DE1155521B - Switchgear for magnetic hammer - Google Patents

Description

GERMAN

kl. 21c 62/52

INTERNATIONAL KL.

PATENT OFFICE H 02 p; G 05 g

E16630VHIb / 2lc

REGISTRATION DATE: OCTOBER 27, 1958

NOTICE
THE REGISTRATION
ANDOUTPUTE
EDITORIAL: OCTOBER 10, 1963

The invention relates to a switching device for magnetic hammers, a single blow or a predetermined number of single blows after switching on also perform in a predetermined work rhythm, with an electronic one Switching element that can be controlled by varying the input values. To avoid accidents whenever possible exclude, such hammers are generally turned on by two buttons. Than are Both hands are inevitably removed from the working area of the ram during a blow. These Keys must be switched in such a way that if one of the two keys is stuck, another Operation of the hammer is excluded. Another security requirement is that the Current flowing through the hammer coil is immediately interrupted when pressure is applied to one of the two Keys stops. It may only be operated again after a blow from the hammer then be possible if both buttons have been released in the meantime.

Switching devices have become known for the stated purpose, some with electron tubes, some with work with contactors or other types of contactors. Such switching devices equipped with contacts have the major disadvantage that the contacts are subject to natural wear. As a result, the duty cycle of the hammer coil, which is decisive for the strength of a blow, is not determined precisely enough to be able to work on parts with such a hammer that are against a change are sensitive to the impact force. In addition, the on-time is unintentionally extended both the generally required rectifier and the hammer coil by impermissible Risk of warming.

Furthermore, switching devices equipped with gas-filled discharge vessels have become known which are made by Multivibrator arrangement are controlled and the disadvantages of switching devices equipped with contacts avoid. Such circuits are quite complex, and the replacement of the discharge vessels, which have a limited service life, is necessary not cheap.

Taking into account the security requirements, the invention only requires a single electronic one Switching element if the hammer is to perform a single blow. If serial or continuous strokes are required, so another controlling device is required, but for much smaller services can be designed as the actual switching device. This advantage is particularly noticeable

Switching device for magnetic hammers

Applicant:

Elmeg Elektro-Mechanik GmbH,
Peine (Hann.)

Hans Rundshagen, Peine (Hann.),
has been named as the inventor

when a transistor is used as the switching element. With little effort, the object connects the Invention the advantages of an electronic switching device with those of a contact system without the To have disadvantages of the contact work.

The invention is characterized in that an electronic switching element (high vacuum tube, im Cathode drop controlled gas rectifier, transistor), which is controlled by varying the input values can be blocked in the idle state by a fixed input value, and that by a short further input value, the effect of which is opposite to the blocking one, the passage of current is initiated. The time constant is either determined by the time constant of the control circuit itself, determined by a special control device or by a feedback circuit. in the In the last case, a short trigger pulse is enough to start the process in a predetermined sense to expire.

In order to enable an accident-proof switch-on according to the two-hand system for safety, this can be Switching device according to the invention can be operated via two pushbuttons, each with a rest and a Working contact are equipped. To generate the passage of current through the electronic switching element According to the invention, the discharge impulse for a capacitor can be used as the introductory input value which takes place via the two normally open contacts of the pushbuttons, while their normally closed contacts short-circuit the capacitor either directly or through a resistor.

After the passage of current through the electronic switching element has been initiated, a from Additional input value derived from the output value

309 727/256

used to maintain the passage of current through the electronic switching element. this happens preferably via an inductive feedback, in which case the time constant is then in a simple manner can be set via a variable series resistor. ~

In an embodiment of the invention, a transformer is used for the inductive feedback, the core of which is magnetized beyond the saturation kink, it being expedient to manufacture the core from a material which has a sharply pronounced saturation kink.
■ "- If serial or continuous impacts are to be carried out, a control device can be used for this (e.g. a multivibrator) which automatically determines the switch-on duration and pause time after the impacts have been initiated. Another switching device of the same type can also be used Construction like the one previously described, which is triggered by the decaying current of the hammer coil when the hammer coil is switched off and has an effect on the output side on the input of the switching device.

