JPH1133791A - Multi step powder molding press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the crack with a proportional pressing method by positioning a punch, using a pressurizing end position stopper at the pressurizing end position. A control device of a fluid cylinder, which drives a movable punch corresponding to the dimension rate of each step part of a molding product, is installed, and the maximum pressure of the fluid pressure cylinder is set smaller than the final molding pressure. SOLUTION: In the case of the first powder part 591, an upper first punch 7 is pressurized by an upper ram against a bottom first punch 27 fixed. The second powder part 592 is pressurized by an upper second punch 8 and a bottom second punch while the upper and bottom second oil pressure cylinders are controlled to equalize the condensation with that of the first powder part 591. The third powder part 593 is controlled and pressurized in the same way. The upper second, bottom second, upper third, and bottom third oil pressure cylinders are controlled so that the lowering speed of the related upper and bottom punches satisfies a given rate relation against the dimension of each step part with respect to the bottom face of the first step part W1 of a molding product W as a basis. Thus the 1st-3rd powder parts 591-593 have the same condensation, so the powder does not move to each other and the crack is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage powder molding press having a movable punch driven by fluid pressure and compressing and molding powder in multiple stages.

[0002]

2. Description of the Related Art Applicants have already precisely controlled the movement of each punch by a hydraulic cylinder in order to form a stepped product, and have measured the size between powder portions compressed at any stage during pressurization. There has been proposed a multi-stage powder molding press in which all the punches are proportionately moved so that all the ratios match the dimensional ratio between the steps of the green compact to be molded (Japanese Patent Laid-Open No. 4-94).
No. 900).

However, when the hydraulic cylinder is driven to the pressurizing completion position, the hydraulic cylinder becomes too large. Therefore, paying attention to the fact that powder movement causing cracks in the molded product does not occur at the stage of solidification just before the completion of pressurization, the proportional control is set to the position before the pressurization completion where the pressing force does not become too large. Proposed a multi-stage powder compacting press that mechanically determines the complete pressurization completion position (Japanese Patent Laid-Open No. 6-1).
98497).

[0004]

However, in the case of the prior art described above, the pressurizing start position or the transfer ending position is determined by the fluid pressure cylinder, resulting in inefficient and expensive equipment.

In addition, the control of the proportional pressurization is performed by digitally and precisely by a computer, which is also an expensive facility.

Further, the amount of deformation of the punch corresponding to each step at the time of completion of pressurization differs depending on the difference in the length of the punch for pressing each step, and if the pressing force of the punch is suddenly released as it is, Since the amount of elastic return of each punch becomes non-uniform, each step of the molded product is partially pushed up or down, and there is a possibility that a crack may occur at the time of removal of the pressurized product. Therefore, a pressure release mechanism is provided so that the pressing force does not suddenly drop, but the adjustment is very troublesome.

The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide a multi-stage powder capable of preventing the occurrence of cracks by applying a proportional pressure with a simple structure. It is to provide a forming press.

It is another object of the present invention to provide a multi-stage powder molding press capable of easily performing a pressure release adjustment.

[0009]

According to the present invention, there is provided an improvement of a mechanically operated mechanical press such as a crank, a toggle, a cam, and the like. The pressurization end position is mechanically positioned, and the pressurizing operation during that time is made proportional to the movement of the upper ram, so that good products can be easily molded even if the capacity of the fluid pressure cylinder is reduced. Things.

Further, when the pressure is released after the completion of the pressurization, in order to prevent the occurrence of cracks due to the difference in the amount of deflection of each punch, a force corresponding to the area is applied to each punch to prevent the crack.

That is, an upper punch assembly attached to the upper ram of the mechanical press body, and a lower punch assembly attached to the mechanical press body, wherein at least one of the upper punch assembly and the lower punch assembly is provided. Is provided with a plurality of punches and a hydraulic cylinder for driving at least one movable punch of the plurality of punches is mounted, and a pressurizing start for positioning a pressurizing start position of the movable punch driven by the hydraulic cylinder is provided. In a machine provided with a position stopper mechanism and a pressurization end position stopper mechanism for positioning a pressurization end position, and in a fluid pressure multi-stage powder molding press, a part of a plurality of powder portions to be compressed by the upper and lower punches is mechanical. Pressing only by the mechanical movement of the punch linked to the upper ram of the press body, the rest of the plurality of powder portions, A fluid pressure cylinder that drives the movable punch so that each powder portion has the same ratio as the dimensional ratio of each step of the final molded product based on the mechanical movement of the upper ram from the pressing start position. Control mechanism, the maximum pressure of the fluid pressure cylinder is set smaller than the final forming pressure, and at the pressurization completion position, the punch is positioned by a mechanical pressurization end position stopper mechanism. I do.

In the composite type multi-stage powder molding press having the above structure, first, the powder is filled in the die hole, and the pressurizing start position of the movable punch driven by the hydraulic cylinder among the upper and lower punches is determined by the hydraulic cylinder. Is positioned by a mechanical pressurization start position stopper mechanism abutted by the fluid pressure. Here, the pressurization start position is a powder filling position when no transfer is performed, and a transfer completion position when transfer is performed.

A part of the plurality of powder portions to be compressed by the upper and lower punches is pressed only by the mechanical movement of the punch linked to the upper ram of the mechanical press body.

On the other hand, the remainder of the plurality of powder portions is converted into the dimensional ratio of each step of the final molded article by the movement of the hydraulic cylinder superimposed on the mechanical movement of the punch. The ratios are controlled so as to be the same.

Since the maximum pressure of the fluid pressure cylinder is set to be smaller than the final molding pressure, the hydraulic press is driven only by the press pressure of the upper ram of the mechanical press main body during the pressing completion position, and the final size Is positioned by the pressure end position stopper mechanism. After the powder is hardened to a predetermined pressure, the powder does not move, so that no crack occurs. In the case of powder molding, it is particularly important that the powder is compacted to a certain degree from the start of pressurization.

Therefore, a high-quality green compact with no cracks and high accuracy can be formed even though it is a small-capacity hydraulic cylinder.

The control mechanism includes upper ram position detecting means for detecting the position of the upper ram, punch position detecting means for detecting the position of each movable punch, a servo amplifier, and an electro-hydraulic servo valve. The gain of the servo amplifier is adjusted so that the movement of the hydraulic cylinder of each movable punch with respect to the movement of the upper ram has a predetermined ratio, thereby obtaining the control target value of the hydraulic cylinder of each movable punch, and the signal from the punch position detecting means. And a servo mechanism for controlling so as to eliminate the deviation from the control target value.

With this configuration, the pressurizing operation can be performed at a speed proportional to the movement of the upper ram only by adjusting the gain of the servo amplifier.

Further, the control mechanism includes a mechanical proportional valve whose flow rate changes in proportion to a mechanical input of an operating member for reciprocating the spool, and a mechanical proportional movement of the upper ram at a predetermined ratio. A motion transmission mechanism for transmitting the motion to the operation member of the valve.

In this way, each movable punch can be actuated in proportion to the movement of the upper ram by the mechanical proportional valve, and electrical control is not required.

Further, when the mechanical pressing force applied by the upper ram applied to the molded product after the pressurization is completed, a pressure release mechanism for removing each step portion of the molded product while applying a small force by using the upper and lower punches. It is characterized by having.

When the pressure is released after completion of pressurization, a separately adjustable valve is attached to each punch in order to prevent the occurrence of cracks due to the difference in the amount of deflection of each punch, and the cylinder is pulled out while applying a weak force to each punch. In addition, the performance of the mechanical press body can be greatly improved.

The depressurizing mechanism includes a pressing means for depressing the upper punch assembly with respect to the upper ram, and a hydraulic cylinder for displacing the movable punch by a fluid pressure cylinder to determine a difference in extension between a plurality of punches of the upper and lower punch assemblies. It is characterized by comprising a pressure relief control means for eliminating the pressure.

As described above, when the movable punch is displaced by the fluid pressure cylinder by the difference of the elongation amount of the plurality of punches in addition to the pressing with the weak force, each step of the molded article is depressed during the depressurizing process. On the other hand, a plurality of punches can always press with an equal force, and cracks can be effectively prevented.

The pressure release control means includes an upper punch assembly position detecting means for detecting a position of the upper punch assembly, a punch position detecting means for detecting a position of the movable punch, a servo amplifier, an electro-hydraulic servo valve, By adjusting the gain of the servo amplifier to be the ratio of the difference between the amount of expansion of each movable punch to the amount of expansion of the punch with the maximum amount of expansion of the plurality of punches, It is preferable to use a servo mechanism that sets the control target value and feeds back a signal from the punch position detection means to control the deviation from the control target value.

That is, since the position of the punch of the lower punch assembly is regulated by the pressing end position stopper mechanism, the movement of the upper punch assembly detected by the upper punch assembly position detecting means is controlled by the upper and lower punch assemblies. Corresponds to the elastic return amount of the punch having the largest deflection amount.

