CN111687356B - Straight bevel gear warm forging precision forming die - Google Patents

Abstract

The straight bevel gear warm forging precision forming die provided by the present invention relates to the field of mechanical manufacturing technology, and comprises a rough forging die composed of an upper tooth die and a lower cavity die, and a fine forging die composed of an upper cavity die and a lower tooth die; wherein, a punching structure composed of elastic elements is arranged in the upper dies of the rough and fine forging dies to prevent the formed tooth blank and the gear from sticking to the upper die; guide cylinders are arranged on the outer circumferences of the tooth dies of the rough and fine forging dies respectively to ensure that the modulus misalignment between the upper and lower dies does not exceed 0.3 mm, and prestress is provided to the tooth dies to prevent the tooth profile from being deformed due to three-way compressive stress, resulting in excessive tooth shape accuracy; at the same time, a floating die lifting structure is arranged in the lower cavity die to float the lower cavity die, and the blank is accurately positioned in cooperation with the shaft neck of the lower cavity die, ensuring that the blank is evenly distributed in the tooth shape of the tooth model cavity during rough forging, reducing the deformation of the gear after the residual stress of the residual stress is eliminated, and facilitating forging a recessed structure toward the inside of the tooth blank on the tooth shape end face and the shaft neck end face of the tooth blank, thereby improving the utilization rate of the blank.

Description

Straight bevel gear warm forging precision forming die

Technical Field

The invention relates to the technical field of mechanical manufacturing, and in particular to a warm forging precision forming die for a straight bevel gear.

Background technique

When the straight bevel gear is warm forged on the automatic line of the electric screw press, on the one hand, due to the anisotropy of the deformed material and the mold frame used for mold installation must be convenient for the manipulator to place and grab the material, a guide column-free structure is usually adopted. It is impossible to achieve a mold error of no more than 0.3mm when the upper and lower molds are closed only by the guide rail accuracy and rigidity of the equipment; on the other hand, when the rough forging tooth die is used as the lower die in the prior art, the positioning surface in the rough forging tooth die is usually larger than the diameter of the blank to be deformed, and the blank to be deformed cannot be accurately positioned in the rough forging tooth die; the existence of these two reasons causes uneven distribution of the blank to be deformed when forming the tooth blank, large deformation of the gear after the residual stress is eliminated, and low precision level. At the same time, when the rough forging tooth die is used as the lower die, it has a long contact time with the high-temperature tooth blank, which is very likely to cause the rough forging tooth die to be tempered and softened at high temperature, greatly reducing the life of the rough forging tooth die, and the general service life does not exceed 3,000 pieces.

In some processes, the positions of the rough forging tooth die and the rough forging cavity die are swapped. The rough forging tooth die is used as the upper die and the rough forging cavity die is used as the lower die. The shaft neck of the rough forging cavity die is used to accurately position the blank to be deformed, and a hydraulic device is used to punch the material. However, due to the "hysteresis" of the hydraulic device, the extruded tooth blank will not be separated from the die cavity of the rough forging tooth die until the equipment slider returns to a certain distance above the bottom dead point. The robot arm cannot normally grab the tooth blank, resulting in an abnormal shutdown of the electric screw press automatic line.

Summary of the invention

The purpose of the present invention is to provide a straight bevel gear warm forging precision forming die, by precise structural design of the forming die, including adjusting the upper and lower die composition of the die, automatic punching of the upper die during forging, precise positioning of the blank and setting of prestress and guide mechanism, etc., to significantly improve the service life of the rough and fine forging dies, improve the tooth profile accuracy and blank utilization rate, and effectively solve the above-mentioned technical problems.

To achieve the above-mentioned object, the present invention proposes the following technical scheme: a straight bevel gear warm forging precision forming die, comprising a rough forging die and a fine forging die formed by an electric screw press automatic line, wherein the rough forging die is defined as a first upper die and a first lower die divided by a die cavity parting surface in the rough forging die, and the fine forging die is defined as a second upper die and a second lower die divided by a die cavity parting surface in the fine forging die;

The first upper die comprises an upper tooth die, a first upper ejector rod, an upper tooth die pressure pad, a first upper transition pad, a first upper pressure pad, a first upper ejector elastic element and a first guide cylinder; the lower end surface of the upper tooth die is provided with an upper tooth model cavity with an open opening facing downward, the first guide cylinder is sleeved on the outer circumference of the upper tooth die, and the lower end surface of the first guide cylinder protrudes downward from the lower end surface of the upper tooth die; the first upper ejector rod is vertically arranged in the inner holes of the upper tooth die and the upper tooth die pressure pad, and is supported by the first upper transition pad movably arranged in the inner holes of the upper tooth die pressure pad and the first upper pressure pad; the first upper transition pad is a step shaft, and the step surface of the first upper transition pad is supported on the upper end surface of the upper tooth die pressure pad; the first upper ejector elastic element is vertically arranged in the inner hole of the first upper pressure pad, the lower end surface of the first upper ejector elastic element abuts against the upper end surface of the first upper transition pad, and the first upper ejector elastic element, the first upper transition pad and the first upper ejector rod constitute a coaxial phase top structure;

The first upper material beating elastic element has at least a first state and a second state in the inner hole of the first upper pressure pad; the first state is that the step surface of the first upper material beating elastic element supporting the first upper transition pad is in contact with the upper end surface of the upper tooth mold pressure pad, and the first upper material beating push rod partially extends into the upper tooth model cavity; the second state is that the first upper material beating elastic element is in a compressed state, and the step surface of the first upper transition pad is separated from the upper end surface of the upper tooth mold pressure pad.

