JP3758147B2 - Progressive pressing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a progressive press processing method for manufacturing a product by sequentially performing a plurality of press processing on a strip steel plate .
[0002]
[Prior art]
First, an example of a progressive press working method according to the prior art will be described in the case of machining a reclining gear 20 used for an automobile seat as shown in FIGS. The reclining gear 20 is provided with a support hole 23 at the center of a large half-cut portion 21 formed in a recess in the center, and an arc shape of a fan-shaped portion 21a formed on one side of the half-cut portion 21 with the support hole 23 as a center. A tooth portion 21b that forms an internal fan-shaped gear is formed at a part of the edge portion of the tooth. An arc-shaped contact surface 22 centered on the support hole 23 is formed in the sector 21a, and an arc projection 24 centered on the support hole 23 is formed on the opposite side. Further, two mounting holes 25 having chamfered portions 25a and two protrusions 26 having a center hole are formed in the flat peripheral portion 20a outside the half punched portion 21.
[0003]
The reclining gear 20 is required to have the accuracy of the shape of the tooth portion 21b that meshes with a member provided in the half-cut portion 21 due to its function. Further, the flatness of the abutting surface 22 that abuts and supports the side surface of the member and the peripheral portion 20a of the reclining gear 20 and the parallelism between the peripheral portion 20a and the abutting surface 22 (hereinafter, these are simply referred to as flatness). Is required). Products that require shearing and other parts that require shearing accuracy and flatness of other parts are not limited to reclining gears, but seats such as reclining guides, seat ratchets, and seat hooks. There are many parts such as door parts such as door latches and door hooks.
[0004]
In the case of manufacturing such a reclining gear, in the progressive press working method, as shown in FIG. 7, the strip steel plate 16 supported by the uncoiler 10 is drawn out in a wound state, and the curl is corrected through the leveler 11. The feeder 12 is fed into the press device 1 for processing. Although simplified in FIG. 7, the press apparatus 1 includes processing stations corresponding to the three processing steps Q1 to Q3 shown in FIG. As shown in FIG. 8, the following cold working is performed on the strip-shaped steel plate 16 made of the spheroidized annealing material fed into the pressing device 1 at each processing station. That is, in each first processing station, processing such as pilot hole punching, punching of the contact surface 22, punching of the mounting hole 25, half punching of the protrusion 26 is performed (indicated by a thick solid line in the first step Q1 in FIG. 8). In each of the following processing stations, the half punched portion 21 is punched out, the support hole 23 is punched out, the arc projection 24 is half punched out, the projection 26 is punched out, and the chamfered portion 25a of the mounting hole 25 is processed (first). indicated by a thick solid line in two steps Q2), at the end of the processing stations, indicated by a thick solid line in the processing such as contour punching is performed (third step Q 3). In this prior art, quenching and tempering is continued, and this reduces flatness, so that a plurality of reclining gears 20 are tightened between the correction jigs so that each portion requiring flatness is brought into contact and corrected. The flatness is improved by performing press tempering, the flatness of the reclining gear 20 is further increased by belt polishing, and the surface is finished by barrel treatment.
[0005]
As a method of heating and pressing with respect to the cold working example described above, as disclosed in JP 2000-033435, the work is heated in the direction of pressing the work after being heated by a high-frequency heater. There is a pressing method in which pressing is performed by a fine blanking method while sandwiching. However, the press working method disclosed here is only a simple fine blanking method, and there is no suggestion about the applicability of the half punch press working and the progressive press working method including this.
[0006]
[Problems to be solved by the invention]
In the first prior art described above, since the press working in each process is performed by cold working, a spheroidized annealing material is required as the strip steel plate 16, and the half-punched part reaches the fracture limit due to cold working. There is a problem that the strength decreases. Furthermore, since the spring back is large, the flatness after processing is reduced, and the residual stress accompanying the processing is also large, so the flatness after quenching and tempering is also reduced. Since planar polishing is required, there is a problem that the number of processing steps increases and the manufacturing cost increases.
[0007]
The present invention solves each of the above problems, eliminates the strength reduction of the processing portion accompanied by the shearing portion such as the half-punched processing portion, and eliminates the strength reduction of the flat surface due to the spring back and residual stress after the press processing. It aims at reducing.
