JPH0677876B2 - Electromagnetic press machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved electromagnetic pressing device, and more particularly to an electromagnetic pressing device suitable for high-speed punching of thin plates.

[Background of the Invention]

For example, when punching or drawing a thin metal plate, a press machine is used. One of the press machines is an electromagnetic press device.

Since this electromagnetic press device obtains a pressing force by linearly moving the ram by an electromagnetic force, it has an advantage that its structure is extremely simple as compared with a general mechanical press such as a crank press or a hydraulic press. .

On the other hand, however, it is technically difficult for this electromagnetic pressing device to perform press working continuously at a higher speed than a mechanical press.

This point will be described more concretely with reference to FIG. The conventional example shown in FIG. 7 well shows the basic structure and characteristics of the electromagnetic press, and is illustrated from the point close to the structure of the present invention. For example, Japanese Patent Application Laid-Open No. 49-92675 discloses an electromagnetic press having this structure.

In FIG. 7, reference numeral 1 denotes a ram drive coil wound in a solenoid shape and fixed to a fixed frame 2. Reference numeral 3 denotes a so-called ram to which a pressing force is applied. A conductor plate 4 is fixed to an upper end surface 3a of the movable element, and an upper die 5 of a press die is fixed to a lower end surface 3b thereof. The lower die 6 is fixed on the plate 2a of the fixed frame 2 so as to face the upper die 5 precisely, and the workpiece 7
Is placed on it. The ram 3 is supported by the slide bearing 8 fixed to the intermediate plate 2b of the fixed frame 2 so as to be slidable in the up / down direction, that is, the pressing direction.

In this example, a special large pulse current generator (not shown) applies a large pulse current to the drive coil 1 through the coil terminal 1a to generate a magnetic flux and a chain of the magnetic flux. The workpiece 7 is pressed by accelerating the ram in the pressing direction by the electromagnetic repulsive force between the induced currents generated in the conductor plate 4 by the interaction.

However, in the above-mentioned conventional example, in order to obtain a sufficient pressing force, it is necessary to pass an extremely large current through the ram drive coil 1 for a short time, but this causes a coil loss due to the coil and the conductor plate 4. The problem that the required size of these parts becomes too large for the application in which the jule loss due to the induced current is large and the press operation is continuously repeated at high speed due to the temperature rise restriction of the ram drive coil 1 and the conductor plate 4. However, this is also unsuitable for continuous press applications in that the compounding force for lifting the ram upward cannot be obtained. Therefore, as an improvement plan, it is considered to use the spring 9 for pulling up the ram as shown by the dotted line in the figure. (For example, JP-A-49-56261)
In this case, it is necessary to increase the electromagnetic force in the pressing direction by an amount corresponding to the restoring force of the spring, and the apparatus becomes large in size, and the object of speeding up cannot be achieved.

It is also conceivable to use a DC or AC electromagnet as the electromagnetic force generator, but even in this case, under the conventional configuration as shown in FIG. 7, it is necessary to directly obtain the necessary pressing force by the magnetic attraction force. Then, there is a problem that the core and coil dimensions become too large. Also, in an apparatus in which the moving part has a large iron core and a large weight to be driven, the energy required for accelerating the moving part is large, and the acceleration energy increases as it accelerates at a high speed. After all, there was an unsuitable side.

As described above, the conventional electromagnetic pressing device has a drawback that it is very difficult to perform press working continuously at high speed.

[Object of the Invention]

The present invention has been conceived in view of this, and therefore, an object of the present invention is to provide an electromagnetic pressing apparatus capable of smoothly performing high-speed and continuous pressing.

[Outline of Invention]

That is, according to the present invention, an iron core which is a magnetic portion is provided on the side of the ram opposite to the side where the press die is fixed, and a substantially M-shaped stator iron core that is arranged to face the iron core with a predetermined gap. Is provided on a fixed frame, and a ram drive coil is wound around and fixed to the stator iron core, and further, a resonance pulsating device is provided between the moving ram and the fixed frame. By causing the ram to reciprocate by resonating as the mass system of the resonance pulsating device, and controlling the ram drive coil to reciprocate by periodically attracting and repulsing the ram. The purpose is to achieve.

Example of Invention

The present invention will be described in detail based on the illustrated embodiments.