The first lower mold comprises a lower cavity mold, a first lower ejector rod, a floating mold lifting elastic element, a lower cavity mold pressure pad, a first lower transition pad, a first lower pressure pad and a first lower ejector rod; the upper end surface of the lower cavity mold is provided with a concave mold cavity with an open opening facing upward, the lower cavity mold is adapted to the upper tooth mold, and the outer circumference of the lower cavity mold is adapted to the inner hole of the first guide cylinder; the lower cavity mold pressure pad is centrally provided with an inner hole, and the first lower ejector rod is vertically provided between the lower cavity mold and the lower cavity mold pressure pad The first lower ejector rod is arranged in the inner hole of the block, and is supported by the first lower transition pad movably arranged in the inner hole of the lower cavity mold pressure pad; the first lower transition pad is arranged as a vertical cylindrical shaft, and the lower end face of the cylindrical shaft is supported on the upper end face of the first lower pressure pad; the first lower ejector rod is vertically arranged in the inner hole of the first lower pressure pad, and the upper end face of the first lower ejector rod abuts against the lower end face of the first lower transition pad, and the first lower ejector rod, the first lower transition pad and the first lower ejector rod constitute a coaxial phase push structure;

The floating mold lifting elastic element is arranged between the lower cavity mold and the first lower pressure pad, the upper end surface of the floating mold lifting elastic element abuts against the lower end surface of the lower cavity mold, and the lower end surface of the floating mold lifting elastic element abuts against the upper end surface of the first lower pressure pad; the floating mold lifting elastic element has at least a first compression state and a second compression state between the lower cavity mold and the first lower pressure pad, the first compression state is that the floating mold lifting elastic element supports the lower end surface of the lower cavity mold and is spaced from the upper end surface of the lower cavity mold pressure pad, and the second compression state is that the floating mold lifting elastic element is compressed to the lower end surface of the lower cavity mold abutting against the upper end surface of the lower cavity mold pressure pad, and the first lower ejector rod partially extends into the concave model cavity.

The second upper mold comprises an upper cavity mold, a second upper ejector pin, an upper cavity mold pressure pad, a second upper transition pad, a second upper pressure pad and a second upper ejector elastic element; an upper concave mold cavity with an open opening facing downward is centrally arranged on the lower end surface of the upper cavity mold, and the upper concave mold cavity portion protrudes downward from the lower end surface of the upper cavity mold to form an outer circle guide portion of the upper cavity mold; the second upper ejector pin is vertically arranged in the inner holes of the upper cavity mold and the upper cavity mold pressure pad, and is supported on the second upper transition pad movably arranged in the inner holes of the upper cavity mold pressure pad and the second upper pressure pad; the second upper transition pad is a stepped shaft, and the stepped surface of the second upper transition pad is supported on the upper end surface of the upper cavity mold pressure pad; the second upper ejector elastic element is vertically arranged in the inner hole of the second upper pressure pad, the lower end surface of the second upper ejector elastic element abuts against the upper end surface of the second upper transition pad, and the second upper ejector elastic element, the second upper transition pad and the second upper ejector pin form a coaxial top structure;

The second upper material-beating elastic element has at least a third state and a fourth state in the inner hole of the second upper pressure pad; the third state is that the step surface of the second upper material-beating elastic element supporting the second upper transition pad is in contact with the upper end surface of the upper cavity mold pressure pad, and the second upper material-beating ejector rod partially extends into the upper concave model cavity; the fourth state is that the second upper material-beating elastic element is in a compressed state, and the step surface of the second upper transition pad is separated from the upper end surface of the upper cavity mold pressure pad.

The second lower die comprises a lower tooth die, a second lower ejector rod, a lower tooth die pressure pad, a second lower transition pad, a second lower pressure pad and a second lower ejector rod, and the lower tooth die is adapted to the upper cavity die; the upper end surface of the lower tooth die is provided with a lower tooth die cavity with an opening facing upward, and the outer circumference of the lower tooth die is sleeved with a second guide cylinder; the upper end surface of the second guide cylinder protrudes upward from the upper end surface of the lower tooth die, and the inner hole of the second guide cylinder is adapted to the outer circumference of the outer circle guide portion of the upper cavity die; the second lower ejector rod is vertically arranged in the lower tooth die and the inner hole of the lower tooth die pressure pad The second lower ejector rod is supported by a second lower transition pad movably arranged in the inner hole of the lower tooth mold pressure pad, and part of the second lower ejector rod extends into the lower tooth model cavity; the second lower transition pad is arranged as a vertical cylindrical shaft, and the lower end face of the cylindrical shaft is supported on the upper end face of the second lower pressure pad; the second lower ejector rod is vertically arranged in the inner hole of the second lower pressure pad, and the upper end face of the second lower ejector rod is in contact with the lower end face of the second lower transition pad, and the second lower ejector rod, the second lower transition pad and the second lower ejector rod constitute a coaxial phase top structure.

Furthermore, the height difference between the lower end face of the first guide cylinder and the lower end face of the upper tooth mold in the vertical direction is defined as H1, the height difference between the upper end face of the second guide cylinder and the upper end face of the lower tooth mold in the vertical direction is defined as H2, and the height of the outer circle guide portion of the upper cavity mold protruding from the lower end face of the upper cavity mold is defined as H3, then H3=H2, H2≥23mm, H1≥40mm.

Furthermore, an exhaust hole is provided on the outer circle guide portion of the upper cavity mold.

