GB1572090A

GB1572090A - Wire wrapping machine and a control system therefor

Info

Publication number: GB1572090A
Application number: GB4562676A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-12-06
Filing date: 1976-11-03
Publication date: 1980-07-23
Also published as: CA1069204A; DE2652041A1; JPS5754912B2; DE2652041C2; JPS5268972A

Description

(54) WIRE WRAPPING MACHINE AND A CONTROL SYSTEM THEREFOR (71) I, KATSUYUKI TOTSU, citizen of Japan, No. 4-7, 3-chome, Oshiage, Sumida-ku, Tokyo, Japan, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a wire wrapping machine and a control system therefor.

Recently, in order to facilitate assembly of electronic circuit parts, a so-called 'wire wrapping' is generally used in which a stripped portion of a lead wire is wrapped tightly, without soldering, around a metal terminal, which protrudes from a base circuit plate, of a circuit element such as electrolytic condenser or resistor.

A working instrument for effecting the wire wrapping operation is generally called a wire wrapping machine and comprises a lead wire wrapping spindle rotatably received in a sheath sleeve, the spindle being rotated by a driving power source of an electric motor or an air motor. The spindle 10, as is shown in Figure 1, is provided at its centre with a hole 14 of a predetermined depth for receiving a bar terminal 12 of a circuit element 11 (Figure 2) and formed longitudinally with a slot 16 on its periphery for holding the lead wire. This spindle 10 is connected through a clutch means as hereinafter described to the motor accommodated in the wrapping machine. The spindle 10 is contained in an outer sleeve 22 having a somewhat larger inner diameter than that of the spindle and being fixed to the machine.

In the wrapping operation of the lead wire such as vinyl wrapped copper wire, the stripped portion of the lead wire 24 is inserted into the slot 16; since the spindle 10 is enclosed in the fixed sleeve 22, the lead wire 24 is held by the slot 16 and an inner circumferential wall of the sleeve 22 without slipping out; then the bar terminal 12 of the circuit element 11 protruding vertically from the circuit base plate 26 is vertically inserted into the central hole 14 of the spindle 10, the spindle is then rotated for a predetermined period whilst the wrapping machine is held so that the stripped portion of the lead wire 24 is tightly wrapped around the bar terminal 12 as shown in Figure 2 to obtain a complete conductive connection. At the open end of the sleeve 22 there is provided a recess 28 for enabling the wrapping of the lead wire from the base of the bar terminal. To achieve a rapid and continuous wrapping of the lead wire the necessity arises of providing a mechanism to ensure that when the motor is stopped the spindle 10 is returned to a specified position in the sleeve 22 to align an open end of the slot 16 with the recess 28 as shown in Figure 3.

For this purpose, in the conventional wrapping machine a ratchet mechanism (not shown) is incorporated so that when the operation of the spindle 10 is stopped after completion of wrapping of the lead wire 24 the spindle 10 is turned reversely under the function of a spring for engagement with the ratchet to stay stationarily at the specific position in the sleeve 22. However, since the spindle is directly connected with the motor the spring has to overcome an excessive load and accordingly reverse rotation by the elasticity is difficult to obtain. To resolve this problem, in the conventional wrapping machine a clutch means is arranged between the spindle and the motor driving shaft to release the connection therebetween for decreasing the resistance load against the spindle. However, inevitably, use of the clutch means results in an increase of the weight of the machine per se and the cost of manufacturing the machine. Furthermore, when an ac motor is used as a power source, there are such disadvantages that the change of rotation is difficult with much noise while when a compressed air motor is used as a power source, a high exhaust noise is caused with use of a separate compressor.

After intensive studies of the above problems, the inventor has employed a dc motor which is conveniently reversible by merely changing the polarity of the supplied electncity to apply a reverse voltage thereto for a long enough period for the spindle to reverse to engage the ratchet after cessation of the motor operation with completion of the wire wrapping. The reversely rotating spindle is engaged with a ratchet to stop at a predetermined position in relation to the sleeve. By this arrangement, the clutch means used in the conventional machine to release a connection between the spindle and the motor becomes unnecessary.