For example, when the upper and lower punch assemblies are each composed of a plurality of punches, the sum of the elastic return amounts (elongation amounts) of the punches having the largest deflection amount among the plurality of punches of each of the upper and lower punch assemblies. Is the amount detected by the upper punch assembly position detecting means. Since the ratio of the amount of extension of the punch of each maximum deflection amount of the upper and lower punch assemblies is determined mechanically, the amount of extension of the punch of the maximum deflection amount of the upper and lower punch assemblies is determined from the detection amount of the upper punch assembly position detecting means. Is determined. Further, the ratio of the difference between the extension of the other punch and the extension of the other punch, which is the maximum extension of the plurality of punches of the upper and lower punch assemblies, is determined mechanically. By multiplying the amount by a predetermined ratio, the shortage of the extension amount of another punch with respect to the punch having the maximum extension amount can be calculated. This relationship is the same in the case where one of the upper and lower punch assemblies is composed of a plurality of punches and the other is composed of one punch.

Therefore, a servo mechanism is configured for controlling each movable punch, and the gain of the servo amplifier of each movable punch is adjusted so as to be the ratio of the difference between the amount of extension of each movable punch and the amount of extension of the maximum amount of punch. By doing so, the punch with the maximum elongation and the other punch can have the same elongation during depressurization.

This pressure release mechanism can also be applied to a case where proportional pressurization is not performed, and also to a case where a punch is moved only by fluid pressure without combining pressurizing motion by mechanical pressure and fluid pressure. It is.

That is, there is provided an upper punch assembly attached to the upper ram, and a lower punch assembly attached to the press body. At least one of the upper punch assembly and the lower punch assembly has a plurality of punches. Is provided and a hydraulic cylinder for driving at least one movable punch of the plurality of punches is mounted, and in a pressurizing process, the movement of the hydraulic cylinder of the movable punch is superimposed on the movement of the upper ram. In a multi-stage powder forming press for forming a stepped molded product, a pressing means for pressing an upper punch assembly against an upper ram, and a difference in the extension amount of a plurality of punches of an upper and lower punch assembly during depressurization are determined by a fluid pressure cylinder. And a pressure release control means for displacing and canceling the movable punch.

In this case, the pressure release control means also includes an upper punch assembly position detecting means for detecting the position of the upper punch assembly, a punch position detecting means for detecting the position of the movable punch, a servo amplifier, Pressure servo valve, and the gain of the servo amplifier is adjusted by adjusting the gain of the servo amplifier to be the ratio of the difference in the amount of expansion of each movable punch to the amount of expansion of the punch with the maximum amount of expansion of the plurality of punches. It is preferable that the servo mechanism be a control target value of the fluid pressure cylinder, and a feedback mechanism feed back a signal from the punch position detecting means to control so as to eliminate a deviation from the control target value.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

FIG. 2 shows a multi-stage powder molding press according to an embodiment of the present invention.

The multi-stage powder molding press 1 has a tool set 3 that is removably mounted on a mechanical press body 2. Various mechanical presses such as a cam, a crank, and a toggle type are applied as the mechanical press body 2.

The tool set 3 has an upper punch assembly 5 attached to the upper ram 4 of the mechanical press body 2 and a lower punch assembly 6 attached to the mechanical press body 2.

The upper punch assembly 5 includes first to third three punches 7, 8, and 9, and three upper first, upper, and lower punches with respect to the upper base portion 10 via a guide rod 10A. 2, upper third punch plates 12, 13 and 14 are assembled so as to be movable in parallel. And, as shown in FIG.
The upper base portion 10 is fixed to the upper ram 4 of the mechanical press body 2 via the cushion cylinder 15. The illustrated mechanical press body 2 is a crank press, the upper ram 4 is connected to a crankshaft 17, a reduction mechanism 18 is provided at one end of the crankshaft 17, and a drive source (not shown) is connected to a drive source via a power transmission mechanism. Connected. An encoder 19 is provided at the other end of the crankshaft 17. Encoder 1
Numeral 9 is configured to output a signal corresponding to the phase of the crankshaft 17. The position of the upper ram 4 is detected by an upper ram position sensor 20 provided on the frame of the mechanical press body 2.

As shown in FIG. 1, upper first to upper third punches 7, 8, and 9 are cylindrical members, and upper first, upper second, upper third punches 7, Assembled in the order of 8 and 9, respectively, upper first, upper second, upper punch plate 1
2, 13, and 14.

Further, the upper base portion 10 is engaged with the lower surfaces of the first, second, and third punch plates 12, 13, 14.
And the first, second, and third pressing start position stoppers 21,
Reference numerals 22 and 23 are provided on the threaded rod 11 which is suspended from the upper base portion 10 and penetrates the upper first, upper second and upper third punch plates 12, 13 and 14. Of these,
The pressurization start position stopper 21 is not used for determining the pressurization start position in the present embodiment. In the case of this embodiment, basically, the upper first punch plate 12
Performs a pressurizing operation in synchronization with the upper ram 4.

Upper first, upper second, upper third punch plates 1
Upper, first, second, and third hydraulic cylinders 24, 25, and 26 as fluid pressure cylinders are interposed between the first, second, and third hydraulic cylinders 24, 25, and 26, respectively. Second
The upper third punches 7, 8, 9 are individually driven relative to the upper base portion 10 by the upper first, upper second, upper third hydraulic cylinders 24, 25, 26 so as to overlap the movement of the upper ram 4. .

The lower punch assembly 6 includes three lower first, lower second and lower third punches 27, 28, 28 corresponding to the upper first, upper second, and upper third punches 7, 8, and 9, respectively. 29 are provided. These lower first, lower second, lower third punches 27, 28,
A cylindrical member 29 is also assembled in the order of lower first, lower second, lower third punches 27, 28, 29 from the outside toward the inside.

Further, pressure end position stoppers 60A, 60, 61 which are engaged with the upper surfaces of the upper first, upper second, upper third punch plates 12, 13, 14 to determine the pressure end position are also provided. ing. The pressing end position stopper 60A of the upper first punch 7 is maintained in a state of being abutted from the start of transfer to the end of pressing.

The lower punch assembly 6 includes a die plate 31 having a die 30 filled with powder, a lower first punch plate 32 disposed below the die plate 31,
A lower second punch plate 33 disposed below the lower first punch plate 32, a lower third punch plate 34 disposed below the lower second punch plate 33, and a lower portion of the lower third punch plate 34 Plate 35 fixed to the frame of the mechanical press body 2 and fixed to the frame, and the yoke plate 3 disposed below the fixed plate 35 and connected to the die plate 31 via a tie rod 36
7 are provided. The lower first, lower second, lower third punch plates 32, 33, 34 are respectively provided with guide holes 32a, 33a, 34a through which tie rods 36 are inserted.
Is provided, and can be moved in parallel by being guided by the tie rod 36.

Lower first, lower second and lower third punches 27, 2
8, 29 are respectively connected to the lower first, lower second and lower third punch plates 3 via the punch holders 38, 39 or directly.
2, 33, 34.

The core rod 40 of the lower third punch 29
Is inserted, and the lower end of the core rod 40 is attached to the yoke plate 37 via the cushion cylinder 41.

In this embodiment, the lower first, lower second, lower third punch plates 32, 33, 34 are fixed plates 3
5 is supported through lower first, lower second, lower third hydraulic cylinders 42, 43, 44 as fluid pressure cylinders, and lower first, lower second, lower third punches 27, 28. , 29
Are lower first, lower second, lower third hydraulic cylinders 42, respectively.
A movable punch that can be driven by 43 and 44 is provided. However, in this embodiment, the lower first hydraulic cylinder 42 is kept at the lower limit position, and the lower first punch 27 is kept fixed to the fixing plate 35.

The lower first hydraulic cylinder 42 includes a piston 42
a is set up on the fixed plate 35, and the cylinder tube 42c is
2b, the cylinder tube 42
c is fixed to the lower first punch plate 32.

Lower second and lower third hydraulic cylinders 43 and 44
Is a cylinder rod 4 having pistons 43a and 44a.
3b and 44b are attached to the fixed plate 35 by the height adjusting mechanism 45,
46, the cylinder tubes 43c, 44
c is movable with respect to the cylinder rods 43b and 44b, and the cylinder tubes 43c and 44c
The lower and second lower and third punch plates 33 and 34 are connected via 3d and 44d.

At the upper ends of the cylinder tubes 43c, 44c, abutting members 43e, 44e are provided so as to protrude. The lower end walls of the cylinder tubes 43c, 44c are connected to the pistons 43a, 4c.
The first position is determined at the upper limit position engaged with 4a. The upper ends of the abutting members 43e, 44e project a predetermined amount from the upper ends of the cylinder rods 43b, 44b.
The abutting members 43e, 44e are pressed downward until the end surfaces of the pressing members 47, 48 operated by the upper ram 4 of the mechanical press body 2 contact the upper ends of the cylinder rods 43b, 44b, and the connecting members 43d, 44d and the punch holder 3 are pressed.
The lower second and lower third punches 28 and 29 are moved downward through the positions 8 and 39, and the pressing start positions of the upper ends of the lower second and lower third punches 28 and 29 are set. On the other hand, the pressure start position can be changed by adjusting the height of the cylinder rods 43b, 44b by the height position adjusting mechanisms 47, 48. Pressing members 47 and 48 are hydraulic cylinders 47A,
It is attached to the upper base 10 via 48A.
The pressing force of the hydraulic cylinders 47A and 47B is
The pressure is set higher than the lower third hydraulic cylinders 43 and 44 and lower than the press pressure of the mechanical press body 2.

