CN212341319U - Measuring circuit for tiny resistance of polyethylene electric melting pipe fitting - Google Patents
Measuring circuit for tiny resistance of polyethylene electric melting pipe fitting Download PDFInfo
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- CN212341319U CN212341319U CN202021970036.XU CN202021970036U CN212341319U CN 212341319 U CN212341319 U CN 212341319U CN 202021970036 U CN202021970036 U CN 202021970036U CN 212341319 U CN212341319 U CN 212341319U
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Abstract
The utility model discloses a measuring circuit of a polyethylene electric melting pipe micro-resistance, which comprises a main control chip, a current expanding circuit, a series resistance circuit and a parallel resistance circuit; the output end of the main control chip is connected with the non-inverting input end of a first operational amplifier U1 and provides a voltage output signal; the inverting input end of the first operational amplifier U1 is connected with a connecting line between a third resistor R3 and a fourth resistor R4; the emitter terminal of the triode T1 is connected with the first connection terminal V1 of the parallel resistor circuit, the third connection terminal V3 is arranged on the connection line between the fourth resistor R4 and the fifth resistor R5, and the three input terminals of the main control chip respectively collect the voltage values of three test points. The utility model has the advantages that: the utility model discloses an its measuring range of measuring circuit is 0.1 omega-10 omega, satisfies the measurement of the electric smelting pipe fitting resistance of all models basically, and has measurement accuracy height, measures accurate characteristics to can improve the welding quality of polyethylene tubular product.
Description
Technical Field
The utility model belongs to the technical field of the electrofusion welding, concretely relates to measurement circuit of polyethylene electric smelting pipe fitting micro resistance.
Background
The polyethylene pipe has the advantages of high strength, durability, corrosion resistance, low production and installation cost, easiness in connection and the like, and is widely applied to the fields of gas delivery, water supply, oil fields and the like. The reliability of polyethylene pipe connection is a key factor influencing the installation quality and the service life of the pipe, and the electric fusion welding is one of the main methods for welding the polyethylene pipe due to the advantages of simple operation, high welding speed, high welding quality and the like.
The basic principle of electric fusion welding is that an electric fusion pipe fitting joint with a pre-embedded resistance wire is sleeved on a pipe, then current with certain intensity is conducted, the resistance wire generates heat to melt the connecting part of the pipe fitting joint and the pipe, resin molecules on two sides of a connecting interface are wound and knotted again under the action of fusion expansion pressure, and the purpose of connection is achieved after cooling.
According to the principle of electric melting welding and practical experience at home and abroad, whether the polyethylene pipe can form reliable welding connection is verified, and the polyethylene pipe has close relation with factors such as the design of the electric melting pipe, the resistance value of a pre-embedded resistance wire in the electric melting pipe, welding voltage provided by an electric melting welding machine, welding process parameters and the like. And the welding voltage output by the electric melting welding machine is calculated by the resistance value of the electric melting pipe fitting. Therefore, the measurement of the resistance value of the resistance wire embedded in the electric melting pipe fitting is of great importance.
Ordinary electric melting welding machine reads pipe fitting parameter through artifical handheld card reader scanning, however, the difference of its resistance has been decided to the difference of diameter, the length of pre-buried resistance wire in the electric melting pipe fitting, receives ambient temperature and equipment live time's influence in addition, and resistance itself also can change. Because the resistance value of the pre-buried resistance wire in the electric melting pipe fitting cannot be accurately measured, the accurate output voltage of the electric melting welding machine cannot be determined, and the welding quality is influenced.
SUMMERY OF THE UTILITY MODEL
The small resistance measuring circuit for the polyethylene electric melting pipe fitting is provided, the electric melting pipe fitting to be measured is connected into the measuring circuit, the resistance of the electric melting pipe fitting can be automatically measured, the welding voltage output of the electric melting welding machine is more accurate by measuring the resistance of each electric melting pipe fitting, and the welding quality is higher.