Furthermore, the upper end face of the first guide cylinder abuts against the lower end face of the upper tooth mold pressure pad, and the lower end face of the second guide cylinder abuts against the upper end face of the lower tooth mold pressure pad. The first guide cylinder has an interference fit with the upper tooth mold, and the second guide cylinder has an interference fit with the lower tooth mold. The interference coefficient is optimally maintained at 4‰-6‰, and the material of the first guide cylinder and the second guide cylinder is H13 mold steel, and the hardness after heat treatment is HRC44-48.

Furthermore, the lower cavity mold pressure pad is also provided with a plurality of through holes penetrating the upper and lower end surfaces of the lower cavity mold pressure pad, and the through holes are evenly arranged around the inner hole of the lower cavity mold pressure pad; the floating mold lifting elastic element is arranged in the through holes and is configured as a spring.

Furthermore, the first upper material-beating elastic element is set as a first nitrogen spring, and the second upper material-beating elastic element is set as a second nitrogen spring; a first cooling mechanism is set in the first upper pressure pad, and a second cooling mechanism is set in the second upper pressure pad; the cooling mechanism is used to adjust the nitrogen spring to a normal working temperature.

It can be seen from the above technical solutions that the straight bevel gear warm forging precision forming die provided by the technical solution of the present invention has achieved beneficial effects:

The straight bevel gear warm forging precision forming die disclosed in the present invention has a simple structure and is easy to operate, comprising a rough forging die composed of an upper tooth die and a lower cavity die, and a fine forging die composed of an upper cavity die and a lower tooth die. During rough forging, the tooth die is on top, and the contact time between the high-temperature blank and the tooth die is the shortest, which basically eliminates the risk of high-temperature tempering and softening of the tooth die. The failure form of the upper tooth die is only normal wear, and the service life of the tooth die is significantly improved. Among them, the present invention respectively arranges a punching structure composed of elastic elements in the upper dies of the rough forging die and the fine forging die to avoid the formed gear blank and gear from sticking to the upper die, that is, the elastic element stores energy when the die is closed, and directly uses the stored energy to separate the blank from the upper die when demolding, thereby solving the "hysteresis" when using a hydraulic device to punch the material; guide cylinders are respectively arranged on the outer circumference of the upper tooth die of the rough forging die and the lower tooth die of the fine forging die, on the one hand, for guiding the cavity die to close the tooth die to ensure that the misalignment of the upper and lower dies does not exceed 0.3mm, and on the other hand, for providing the cavity die with prestress within the covering range of the guide cylinder to avoid deformation of the tooth profile of the tooth die and prevent flash of the blank during upsetting during closing the die.

The present invention arranges a floating die lifting structure composed of an elastic structure on the lower die of the rough forging die, floats the lower cavity die from the lower cavity die pressure pad, and cooperates with the cavity die journal to accurately position the blank, ensuring that the blank to be deformed is evenly distributed in the tooth shape of the tooth model cavity during rough forging, improving the tooth shape accuracy, and reducing the deformation of the gear after the residual stress is eliminated; at the same time, it is also convenient to compress the floating die lifting structure when closing the die during rough forging, so that the first lower ejector rod partially extends into the concave model cavity, and cooperates with the first upper ejector rod to forge a recessed structure toward the inside of the tooth blank on the tooth shape end face and the journal end face of the tooth blank, thereby increasing the utilization rate of the blank by 3%.

In addition, the structure of providing prestress with the guide cylinder in the precision forging tooth die not only ensures that the modulus error between the upper and lower dies does not exceed 0.3mm, but also avoids the deformation of the tooth profile of the precision forging tooth die under the three-way compressive stress state, thereby avoiding the problem of decreased tooth shape accuracy caused by die deformation; at the same time, exhaust holes are arranged on the outer circle guide part of the precision forging upper cavity die to ensure that the lubricant is evenly distributed on the tooth surface of the precision forging gear, ensure the consistency of the precision forging tooth shape accuracy, and improve the die life by more than 68.75%.

It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and/or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG1 is a schematic structural diagram of a straight bevel gear rough forging die;

FIG2 is a schematic structural diagram of a straight bevel gear precision forging die;

FIG3 is a cross-sectional view of the upper tooth mold with the first guide cylinder in FIG1;

FIG4 is a cross-sectional view of the first upper pressure pad in FIG1 ;

FIG5 is a cross-sectional view of the lower cavity mold in FIG1 ;

FIG6 is a cross-sectional view of the pressure pad of the lower cavity mold in FIG1;

FIG7 is a cross-sectional view of the first lower pressure pad in FIG1 ;

FIG8 is a cross-sectional view of the upper cavity mold in FIG2;

FIG9 is a cross-sectional view of the second upper pressure pad in FIG2 ;

FIG10 is a cross-sectional view of the lower tooth mold in FIG2 .

In the figure, the specific meaning of each mark is as follows:

1-upper tooth mold, 2-first upper ejector rod, 3-upper tooth mold pressure pad, 4-first upper transition pad, 5-first upper pressure pad, 6-first upper ejector elastic element, 7-first guide cylinder, 8-lower cavity mold, 9-first lower ejector rod, 10-floating mold lifting elastic element, 11-lower cavity mold pressure pad, 12-first lower transition pad, 13-first lower pressure pad, 14-first lower ejector rod, 15-upper cavity mold, 16-second upper ejector rod, 17-upper cavity mold pressure pad, 18-second upper transition pad, 19-second upper pressure pad, 20-second upper ejector elastic element, 21-lower tooth mold, 22-second lower ejector rod, 23-lower tooth mold pressure pad, 24-second lower transition pad, 25-second lower pressure pad, 26-second lower ejector rod, 27-second guide cylinder.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and/or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and/or their collections. "Up", "down" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

Based on the prior art, in the forging process of spur bevel gears, when the tooth die is used as the lower die for rough forging, there is a problem of inaccurate positioning of the blank, resulting in uneven distribution of the blank between the tooth shapes when the die is closed and a low tempering and softening life of the tooth die. When the tooth die is used as the upper die for rough forging, there is a "hysteresis" problem of the hydraulic punching mechanism; in addition, there are a series of technical problems such as the requirement that the misalignment of the die does not exceed 0.3mm when only relying on equipment positioning and guide rails during forging. The present invention aims to propose a straight bevel gear warm forging precision forming die, which has a simple structure, effectively solves the above technical problems, and improves the life of the die and the precision of the formed gear as a whole.