The fixed plate 35 is engaged with slide blocks 53, 54 provided on the lower surface of the lower second, third punch plates 32, 33 so as to be slidable in the horizontal direction. The pressing end position stoppers 49 and 50 for determining the pressing end positions of the three punches 28 and 29, and the slide blocks 53 and 54 are slid to stop the stoppers 49 and 5.
Stopper release mechanisms 51 and 52 for removing from zero are provided.

On the other hand, the upper punch assembly 5 includes an upper first punch position detecting sensor 71 and an upper second punch position detecting sensor 7.
2, an upper third punch position detection sensor 73 is provided, and the lower punch assembly 5 includes a lower first punch position detection sensor 81;
A lower second punch position detection sensor 82 and a lower third punch position detection sensor 83 are provided.

FIG. 3 shows the upper first to third hydraulic cylinders 2.
4 to 26 and the lower second and lower third hydraulic cylinders 43 and 44
Is shown in FIG. In this embodiment, the lower first hydraulic cylinder does not exist, but six hydraulic cylinder control circuits are assembled assuming the case of having the lower first hydraulic cylinder. Further, the upper first hydraulic cylinder 24 does not operate the proportional pressurization but performs only the pressure release after the pressurization.

The upper first to upper third hydraulic cylinders 24 to 26 and the lower second and lower third hydraulic cylinders 43 and 44 are all reciprocating cylinders, and the piston 25a is operated by a hydraulic servo valve 55 as an electro-hydraulic servo valve. , 26a, 43a,
The speed of the upper and lower second and third hydraulic cylinders 25, 26, 43, and 44 is controlled by controlling the supply and discharge of hydraulic pressure to and from the two chambers separated by 44a. In addition, each of the hydraulic cylinders 25, 26;
The high pressure relief valve 56 and the low pressure relief valve 57
The high-pressure relief valve 56 and the low-pressure relief valve 57 can be selectively selected by a switching valve 58. Further, check valves 59 which are closed in the discharge direction and opened in the supply direction are provided in parallel on the cylinder lower chamber side of the lower second and third hydraulic cylinders 43 and 44.

As shown in FIG. 4, the pressurizing start timing is determined by the encoder 19 corresponding to a predetermined phase of the upper ram 4.
Is determined by the trigger signal from. The movement of the upper ram 4 is monitored by the upper ram position sensor 20, and the upper ram 4
Upper and lower second and third punches 8, 9; 28,
29 is controlled in an analog manner. That is, for example, taking the upper second punch 8 as an example, as shown in FIG.
00A controls the hydraulic servo valve 55. Then, the movement of the upper second hydraulic cylinder 25 is detected by the punch position detection sensor 72, and the detected amount is fed back and controlled so as to reach the target position.

FIG. 9 shows a control system of the servo driver amplifier.

That is, the upper second and upper third hydraulic cylinders 2
5, 26 and lower second, lower third hydraulic cylinders 43, 44
Further, five servo driver amplifiers 100A to 100E corresponding to the upper first hydraulic cylinder 24 are provided.
Each of the servo driver amplifiers 100A to 100E has an input terminal a to which a signal from the upper ram position sensor 20 is input.
And a feedback terminal b to which signals from the punch position detection sensors 72, 73, 82, 83 corresponding to the hydraulic cylinders 25, 26, 43, 44 are fed back.
An output terminal c for outputting a control signal to the hydraulic servo valve 55 and a presetter input terminal d are provided. The presetter input terminals include four terminals corresponding to four channels of channels 1 to 4 (CH1 to CH4).

Servo drive amplifiers 100A to 100E
Will be described by taking a servo driver amplifier 100A as an example. Inside thereof, a front-stage variable amplifier 101 for adjusting a feedback gain, and a rear-stage variable amplifier connected in series to the front-stage variable amplifier 101 to adjust a loop gain 102, a channel switch 103 connected in series to the subsequent variable amplifier 102 and switching channels by a presetter input terminal d, and a voltage-current converter 104 connected in series to the channel switch 103 to convert a voltage signal into a current signal. And A command signal amplifier 105 for amplifying a feedback signal input from the feedback terminal b is provided between the front stage variable amplifier 101 and the rear stage variable amplifier 102.
Is provided.

The servo driver amplifiers 100A to 100A
0E is a channel 1 (CH1) for making the servo system 0N to perform feedback control of the hydraulic servo valve 55, and a channel 2 for fully opening the hydraulic servo valve 55 and increasing the speed at a high speed.
(CH2), a channel 3 (CH3) for fully opening the hydraulic servo valve 55 and descending at a high speed, and a channel 4 (CH4) for squeezing the hydraulic servo valve 55 and slowly descending or ascending to release a low pressure. The channel is switched by a signal input from the encoder 19 to the presetter input terminal d. That is, the channel 1 (CH1) is connected to the upper ram position sensor 2
0, pre-amplifier 101, post-amplifier 102, command signal amplifier 105, and punch position sensors 72, 73,
Channel 2 where the circuits of 82 and 83 live.
4 to 4 (CH2 to 4) can be set to the ascending, descending, and stopping positions without using these circuits.

The switching timing of this channel is as follows.
As shown in FIG. 8B, a signal is emitted by the encoder 19 corresponding to each phase of the stroke diagram. FIG. 8B is a general explanation of the switching timing, and does not show individual specific control of the hydraulic cylinder.
That is, from the top dead center (0 °) of the upper ram 4 to the pressurization start point (), the encoder 19 sends the channel 2 (CH).
In 2), a signal is input, each hydraulic servo valve 55 is fully opened, and each hydraulic cylinder rises or descends at a high speed (illustration of the high-speed descent is omitted). When the pressurization start point () is reached, the signal is switched from the encoder 19 to the channel 1 (CH1) and the servo control is started. When the pressurization is completed and the bottom dead center (180 °) of the upper ram 4 is reached (), the signal is switched from the encoder 19 to the channel 4 (CH4), and the hydraulic servo valve 55
Is squeezed, and the pressure is released at a low speed or a low speed. After the pressure is released, when the lock of the pressure completion position of the lower second punch 28 is released (), a part of the upper punch is switched to the channel 3 (CH3) and lowered at a high speed to step the upper punch as described later. From the molded product. Further, at the time when the removal of the molded product is completed (), each hydraulic servo valve 55 is fully opened and switched to high-speed ascent.

In the mechanical press, the movement of the upper ram 4 is mechanically predetermined, unlike the hydraulic press, and phase signals are respectively issued at the start of pressurization, at the end of pressurization, at the pressurization stroke, and at the end of extraction. Also, encoder 1
The signal is not limited to 9, and a signal may be obtained from the sequencer.

A potentiometer is used as the upper ram position sensor 20 and each of the punch position detection sensors 72, 73, 82, 83, and the upper ram position sensor 20 and the punch position detection sensors 72, 73, 82, 83 The position 4 and the punch position signals are extracted as voltage changes.

That is, the sensor input from the upper ram position sensor 20 changes the voltage of the servo driver amplifier 100A
~ 100D. In response to this input signal, the upper ram 4 is controlled as a control target value for each of the upper and second hydraulic cylinders 25 and 26 and the lower and second hydraulic cylinders 43 and 44 by adjusting the gain of the preamplifier 101. Set so as to have a predetermined ratio. Punch position detection sensor 7
The signals from 2, 73, 82 and 83 are supplied to the pre-amplifier 1
The signal is amplified at a predetermined amplification factor and fed back so as to be at the same level as the signal amplified by 01.

Next, regarding the operation of the powder molding press of the present embodiment, the stroke diagram shown in FIG. 5, the punch operation diagram shown in FIG. 6, the operation diagram of the entire tool set shown in FIG. Explanation will be made based on the feedback system diagram shown in FIG.

That is, the pressing process of this embodiment is as follows.
A transfer process, a proportional pressurizing process, a depressurizing process,
It has an extraction process.

First, the positions of the lower second and lower third punches 28 and 29, the die 30, and the core rod 40 are set to the initial positions, and the powder 59 is filled in the die hole 30a. Die 3
0, the filling depth up to the upper end of the lower first punch 27, the filling depth up to the upper end of the second punch 28,
The ratio of the filling depth up to the upper end of the punch 29 is set to be the same ratio as the dimensional ratio of each stepped portion W1, W2, W3 of the final molded product W.