The utility model adopts the technical proposal that:
a measuring circuit for a micro resistor of a polyethylene electric melting pipe fitting comprises a main control chip, a current expanding circuit, a series resistance circuit and a parallel resistance circuit;
the current amplifying circuit comprises a first operational amplifier U1, a second operational amplifier U2 and a triode T1, wherein the output end of the first operational amplifier U1 is electrically connected with the non-inverting input end of the second operational amplifier U2, the negative power end of the second operational amplifier U2 is grounded, the positive power end of the second operational amplifier U2 is connected with the positive electrode of a direct current power supply, the output end of the second operational amplifier U2 is connected with the base electrode end of the triode T1, the inverting input end of the second operational amplifier U2 is electrically connected with a connecting wire between the output end of the second operational amplifier U2 and the base electrode end of the triode T1, and the collector electrode of the triode T1 is connected with the positive electrode of the direct current power supply;
the series resistor circuit is formed by sequentially connecting a third resistor R3, a fourth resistor R4 and a fifth resistor R5 in series, the other end of the third resistor R3 is grounded, and the other end of the fifth resistor R5 is grounded;
the parallel resistance circuit comprises a first connection end V1, a second connection end V2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10, wherein one end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is connected with the first connection end V1, and the other end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is connected with the second connection end V2;
the output end of the main control chip is connected with the non-inverting input end of a first operational amplifier U1 and provides a voltage output signal;
the inverting input end of the first operational amplifier U1 is connected with a connecting line between a third resistor R3 and a fourth resistor R4;
the emitter terminal of the triode T1 is connected to the first connection terminal V1 of the parallel resistance circuit,
a third connection V3 is provided on the connection line between the fourth resistor R4 and the fifth resistor R5,
the three input ends of the main control chip are respectively connected with the first connecting end V1, the second connecting end V2 and the third connecting end V3, and voltage values of three test points are respectively collected.
On the basis of the scheme, the first connection end V1 is connected with the anode of the first diode D1, and the cathode of the first diode D1 is connected with the anode of a power supply;
the second connection end V2 is connected with the anode of a second diode D2, and the cathode of the second diode D2 is connected with the anode of a power supply;
the third connection terminal V3 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the power supply anode.
Preferably, the positive power terminal of the second operational amplifier U2 is connected to one point on the connection line of the power supply positive electrode 12V through the fourth capacitor C4, and the other end of the fourth capacitor C4 is grounded.
Preferably, a second resistor R2 is connected to a connecting line between the output end of the main control chip and the non-inverting input end of the first operational amplifier U1.
Preferably, the main control chip is an STM32 chip, the DAC module of the main control chip is an output terminal and provides a voltage signal, and the ADC module of the main control chip is an input terminal and respectively collects voltage values of the first connection terminal V1, the second connection terminal V2 and the third connection terminal V3.
Preferably, the main control chip is connected with a clock circuit and a reset circuit.
Preferably, the resistances of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are all 10 Ω.
The utility model has the advantages that:
the utility model discloses an its measuring range of measuring circuit is 0.1 omega-10 omega, satisfies the measurement of the electric smelting pipe fitting resistance of all models basically, and has measurement accuracy height, measures accurate characteristics to can improve the welding quality of polyethylene tubular product.
Drawings
Fig. 1 is a measurement circuit diagram according to an embodiment of the present invention;
fig. 2 is a diagram of a main control chip and its peripheral circuit according to an embodiment of the present invention;
fig. 3 is a current expanding circuit diagram according to an embodiment of the present invention;
fig. 4 is a parallel resistor circuit according to an embodiment of the present invention.
Detailed Description
The technical solution of the present invention will be further explained with reference to the drawings in the embodiments of the present invention.
The utility model provides a measuring circuit of polyethylene electric smelting pipe fitting micro resistance, includes main control chip STM32F103ZET6, expands a class circuit, series resistance circuit and parallel resistance circuit.
The current amplifying circuit comprises a first operational amplifier U1, a second operational amplifier U2 and a triode T1, wherein the output end of the first operational amplifier U1 is electrically connected with the non-inverting input end of the second operational amplifier U2, the negative power end of the second operational amplifier U2 is grounded, the positive power end of the second operational amplifier U2 is connected with the positive electrode 12V of a power supply, the output end of the second operational amplifier U2 is connected with the base electrode end of the triode T1, the inverting input end of the second operational amplifier U2 is connected with a connecting wire between the output end of the second operational amplifier U2 and the base electrode end of the triode T1, and the collector end of the triode T1 is connected with the positive electrode +5V of a.
The series resistor circuit is formed by sequentially connecting a third resistor R3, a fourth resistor R4 and a fifth resistor R5 in series, wherein the other end of the third resistor R3 is grounded, and the other end of the fifth resistor R5 is grounded.
The parallel resistance circuit comprises a first connection end V1, a second connection end V2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor 10, wherein one end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor 10 is connected with the first connection end V1, and the other end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor 10 is connected with the second connection end V2. The resistances of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor 10 are all 10 Ω.
The DAC module of the main control chip is connected with the non-inverting input end of the first operational amplifier U1 for the output end, provides the voltage output signal, and the second resistor R2 is connected to the connecting line of the output end of the main control chip and the non-inverting input end of the first operational amplifier U1.
