is restrained in the upper cavity, but the upper surface of the first flange 3 is in an unconstrained open state.

Therefore, as shown in FIG. 4B, when hitting the center of the upper surface of the first flange 3 in the longitudinal direction with the second punch 29b, the first flange 3 and the first flange lower round bar 100a are not penetrated. While the hollow 7b is formed, the length of the round bar 100a extends toward the first flange 3 by the volume of the non-penetrating hollow 7b. The length of the second punch (29b) is formed into a length that can leave the material for forming the second flange (3) below the non-penetrating hollow (7b) after punching. In this way, the hollow body 1 is formed in the lower portion of the first flange, and the round bar 100b for forming the second flange remains in the lower portion of the hollow body 1.

The second molding step forms a non-penetrating hollow 7b, and extends a substantial material to the non-penetrating hollow 7b so that the round bar 100a is opposite to the pressing direction of the second punch 29b. 3) it can be said to be the back extrusion forging step. There is no material loss at this stage. FIG. 3C shows the secondary forging 102 thus formed.

The third molding step restrains the first flange 3 and the body 1 of the second forged product 102 obtained in the second molding step, and upsetting the non-penetrating round bar 100b to the body 1. Forming a second flange 5 that is continuous with.

As shown in FIG. 4A, in order to perform the third molding step, the first flange 3 and the body 1 of the secondary forging 102 are first restrained by the clamp 23. In addition, a cavity 15 corresponding to the second flange 5 is formed in the third die 17c of the lower mold of the third molding step, and the third punch 19c of the upper mold is the non-penetrating hollow 7c. It is formed with an outer diameter that is inserted into). Reference numeral 19c is a sleeve.

As shown in FIG. 4B, the non-penetrating round bar 100b is hit by the third punch 17c by hitting the non-penetrating hollow 7b of the second forged product 102 constrained by the clamp 23 with the third punch 29c. When pressurized into the cavity 15 of), the non-penetrating round bar 100b of the second forged product 102 is upset or compressed in the shape of the cavity 15 to form the second flange 5. At this time, since the rest portion except the non-penetrating round bar 100b is restrained, when the non-penetrating round bar 100b compresses and expands in the cavity 15, the intermediate point of the non-penetrating round bar 100b with respect to the longitudinal direction is First, it expands outward, and the lower end of the non-penetrating round bar 100b is pressed upward. By this process, the grain flows of the second flange overlap with each other in a semi-elliptic shape. 3 (d) shows the third forging product 103 thus formed. As shown in (d) of FIG. 3, since only the second flange 5 is molded in the third molding step, the amount of burrs 11c generated on the mating surface is insignificant.

As such, the forging according to the present invention is forged by a portion of each part of the long hollow hollow forging gradually by part, it can be made in cold or heat below 900 ℃.

Referring to FIG. 3, it can be seen that the bottom of the non-penetrating hollow 7b remains in the third forging product 103 as it is. In the fourth molding step, the through hole 25 is formed by punching the bottom of the non-penetrating hollow 7b. According to the present invention, FIG. 3 (e) shows the fourth cut forging 104 having the bottom perforated. The fourth forged product is made into a long hollow hollow forged product as shown in Figs. 1 and 2A through a conventional post-treatment process (trimming, cutting, heat treatment, calibration, inspection).

As described above, according to the present invention, a slight burr loss occurs in the third molding step, and in the fourth step, as much as the volume of the through hole 25 when punched in the lower part of the non-penetrating hollow 7b. Only punching losses occur, resulting in a very low material loss and a high product yield, while forming a hollow. In addition, the cutting amount is drastically reduced, thereby shortening the time required to produce the product, and molding each part of a long hollow hollow forging by restraining forging at each stage, thereby improving mold durability and extending the life of the mold. will be.

In addition, according to the present invention, as shown in Figure 1, the internal annealing and densification effect on the flange (3, 5) on which the gear teeth are to be formed is large, and the grain flow (GF) and tissue arrangement of the flange and The trunk line and tissue arrangement of the body are not only uniform and continuous without boiling, but also have the advantage of overlapping the semi-elliptic shape around the root of the gear tooth to be formed on the flange. Through this, the present invention is to improve the overall mechanical properties (durability, crack resistance and impact resistance) of the forged product, and to obtain the effect of extending the life of the gear.

Figure 1 is a front cross-sectional view showing a long hollow hollow forging according to the present invention with a streamline.

Figure 2a is an external perspective view of a long hollow forging according to the present invention.

FIG. 2B is a perspective view of the hollow shaft both-speed gears formed with gear teeth on the flange after the after-processing of the long hollow hollow forging shown in FIG. 2A; FIG.

Figure 3 is a front view of each step of the intermediate forging produced when forming a long hollow hollow forging with a round bar by the method according to the present invention.

Figures 4a and 4b is a cross-sectional view of a step-by-step mold and intermediate forging used in the formation of a long hollow hollow forging according to the present invention.

5A and 5B show a method of forming a long hollow hollow forging by a conventional simultaneous forging method.

6 shows a method of molding a long hollow hollow forging by a conventional cross rolling forging method.

                 Explanation of symbols on the main parts of the drawings

1: Body 3, 3a, 3b, 5, 5a, 5b: Flange

7a, 7b: hollow 9a, 9b: gear tooth

11a, 11b, 11c burrs 13 and 15 cavities

17a, 17b, 17c: Dies 19a, 19b, 19c: Sleeve

21a, 21b, 21c: rear punch 23: clamp

25: through hole 27a, 27b, 27c: front punch

100, 100a, 100b: round bar 101 ~ 105: intermediate forging

Claims (2)

A first flange formed by compressing and expanding a predetermined length of one end of the round bar such that grain flows of the compressed and expanded portion overlap each other in a semi-elliptic shape about an inner side thereof; A hollow body formed by increasing the length of the first flange lower round bar by a length corresponding to the volume of the non-penetrating hollow while punching the centers of the first flange and the first flange lower round bar in a longitudinal direction to form a non-penetrating hollow; Compressing and expanding the remaining non-penetrating round bar under the hollow body so that the grain flows of the compression-expanded portion overlap with each other in a semi-ellipse shape, and the center is formed by perforating the non-penetrating hollow. A long hollow hollow forged product comprising a; second flange. A first molding step of forming a first flange by pressing the open part of the round bar after inserting the round bar into the cavity of the mold capable of opening the first flange forming part of the round bar and restraining the rest; The first flange lower round bar of the first forged product obtained in the first molding step is restrained in the mold and the first flange is blown to form a non-penetrating hollow by hitting the center of the upper surface of the first flange with a punch for forming a hollow in a longitudinal direction. At the same time, the second molding step of forming a hollow body by extending the first flange lower round bar to the first flange side by the volume of the non-penetrating hollow; The first flange and the hollow body of the secondary forging obtained in the second molding step are restrained with a clamp, and the second flange is attached to the bottom of the hollow body by pressing and expanding in the cavity of the mold while the non-penetrating round bar under the hollow body is not restrained. Forming a third molding step; And And a fourth molding step of forming a through-hole by drilling the center of the second flange of the third forging product obtained in the third molding step so as to communicate with the non-penetrating hollow.

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