Since each of the steps W1, W2, and W3 of the final product has a step on both the upper surface and the lower surface, the powder is transferred, and the ratio of the step on the upper surface is adjusted to the ratio of the step on the upper surface of the final molded product. The ratio is set to be the same as the ratio.

FIGS. 5A, 6A and 7A show the transfer start position. This transfer is
The punch 28 and the lower third punch 29 are lowered by a predetermined amount, and the upper second punch 8 and the upper third punch 9 are inserted into the die hole 30a by a predetermined amount.

The relative positions of the upper first, second, and third punches 7, 8, and 9 are relative to the upper first, second, and third punch plates 12, 1, and 2.
3 and 14 are upper first, second and third hydraulic cylinders 24 and 2 respectively.
Upper first pressure end position stopper 6 by hydraulic pressures 5 and 26
3, upper second, upper third pressurization start position stoppers 22 and 23 are abutted and positioned. In this embodiment, the upper and second punches 8,
Nine lower ends project downward. And the upper second punch 8
The protrusion amount is larger than that of the upper third punch 9, and the insertion amount of the upper second and third punches 8 and 9 into the die hole 30 a is determined based on the lower end surface of the upper first punch 7.

The transfer start position is when the upper ram 4 moves downward and the lower end of the lower second upper punch 8 reaches the upper surface of the die 30. At this position, the cylinder tube of the lower second hydraulic cylinder 43 is moved. 43c upper end butting part 43e
The lower end of the push-down member 47 abuts.

Then, in synchronization with the movement of the upper ram 4, the lower second
The hydraulic cylinder 43 contracts and the second powder portion 592 sandwiched between the upper second punch 8 and the lower second punch 28 moves downward, and the upper end of the upper third punch 14 reaches the upper surface of the die 30 on the way. Then (see FIGS. 5B and 6B), the upper ram 4
The third powder portion 593 sandwiched between the upper third punch 9 and the lower third punch 29 also starts moving downward in synchronization with the movement of
The pressing members 47 and 48 are lower second and third hydraulic cylinders 4.
When the upper and lower cylinder rods 43b, 44b abut against the upper ends, the lower and second punches 28, 29 stop, the transfer ends, and the pressurizing start position is reached (FIG. 5).
(c), FIG. 6 (c), FIG. 7 (b)).

In this transfer step, each of the servo driver amplifiers 100A to 100E is connected to channel 2 (CH2).
Each hydraulic servo valve 55 is fully opened, and each hydraulic cylinder 24, 25, 26, 43, 44 is pressurized at a high pressure.

Hydraulic oil flows into the lower cylinder of the upper first hydraulic cylinder 24 and presses the upper first punch plate 12 against the upper first pressurizing end position stopper 63 by hydraulic pressure. In addition, hydraulic oil flows into the upper second and third hydraulic cylinders 25 and 26 into the upper chambers of the cylinders and is pressed against the upper second and third pressurization start position stoppers 22 and 23 by hydraulic pressure.

On the other hand, the lower second and third hydraulic cylinders 43, 4
With respect to 4, the hydraulic oil is filled in the cylinder upper chamber, and the hydraulic cylinders 43 and 44 are forcibly pushed down against the oil pressure by the press pressure of the mechanical press via the push-down members 47 and 48. At this time, the cylinder lower chamber is expanded to a negative pressure, and the cylinder lower chamber is filled with oil through the check valve 59.

The transfer end time is the pressurization start time, and when the pressurization start position is reached, the encoder 19 transmits the upper, second and third hydraulic cylinders 25, 26
A signal is input to the input terminal of the channel 1 (CH1) of the presetter input terminal of each of the servo driver amplifiers 100A to 100D of the lower and second and third hydraulic cylinders 43 and 44, and the channel switch 103 is set to the channel 1
The mode is switched to the servo control of (CH1), and pressurization of the powder starts. The servo driver amplifier 100E of the upper first hydraulic cylinder 24 remains in channel 2 (CH2).

In the pressing step, as shown in the stroke diagrams of FIGS. 5C to 5D, the first powder portion 591 sandwiched between the upper first punch 7 and the lower first punch 27 is fixed. The upper first punch 7 is connected to the upper ram 4 with respect to the lower first punch 27.
Pressurized by the movement of.

On the other hand, the upper second punch 8 and the lower second punch 28
The upper second hydraulic cylinder 25 and the lower second hydraulic cylinder 44 are controlled such that the second powder portion 592 sandwiched by the upper and lower rams 4 has the same degree of compression as the first powder portion 591 pressed by the movement of the upper ram 4. And pressurized. In addition, the third
The third powder portion 593 sandwiched between the punch 9 and the lower third punch 29 is pressurized by controlling the upper third hydraulic cylinder 26 and the lower third hydraulic cylinder 44.

FIG. 6F shows the dimensional relationship of the final molded product W.
As shown in the figure, the first step portion W1
The upper surface height of the step portion W1 is H1, the lower surface height of the second step portion W2 is H4, the upper surface height of the second step portion W2 is H2 + H4, the lower surface height of the third step portion W3 is H5, the third step portion. The height of the upper surface of W3 is H3
+ H5, the lowering speed of the upper first punch 7 is V1U, the lowering speed of the upper second punch 8 is V2U, the lowering speed of the lower second punch 28 is V2L, the lowering speed of the upper third punch 9 is V3U,
Assuming that the lowering speed of the lower third punch 29 is V3L, V1U: V2U: V2L: V3U: V3L = H1: (H
2 + H4): H4: (H3 + H5): H5 so as to satisfy the following relationship: upper second and upper third hydraulic cylinders 25,26, lower second and lower third hydraulic cylinders 43,4.
4 is controlled.

With this control, the first to third powder portions 591, 592, 593 can always be compressed with the same degree of compression.
The movement of the powder between the holes 93 is prevented, and the occurrence of cracks can be prevented. The speed controlled by the upper second hydraulic cylinder 25 and the upper third hydraulic cylinder 26 is actually (V2
(U-V1U) and (V3U-V1U), and the upper and second hydraulic cylinders 25 and 26 are contracted.

The setting of the speed ratio can be easily performed by adjusting the gain of the pre-amplifier 101 of each of the servo driver amplifiers 100A to 100D.

That is, since the upper first punch 7 is the same at the speed of the upper ram 4, the upper second hydraulic cylinder 25 is (H2 + H4-H1) / H1 of the speed of the upper ram 4, and the upper third hydraulic cylinder 26 is (H3 + H5-H1) of the speed of the upper ram 4
H1 and the lower second hydraulic cylinders 43 and 44 may be operated at the ratio of H4 / H1 and H5 / H1 of the speed of the upper ram.

Therefore, each servo driver amplifier 10
The gain of the pre-amplifier 101 from 0A to 100D is set so as to be relatively in the ratio. By simply adjusting the gain of the pre-amplifier 101 in this manner, the input signal of the upper ram 4 is amplified at a predetermined ratio, and the upper ram 4, upper third, lower third The second and lower third hydraulic cylinders 25, 26, 43, 44 can be operated.

When the pressing is completed, the upper surfaces of the second and third punch plates 13 and 14 are respectively pressed as shown in FIGS. 5 (d), 6 (d) and 7 (c). It stops when it hits the position stoppers 60 and 61.

In the pressing step, the pressing reaction force acting on the upper first punch 7 acts on the upper ram 4 of the mechanical press body 2 through the upper first pressing start position stopper 60A and the upper base part 10, and The pressure reaction force acting on one punch 27 acts on the frame of the mechanical press body 2 through the fixing plate 35.

On the other hand, the pressurizing reaction force acting on the upper second and third punches 8 and 9 acts on the upper ram 4 through the upper second and third hydraulic cylinders 25 and 26 and the upper base portion 10, and Second, the pressurizing reaction force acting on the third punches 28 and 29 is reduced by the lower second and third hydraulic cylinders 43 and 44 and the fixed plate 3.
5 to act on the mechanical press body 2.

The upper and lower second and third hydraulic cylinders 25 and 2
6; 43, 44 are smaller than the final forming pressure, are driven only by the pressing pressure of the upper ram 4 of the mechanical press main body during the pressing completion position, and the final dimension is the pressing end position stopper. Positioned by mechanism.

In this pressurizing step, the hydraulic oil flows into the lower cylinder of the upper second and third hydraulic cylinders 25 and 26 and is discharged from the upper cylinder of the cylinder. On the other hand, the pressure is raised at a predetermined ratio. The hydraulic cylinders 25 and 26 are forcibly raised, the pressure in the cylinder upper chamber is increased, and the excessive hydraulic pressure is released through the high-pressure relief valve 56.

Also, the lower second and lower third hydraulic cylinders 43,
Hydraulic oil flows into the lower cylinder chamber of 44 and discharges hydraulic oil from the upper cylinder chamber, and the cylinder descends at a predetermined ratio to the speed of the upper ram 4. When the powder is hardened to some extent and the hardness becomes higher, the lower second and lower third hydraulic cylinders 43 and 44 are forcibly lowered by losing the pressing pressure of the mechanical press main body 2 and the pressure of the cylinder upper chamber increases. Then, the excessive hydraulic pressure is released through the high-pressure relief valve.