The inverting input end of the first operational amplifier U1 is connected with a connecting line between the third resistor R3 and the fourth resistor R4, the emitter end of the triode T1 is connected with the first connecting end V1 of the parallel resistor circuit, and the third connecting end V3 is arranged on the connecting line between the fourth resistor R4 and the fifth resistor R5.
The three input ends of the main control chip ADC module are respectively connected with the first connection end V1, the second connection end V2 and the third connection end V3, voltage values of three test points are respectively collected and converted, and a resistance value to be tested is calculated.
The first connection end V1 is connected with the anode of the first diode D1, the cathode of the first diode D1 is connected with the power supply anode 3.3V, the second connection end V2 is connected with the anode of the second diode D2, the cathode of the second diode D2 is connected with the power supply anode 3.3V, the third connection end V3 is connected with the anode of the third diode D3, and the cathode of the third diode D3 is connected with the power supply anode 3.3V.
The positive power terminal of the second operational amplifier U2 is connected to the fourth capacitor C4 at one point on the connection line of the power supply positive electrode 12V, and the other end of the fourth capacitor C4 is grounded.
Fig. 1 is a measurement circuit diagram, which can realize automatic measurement of the micro-resistance of the electric melting pipe fitting.
FIG. 2 is a main control chip STM32F103ZET6 and a peripheral circuit thereof, wherein an STM32 chip is used for controlling automatic measurement of the resistance value of an electric melting pipe fitting of the whole measuring circuit; the peripheral circuit of the STM32 chip comprises a clock circuit and a reset circuit, wherein the clock circuit provides a reference clock for the normal operation of the STM32 chip, and the reset circuit completes the initialization of the STM32 chip. The DAC module and the ADC module of STM32 chip have mainly been used in the measuring circuit design, and the DAC module provides input voltage for measuring circuit, and the ADC module is used for gathering the voltage value of test point V1, V2, V3 for the calculation of electrofusion tube spare resistance. And the main control chip converts the acquired three-point voltage value and the parallel resistance value to obtain the resistance value to be measured.
Fig. 3 is a current spreading circuit. The second operational amplifier U2 is voltage follower, has low output impedance, acts as a constant voltage source for the following circuit, and has isolation. When the output voltage of the operational amplifier U2 turns on the transistor T1, the weak current signal is amplified into a current signal with a larger amplitude by the T1, thereby achieving the purpose of current expansion. Because the resistance of the pipe fitting to be measured is smaller, large current is introduced into the voltage division circuit, and the accuracy of measurement can be improved.
Fig. 4 shows a voltage divider circuit, where R6, R7, R8, R9, and R10 are internal resistors of the measurement circuit, the resistance is 10 Ω, and the parallel resistor is 2 Ω. Because the high current signal flows into the voltage division circuit, a plurality of resistors are required to be connected in parallel to prevent burning. When the resistance value of the electric melting pipe fitting is measured, the electric melting pipe fitting to be measured is connected between the second connecting end V2 and the third connecting end V3 of the test point, and when the pipe fitting is not measured, the second connecting end V2 and the third connecting end V3 of the test point are connected together. The resistance value of the electric melting pipe fitting is calculated by the partial pressure of the internal resistance of the measuring circuit, and the partial pressure formula is
The calculation formula for obtaining the resistance value of the electric melting pipe fitting is
The diodes D1, D2 and D3 play a protection role, and conduct when the voltage at the points of the first connection end V1, the second connection end V2 and the third connection end V3 exceeds 3.3V, and the voltage 1 at the points of V1, V2 and V3 is clamped at 3.3V because the conduction voltage drop of the diodes is small.
The circuit principle of the present invention will be described in further detail below.
The utility model discloses an among the measuring circuit of polyethylene electric smelting pipe fitting micro resistance, the STM32 chip is main control chip, controls whole measuring circuit's work. Firstly, a DAC module of an STM32 chip gives a voltage signal, the voltage signal flows into an operational amplifier U1 through R2, and the U1 and an external circuit thereof form a non-inverting amplifying circuit to amplify the voltage signal output by the DAC module. The output signal of the U1 is amplified into a large current signal by the current spreading action of the U2 and T1 circuits, and flows into the voltage dividing circuit. The voltage of test point V1, V2, V3 is gathered to STM 32's ADC module, and the voltage difference between V1 and V2 is the voltage drop of measuring circuit internal resistance, and the voltage difference between V2 and V3 is the voltage drop on the electric smelting pipe fitting resistance that awaits measuring, and through the partial pressure principle, the computational formula who obtains electric smelting pipe fitting resistance is for
The utility model discloses a measuring circuit of polyethylene electric smelting pipe fitting micro resistance, its measuring range is 0.1 omega-10 omega, satisfies the measurement of the electric smelting pipe fitting resistance of all models basically, and has measurement accuracy height, measures accurate characteristics to can improve the welding quality of polyethylene tubular product.