The straight bevel gear warm forging precision forming die of the present invention is further specifically introduced below in conjunction with the embodiments shown in the accompanying drawings.

As shown in Figures 1 and 2, a straight bevel gear warm forging precision forming die includes a rough forging die and a fine forging die formed by an electric screw press automatic line, wherein the rough forging die is defined as a first upper die and a first lower die divided by a cavity parting surface in the rough forging die, and the fine forging die is defined as a second upper die and a second lower die divided by a cavity parting surface in the fine forging die; the first upper die includes an upper tooth die 1, the first lower die includes a lower cavity die 8, the second upper die includes an upper cavity die 15, and the second lower die includes a lower tooth die 21, that is, the cavity die journal is used to position the blank during rough forging, the high-temperature blank mainly stays on the lower cavity die 8 during rough forging, and its contact time with the upper tooth die 1 is also reduced, and the risk of the upper tooth die 1 being susceptible to high-temperature tempering softening is basically eliminated, and the failure form of the upper tooth die 1 is changed from the past collapse, deformation, cracking, and rapid wear early failure form to the current normal wear failure, and the service life of the upper tooth die 1 is changed from the past forming no more than 3,000 pieces to the current forming far more than 10,000 pieces, extending the service life of the rough forging tooth die by more than 200%.

In order to avoid the "hysteresis" of the upper tooth mold 1 when the upper tooth mold 1 is punched by a hydraulic device on the electric screw press automatic line, and the technical problem that the existing electric screw press automatic line has no guide column structure and can not achieve the technical problem that the error of the upper and lower molds does not exceed 0.3mm when the upper and lower molds are clamped only by the accuracy and rigidity of the equipment guide rails, the present invention improves the structure of the upper tooth mold 1 as follows. As shown in Figures 3 and 4, the first upper mold also includes a first upper punching push rod 2, an upper tooth mold pressure pad 3, a first upper transition pad 4, a first upper pressure pad 5, a first upper punching elastic element 6 and a first guide cylinder 7, wherein the lower end face of the upper tooth mold 1 is provided with an upper tooth mold cavity with an open opening facing downward, the first guide cylinder 7 is sleeved on the outer circumference of the upper tooth mold 1, and the lower end face of the first guide cylinder 7 protrudes downward from the lower end face of the upper tooth mold 1. The first upper material beating ejector rod 2 is vertically arranged in the inner holes of the upper tooth mold 1 and the upper tooth mold pressure pad 3, and is supported by the first upper transition pad 4 movably arranged in the inner holes of the upper tooth mold pressure pad 3 and the first upper pressure pad 5; the first upper transition pad 4 is a step shaft, and the step surface of the first upper transition pad 4 is supported on the upper end surface of the upper tooth mold pressure pad 3; the first upper material beating elastic element 6 is vertically arranged in the inner hole of the first upper pressure pad 5, the lower end surface of the first upper material beating elastic element 6 is in contact with the upper end surface of the first upper transition pad 4, and the first upper material beating elastic element 6, the first upper transition pad 4 and the first upper material beating ejector rod 2 constitute a coaxial phase top structure.

To ensure that the first upper material ejector rod 2 can quickly separate the tooth blank from the upper tooth mold 1 during demolding, the first upper material ejector elastic element 6 has at least a first state and a second state in the inner hole of the first upper pressure pad 5. Specifically, in the first state, the step surface of the first upper transition pad 4 supported by the first upper material ejector rod 6 is in contact with the upper end surface of the upper tooth mold pressure pad 3. At this time, the end part of the first upper material ejector rod 2 close to the upper tooth mold 1 extends into the upper tooth model cavity under the action of the first upper material ejector elastic element 6; the second state is that the first upper material ejector elastic element 6 is in a compressed state, and under the action of the mold closing pressure, the step surface of the first upper transition pad 4 is separated from the upper end surface of the upper tooth mold pressure pad 3.

The upper tooth mold 1 of the present invention is initially in the first state due to the action of the first upper material-beating elastic element 6. When the mold is closed, it is squeezed by the blank in the upper tooth model cavity. The first upper material-beating ejector rod 2 compresses the first upper material-beating elastic element 6 upward through the first upper transition pad 4, thereby realizing the pre-tightening and energy storage of the first upper material-beating elastic element 6; when demolding, the upper tooth mold 1 immediately returns upward after the slider of the electric screw press reaches the bottom dead center. The first upper material-beating elastic element 6 automatically restores its deformation without hydraulic startup, and quickly releases the stored energy. The first upper material-beating elastic element 6 pushes the first upper material-beating ejector rod 2 downward through the first upper transition pad 4 until it partially extends into the tooth model cavity of the upper tooth mold 1. The first upper material-beating ejector rod 2 pushes the formed tooth blank out of the tooth model cavity, so that the tooth blank is separated from the upper tooth mold 1 and always remains in the cavity mold 8, thereby avoiding the phenomenon that the tooth blank adheres to the upper tooth mold 1 and causes the tooth blank to fall from the upper tooth mold 1 and be damaged.