After the powder is hardened to a predetermined pressure, no movement of the powder occurs, so that no crack occurs. In the case of performing powder molding, it is particularly important from the start of pressurization to the hardening to a certain degree. Therefore, the upper and second hydraulic cylinders 25 and 26 and the lower second and lower third hydraulic cylinders 43 and 44 are arranged between them. A non-defective product can be obtained if it is operated accurately in proportion to the movement of the upper ram 4.

Therefore, the small-capacity hydraulic cylinder 25,
26; 43 and 44, cracks are not generated, and a high-precision green compact with high accuracy can be formed.

The final pressing force is determined by the upper pressing end position stoppers 62, 60, 61, the lower pressing position stopper 49,
All are carried by the mechanical press body 2 via 50.

The hydraulic pressure supplied to the upper, second and third hydraulic cylinders 25, 26 is relieved by a high-pressure relief valve 56. Also, the lower second and lower third punch plates 33 and 3
The slide blocks 53 and 54 of No. 4 abut against the stoppers 49 and 50, respectively, and are stopped. The hydraulic oil supplied to the lower second hydraulic cylinder 43 is relieved through the high-pressure relief valve 56.

Next, after the pressurization is completed, the molded product is extracted together with the depressurization (see FIGS. 5 (d) to (f), FIGS. 6 (d) to (f), FIGS. 7 (c) and 7 (e). ).

That is, at the end of pressurization, the encoder 19
, A signal is input to the terminal of channel 4 (CH4) of the presetter input terminal d, and each servo amplifier driver 100
The channel changeover switches 103 of A to 100E are switched to channel 4 (CH4), and the first, second, and third hydraulic cylinders 24, 25, and 26 are slowly lowered, and
The lower second and lower third hydraulic cylinders 43 and 44 are raised at a very low speed, and at the same time, the switching valve 58 is switched so that the high pressure relief valve 5
6 switches to the low-pressure relief valve 57.

At the end of pressurization, the upper ram 4 starts moving upward from the bottom dead center, but the cushion cylinder 15 is filled with air pressure, and the upper punch assembly 5 is pushed downward as a whole. Even when the upper ram 4 moves, the molded product is pressed by the upper first, second, and third punches 7, 8, and 9. Each stepped portion W1, W2, W3 of the molded product W is maintained in a state of being sandwiched between the upper and lower first, second, and third punches 7, 27; 8, 28; When the upper ram 4 moves upward, the mechanical press pressure is released. When the pressing force is suddenly released, the amount of deformation of each of the punches corresponding to each of the compressed steps W1, W2, and W3 is different. Each step may not be pressed or may be pressed too hard, and there is a possibility that cracks may occur locally at the time of extraction. For example, if the sheet is extracted in a state where the gap is open, a crack occurs when the sheet is extracted.

Therefore, hydraulic oil is caused to flow into the upper chamber of the first, second, and third hydraulic cylinders 24, 25, and 26 so as to be moved down at a very low speed, and the upper surfaces of the steps W1, W2, and W3 are pressed from above. On the other hand, the lower second and third hydraulic cylinders 43, 4
As for No. 4, the hydraulic oil flows into the cylinder upper chamber so as to rise at a very low speed and presses the lower surfaces of the steps W2 and W3 from below. At this time, the pressure that holds down W1, W2, and W3 is regulated by the low-pressure relief valve 57. Therefore, the hydraulic servo valve 55 and the low-pressure relief valve 57 constitute a pressure release mechanism.

In this manner, each step W1,
The pressure acting on each punch and the like can be released while pressing W2 and W3 with each punch. If you do this,
The rapid extension of the punch is suppressed, and the occurrence of cracks is prevented.

Next, the die plate 30 is pulled down by the lower ram (not shown) via the yoke plate 37, and the lock mechanisms of the lower second and lower third punches are sequentially operated by the lower second and lower third stopper releasing mechanisms 51 and 52. , And moved downward in the order of the lower second and third punches to form step portions W2 and W3.
From the upper surface of the die plate 30 and the second lower surface.
The tip of the punch 28 and the lower third punch 29 is attached to the first punch 2
7 and lowered until it matches the position of the leading end, and the extraction is completed.

In the case of the product shown in FIG.
Is released when the die plate 30 reaches the upper end position of the lower second punch 28 (see e1 in FIG. 5), and the die plate 30 and the tip of the lower second punch 28 descend while keeping the surface position. Then, the die plate 30 is moved to the lower third punch 2.
When the upper end reaches the upper end position 9 (see e in FIG. 5 and FIG. 6 (e)), the lock of the lower third punch 29 is released, and the upper ends of the die plate 30, the lower second and lower third punches 28 and 29 are removed. It descends with the surface position. That is, the thinnest second step portion W2
, The third thinner step W3 and the thickest first step W1 are sequentially removed. The lower second and lower third punches 28,
The lowering of 29 is performed mechanically.

Hydraulic oil flows into the upper and lower hydraulic cylinders 43 and 44 in a squeezed manner into the upper chamber of the cylinder and is raised at a very low speed. The mechanical movement of the lower ram against this driving force is performed. Is forcibly lowered. At this time, the hydraulic oil in the upper chamber is relieved from the low-pressure relief valve 57. On the other hand, the cylinder lower chamber side is forcibly expanded and hydraulic oil flows in through the check valve 59.

On the other hand, as shown in FIG. 8B, a signal is output from the encoder 19 in synchronization with the time when the lock of the lower second punch 28 is released and the lower second punch 28 starts to descend, and the upper first, upper third Servo driver amplifier 10 for hydraulic cylinders 24 and 26
0E and 100B, the servo driver amplifiers 100E and 100B are switched to channel 3 (CH3), and the first and third hydraulic cylinders 24 and 26 are lowered at high speed. The upper third punch plate 12 stops when it hits the upper third punch pressing start position stopper 23, and then stops when it hits the upper first punch lower limit position stopper 21. When the upper third punch plate 14 abuts against the upper third punch pressing start position stopper 23, the lower end surface of the upper third punch 9 is flush with the lower end surface of the upper second punch 8 (e2 in FIG. 5). reference). This time is set so as to correspond to the time when the lock of the lower third punch 29 is released. Thereafter, the upper first punch plate 12 abuts against the upper first punch lower limit position stopper 21 and stops, and the tip of the upper first punch 7 is flush with the tips of the upper and second punches 8 and 9. At this point, die plate 3
The upper surface, the lower second punch 28 and the lower third punch 29 are set so as to correspond to the extraction completion point at which the leading ends of the lower and lower third punches 29 have been lowered to the positions matching the leading ends of the lower first punch 27 (FIG.
(f) and FIG. 7 (f)).

Since the upper punch assembly 5 is pressed by the cushion cylinder 15 as a whole, the upper first and upper third punches 7 and 9 relatively move to the respective steps W of the molded product W.
The upper second punch 8 separates from the step W2 of the molded product W while maintaining the state of being in contact with the upper surface of the first and third W3.

When the removal of the molded product W is completed, the upper first, second, and third punches 7, 8, and 9 are depressurized and aligned with the tip of the upper second punch 8, and the cushion cylinder 15 And the entire upper punch assembly 5 rapidly rises upward and separates from the upper surface of the die 30.

When the extraction is completed (FIG. 8B)
The signal is input from the encoder 19 to the channel 2 terminal of the presetter input terminal d of the servo amplifier drivers 100E, 100C, and 100D and to the channel 3 (CH3) terminal of the presetter input terminal of the servo amplifier driver 100A. The servo driver amplifiers 100E, 100C, and 100D are switched to the channel 2 (CH).
2), and the servo driver amplifier 100A becomes channel 3 (CH3).

Therefore, as shown in FIG. 5, the upper first hydraulic cylinder 24 rises at a high speed and the upper first punch plate 1
2 hits the upper first pressurizing end position stopper 63 at high pressure, the upper second hydraulic cylinder 25 descends at a high speed, and the upper second punch plate 13 moves to the upper second pressurizing start position stopper 2.
It hits 2 at high pressure. Further, the lower second and third hydraulic cylinders 43 and 44 rise at high speed to reach the upper limit position and return to the transfer start position. On the other hand, the upper third hydraulic cylinder 26
Continuously presses the upper third punch plate 14 against the upper third punch pressing start position stopper 23 at high pressure.

In the above-described embodiment, the case where the electrically controlled hydraulic servo valve 55 is used has been described as an example. However, the present invention is not limited to the hydraulic servo valve 55, and the mechanical servo valve shown in FIG. Proportional pressurization can also be realized by a proportional valve.