Wherein, R1 ═ 10K Ω; r2 ═ 1K Ω; r3 ═ R4 ═ 300K Ω; r5 ═ 10K Ω.
It is to be understood that although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. A measurement circuit for a micro resistor of a polyethylene electric melting pipe fitting is characterized by comprising a main control chip, a current expansion circuit, a series resistance circuit and a parallel resistance circuit;
the current amplifying circuit comprises a first operational amplifier U1, a second operational amplifier U2 and a triode T1, wherein the output end of the first operational amplifier U1 is electrically connected with the non-inverting input end of the second operational amplifier U2, the negative power end of the second operational amplifier U2 is grounded, the positive power end of the second operational amplifier U2 is connected with the positive electrode of a direct current power supply, the output end of the second operational amplifier U2 is connected with the base electrode end of the triode T1, the inverting input end of the second operational amplifier U2 is electrically connected with a connecting wire between the output end of the second operational amplifier U2 and the base electrode end of the triode T1, and the collector electrode of the triode T1 is connected with the positive electrode of the direct current power supply;
the series resistor circuit is formed by sequentially connecting a third resistor R3, a fourth resistor R4 and a fifth resistor R5 in series, the other end of the third resistor R3 is grounded, and the other end of the fifth resistor R5 is grounded;
the parallel resistance circuit comprises a first connection end V1, a second connection end V2, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a tenth resistor R10, wherein one end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is connected with the first connection end V1, and the other end of each of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 is connected with the second connection end V2;
the output end of the main control chip is connected with the non-inverting input end of a first operational amplifier U1 and provides a voltage output signal;
the inverting input end of the first operational amplifier U1 is connected with a connecting line between a third resistor R3 and a fourth resistor R4;
the emitter terminal of the triode T1 is connected with the first connecting terminal V1 of the parallel resistance circuit;
a third connection terminal V3 is disposed on the connection line between the fourth resistor R4 and the fifth resistor R5;
the three input ends of the main control chip are respectively connected with the first connecting end V1, the second connecting end V2 and the third connecting end V3, and voltage values of three test points are respectively collected.
2. The circuit for measuring the micro-resistance of the polyethylene electric melting pipe fitting according to claim 1, wherein the first connection end V1 is connected with the anode of a first diode D1, and the cathode of the first diode D1 is connected with the anode of a power supply;
the second connection end V2 is connected with the anode of a second diode D2, and the cathode of the second diode D2 is connected with the anode of a power supply;
the third connection terminal V3 is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the power supply anode.
3. The circuit for measuring the micro-resistance of the polyethylene electric melting pipe fitting according to claim 1, wherein a positive power supply end of the second operational amplifier U2 is connected with a fourth capacitor C4 at one point of a connecting line of a power supply positive electrode 12V, and the other end of the fourth capacitor C4 is grounded.
4. The circuit for measuring the micro-resistance of the polyethylene electric melting pipe fitting according to claim 1, wherein a second resistor R2 is connected to a connecting line of an output end of the main control chip and a non-inverting input end of the first operational amplifier U1.
5. The measurement circuit of the polyethylene electric melting pipe fitting micro-resistance according to claim 1, wherein the main control chip is an STM32 chip, a DAC module of the main control chip is an output terminal and provides a voltage signal, and an ADC module of the main control chip is an input terminal and respectively collects voltage values of a first connection terminal V1, a second connection terminal V2 and a third connection terminal V3.
6. The circuit for measuring the micro-resistance of the polyethylene electric melting pipe fitting according to claim 5, wherein the main control chip is connected with a clock circuit and a reset circuit.
7. The circuit for measuring the micro-resistance of the polyethylene electrofusion pipe fitting according to claim 1, wherein the resistances of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are all 10 Ω.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021970036.XU CN212341319U (en) | 2020-09-10 | 2020-09-10 | Measuring circuit for tiny resistance of polyethylene electric melting pipe fitting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021970036.XU CN212341319U (en) | 2020-09-10 | 2020-09-10 | Measuring circuit for tiny resistance of polyethylene electric melting pipe fitting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212341319U true CN212341319U (en) | 2021-01-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021970036.XU Expired - Fee Related CN212341319U (en) | 2020-09-10 | 2020-09-10 | Measuring circuit for tiny resistance of polyethylene electric melting pipe fitting |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212341319U (en) |
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2020
- 2020-09-10 CN CN202021970036.XU patent/CN212341319U/en not_active Expired - Fee Related
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210112 Termination date: 20210910 |