First, the configuration will be described with reference to FIG. The same reference numerals as those in FIG. 7 described above indicate the same or corresponding parts, and the description thereof will be omitted. In this embodiment, an iron core 10 which is a magnetic portion is fixed to an upper end surface 3a of a ram 3 which is a mover, and a substantially M-shaped fixed iron core 11 having a surface facing the upper surface is fixed to a fixed frame 2. It is fixed to. A ram drive coil 12 is wound around the protruding portion 11a of the fixed iron core 11, and 12a is a terminal of this ram drive coil. Reference numeral 13 is a spring for both compression and tension that supports the ram 3 in the vertical direction, and is a resonance movement device.

With the above configuration, the pressing operation of this device is performed as follows. First, connect a power source (not shown) to the coil terminal 12a, and pass an alternating current through the coil 12, then the stator core 11
An alternating magnetic flux φ is generated in the magnetic circuit formed by the iron core 10 and the iron core 10 is attracted upward by the magnetic attraction force by the same principle as that of the plunger type AC magnet.

Meanwhile the electromagnetic force acting on the case core 10, as is well known, substantially constant force (attraction force) F _DC and periodically changes (repeat suction-repulsion sinusoidally) composite force of the alternating force F _AC And is represented by the following equation.

Fm = F _DC + F _AC = F _DC + F _AC m cos ωt (1) where Fm; total electromagnetic force F _AC m; maximum value of AC force (single amplitude) ω; angular frequency of force t; time and Ram 3, iron core 1 compared to the case where only force F _DC is applied
0, by designing the device in advance so that the gravity acting on the entire mass of the movable part composed of the upper mold 5 and the reaction force of the spring device are balanced at the position where the gap length is g ₀ , this g ₀ The movable part is forced to vibrate as a spring-mass system with the _AC force F _AC as the exciting force centering on the position. When the ram portion is accelerated by such a method, the ram can be smoothly accelerated from the stationary state to the steady vibration state. Then, when the material reaches a steady state, the work 7 is fed onto the lower side 6 to perform press working. At this time, if the punch tip 5a of the upper die 5 is almost at the position of the workpiece at the position where the gap length is g ₀ , the ram speed at this position is the maximum as described later, Sufficient pressing force can be obtained.

As can be seen from the above description, this device is a vibrating electromagnetic press that utilizes a type of electromagnetic vibration. When applied to punching of a thin metal plate where the energy consumed in one press is relatively small, steady changes in speed and kinetic energy of the ram due to one punching are small, and steady vibration without pressing is performed. Continuous pressing is possible with only a slight decrease in vibration amplitude. If the speed is so large that the energy cannot be replenished from the power supply before the next press, the press working is performed every several cycles to reach the required speed. In this case, the number of presses per unit time is reduced, but there is an advantage that continuous pressing can be performed even when the press reaction force is considerably large.

By the way, regarding the operation characteristics of the apparatus of this example, as a result of performing model simulation, it was found that the press performance was significantly changed depending on the value of the angular frequency ω of the alternating-current force F _AC and had an optimum value. Therefore, this will be described with reference to FIGS.

FIG. 2 shows a simulation model of vibration characteristics for the apparatus of the embodiment shown in FIG. That is, the vibration characteristics of this press machine are as follows: the total mass of the moving part (ram, iron core, upper die, etc.) is m, the spring constant of the spring device is k, the AC force that is the exciting force is F _AC , and the moving part It can be replaced with a one-degree-of-freedom “spring-mass system” model in which the equivalent viscous damping coefficient is C. The equation of motion when the position of any one point of the movable part in the above-described gap length g ₀ is the reference axis l (x = 0) of the displacement x and the pressing direction (downward) is the positive direction of the displacement x is here, Then, the displacement x at an arbitrary time t can be solved by solving the equation (2), and for the steady vibration state, x = Xm cos (ωt−) (3) where Xm; maximum displacement amplitude x It is expressed in the form of the phase angle with respect to F _AC . The speed v is Next, when the maximum value of the excitation force F _AC m is added to the mass m (thus, the ram section) as a static load, and the displacement is Xst (the static deflection of the spring device), this is obviously Xst = F _AC m / k… (4) Therefore, if the ratio of Xst and the maximum amplitude Xm during forced vibration is defined as the amplitude magnification μ, then μ ＝ Xm / Xst ＝ kXm / F _AC m… （5）, and μ is Excitation force (F _AC ) of force (kXm) generated during vibration
It turns out that it is also a magnification for m).