That is, there is provided a movement transmitting mechanism 63 for mechanically converting the mechanical movement of the upper ram 4 into the operation amount of the mechanical proportional valve 62. For example, as shown in FIG. 8, a cam mechanism 64 and a lever 65 are used as the motion transmitting mechanism, and the crankshaft 17 driving the upper ram 4 and the camshaft 64a are used.
And a lower end of a cam follower 64b abutting against a cam 64a is abutted against one end of a lever 65, and the spindle of the mechanical proportional valve 62 is operated by the lever 65. A configuration for reciprocating 62a is adopted. In addition,
The cam 64 reduces the movement of the upper ram 4 because the stroke of the mechanical proportional valve 62 is small.

In this manner, by making the cam 64a appropriately shaped, it is possible to perform a motion proportional to the motion of the crankshaft 17.

As shown in FIG. 10 (b), the mechanical proportional valve 62 is provided with a guide hole 62d in which a spool 62c is reciprocally movable and inserted in a valve box 62b, and a return port is provided on one side of the valve box 62b. Three ports, i.e., first and second supply connection ports 62f and 62g, are provided on both sides of 62e, and first and second load connection ports 62h and 62i are provided on the other side surface. The spool 62c inserted into the guide hole 62c is provided with three lands at positions corresponding to the first and second supply connection ports 62f and 62g and the return port 62e, and one end of the spindle 62a is moved from the end face of the valve box 62b. It is protruding. A spring chamber 62j is provided at one end of the guide hole 62d, and a spring 6 for urging the spindle 62a as an operating member in a direction to project into the spring chamber 62j.
2k is attached.

The amount of oil supplied to the hydraulic cylinder is controlled by changing the position of the land portion of the spool 62c by pushing the spindle 62a. In the figure, when the spool 62c moves upward at the neutral position, the second supply connection port 62f and the second load connection port 62i are connected, and the first load connection port 62h and the return connection port 62e are connected. Further, when moving downward, the first supply connection port 62g communicates with the first load connection port 62h, and the second load connection port 62i and the return connection port 62h.
e is communicated.

Accordingly, the supply amount is adjusted according to the mechanical input to the spindle 62a.

In the above-described embodiment, the case where the tool set 3 is detachably mounted on the mechanical press body 2 has been described as an example. However, it is needless to say that a system in which the tool set 3 is directly assembled to each punch 3 instead of the tool set system may be used. It is.

[Other Embodiments of the Pressure Relief Mechanism] Next, another embodiment of the pressure release mechanism will be described with reference to FIGS.

In the above embodiment, the upper punch assembly 5 is pressed by the cushion cylinder 15 constituting the pressure release mechanism, and the force for pressing the whole punch is the same, but there is a difference in the amount of deflection of each punch. I have. Although the molded product W is pressed from above and below between the upper punch assembly 5 and the lower punch assembly 6 by the cushion cylinder 15, the pressing force of the mechanical press is released and the deflection amount, which is the elastic deformation amount of each punch, is released. Depending on the difference, each step W1, W2,
There is a difference in the force with which W3 is pressed, and one punch strongly presses the corresponding step, and one punch does not press the corresponding step. In some cases, cracks may occur between the steps. .

In this embodiment, the upper and lower third punches 9 and 29 are the longest, and the upper and lower first punches 7 and 27 are the shortest in both the upper and lower punch assemblies 5 and 6. The deflection amount (shrinkage amount) λ of each punch is λ = (L, where L is the length, A is the cross-sectional area, E is the longitudinal elastic modulus, and F is the acting compressive force.
F / EA), since the pressing force per unit area is the same in powder metallurgy, the bending amount of each punch is the largest in the upper and lower third punches 9 and 29 and the largest in the upper and lower first punches 7 and 27. It becomes a small relationship.

In the depressurization in the above embodiment, the upper first, second upper punches 7 and 8 and the upper third punch 9 are connected to each other in order to prevent cracks in the molded product due to the difference in the amount of deflection of each punch. The strength of each punch and punch adapter is adjusted so that the amount of deflection is the same, and the lower first and lower punches 27 and 28 and the lower third punch 29 have the same amount of deflection. Because a large pressing force per unit area acts (for example, in iron-based powder metallurgy, 5 [ton /
cm2]), if the strength is too low, each punch as a mold may be damaged.

If cracks still occur,
Since it is possible to know where the deflection is small depending on the place where the occurrence occurs, the upper and lower punch assemblies 5 and 6 are disassembled to reduce the strength.

In this embodiment, such disassembly and adjustment are not required, and the shortage of the amount of deflection of the upper first and second punches 7 and 8 and the lower first and second punches 27 and 28 is freely compensated. It is to be.

That is, as shown in FIG. 11, the pressure releasing mechanism includes a cushion cylinder 15 as a pressing means for pushing down the upper punch assembly 5 with respect to the upper ram 4, and the upper and lower punch assemblies 5 and 6 at the time of pressure release. A depressurization control mechanism 100 as depressurization control means for displacing a difference in the elongation amounts of a plurality of punches by upper and lower first and second hydraulic cylinders 24, 25; 42, 43 as fluid pressure cylinders. Have.

As shown in FIG. 12, the depressurizing control mechanism 100 includes an upper punch assembly position sensor 220 as upper punch assembly position detecting means for detecting the position of the upper punch assembly 5, and a movable punch as a movable punch. Upper and lower first and second punches 7, 8 for detecting the positions of the first and second punches 7, 8;
Punch position sensors 71, 72, 81, 82, pressure relief control servo amplifier 106, and electro-hydraulic servo valve 55 for controlling upper and lower first and second hydraulic cylinders 24, 25; 42, 43. I have.

The gain of the servo amplifier 106 for depressurizing control is determined by setting the upper and lower first and second punches 7 and 8 with respect to the amount of expansion of the upper and lower third punches 9 and 29 as the punches having the maximum expansion amount among the plurality of punches. The first and second hydraulic cylinders 24, 25; 42, 43 are controlled to be control target values of the upper and lower first and second hydraulic cylinders 24, 25;
A servo mechanism is configured to perform feedback control on signals from the second punch position sensors 71 and 72 to eliminate the deviation from the control target value.

In this embodiment, a servo amplifier 106 for proportional pressure release is added to the control circuit shown in FIG. 9 in addition to the servo amplifier 101 used for proportional pressurization control. The feedback circuits 108 and 109 are connected in series to each feedback system, and the feedback circuit for proportional pressure release is selectively switched in channel 4 by a signal from the encoder 19. Note that one switching element 109 is connected to an inversion element 110. In the figure, reference numeral 111 denotes a buffer.

Upper and lower first and second hydraulic cylinders 24 and 25;
The hydraulic circuits 42 and 43 are completely the same as the circuit configuration shown in FIG.

In the pressurizing process, the piston of the cushion cylinder 15 does not operate because it is abutted against the upper bottom wall or the like at the upper limit position, and the upper punch assembly 5 moves exactly the same as the upper ram 4. In this embodiment, the upper ram sensor 20 is omitted, and as shown in FIG. 13, the control in the proportional pressurizing process also uses the upper punch assembly sensor 220 as the upper ram sensor.

The reason why the displacement amount of the upper punch assembly 5 is obtained as described above is that the displacement amount of the upper punch assembly 5 is the extension of the punch having the largest elastic deformation amount in each of the upper and lower punch assemblies 5 and 6. It is based on the recognition that it corresponds to the sum of the quantities. In this embodiment, the amount of extension of the upper and lower third punches 9 and 29 is the maximum, and the amount of extension of each of the upper and lower third punches 9 and 29 and the amount of extension of the upper and lower third punches 9 and 29 are determined based on the displacement amount S of the upper punch assembly 5. The difference between the amount of elongation of 29 and the amount of elongation of the upper and lower second and first punches 8, 28; 7, 27 is determined mechanically and can be calculated by simple proportional distribution.

That is, as shown in FIG. 11, the lower end of the lower punch assembly 6 is moved by the pressing end position stopper mechanism.
Since the positions of the second and third punches 27, 28, and 29 are regulated, the displacement amount S of the upper punch assembly 5 detected by the upper punch assembly position sensor 220 is smaller than that of the upper and lower punch assemblies 5, 6. The sum (S = Δλ3A +) of the extension amounts Δλ3A and Δλ3B of the upper and lower third punches 9 and 29 having the largest deflection amount.
Δλ3B).

The ratio (Δλ 3A) of the amount of extension of the upper and lower third punches 9, 29 of the maximum deflection amount of the upper and lower punch assemblies 5, 6.
/ Δλ3B) is fixed to a constant ratio ε in terms of material mechanics.
From the detection amount S of the upper punch assembly position sensor 220, the extension amounts Δλ3A, Δλ3B of the upper and lower third punches 9, 29 are determined as follows.

Δλ3A = S · ε / (1 + ε) Δλ3B = S / (1 + ε) Furthermore, the upper and lower third punches 9 and 29 in which the extension amount of the upper and lower punch assemblies 5 and 6 is the largest are the upper and lower portions of the extension amounts Δλ3A and Δλ3B. 1, the difference between the extension amounts of the second punches 7, 8; 27, 28 X = (Δλ3A−Δλ1A), Y = (Δλ3A−Δλ2A), U
= (Δλ3B−Δλ1B) and V = (Δλ3B−Δλ2B) are also determined mechanically. Therefore, if a predetermined ratio is multiplied by the detection amount S of the upper punch assembly position sensor 220, the elongation amount becomes the maximum. The shortage of the extension amount of the other upper and lower first and second punches 7 with respect to the third punches 9 and 29 can be calculated.