According to one aspect of the present invention there is provided a control system for a wire wrapping machine having a lead wire wrapping spindle supported in an outer sleeve for rotation in one direction to wrap said lead wire and in an opposite direction to reposition said spindle with respect to said sleeve, the rotation of said spindle in the opposite direction being limited by engagement with a ratchet mechanism, the control system comprising a reversible DC motor for driving said spindle, a first rectifier circuit connected to a source of current for supplying current of a predetermined polarity, a second rectifier circuit connected to the source of current for supplying current of an opposite polarity and a switching circuit having a control operable to connect said first rectifier circuit to said motor for wrapping said lead wire, said switching circuit being thereafter operable to connect after the elapse of a first predetermined interval said second rectifier circuit to said motor to reverse the rotation of said motor to cause said spindle to rotate into engagement with said ratchet mechanism, and on the elapse of a second predetermined interval to disconnect said second rectifier circuit from said motor thereby removing the supply from said motor independently of said ratchet mechanism.

According to another aspect of the present invention there is provided a wire wrapping tool comprising a housing adapted to be manually held, a tubular sleeve extending from said housing and a wire wrapping spindle rotatably supported by said housing and extending through said sleeve, said housing containing a control system according to any preceding claim.

Reference is now made to the accompanying drawings, in which: Figure 1 is a partially broken away perspective view of a wire wrapping machine; Figure 2 is a perspective pictorial view illustrative of lead wire being wrapped tightly to the bar terminal of the circuit element by the wire wrappingmachine, Figure 3 is a front elevation of the spindle with the sleeve showing the position where the slot of the spindle is aligned with the recess of the sleeve; Figure 4 is a circuit diagram of the control means of the wire wrapping machine; and Figure 5 is a pictorial view of the wire wrapping machine in accordance with the present invention.

In Figure 4, the reference symbol T is a transformer for dropping the voltage of an alternating current supplied from a commercially available power source E to a desired value and to the output of the transformer T are connected a first rectifying circuit 36 and a second rectifying circuit 38 for obtaining their proper dc current through the rectifying elements 32 and 34 such as rectifying diodes of selenium or the like. Reference numeral 40 represents a dc motor of small type accommodated in a wire wrapping machine 39 and one of the inputs (IN1) of the motor 40 is connected to a positive output of the first rectifying circuit 36 through the motor switch SW3 and to a negative output of the second rectifying circuit 38. Another input (IN2) of the motor 40 is connected switchably to the negative output of the first rectifying circuit 36 and the positive output of the second rectifying circuit 38 through the relay contact RY1-1 co-operative with the relay provided in the relay control circuit as hereinafter described. The relay contact RY1-1 is so controlled that it is connected to the negative output of the first rectifying circuit 36 during the wire wrapping operation to rotate the motor 40 normally.

Therefore it will be appreciated that when the motor switch SW3 is turned off and the relay contact RY1-1 is connected to the positive output of the second rectifying circuit 38 under the operation of the relay circuit, power supply from the first rectifying circuit 36 to the motor 40 is interrupted and reverse current is supplied from the second rectifying circuit 38 to the motor 40 to permit the motor to rotate reversely.

In the motor circuit of the first rectifying circuit 36, through a diode D1 there is inserted in parallel a chargeable and dischargeable electrolytic condenser EC3 of a great capacity so that a voltage of constant value is applied to the condenser ECs when the motor 40 rotates normally on closure of the motor switch SWB.