The invention is explained on the basis of the illustrated circuit example, the one as a switching element Transistor was used.

In the drawing, HS is the hammer coil to be operated. A resistor R ₃ is connected in parallel to it in series with a rectifier Gl. When the hammer is actuated, the rectifier Gl blocks the passage of current. In contrast, it lets through the current that occurs when the hammer coil is switched off. Here, the resistance R _{s should} be dimensioned so that no inadmissibly high voltage occurs across it. If necessary, the resistor R ₃ can also be omitted entirely.

U ₁ is the voltage with which the electronic switching element is blocked against the passage of current. U ₂ is the voltage that actuates the hammer coil and thus the hammer via the electronic switching element. DTl and DT 2 are two pushbuttons, each with a normally closed contact and a normally open contact. They are designed to trigger the blow of the hammer and to switch off the current flowing through the hammer coil immediately when they are released.

Tr is a transformer with three windings I, II and III, the winding III is in series with a resistor R, parallel to the hammer coil, so that voltage is always applied to the circuit formed by this coil and the resistor R _{2 when this is also} rests against the hammer spool. One end of the winding II of the transformer Tr is connected to the base of the transistor T, and the other end of the winding is connected to the source for the reverse voltage U ₁ via the working contacts of the pushbuttons DT1 and DT 2, which are connected in series. When switching on, a voltage must be present at this winding II which _{compensates for the applied reverse voltage CZ 1} and also has an excess amount which is sufficient to switch the electronic switching element fully to continuity. The winding I of the transformer Tr is also connected to the voltage U ₁ via a capacitor C and a resistor A ₁ when the pushbuttons DTl and DT 2 are pressed, in the rest position of the buttons DTl and DT 2 the capacitor is through the normally closed contacts of these two buttons, which are also in series, short-circuited.

If the two buttons DT1 and DT 2 are depressed, their normally closed contacts are opened and the capacitor C is enabled. Furthermore, the voltage U _{1 is applied} as a blocking voltage to the base of the transistor via the working contacts of both buttons in series, and to the circuit consisting of the winding I of the transformer Tr, the capacitor C and the resistor .R _1. In this last-mentioned circuit, a short burst of charge flows to the capacitor C, which generates a voltage at the winding II of the transformer Tr , which switches the transistor to continuity. R ₁ is dimensioned in such a way that the current cannot swing back, so that the capacitor C is charged aperiodically.

The electronic switching element is released for a short time by the charging surge. This is sufficient to _see on the hammer coil voltage ΕΛ be effectively letting. In the circuit consisting of the winding III and the resistor R _{2 a} current begins to flow, which increases essentially according to an exponential function. This current now maintains the voltage applied to the winding II in the same way as it did before the charging surge for the capacitor C was created. As a result, the switching element remains switched to continuity.

Another idea of the invention is to design the transformer Tr in such a way that the current flowing through the winding III magnetizes the core well into saturation when the steady-state value is reached and the saturation knee is already reached when the increasing current continues to rise approximately linearly . Then the voltage applied to winding II is approximately constant until this kink is reached and then collapses. Since this voltage switches the electronic switching element to continuity, the process is then ended. In order to let the collapse of the voltage present at the winding II of the transformer Tr occur as suddenly as possible and thus sharply limit the duration of the switch-on pulse, it is expedient as a further embodiment of the invention to use a material for the core of the transformer Tr has a sharp saturation kink.

The time constant of the circuit of the coil III of the transformer Tr which determines the pulse duration can be changed in any of the known ways, with which the pulse duration can then also be made variable, which, as previously mentioned, determines the impact strength. For example, another, possibly variable, self-inductance can be switched into the circuit. In the drawing, the resistor R _{2 is shown} variable for the purpose.