For the sake of simplicity, the deflection amounts (shrinkage amounts) of the upper, lower, first, and second punches due to the elastic deformation at the time of completion of the pressing with the maximum pressing force are represented by λ1A, λ2A, λ3A, λ1B,
Assuming that λ2B and λ3B, the above X,
Y, U, and V can be expressed as follows.

X = (S / λ3A) · (ε / (1 + ε)) · (λ3A−λ1A) Y = (S / λ3A) · (ε / (1 + ε)) · (λ3A−λ2A) U = (S / λ3B) · (1 / (1 + ε)) · (λ3B−λ1B) V = (S / λ3B) · (1 / (1 + ε)) · (λ3B−λ2B) , The third punches 7, 8 and 9 are set to 1 [mm], 1.5 [m
m], 2 [mm], lower first, second, third punches 27, 2
The deflection amounts of 8 and 29 are 1 [mm],
If 1.5 [mm] and 2 [mm], the upper second punch 8
Is 12.5% of S, the correction amount X of the upper first punch 7 is 25% of S, and the correction amount V of the lower second punch 28 is 1 of S.
The operation may be performed so that the correction amount U of the lower first punch 27 is 2.5%, and the correction amount U of S is 25% of S.

The setting of this ratio can be easily performed by adjusting the gain of the servo amplifier 106 for depressurization control described above.

Since the lower first punch 27 is restricted by the fixed plate 35 and the lower second and lower punches 28 and 29 are restricted from being displaced downward by the pressure end position stoppers 49 and 50, the lower third punch 27 is restricted. Lower 1st, 2nd based on 29
The punches 27 and 28 are displaced upward by X and Y.

Similarly, the first, second, and third punches 7, 8,
9 is also a pressing end position stopper 2 with respect to the upper base 10.
Since the upward displacement is regulated by 4, 25, 26, the first and second upper punches 9 are moved upward by U and V.
The punches 7, 8 are displaced downward. Since the upper punch assembly 5 is lifted upward as a whole, the upper first, second, third
The lower ends of the punches 7, 8, 9 are displaced upward with respect to the mechanical press body 2.

The shortage of the amount of deflection can be calculated by the above equation. However, since the shortage is affected by the friction between each punch and the molded product and the slight deflection of portions other than each punch, the occurrence of cracks and the like is actually reduced. Take into account the correction.

In this embodiment, in FIG. 12, a signal is input from the encoder 19 to the presetter input terminal d at the end of pressurization, and each servo amplifier driver 10
The channel changeover switches 103 of 0A, 100E, 100F, and 100C are switched to channel 4 (CH4), and the first and second hydraulic cylinders 24 and 25 are lowered, and the first and second hydraulic cylinders 42 and 43 are also lowered. Be raised.

At the end of pressurization, as shown in FIG. 14, the upper ram 4 starts to move upward from the bottom dead center, but the air pressure is filled in the cushion cylinder 15 and the upper punch assembly 5
Is pressed down as a whole, and the molded product is pressed by the upper first, second, and third punches 7, 8, and 9 even if the upper ram 4 moves, and the step portions W1, W2, W3 is upper and lower first, second, third punches 7, 27; 8, 28; 9, 29
It is maintained in a state sandwiched between. When the upper ram 4 moves upward, the mechanical press pressure is released. If the pressing force is suddenly released, the amount of deformation of each punch corresponding to each of the compressed steps W1, W2, W3 will be different. Each step may not be pressed or may be pressed too hard, and cracks may occur during extraction.

In this embodiment, with respect to the upper first punch 7, the input signal from the upper punch assembly position sensor 220 is amplified by the gain-adjusted servo amplifier 106 to obtain (S / λ3A) (ε / ( 1 + ε)) ・ (λ3A-λ
1A) is set as the control target value of the upper first hydraulic cylinder 24, and the electrohydraulic servo valve 55 is controlled so that the position signal from the upper first punch position sensor 71 is fed back to eliminate the deviation.

Similarly, with respect to the upper second punch 8, the input signal from the upper punch assembly position sensor 220 is amplified by the gain-adjusted servo amplifier 106, and (S
/ Λ3A) · (ε / (1 + ε)) · (λ3A−λ2A) is input as the control target value of the upper second hydraulic cylinder 25, and the position signal from the upper second punch position sensor 72 is fed back to determine the deviation. So that the electro-hydraulic servo valve 55
Is controlled.

For the lower first punch 27, the input signal from the upper punch assembly position sensor 220 is amplified by the servo amplifier 106 whose gain has been adjusted, and (S / λ3
B) · (1 / (1 + ε)) · (λ3B−λ1B) is input as the control target value of the lower first hydraulic cylinder 42, and the position signal from the lower first punch position sensor 81 is fed back to eliminate the deviation. The electro-hydraulic servo valve 55 is controlled in such a manner.

For the lower second punch 28, the input signal from the upper punch assembly position sensor 220 is amplified by the gain-adjusted servo amplifier 106 to obtain (S / λ 3
B) · (1 / (1 + ε)) · (λ3B−λ2B) is input as the control target value of the lower second hydraulic cylinder 43, and the position signal from the lower second punch position sensor 82 is fed back to eliminate the deviation. The electro-hydraulic servo valve 55 is controlled in such a manner.

In this depressurizing step, in the above embodiment,
In the hydraulic circuit of FIG. 3, the switching valve 58 is switched from the high-pressure relief valve 56 to the low-pressure relief valve 57. In the present embodiment, the high-pressure relief valve 56 is used without switching the low-pressure relief valve 57. Is also good.

That is, as shown in FIG. 15A, at the end of the pressurization, the servo amplifier drivers 100E and 100E
Switch A, 100F, 100C to channel 4,
The pressure relief servo is turned ON. FIG. 15A is a timing chart of the servo amplifier driver, except for CH4, which is completely the same as FIG.

As a result, as shown in an exaggerated manner in FIG. 11, the extension amounts X, Y, U, and X of the first and second punches 7 and 8; 27 and 28 with respect to the third and upper and lower punches 9 and 29 are exaggerated.
V is eliminated, and each stepped portion W1, W2, W3 of the molded article W is moved up and down first, second, and third punches 7, 27; 8, 28; 9, 29.
Is depressurized while always being pressed with equal force,
The occurrence of cracks in the molded article W can be prevented.

FIG. 15 is a stroke diagram exaggerating the state of proportional pressure release. This stroke diagram shows the position of the contact surface of each punch with the molded product.

The lower first punch 27 is pushed upward by the lower first hydraulic cylinder 42 by the difference U in extension from the lower third punch 29, and the upper end surface of the lower first punch 27 is Is displaced by the same amount (Δλ3B) as that of the upper end surface.

The lower second punch 28 is pushed upward by the lower second hydraulic cylinder 43 by the difference V in extension from the lower third punch 29, and the upper end surface of the lower second punch 28 The same amount as the upper end surface of the punch 29 (Δλ3B)
Only displace.

The upper first punch 7 is pushed down by the upper first hydraulic cylinder 24 by the difference X in the extension amount from the upper third punch 9, and the lower end surface of the upper first punch 7 is Is displaced by the same amount (Δλ3A) as that of the lower end surface.
The position of the lower end face of the upper first punch 7 is displaced upward by Δλ3B with reference to the position at the end of pressurization.

The upper second punch 8 is pushed down by the upper second hydraulic cylinder 25 by the difference Y in extension from the upper third punch 9, and the lower end surface of the upper second punch 8 is Is displaced by the same amount (Δλ3A) as that of the lower end surface.
The position of the lower end surface of the upper second punch 8 is also displaced upward by Δλ3B with reference to the position at the end of pressurization.

When the mechanical pressure applied by the crankshaft 17 is released and the elasticity is restored, the elongation stops, and the molded product W is kept pressed by the cushion cylinder 15.

Next, in the case of the product shown in FIG. 6, the die plate 30 is pulled down via the yoke plate 37 by the lower ram (not shown), and the lower second and third stopper release mechanisms 51 are provided in the same manner as in the above embodiment. , 52, the locking mechanism of the lower second and lower third punches 28 and 29 is released in order, and the lower and second punches 28 and 29 are sequentially moved downward to separate from the step portions W2 and W3. Specifically, the upper surface of the die plate 30, the upper ends of the lower second punch 28 and the lower third punch 29 are lowered until they match the upper end position of the lower first punch 27, and the molded product is extracted. On the other hand, the upper punch lowers the upper first and upper third punches at the same time when the lower second punch starts lowering, and becomes the state shown in FIG.

This series of extraction steps is completely the same as that of the above embodiment, and the description is omitted.