The positive output of the condenser ECs is connected to a base terminal bl of the transistor TR1 of a voltage amplifying circuit between an emitter terminal el of which and a base terminal b2 of the transistor TR2 of the next stage a variable resistor VR1 and a resistor Rs are connected in series. The emitter terminal e2 of the transistor TR2 and the base terminal b3 of a transistor TRs are connected through the resistor R7 and in the input (IN1) side of the motor 40 there are connected the resistor R3 connected with the emitter terminal el, a chargeable and dischargeable electrolytic condenser EC4 connected with the base terminal b2. a resistor R, connected with the emitter terminal e! and the diodes D3 and D4 connected in series with the emitter terminal es. The capacity of the electrolytic condenser EC4 is smaller than that of the electrolytic condenser EC3.

The positive output of the first rectifying circuit 36 is connected to the emitter terminal e3 of the transistor TR3 via the resistor Rs and also to the collectors C1, C2 of the transistors TR1, TR2 with the collector C3 of the transistor TR3 connected through the relay RY1. The relay contact RYi -1 controlled by the relay RY1 is inserted into the circuit so that the input (IN2) of the motor 40 can be switch ably connected to the negative output of the first rectifying circuit 36 and the positive output of the second rectifying circuit 38. The relay contact RY1-2 controlled by the relay RY1 is inserted as a normally open contact between the connection of the positive output of the electrolytic condenser EC3 with the base terminal bi of the transistor TR1 and the input (IN1) line of the motor 40 through the resistor R2. The diode D2 and the resistor R4 are inserted between the connection of the relay contact RY, with the resistor R2 and the positive output of the electrolytic condenser EC4. By this arrangement, when the relay contact RY1-2 is closed by the energization of the relay RY1, the electrolytic condenser EC3 is discharged through the resistor R2 whereas the electrolytic condenser EC4 is discharged through the resistor R4 and the diode D2.

The motor switch SW3, when the supply of current from the first rectifying circuit 36 to the motor 40 is cut off, shortcircuits the motor circuit to electrically connect the inputs IN1 and IN2 of the motor 40.

As schematically illustrated in Figure 5 the wire wrapping machine thus constructed contains a small dc motor 40 as a driving source and the rotary shaft of the motor 40 is connected to a gearing mechanism 44 with a planet wheel whereas an output shaft of the gearing mechanism is connected to the lead wire wrapping spindle 10 through a ratchet mechanism 46. The spindle 10 rotates normally and reversely in the sleeve 22, and in case of the reverse rotation the spindle 10 is held by the ratchet mechanism 46 at a position where the open end of the lead wire holding slot 16 is aligned with the recess 28 of the sleeve 22 as best shown in Figure 3.

In operation of the control means for the wire wrapping machine according to the invention, when the bar terminal 12 of the circuit element is vertically inserted into the terminal insertion hole 14 provided in the spindle 10 to close the motor switch SW3; i.e.

connect positive terminal circuit 36 to motor input IN1, the motor 40 is driven by current supply from circuit 36 to allow the spindle 10 to rotate in the sleeve 22 for tightly wrapping the lead wire (see Figure 2). During this process, the current flows through the diode D1 in the positive direction to charge the electrolytic condenser EC3 until the charging is completed. When the wrapping operation process is finished, the switch SW3 is changed over so that the negative terminal of circuit 36 is connected to input IN1 the current supply from the first rectifying circuit 36 to the motor 40 is interrupted simultaneously as the motor switch SW3 is switched to directly connect the motor inputs IN1 and IN2, and short circuit current is passed through the motor 40, thus generating an electromagnetic brake to stop the motor instantly. By changing over the motor switch SW3, the discharging current of the electrolytic condenser EC3 flows through the transistor TR1 and the resistor R3 to make the voltage of the resistor R3 substantially equal to the discharge voltage of the electrolytic condenser EC3. Further, the discharge voltage charges the electrolytic condenser EC4 via the variable resistor VR1 and the resistor Ra and is then applied to the resistors R6, R7 and the diodes D3, D4.