If one of the keys or both keys are released after the impact has been initiated by pressing both keys, the control circuit of coil II and thus the current flowing through hammer coil HS are immediately interrupted.

If the two keys DT1 and DT2 are kept depressed, the hammer only performs a single blow. If both pushbuttons are released after the blow, the capacitor C is short-circuited and discharged via their break contacts. The process described above can then be repeated.

However, if one of the two keys has been clamped, the capacitor C is not discharged. Depressing the previously released button does not result in a charging surge, so that a new impact cannot take place. There is therefore the certainty that a new strike can only be performed if both keys have previously been returned to their starting position.

In order to execute series or continuous blows with a switching arrangement according to the invention, it is only necessary necessary to give the initial push to charge the capacitor repeatedly. Any known arrangement, such as a multivibrator, can be used for this purpose. One Such an arrangement has the advantage that, because the switching device itself determines the pulse duration, it is independent the triggering of successive blows is determined by the set impact strength, while in the arrangements known so far only the pause between two successive ones Hitting can be adjusted. In switching devices with transistors there is still the advantage given that the power to be generated by the control unit can be much smaller than when that Switching element would be controlled directly. It only needs to be sufficient to charge the capacitor.

Another way of performing continuous or series strikes is from the decaying one Current of the hammer coil inductively again derive an initial shock for an arrangement that was previously described is built equivalent. The switch-off surge then becomes the triggering of the actual one Switching element used.

Claims (1)

PATENT CLAIMS: 35 1. Switching device for magnetic hammers with an electronic switching element (high vacuum tube, transistor), which can be controlled by varying the input values, characterized in that this switching element (T ) is blocked in the idle state by a fixed input voltage (CZ ₁ ) and that by switching a short further input voltage, the effect of which is opposite to the blocking one, the passage of current is initiated. 3. Switching device according to claim 1, characterized in that for the accident-proof switching on after the two-hand system, the actuation of the switching device via two pushbuttons (DTl, DT 2) , each equipped with a normally closed contact and a normally open contact. 3. Switching device according to one of the preceding claims, characterized in that for generation the input voltage initiating the passage of current in the electronic switching element (T) the charging current surge is used for a capacitor (C). 4. Switching device according to claim 3, characterized in that the capacitor (C) used to generate the triggering input voltage is short-circuited either directly or via a resistor in the rest position of the pushbuttons (DTl, DT 2) by their series break contacts. 5. Switching device according to claim 1 to 4, characterized in that after the initiation of the Current passage through the electronic switching element (T) the passage of current through one of the Further input voltage derived from the output value is maintained. 6. Switching device according to claim 5, characterized in that an inductive feedback is used to generate the current passage through the electronic switching element (T) maintaining the input voltage (Tr). 7. Switching device according to claim 6, characterized in that the inductive feedback is carried out via a transformer (Tr) , the core of which is magnetized beyond the saturation kink. 8. Switching device according to claim 7, characterized in that a core made of a material is used for the feedback transformer (Tr) which has a sharply pronounced saturation kink. 9. Switching device according to one of the preceding claims, characterized in that the Time constant of the return path is adjustable. 10. Switching device according to claim 2 and / or 4, characterized in that the series of working contacts of the pushbuttons (DT 1, DT 2) when opening one or both contacts also interrupt the current flowing through the hammer coil directly or indirectly. 11. Switching device according to one of the preceding claims, characterized in that for Execution of series or continuous strokes the switching device by a control device (multivibrator) is controlled. 12. Switching device according to one of claims 1 to 10, characterized in that for execution of series or continuous blows through another switching device with the same mode of operation the decaying current that occurs when the hammer coil is switched off is controlled, which acts on the output side on the input of the actual switching device. Considered publications:
U.S. Patent No. 2,750,538. 1 sheet of drawings © 309 727/256 10.