As shown in combination with Figures 5 to 7, the first lower mold also includes a first lower ejector rod 9, a floating mold lifting elastic element 10, a lower cavity mold pressure pad 11, a first lower transition pad 12, a first lower pressure pad 13 and a first lower ejector rod 14. The upper end surface of the lower cavity mold 8 is provided with a concave mold cavity with an open opening facing upward. The lower cavity mold 8 is adapted to the upper tooth mold 1, and the outer circumference of the lower cavity mold 8 is adapted to the inner hole of the first guide cylinder 7. The lower cavity mold pressure pad 11 is centrally provided with an inner hole, and the first lower ejector rod 9 is vertically arranged in the lower cavity mold 8 and the inner hole of the lower cavity mold pressure pad 11. The first lower ejector rod 9 is supported by the first lower transition pad 12 movably arranged in the inner hole of the lower cavity mold pressure pad 11. Among them, the first lower transition pad 12 is set as a vertical cylindrical shaft, and the lower end face of the cylindrical shaft is supported on the upper end face of the first lower pressure pad 13; the first lower ejector rod 14 is vertically set in the inner hole of the first lower pressure pad 13, and the upper end face of the first lower ejector rod 14 is against the lower end face of the first lower transition pad 13, and the first lower ejector rod 14, the first lower transition pad 12 and the first lower ejector rod 9 constitute a coaxial phase top structure. The floating mold lifting elastic element 10 is set in the lower cavity mold 8 to float the lower cavity mold 8 from the lower cavity mold pressure pad 11. On the one hand, it is to cooperate with the lower cavity mold shaft neck to accurately position the blank, ensure that the blank is evenly distributed in the tooth shape of the upper tooth model cavity during rough forging, reduce the deformation of the gear after the residual stress is eliminated, and improve the tooth shape accuracy; on the other hand, it is to improve the utilization rate of the blank during rough forging.

Specifically, the floating mold lifting elastic element 10 is arranged between the lower cavity mold 8 and the first lower pressure pad 13, the upper end surface of the floating mold lifting elastic element 10 abuts against the lower end surface of the lower cavity mold 8, and the lower end surface of the floating mold lifting elastic element 10 abuts against the upper end surface of the first lower pressure pad 13. The floating mold lifting elastic element 10 has at least a first compression state and a second compression state between the lower cavity mold 8 and the first lower pressure pad 13. The first compression state is that the floating mold lifting elastic element 10 supports the lower end surface of the lower cavity mold 8 and is spaced from the upper end surface of the lower cavity mold pressure pad 11, that is, it floats above the lower cavity mold pressure pad 11; the second compression state is that the floating mold lifting elastic element 10 is compressed to the lower end surface of the lower cavity mold 8 abuts against the upper end surface of the lower cavity mold pressure pad 11, and the first lower ejector rod 9 partially extends into the concave mold cavity. When the mold is closed, the floating die lifting elastic element 10 is compressed under the pressure of the upper tooth mold 1, and the floating die lifting elastic element 10 is in the second compressed state. The end of the first lower ejector rod 9 close to the first upper mold contacts the blank in the concave model cavity, and a concave structure is forged towards the inside of the gear blank on the shaft neck end face of the gear blank during forming.

At the same time, in the upper tooth mold 1, when the mold is closed, when the first upper punching elastic element 6 is in the second state, the end of the first upper punching push rod 2 close to the first lower mold also partially extends into the upper tooth model cavity to contact the blank, and a concave structure toward the inside of the tooth blank is forged on the tooth-shaped end surface of the formed tooth blank. The concave structures at both ends of the tooth blank can significantly increase the material utilization rate by 3% on the basis of the existing blank utilization rate.

During rough forging, since the first guide cylinder 7 is arranged on the outer circumference of the upper tooth die 1, the lower cavity die 8 can be accurately guided when the molds are closed to ensure that the central axes of the upper tooth die 1 and the lower cavity die 8 coincide with each other, and the misalignment between the upper and lower molds is controlled within 0.3mm. At the same time, prestress is provided to the upper tooth die 1 to prevent the tooth profile deformation caused by the three-way compressive stress on the upper tooth die 1, resulting in excessive tooth shape accuracy and flash problems.

As shown in combination with FIG8 and FIG9, the second upper mold further includes a second upper ejector pin 16, an upper cavity mold pressure pad 17, a second upper transition pad 18, a second upper pressure pad 19 and a second upper ejector elastic element 20, wherein the lower end surface of the upper cavity mold 15 is centrally provided with an upper concave mold cavity with an open opening facing downward, and the upper concave mold cavity portion protrudes downward from the lower end surface of the upper cavity mold 15 to form an outer circle guide portion of the upper cavity mold. The second upper ejector pin 16 is vertically arranged in the inner holes of the upper cavity mold 15 and the upper cavity mold pressure pad 17, and is supported on the second upper transition pad 18 movably arranged in the inner holes of the upper cavity mold pressure pad 17 and the second upper pressure pad 19; the second upper transition pad 18 is a stepped shaft, and the stepped surface of the second upper transition pad 18 is supported on the upper end surface of the upper cavity mold pressure pad 17. The second upper material beating elastic element 20 is vertically arranged in the inner hole of the second upper pressure pad 19, the lower end surface of the second upper material beating elastic element 20 is in contact with the upper end surface of the second upper transition pad 18, and the second upper material beating elastic element 20, the second upper transition pad 18 and the second upper material beating ejector rod 16 form a coaxial phase ejection structure.