During this process, the voltage of the resistor Ra is substantially equal to the voltage of the electrolytic condenser EC4 and provides the base voltage of the transistor TR3. When the voltage of the resistor Re becomes higher than the emitter voltage, the transistor TR3 operates as a switch and permits the collector current of the collector C3 to pass therethrough to energize the relay RY1. The relay contact RYi -1 controlled by the relay RY1 is switched to break the connection of the input (IN2) of the motor 40 to the negative output of the first rectifying circuit and instead to connect the positive output of the second rectifying circuit 38 with the input terminal (IN2). In other words, the voltage of the circuit 38 is supplied to the motor 40 to permit the motor to rotate in a reverse direction. Since, however, the ratchet mechanism 46 is inserted into the spindle 10 connected to the motor 40 the spindle 10 is halted at a predetermined position as shown in Figure 3 to stop actuation of the motor. In this operation, the motor is constrained to stop rotation while being supplied with the reverse voltage with possible damage to the motor by burning or demagnetization, for example. In order to avoid these defects, the relay contact RY1-2 controlled by the relay RY1 is closed by energisation thereof to discharge the condensers EC3 and EC4 through the resistors R2 and R4 until the voltage thereof falls to below the release voltage of the relay RY1 so that the relay RY1 is de-energised to switch the relay contact RY1-1 to the negative output of the first rectifying circuit 36 for discontinuing the application of the reverse voltage while re opening the relay contact RY1-2 to obtain the constant open position. One cycle of the wire wrapping process in the control means is thus finished.

It follows that relay RY1 is energised for a time determined by the choice of EC, R4 to set the period for which the reverse voltage is applied (namely, the discharge time of capacitor Etc4). Furthermore, the variable resistor VR1 provides a fine adjustment of the period for which the reverse voltage is applied.

As hereinbefore described, in accordance with a control means of the present invention, the dc motor accommodated in the wire wrapping machine is supplied with a reverse voltage for the short time to reverse the operation of the motor so that the lead wire wrapping spindle is positioned at a predetermined position in relation to the fixed sleeve.

Accordingly, a clutch mechaism which is necessary with the conventional machine can be left out with reduction of the cost and decrease of the weight of the machine as well as elimination of the troubles caused by the clutch mechanism. Moreover, in the control means, the motor is shortcircuited simultaneously with the interruption of the current to the motor to instantaneously stop the motor. After the complete cessation of the motor, the reverse voltage is applied to the motor and switched off after a predetermined period of time in order to avoid the demagnetization of the permanent magnet forming a stator of the dc motor. Further, use of the dc motor results in less noise on the wrapping operation and does not require any compressor.

WHAT I CLAIM IS: 1. A control system for a wire wrapping machine having a lead wire wrapping spindle supported in an outer sleeve for rotation in one direction to wrap said lead wire and in an opposite direction to reposition said spindle with respect to said sleeve, the rotation of said spindle in the opposite direction being limited by engagement with a ratchet mechanism, the control system comprising a reversible DC motor for driving said spindle, a first rectifier circuit connected to a source of current for supplying current of a pre determined polarity, a second rectifier circuit connected to the source of current for supplying current of an opposite polarity and a switching circuit having a control operable to connect said first rectifier circuit to said motor for wrapping said lead wire, said switching circuit being thereafter operable to connect after the elapse of a first predetermined interval said second rectifier circuit to said motor to reverse the rotation of said motor to cause said spindle to rotate into engagement with said ratchet mechanism, and on the elapse of a second predetermined interval to disconnect said second rectifier circuit from said motor thereby removing the supply from said motor independently of said ratchet mechanism.

2. A system according to claim 1, wherein the switching circuit includes a condenser connected to said first rectifier circuit for energization on passage of current from said first rectifier to said motor, means on completion of the wrapping of said wire for disconnecting said condenser from said first rectifier circuit and simultaneously forming a closed circuit for discharging said condensor, and a relay control circuit having a relay actuable to connect said motor to said second rectifier circuit, said relay control circuit being energized by the discharge of said condenser to actuate after said first predetermined interval to connect said motor to said second circuit to thereby cause said motor to rotate reversely and after said second further predetermined interval to deactivate said relay to disconnect said motor from said second rectifier circuit.