[0008]
[Means for Solving the Problems]
Therefore, progressive stamping method of the present invention is a progressive stamping process for producing the product sequentially subjected to multiple press working the steel strip, only the range to be processed to the next of the steel strip before pressing The first step of heating to the temperature range A of the temperature (° C.)-Elongation rate δ (%) curve shown in FIG. 6 and the temperature of the heated range of the strip steel plate are the temperature range of A. The second step of performing press working with shear in the same range in the state, and the temperature (° C.) − Tensile strength σB (kg) shown in FIG. 6 in which the heated range of the strip steel plate is lower than the second step / Mm ² ) It is characterized by comprising a third step of performing press working including processing for correcting distortion in the same range in a state where the temperature is in the temperature range B of the curve .
As shown in FIG. 6, in the temperature range A, the elongation δ (%) of the strip steel plate is higher than that before heating (at room temperature) (temperature range A: 40 to 55%, heating) (Previous: 35%) No breakage occurs even when press working including half punching with shearing. Further, in the temperature range of B, the tensile strength σB (kg / mm ² ) of the strip steel plate is lower than that before heating (at room temperature) (temperature range B: 45 to 25 kg / mm ² , before heating: 48 kg / mm ² ) Even if press processing including processing for correcting distortion is performed, the spring back after processing can be reduced as compared with the case of processing at normal temperature .
Furthermore, the temperature range of A may be 550 to 600 ° C, and the temperature range of B may be 350 to 400 ° C.
[0009]
In the invention of the preceding paragraph, it is preferable that the press working with shear in the second step is a half punching process, and the press working for correcting the distortion in the third process is a flat straightening.
[0010]
The heating in the first step of the inventions of the preceding two items is preferably performed by a high frequency heating device.
[0011]
Furthermore, it is desirable that the material heated by the high-frequency heating device before being fed into the press device is fed out from the press device using a feeder.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the progressive press working method according to the present invention will be described with reference to FIGS. 1, 2, 4 and 5. FIG. FIG. 1 is a diagram showing the overall arrangement of the apparatus used in this embodiment . FIG. 7 shows that a heating coil 14a of a high-frequency heating apparatus 14 for heating the strip steel plate 16 is provided between the feeder 12 and the pressing apparatus 13 . It is only different from the prior art shown. The reclining gear 20 manufactured according to this embodiment is the one shown in FIGS. 4 and 5 as described in the prior art. Further, the steel strip 16 in the hot-rolled structural carbon steel (S30C), characteristics of tensile strength σB and elongation δ for that temperature is shown in FIG.
[0013]
The apparatus used in this embodiment is composed of an uncoiler 10, a leveler 11, a feeder 12, a pressing device 13 and a high-frequency heating device 14, and a heating coil 14a is shown between the feeder 12 and the pressing device 13 in FIG. The heating coil 14a of the high-frequency heating device 14 constituting the heating station corresponding to the first step P1 is provided, and the press device 13 includes two processing stations corresponding to the second step P2 and the third step P3 shown in FIG. The apparatus is the same as that used in the prior art shown in FIG. 7 except that it is provided. In the progressive pressing method of this embodiment, as shown in FIG. 1, the strip steel plate 16 supported by the uncoiler 10 in the wound state is drawn out, and the feeder 12 corrects curl through the leveler 11 and then the feeder 12. Through the heating coil 14a of the high-frequency heating device 14, it is intermittently fed (retracted) into the press device 13. The portion provided with the heating device 14a is a heating station in which the first step P1 shown in FIG. 2 is performed. Although shown in FIG. 1 in a simplified manner, the pressing device 13 includes the second step P2 shown in FIG. Two processing stations corresponding to the third step P3 are provided.
[0014]
In the first step P1, the high-frequency heating device 14 outputs the oscillated high-frequency current to the heating coil 14a, and electromagnetically heats the strip steel plate 16 in the heating station. As a result, the range of the strip-shaped steel plate 16 that is sent to the press device 13 and processed next is the temperature range in which the fracture is prevented at the time of half-punching of the half-punched portion 21, that is, the elongation δ is larger than room temperature. Is rapidly heated to a temperature range of 550 to 600 ° C. or higher (see temperature range A in FIG. 6).