To ensure that the second upper ejector pin 16 can quickly separate the formed gear from the upper cavity mold 15 during demolding, the second upper ejector elastic element 20 has at least a third state and a fourth state in the inner hole of the second upper pressure pad 19; specifically, the third state is that the second upper ejector elastic element 20 supports the step surface of the second upper transition pad 18 to contact the upper end surface of the upper cavity mold pressure pad 17, and the second upper ejector pin 16 partially extends into the upper concave model cavity; the fourth state is that the second upper ejector elastic element 20 is in a compressed state, and the step surface of the second upper transition pad 18 is separated from the upper end surface of the upper cavity mold pressure pad 17.

Similar to the rough forging process, initially, the second upper forging elastic element 20 is in the third state. When the mold is closed, it is squeezed by the blank in the upper concave model cavity, and the second upper forging push rod 16 compresses the second upper forging elastic element 20 upward through the second upper transition pad 18 to achieve pre-tightening and energy storage of the second upper forging elastic element 20; when demolding, the upper cavity mold 15 immediately returns upward after the slider of the electric screw press reaches the bottom dead center, and the second upper forging elastic element 20 automatically restores its deformation without hydraulic startup, and quickly releases the stored energy. The second upper forging elastic element 20 pushes the second upper forging push rod 16 downward through the second upper transition pad 18 until it partially extends into the upper concave model cavity, and the second upper forging push rod 16 pushes the gear obtained by fine forging out and separates from the upper cavity mold 15.

As shown in Figure 10, the second lower mold also includes a second lower ejector rod 22, a lower tooth mold pressure pad 23, a second lower transition pad 24, a second lower pressure pad 25 and a second lower ejector rod 26, wherein the lower tooth mold 21 is adapted to the upper cavity mold 15, the upper end face of the lower tooth mold 21 is provided with a lower tooth mold cavity open upward, and the outer circumference of the lower tooth mold 21 is sleeved with a second guide cylinder 27; the upper end face of the second guide cylinder 27 protrudes upward from the upper end face of the lower tooth mold 21, and the inner hole of the second guide cylinder 27 is adapted to the outer circumference of the outer circle guide part of the upper cavity mold. The second lower ejector rod 22 is vertically arranged in the inner holes of the lower tooth mold 21 and the lower tooth mold pressure pad 23, and the second lower ejector rod 22 is supported by the second lower transition pad 24 movably arranged in the inner hole of the lower tooth mold pressure pad 23, and the second lower ejector rod 22 partially extends into the lower tooth mold cavity; the second lower transition pad 24 is arranged as a vertical cylindrical shaft, and the lower end face of the cylindrical shaft is supported on the upper end face of the second lower pressure pad 25. The second lower ejector rod 26 is vertically arranged in the inner hole of the second lower pressure pad 25, and the upper end face of the second lower ejector rod 26 abuts against the lower end face of the second lower transition pad 24, and the second lower ejector rod 26, the second lower transition pad 24 and the second lower ejector rod 22 constitute a coaxial phase top structure.

The second guide cylinder 27 in the precision forging achieves the same technical effect as that in the rough forging, guiding and providing prestress. Specifically, the second guide cylinder 27 on the outer circumference of the lower tooth mold 21 cooperates with the outer circular guide part of the upper cavity mold when the mold is closed, accurately guides the upper cavity mold 15, ensures that the central axis of the upper cavity mold 15 and the lower tooth mold 21 coincide, and controls the misalignment between the upper and lower molds of the precision forging within 0.3mm. At the same time, prestress is provided to the lower tooth mold 21 to avoid the problem of reduced tooth shape accuracy caused by deformation of the tooth mold tooth profile under the three-way compressive stress state of the lower tooth mold, thereby reducing the wear of the tooth mold. In the embodiment, in order to improve the consistency of tooth shape accuracy during precision forging and increase the life of the precision forging mold, exhaust holes are arranged on the outer circular guide part of the upper cavity mold to ensure the uniform distribution of lubricants on the tooth surface of the upper tooth mold cavity, and the life of the precision forging mold is increased by more than 68.75%.

In the embodiment, in order to ensure that the first guide cylinder 7 and the second guide cylinder 27 have sufficient rigidity to guide the cavity mold and provide prestress, the first guide cylinder 7 and the second guide cylinder 27 are made of H13 mold steel with a hardness of HRC44-HRC48, and the upper end face of the first guide cylinder 7 abuts against the lower end face of the upper tooth mold pressure pad 3, and the lower end face of the second guide cylinder 27 abuts against the upper end face of the lower tooth mold pressure pad 23. The first guide cylinder 7 has an interference fit with the upper tooth mold 1, and the second guide cylinder 27 has an interference fit with the lower tooth mold 21. The interference coefficient is maintained at 4‰-6‰ for the best. At the same time, in order to ensure the implementation effect of the first guide cylinder 7 and the second guide cylinder 27, the height difference between the lower end face of the first guide cylinder 7 and the lower end face of the upper tooth mold 1 in the vertical direction is defined as H1, the height difference between the upper end face of the second guide cylinder 27 and the upper end face of the lower tooth mold 21 in the vertical direction is defined as H2, and the height of the outer circle guide part of the upper cavity mold protruding from the lower end face of the upper cavity mold 15 is H3, then H3=H2, H2≥23mm, H1≥40mm; when the lower cavity mold 8 does not contact the blank in the upper tooth mold 1, the entire outer circumference has entered the interior of the first guide cylinder 7 by more than 5mm.