During this time, the servo system for depressurization is at 0 N, and is forced to descend by mechanical movement of the lower ram against this driving force. At this time, the hydraulic oil in the cylinder upper chamber is released from the high-pressure relief valve 56. On the other hand, the cylinder lower chamber side is forcibly expanded and hydraulic oil flows in through the check valve 59.

In the above embodiment, the case where the electrically controlled hydraulic servo valve 55 is used has been described as an example. However, the present invention is not limited to the hydraulic servo valve 55, and is not limited to the hydraulic servo valve 55 shown in FIG. It is also possible to achieve proportional pressure relief with a mechanical proportional valve.

In the above embodiment, it is assumed that the proportional pressurization is performed by each hydraulic cylinder in the pressurizing process. However, the proportional pressurization is performed without performing the proportional pressurization. Is also good.

Further, this pressure release mechanism can be applied even when the proportional pressurization is not performed, and also when the punch is moved only by the fluid pressure without combining the pressurizing motion by the mechanical pressure and the fluid pressure. It is.

[0154]

As described above, according to the present invention, there is provided an improvement of a mechanically operated mechanical press such as a crank, a toggle, a cam, and the like. Since the upper and lower punches are made to move in proportion to the movement of the upper ram during the pressure stroke, a good product can be easily formed even if the capacity of the fluid pressure cylinder is small.

When the pressurizing force of the upper ram of the mechanical press main body is released after the pressurization is completed, the fluid pressure cylinder is operated to press each step of the molded product with a small force, so that each punch is formed. Cracks due to differences in the amount of deflection can be prevented.

Further, if the movable punch is displaced by the fluid pressure cylinder so as to eliminate the difference in the amount of deflection between the punches in proportion to the movement of the upper punch assembly,
The difference in the amount of deflection between the punches can be easily corrected, and the pressure relief adjustment can be performed extremely easily.

[Brief description of the drawings]

FIG. 1A is a schematic sectional view of a tool set of a multi-stage powder compacting press according to an embodiment of the present invention, and FIG. 1B is a sectional view near a fixed rod.

FIG. 2 is a schematic view of an upper ram portion of a mechanical press body of a multi-stage powder molding press according to one embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram of a hydraulic cylinder that drives each punch of the tool set of FIG. 1;

FIG. 4 is a view showing an operation procedure of the hydraulic servo valve of FIG. 3;

FIG. 5 is a stroke diagram of the apparatus of FIG. 1;

FIG. 6 is a diagram illustrating a series of operations of each punch of the tool set in FIG. 1;

FIG. 7 is a diagram illustrating a series of operations of the tool set in FIG. 1;

FIG. 8 is a schematic diagram of a hydraulic servo valve that controls each hydraulic cylinder of FIG. 1;

FIG. 9 is a system diagram of a servo system of the hydraulic cylinder of FIG. 1;

FIG. 10 is a schematic explanatory view when a mechanical proportional valve according to another embodiment of the present invention is used.

FIG. 11 is a schematic explanatory view showing another embodiment of the pressure release mechanism of the present invention.

FIG. 12 is a diagram illustrating a control configuration example of a pressure release mechanism of FIG. 11;

FIG. 13 is a diagram illustrating an example of installation of an upper punch assembly position sensor.

FIG. 14 is an explanatory diagram of a pressure relief step according to the present embodiment.

15 (a) is an operation timing chart of the servo driver amplifier of FIG. 12, and FIG. 15 (b) is a stroke diagram of a pressure relief process according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Multi-stage powder molding press 2 Mechanical press main body 3 Tool set 4 Upper ram 5 Upper punch assembly 6 Lower punch assembly 7 Upper first punch 8 Upper second punch 9 Upper third punch 10 Upper base part 17 Crankshaft 19 Encoder 20 Upper ram position sensor 21 Upper first punch pressing start position stopper 22 Upper second punch pressing start position stopper 23 Upper third punch pressing start position stopper 24 Upper first hydraulic cylinder 25 Upper second hydraulic cylinder 26 Upper third Hydraulic cylinder 27 Lower first punch 28 Lower second punch 29 Lower third punch 30 Die 31 Die plate 43 Lower first hydraulic cylinder 44 Lower second hydraulic cylinder 45, 46 Height adjustment mechanism (filling position) 47, 48 Holding member 49, 50 Pressing end position stopper. 51, 52 Stopper release mechanism 55 Hydraulic servo valve 59 Powder 591, 592, 593 First, second, third powder portions 60 Pressurization end position stopper (upper second punch) 61 Pressurization end position stopper (upper third punch) 60A Pressurization end position stopper (upper first punch) 62 Mechanical proportional valve 100A to 100E Servo driver amplifier (servo amplifier)

Claims (8)

[Claims] 1. An upper punch assembly attached to an upper ram of a mechanical press body, and a lower punch assembly attached to the mechanical press body, wherein at least one of the upper punch assembly and the lower punch assembly is provided. Is provided with a plurality of punches and a hydraulic cylinder for driving at least one movable punch of the plurality of punches is mounted, and a pressurizing start for positioning a pressurizing start position of the movable punch driven by the hydraulic cylinder is provided. A position stopper mechanism, and a pressure end position stopper mechanism for positioning a pressure end position, wherein a part of the plurality of powder portions to be compressed by the upper and lower punches is partially driven by an upper ram of a press body. And pressurize only the rest of the plurality of powder portions based on the mechanical movement of the upper ram from the pressing start position. A control mechanism is provided for controlling the hydraulic cylinder of the movable punch so that each powder portion has the same ratio as the dimensional ratio of each step of the final molded product. A multi-stage powder molding press, wherein the pressure is set to be smaller than the pressure, and the punch is positioned by a mechanical pressure end position stopper mechanism at the pressure end position. 2. The control mechanism includes an upper ram position detecting means for detecting a position of the upper ram, a punch position detecting means for detecting a position of each movable punch, a servo amplifier, and an electro-hydraulic servo valve. By adjusting the gain of the servo amplifier so that the movement of the hydraulic cylinder of each movable punch with respect to the movement of the upper ram has a predetermined ratio, the control target value of the hydraulic cylinder of each movable punch is obtained. 2. The multi-stage powder molding press according to claim 1, wherein the servo mechanism is configured to feed back the signal of (1) and perform control so as to eliminate the deviation from the control target value. 3. A control mechanism comprising: a mechanical proportional valve for changing a flow rate in proportion to a mechanical input of an operating member for reciprocating a spool; and a mechanical proportional valve for controlling a mechanical movement of an upper ram at a predetermined ratio. The multi-stage powder molding press according to claim 1, further comprising: a motion transmission mechanism that transmits the motion to an operation member of the valve. 4. A pressure for depressurizing each step of the molded product with a weak force by means of upper and lower punches when the mechanical pressure applied by the upper ram applied to the molded product after the pressing is released. 2. The method according to claim 1, further comprising a pulling mechanism.
Or a multi-stage powder molding press according to 3. 5. A pressurizing mechanism comprising: a pressing means for pressing down an upper punch assembly with respect to an upper ram; 5. The multi-stage powder molding press according to claim 4, further comprising a pressure relief control means for displacing and eliminating the pressure. 6. A depressurizing control means includes an upper punch assembly position detecting means for detecting a position of an upper punch assembly, a punch position detecting means for detecting a position of a movable punch, a servo amplifier, and an electro-hydraulic servo. A fluid pressure of the movable punch by adjusting a gain of the servo amplifier to be a ratio of a difference of an extension amount of each movable punch to an extension amount of a maximum extension amount of the plurality of punches. 6. The multi-stage powder molding press according to claim 5, wherein a servo mechanism is used as a control target value of the cylinder, and a feedback mechanism feeds back a signal from the punch position detecting means to control the deviation from the control target value. . 7. An upper punch assembly attached to an upper ram, and a lower punch assembly attached to a press body, wherein at least one of the upper punch assembly and the lower punch assembly has a plurality of punches. And a hydraulic cylinder for driving at least one movable punch of the plurality of punches is mounted, and in a pressurizing process, the movement of the hydraulic cylinder of the movable punch is superimposed on the movement of the upper ram. In a multi-stage powder forming press for forming a stepped molded product, a pressing means for pressing an upper punch assembly against an upper ram, and a difference in elongation of a plurality of punches of an upper and lower punch assembly during depressurization are determined by a fluid pressure cylinder. A multistage powder molding press, comprising a pressure release control means for displacing and eliminating a movable punch. 8. A pressure relief control means includes: an upper punch assembly position detecting means for detecting a position of an upper punch assembly; a punch position detecting means for detecting a position of a movable punch; a servo amplifier; A fluid pressure of the movable punch by adjusting a gain of the servo amplifier to be a ratio of a difference of an extension amount of each movable punch to an extension amount of a maximum extension amount of the plurality of punches. 8. The multi-stage powder molding press according to claim 7, wherein a servo mechanism is used as a control target value of the cylinder, and a signal from the punch position detecting means is fed back to perform control so as to eliminate a deviation from the control target value. .