[0015]
The range of the strip-shaped steel plate 16 heated by the high-frequency heating device 14 is transferred from the heating coil 14a to the first processing station in the press device 13, and is in a temperature range A shown in FIG. Processing in the second step P2, that is, processing such as pilot hole punching, half punching of the half punched portion 21, punching of the contact surface 22, half punching of the arc projection 24, punching of the support hole 23 and the mounting hole 25 is performed ( (Indicated by a thick solid line in the second step P2 of FIG. 2). The temperature of the heated range of the strip steel plate 16 is lowered by transmission to the mold in the second step P2, and is a temperature range in which the spring back after processing is reduced from room temperature although it is lower than the temperature range A, that is, tensile. The strength σB is a temperature range of 350 to 400 ° C. or more (see temperature range B in FIG. 6), which is smaller than normal temperature. The temperature of the strip steel plate 16 is adjusted by changing the heat transfer state by adjusting the clearance between the mold and the strip steel plate 16 in the second step P2.
[0016]
Next, the range of the strip steel plate 16 processed at the first processing station in the press device 13 is transferred to the second processing station in the press device 13 and is in the temperature range B shown in FIG. In the state, the processing of the third step P3, that is, the punching of the outer shape, the punching of the protrusion 26, the processing of the chamfered portion 25a of the mounting hole 25 (shown by a thick solid line in the third step P3 of FIG. 2), and the reclining gear 20 The peripheral portion 20a, the half punched portion 21 and the abutting surface 22a are strongly pressed from both sides by a mold so as to perform flattening molding of these portions.
[0017]
In this embodiment, since the structural carbon steel hot-rolled material is used as the strip-shaped steel plate 16, quenching and tempering are continuously performed. However, the flat surface forming in the third step P3 is performed in the temperature range B described above. Since the residual stress associated with the flattening molding is small, the flatness is not lowered by quenching and tempering. Therefore, the press temper and the belt polishing process as in the prior art described above are unnecessary. Finally, the surface is finished by barrel processing, and the processing of the reclining gear 20 by the progressive press method is completed.
[0018]
According to the above-described embodiment, the range of the strip-shaped steel plate 16 heated at high frequency in the first step P1 is the temperature range A in which breakage is prevented during the half-punch press processing of the half-punch portion 21 in the second step P2. , i.e., elongation δ is performing press working including the half die cutting with Oite shear temperature range which is larger than the normal temperature, the tooth portions 21b requiring precision formed only shear without breaking occurs In addition, there is no possibility that the connecting portion of the half punched portion is broken and the strength is not lowered. In the third step P3, the temperature of the strip steel plate 16 is lower than the temperature range A, but the temperature range B in which the springback after processing is reduced from room temperature, that is, the temperature range in which the tensile strength σB is lower than room temperature. Since press processing including flattening molding is performed in B, the decrease in flatness due to quenching and tempering after press processing is reduced, thereby eliminating the need for a post-process that improves flatness, thereby reducing manufacturing costs. Can be made.
[0019]
Further, in this embodiment, the heating in the first step P1 is performed by the high-frequency heating device 14, and thereby the time required to heat the strip steel plate 16 is shortened, so that the processing cycle of the progressive press working method is increased. Productivity.
[0020]
In the above-described embodiment, S30C is used as the strip-shaped steel plate 16, or S45C is often used. In these cases, quenching and tempering after progressive pressing is required as described above. . However, if a high-strength material such as high-carbon steel (for example, S65C) is used, quenching and tempering after the progressive press work becomes unnecessary, so that productivity and flatness can be further improved.
[0021]
A modification of the apparatus shown in FIG. 1 is shown in FIG. In the apparatus of FIG. 3, a feeder 15 is provided behind the press apparatus 13, and the strip 15 is sandwiched between a pair of rollers that intermittently rotate in the opposite direction by the feeder 15. Thus, it is fed out from the press device 13. The reason why the feeder 15 that operates in this manner is arranged behind the press device 13 is as follows. In the apparatus of FIG. 1, the strip steel plate 16 is intermittently transferred into the press apparatus 13 from the feeder 12 positioned in front of the press apparatus 13 and is intermittently transferred in the press apparatus 13. However, this intermittent transfer and transfer are performed synchronously. Thus, when the strip steel plate 16 is fed into the press device 13, it is weakened in strength immediately after being heated at high frequency. Therefore, the feeding speed of the strip steel plate 16 into the press device 13 by the feeder 12 and the inside of the press device 13 are reduced. If the transfer speed of the belt-shaped steel plate 16 is deviated at this time, the belt-shaped steel plate 16 may be buckled and deformed due to the resultant reaction force, which may become unusable. For this reason, it is necessary to constantly check the transfer mechanism in the press device 13 so as to prevent such a shift, and to wipe off factors that deviate the transfer speed, such as dust. However, if the feeder 15 is installed behind the press device 13 so that the strip steel plate 16 is fed out of the press device 13, the strip steel plate 16 can be transferred at a stable speed without wiping off dust continuously. Yes. In this case, the feeder 12 on the front side stops the feeding operation when the strip steel plate 16 is inserted into the feeder 15 on the rear side (specifically, the gap between the pair of rollers is widened, and the strip steel plate 16 removes the feeder 12 from the feeder 12. Just pass through).