3. A system according to claim 2, wherein said means for disconnecting said condenser comprises a motor controlling switch having a first contact connecting one input of the motor to the positive output of said first rectifier circuit and a second contact connecting the one input of the motor to the negative output of said first rectifier circuit, and said relay includes a first switch having a first contact connecting the other input of the motor to the negative output of the first rectifying circuit and a second contact connecting the other input of the motor to the positive output of the second rectifier circuit, said switches being normally maintained with their first contacts connected to said motor.

4. A system as claimed in claim 3 in which in the first contact position of said motor controlling switch the condenser is charged in a first direction and in which in said second contact position of said motor controlling switch the condenser is discharged via a first stage of a transistorised amplifier circuit to energise said relay thereby providing, via said second contact of said first relay switch, reverse current for said motor to cause said motor to reverse direction.

5. A system as claimed in claim 4 in which the transistorised amplifier circuit includes a second condenser which is charged, via said first stage of the transistorised amplifier circuit, during the discharge of said condenser and in which said second condenser is discharged via the contacts of a second normally open switch on said relay, the discharge time of said second condenser determining the time period during which the relay is energised and thereby the said second predetermined time period that the reverse current is applied to said motor.

6. A system according to claim 5 wherein the discharge time of the second condenser is

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. opening the relay contact RY1-2 to obtain the constant open position. One cycle of the wire wrapping process in the control means is thus finished. It follows that relay RY1 is energised for a time determined by the choice of EC, R4 to set the period for which the reverse voltage is applied (namely, the discharge time of capacitor Etc4). Furthermore, the variable resistor VR1 provides a fine adjustment of the period for which the reverse voltage is applied. As hereinbefore described, in accordance with a control means of the present invention, the dc motor accommodated in the wire wrapping machine is supplied with a reverse voltage for the short time to reverse the operation of the motor so that the lead wire wrapping spindle is positioned at a predetermined position in relation to the fixed sleeve. Accordingly, a clutch mechaism which is necessary with the conventional machine can be left out with reduction of the cost and decrease of the weight of the machine as well as elimination of the troubles caused by the clutch mechanism. Moreover, in the control means, the motor is shortcircuited simultaneously with the interruption of the current to the motor to instantaneously stop the motor. After the complete cessation of the motor, the reverse voltage is applied to the motor and switched off after a predetermined period of time in order to avoid the demagnetization of the permanent magnet forming a stator of the dc motor. Further, use of the dc motor results in less noise on the wrapping operation and does not require any compressor. WHAT I CLAIM IS:

1. A control system for a wire wrapping machine having a lead wire wrapping spindle supported in an outer sleeve for rotation in one direction to wrap said lead wire and in an opposite direction to reposition said spindle with respect to said sleeve, the rotation of said spindle in the opposite direction being limited by engagement with a ratchet mechanism, the control system comprising a reversible DC motor for driving said spindle, a first rectifier circuit connected to a source of current for supplying current of a pre determined polarity, a second rectifier circuit connected to the source of current for supplying current of an opposite polarity and a switching circuit having a control operable to connect said first rectifier circuit to said motor for wrapping said lead wire, said switching circuit being thereafter operable to connect after the elapse of a first predetermined interval said second rectifier circuit to said motor to reverse the rotation of said motor to cause said spindle to rotate into engagement with said ratchet mechanism, and on the elapse of a second predetermined interval to disconnect said second rectifier circuit from said motor thereby removing the supply from said motor independently of said ratchet mechanism.

determined by a resistor means connected in series therewith.

7. A control system for a wire wrapping tool substantially as described with reference to the accompanying drawings.

8. A wire wrapping tool comprising a housing adapted to be manually held, a tubular sleeve extending from said housing and a wire wrapping spindle rotatably supported by said housing and extending through said sleeve, said housing containing a control system according to any preceding claim. ~ ~ ~