Further in combination with the embodiment shown in FIG1 , the lower cavity mold pressure pad 11 is also provided with a plurality of through holes penetrating the upper and lower end surfaces of the lower cavity mold pressure pad 11 , and the through holes are evenly arranged around the inner hole of the lower cavity mold pressure pad, and the floating mold lifting elastic element 10 is arranged in the through holes and is set as a spring. In the embodiment shown in the accompanying drawings, four through holes are arranged around the inner hole of the lower cavity mold pressure pad, and the spring is a rectangular spring with a model of SG25X12.5X125. Four rectangular springs are evenly distributed in the through holes as a combination, and the preset compression stroke of the rectangular spring is 10 mm, that is, the floating height of the lower cavity mold 8 on the upper end surface of the lower cavity mold pressure pad 11 does not exceed 10 mm.

In order to reduce the axial space occupied by the upper punching elastic element in the upper die, the first upper punching elastic element 6 is set as the first nitrogen spring, and the second upper punching elastic element 20 is set as the second nitrogen spring. The model of the nitrogen spring is U4700-16. At the same time, since the nitrogen spring has high requirements for the ambient temperature of use, the normal operating temperature of the nitrogen spring is in the range of 0℃-40℃, otherwise it will cause the early failure of the nitrogen spring seal, reduce the normal service life of the nitrogen spring, and affect the continuity of the automatic line production. Therefore, in order to ensure the stability of the working environment temperature of the nitrogen spring, the embodiment is provided with a first cooling mechanism in the first upper pressure pad 5 and a second cooling mechanism in the second upper pressure pad 19, and the nitrogen spring is adjusted to the normal working temperature, as shown in Figures 4 and 9. The cooling mechanism can be specifically implemented by combining a temperature measuring thermocouple with a cooling circulation channel. For example, the lower limit temperature of the temperature measuring thermocouple is set at 10°C and the upper limit temperature is set at 30°C. The signal is transmitted to the control center PLC through the temperature measuring thermocouple. The PLC instructs the switch to introduce compressed air into the cooling circulation channel to ensure that the nitrogen spring works within the specified ambient temperature.

The straight bevel gear warm forging precision forming die of the present invention changes the damage form of the rough and fine forging dies into normal wear failure by adjusting the die composition, automatically punching the upper die, accurately positioning the blank and setting a prestressed guide mechanism, thereby significantly increasing the service life of the rough and fine forging dies and improving the tooth profile accuracy and blank utilization rate.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims (8)