In addition, the strip | belt-shaped steel plate 16 drawn | fed out from the feeder 15 is cut | disconnected by predetermined length, for example with the cutter 17 provided as an option, and is thrown into a scrap processing process.
[0022]
The embodiment of the present invention has been described above. However, the present invention is not intended to be limited to the above-described embodiment, and any progressive press working method according to the spirit of the present invention can be used. But you can.
[0023]
【The invention's effect】
According to the present invention, in the second step, in the state where the elongation rate of the heated range of the band-shaped metal plate is a temperature higher than room temperature, the range includes a process involving shearing such as a half punching process. Since the press working is performed, the risk of the strength being lowered due to breakage in the processed portion with shearing is greatly reduced. Further, in the third step, a press including processing for correcting distortion such as flat surface correction molding in the same range in a state where the tensile strength in the heated range of the band-shaped metal plate is lower than normal temperature. Since the processing is performed, there is no decrease in flatness due to springback or residual stress after press processing, thereby eliminating the need for post-processing to improve the flatness, thereby reducing the manufacturing cost.
[0024]
Moreover, according to what heated in the 1st process was performed with the high frequency heating apparatus, since the time required to heat the processing range of a strip steel plate is shortened, the processing cycle of a progressive press processing method is raised and productivity is increased. Can be improved.
[0025]
Furthermore, since the strip steel plate is fed out by a feeder installed on the rear side of the press device, the strip steel plate can be reliably transferred at a stable speed in the press device, and the strip shape is weakened due to high frequency heating. The steel plate does not buckle.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall arrangement of an apparatus used in an embodiment of a progressive press working method according to the present invention.
FIG. 2 is a diagram showing each processing step in the embodiment shown in FIG. 1;
3 is a diagram showing a modification of the overall arrangement of the apparatus shown in FIG.
4 is a plan view showing a shape of an example of a product manufactured in the embodiment shown in FIG. 1. FIG.
5 is a cross-sectional view taken along the line 5-5 in FIG.
6 is a diagram showing the characteristics of tensile strength and elongation rate with respect to temperature of an example of a material used for the strip steel plate used in the embodiment shown in FIG. 1; FIG.
FIG. 7 is a diagram showing an overall arrangement of an apparatus used in an example of a progressive press working method according to the prior art.
FIG. 8 is a diagram showing each processing step in the embodiment shown in FIG. 7;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 13 ... Press apparatus, 15 ... Back side feeder, 16 ... Strip steel plate , 20 ... Product (reclining gear ), P1 ... 1st process, P2 ... 2nd process, P3. ..Third process

Claims (5)

In progressive stamping process for producing the product sequentially subjected to multiple press working the steel strip, the temperature (℃) shown in FIG. 6 only the range to be processed to the next of the steel strip before pressing - elongation [delta] ( %) In the first step of heating to the temperature range A of the curve, and in the state where the temperature in the heated range of the strip steel plate is in the temperature range of A, press working with shearing in the same range is performed. The temperature in the temperature range of B in the temperature (° C.)-Tensile strength σ B (kg / mm ² ) curve shown in FIG. 6 where the heated range of the strip steel plate is lower than the second step and the second step . A progressive press working method characterized by comprising a third step of performing a press work including a process of correcting distortion in the same range in a state where The progressive press working method according to claim 1, wherein the temperature range of A is 550 to 600 ° C, and the temperature range of B is 350 to 400 ° C. 2. The progressive press working method according to claim 1, wherein the press working with shearing in the second step is half punching, and the press working for correcting distortion in the third step is flat straightening. Progressive press working method. In progressive press processing method according to claim 1 to 3, wherein, progressive stamping process heating in the first step and performing a high-frequency heating apparatus. In progressive stamping process for producing the product sequentially subjected to multiple press working the steel strip, heating the steel strip by high-frequency heating device provided on the front side of the press device for performing press working, the high-frequency heating apparatus 5. A progressive press working method according to claim 1 , wherein the feeder on the front side stops the feeding operation when the strip steel plate is put into a feeder provided behind the press device. .

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