Next, FIG. 3 shows the excitation force F _AC as a reference curve as an example of the simulation result for the specific embodiment device when the phase angle is obtained by the above equations (3) and (4).
The steady-state vibration curve regarding displacement x and velocity v and its phase relationship are shown. So, in terms of press performance,
It is clear that it is ideal (the largest pressing force can be obtained) that the velocity v and the excitation force F _AC are maximum and the displacement x increases in the positive (+) direction. Let's see this figure from a different perspective. Then, as can be seen, for example, from the point that the velocity v is maximum and the x direction increases downward, it can be seen that the exciting force F _AC at this time is not the maximum and is not an ideal condition. This relationship changes significantly with the phase angle.

Therefore, as a result of examining the ideal condition by changing the phase angle, as shown in FIG. I found that I should choose (point). Then, for this purpose, the relationship of the phase angle and the device ^{parameters, = tan -1 (2ξγ / C1} -γ 2) ... (6) Here, xi]; ratio limits viscous damping coefficient C _C the C gamma; F _{Since it is} the angular frequency ω (or frequency) of _AC and the natural angular frequency ωn (or natural frequency n) of the movable part, unless ξ is zero (in the example device, approximately 0 <ξ <0.1, γ1.0 This condition is satisfied and γ =
Since it is ω / ωn (or / n), it was concluded that the excitation angular frequency (or frequency) should eventually be substantially matched with the natural angular frequency (or natural frequency) of the movable part.

The natural angular frequency ωn is Therefore, it is only necessary to design the device and set the vibration frequency in advance so that this value will be the desired press speed (the number of presses per unit time). Further, in this case, as shown in FIG.
It was also found that there is an advantage that a large pressing force can be obtained with a small exciting force and a driving device can be downsized at the same time.

FIG. 6 shows another embodiment of the present invention, in which the vertical relationship between the iron core 10 and the fixed iron core 11 is reversed, and the auxiliary load 15 for adjusting the natural frequency is provided on the upper support 14. Except for the above, the configuration and operation are almost the same as those of the embodiment shown in FIG. This has the advantage that the natural frequency can be finely adjusted, and that the magnetic gap becomes small when the ram 3 moves in the pressing direction, and a large pressing force can be obtained.

〔The invention's effect〕

According to the electromagnetic pressing device of the present invention described above, an iron core, which is a magnetic portion, is provided on the side of the ram opposite to the side on which the press die is fixed, and a substantially M-shaped member is arranged to face the iron core with a predetermined gap. A V-shaped stator core is provided on a fixed frame, and a ram drive coil is wound around and fixed to the stator core, and a resonance drive is provided between the moving ram and the fixed frame. The ram is reciprocally moved by reciprocally moving the ram as a mass system of the resonance pulsating device to reciprocate the ram, and the ram drive coil is controlled to reciprocate by periodically attracting and repulsing the ram. Therefore, the ram resonates with the resonance motion device, and the ram reciprocates at the speed of this resonance, so that the speed is very high, and therefore high-speed and continuous press working is performed. Can Kill.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an electromagnetic pressing device of the present invention, and FIG. 2 is an equivalent diagram for explaining the operating principle thereof.
FIGS. 3 and 4 are characteristic diagrams showing the relationship between the exciting force, displacement, and velocity with respect to the angular velocity, FIG. 5 is a characteristic diagram showing the relation between the angular frequency ratio and the magnification, and FIG. 6 is the electromagnetic press device of the present invention. FIG. 7 is a partially cutaway side view showing another embodiment, and FIG. 7 is a partially cutaway side view showing a conventional electromagnetic pressing device. 2 ... Fixed frame, 3 ... Ram, 5 ... Press type, 8
...... Guide bearing, 12 …… Ram drive coil, 13 …… Resonant vibration device.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-51-151871 (JP, A) JP-A-49-92675 (JP, A) JP-A-49-56261 (JP, A)

Claims (1)

[Claims] 1. A ram having a press die at its tip and having a magnetic portion at least at a part thereof so as to be capable of reciprocating motion, a guide bearing for guiding and supporting the ram, and the guide bearing. A fixed frame supporting the ram, and a ram drive coil supported by the fixed frame and arranged to face the magnetic portion of the ram. An electric current is passed through the ram drive coil to move the ram. In an electromagnetic pressing device that is linearly moved to perform press working, an iron core that is a magnetic part is provided on the side of the ram opposite to the side where the press die is fixed, and a predetermined gap is provided between the iron core and the iron core. A substantially M-shaped stator core arranged opposite to each other is provided on the fixed frame, the ram drive coil is wound around and fixed to the stator core, and further, resonance occurs between the moving ram and the fixed frame. Movement device The ram driving coil is reciprocated by resonating the ram as a mass system of the ram, and reciprocating the ram drive coil by periodically attracting and repulsing the ram. An electromagnetic press device characterized by being controlled to move.