1. A straight bevel gear warm forging precision forming die, comprising a rough forging die and a fine forging die formed by an electric screw press automatic line, wherein the rough forging die is defined as a first upper die and a first lower die with the die cavity parting surface as the boundary, and the fine forging die is defined as a second upper die and a second lower die with the die cavity parting surface as the boundary; characterized in that the first upper die comprises an upper tooth die, a first upper punching ejector rod, an upper tooth die pressure pad, a first upper transition pad, a first upper pressure pad, a first upper punching elastic element and a first guide cylinder; The lower end surface of the upper tooth mold is provided with an upper tooth model cavity which is open downward, the first guide cylinder is sleeved on the outer circumference of the upper tooth mold, and the lower end surface of the first guide cylinder protrudes downward from the lower end surface of the upper tooth mold; the height difference between the lower end surface of the first guide cylinder and the lower end surface of the upper tooth mold in the vertical direction is defined as H1, then H1≥40mm; the first upper material ejector rod is vertically arranged in the inner holes of the upper tooth mold and the upper tooth mold pressure pad, and is supported on the first upper transition pad movably arranged in the inner holes of the upper tooth mold pressure pad and the first upper pressure pad; the first upper transition pad is a step shaft, and the step surface of the first upper transition pad is supported on the upper end surface of the upper tooth mold pressure pad; the first upper material elastic element is vertically arranged in the inner hole of the first upper pressure pad, the lower end surface of the first upper material elastic element is in contact with the upper end surface of the first upper transition pad, and the first upper material elastic element, the first upper transition pad and the first upper material ejector rod constitute a coaxial phase top structure; The first upper punching material elastic element has at least a first state and a second state in the inner hole of the first upper pressure pad; the first state is that the step surface of the first upper punching material elastic element supporting the first upper transition pad is in contact with the upper end surface of the upper tooth mold pressure pad, and the first upper punching material ejector rod partially extends into the upper tooth mold cavity; the second state is that the first upper punching material elastic element is in a compressed state, and the step surface of the first upper transition pad is spaced from the upper end surface of the upper tooth mold pressure pad; The first lower mold comprises a lower cavity mold, a first lower ejector rod, a floating mold lifting elastic element, a lower cavity mold pressure pad, a first lower transition pad, a first lower pressure pad and a first lower ejector rod; The upper end surface of the lower cavity mold is provided with a concave model cavity with an open mouth facing upward, the lower cavity mold is adapted to the upper tooth mold, and the outer circumference of the lower cavity mold is adapted to the inner hole of the first guide cylinder; the lower cavity mold pressure pad is centrally provided with an inner hole, the first lower ejector rod is vertically arranged in the lower cavity mold and the inner holes of the lower cavity mold pressure pad, and the first lower ejector rod is supported by a first lower transition pad movably arranged in the inner hole of the lower cavity mold pressure pad; the first lower transition pad is arranged as a vertical cylindrical shaft, and the lower end surface of the cylindrical shaft is supported on the upper end surface of the first lower pressure pad; the first lower ejector rod is vertically arranged in the inner hole of the first lower pressure pad, the upper end surface of the first lower ejector rod is in contact with the lower end surface of the first lower transition pad, and the first lower ejector rod, the first lower transition pad and the first lower ejector rod constitute a coaxial phase ejection structure; The floating mold-lifting elastic element is arranged between the lower cavity mold and the first lower pressure pad, the upper end surface of the floating mold-lifting elastic element abuts against the lower end surface of the lower cavity mold, and the lower end surface of the floating mold-lifting elastic element abuts against the upper end surface of the first lower pressure pad; the floating mold-lifting elastic element has at least a first compression state and a second compression state between the lower cavity mold and the first lower pressure pad, the first compression state is that the floating mold-lifting elastic element supports the lower end surface of the lower cavity mold and is spaced from the upper end surface of the lower cavity mold pressure pad, and the second compression state is that the floating mold-lifting elastic element is compressed until the lower end surface of the lower cavity mold abuts against the upper end surface of the lower cavity mold pressure pad, and the first lower ejector rod partially extends into the concave mold cavity; The second upper mold includes an upper cavity mold, and the second lower mold includes a lower tooth mold, and the lower tooth mold is adapted to the upper cavity mold; The second upper mold further comprises a second upper ejector pin, an upper cavity mold pressure pad, a second upper transition pad, a second upper pressure pad, and a second upper ejector elastic element; The lower end surface of the upper cavity mold is centrally provided with an upper concave model cavity with an open opening facing downward, and the upper concave model cavity portion protrudes downward from the lower end surface of the upper cavity mold to form an outer circle guide portion of the upper cavity mold; the second upper punching ejector rod is vertically arranged in the inner holes of the upper cavity mold and the upper cavity mold pressure pad, and is supported on the second upper transition pad movably arranged in the inner holes of the upper cavity mold pressure pad and the second upper pressure pad; the second upper transition pad is a step shaft, and the step surface of the second upper transition pad is supported on the upper end surface of the upper cavity mold pressure pad; the second upper punching elastic element is vertically arranged in the inner hole of the second upper pressure pad, the lower end surface of the second upper punching elastic element is in contact with the upper end surface of the second upper transition pad, and the second upper punching elastic element, the second upper transition pad and the second upper punching ejector rod form a coaxial phase top structure; The second upper punching elastic element has at least a third state and a fourth state in the inner hole of the second upper pressure pad; the third state is that the step surface of the second upper punching elastic element supporting the second upper transition pad is in contact with the upper end surface of the upper cavity mold pressure pad, and the second upper punching ejector pin partially extends into the upper concave mold cavity; the fourth state is that the second upper punching elastic element is in a compressed state, and the step surface of the second upper transition pad is spaced from the upper end surface of the upper cavity mold pressure pad; The second lower mold also includes a second lower ejector rod, a lower tooth mold pressure pad, a second lower transition pad, a second lower pressure pad and a second lower ejector rod; the upper end surface of the lower tooth mold is provided with a lower tooth mold cavity with an open opening facing upward, and the outer circumference of the lower tooth mold is sleeved with a second guide cylinder; the upper end surface of the second guide cylinder protrudes upward from the upper end surface of the lower tooth mold, and the inner hole of the second guide cylinder is adapted to the outer circumference of the outer circle guide part of the upper cavity mold; the second lower ejector rod is vertically arranged in the inner holes of the lower tooth mold and the lower tooth mold pressure pad, and ... The rod is supported by a second lower transition pad movably arranged in the inner hole of the lower tooth mold pressure pad, and the second lower ejector rod partially extends into the lower tooth model cavity; the second lower transition pad is arranged as a vertical cylindrical shaft, and the lower end face of the cylindrical shaft is supported on the upper end face of the second lower pressure pad; the second lower ejector rod is vertically arranged in the inner hole of the second lower pressure pad, and the upper end face of the second lower ejector rod is in contact with the lower end face of the second lower transition pad, and the second lower ejector rod, the second lower transition pad and the second lower ejector rod constitute a coaxial phase top structure. 2. The straight bevel gear warm forging precision forming mold according to claim 1 is characterized in that the height difference between the upper end surface of the second guide cylinder and the upper end surface of the lower tooth mold in the vertical direction is defined as H2, and the height of the outer circle guide part of the upper cavity mold protruding from the lower end surface of the upper cavity mold is H3, then H3=H2, H3≥23mm. 3. The straight bevel gear warm forging precision forming die according to claim 1, characterized in that an exhaust hole is provided on the outer circle guide portion of the upper cavity die. 4. The straight bevel gear warm forging precision forming die according to claim 1 is characterized in that the upper end face of the first guide cylinder abuts against the lower end face of the upper tooth die pressure pad, the lower end face of the second guide cylinder abuts against the upper end face of the lower tooth die pressure pad, and the first guide cylinder has an interference fit with the upper tooth die, and the second guide cylinder has an interference fit with the lower tooth die. 5. The straight bevel gear warm forging precision forming mold according to claim 1 is characterized in that the lower cavity mold pressure pad is also provided with a plurality of through holes penetrating the upper and lower end surfaces of the lower cavity mold pressure pad, and the through holes are evenly arranged along the circumference of the inner hole of the lower cavity mold pressure pad; the floating mold lifting elastic element is arranged in the through hole and is set as a spring. 6. The straight bevel gear warm forging precision forming die according to claim 4, characterized in that the first guide cylinder and the second guide cylinder are made of H13 die steel. 7. The straight bevel gear warm forging precision forming die according to claim 1, characterized in that the first upper punching elastic element is set as a first nitrogen spring, and the second upper punching elastic element is set as a second nitrogen spring. 8. The straight bevel gear warm forging precision forming die according to claim 7, wherein a first cooling mechanism is provided in the first upper pressure pad, and a second cooling mechanism is provided in the second upper pressure pad.