CN109000863A - A kind of air tightness detection system and its detection method of SLM device molding cavity - Google Patents
A kind of air tightness detection system and its detection method of SLM device molding cavity Download PDFInfo
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- CN109000863A CN109000863A CN201810900882.5A CN201810900882A CN109000863A CN 109000863 A CN109000863 A CN 109000863A CN 201810900882 A CN201810900882 A CN 201810900882A CN 109000863 A CN109000863 A CN 109000863A
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- molding cavity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
- G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
- G01M3/3272—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers for verifying the internal pressure of closed containers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/28—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds
- G01M3/2807—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes
- G01M3/2815—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes using pressure measurements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
- G01M3/34—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by testing the possibility of maintaining the vacuum in containers, e.g. in can-testing machines
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Examining Or Testing Airtightness (AREA)
Abstract
The invention belongs to metal 3D printing fields, and disclose a kind of air tightness detection system and its method for selective laser fusing (SLM) equipment molding cavity, including forming cavity upper and lower cavities, chamber pressure sensor, cavity temperature sensor, air inlet pressure sensor, intake solenoid valve, outlet solenoid valve, vacuum solenoid, vacuum pump, programmable logic controller (PLC) (PLC), industrial personal computer, touch screen, inert gas inleting pipe road passes through intake solenoid valve and the lower chamber connection, pressure sensor is installed, for measuring admission pressure on air inlet pipeline；The lower chamber is equipped with pressure sensor and temperature sensor, is respectively used for measuring the pressure and temperature value of cavity；Outlet solenoid valve and vacuum solenoid are mounted on the upper cavity top, and vacuum pump passes through vacuum solenoid and the upper cavity connection；Pressure sensor, temperature sensor, solenoid valve, vacuum pump are connected with PLC, and PLC and touch screen are connected with industrial personal computer.It is the configuration of the present invention is simple, easy to operate.
Description
Technical field
The present invention relates to metal 3D printing fields, and in particular to a kind of air-tightness of selective laser melting unit molding cavity
Detection system and its detection method.
Background technique
The main direction of development of the current metal 3D printing technique of selective laser smelting technology (SLM), which is based on quick
The thought of forming successively selectively melts metal powder using laser beam, to realize that increment manufactures.SLM technology has small
In batches, personalized feature, is very suitable to the manufacture with complex internal structural metal parts.
Due to SLM technology be the process of increasing material manufacturing is realized by high energy laser beam high temperature melting metal powder, if
Oxygen content inside equipment molding cavity cannot be maintained at very low level, will lead to oxidization of metal powder, so that part is beaten
Print failure or mechanical property reduce.Further, since inevitably exist in metal powder carbon and some other
Impurity, if too high oxygen level, these impurity will combustion gasification generation smog pollution powder during laser fusing
Bed, and smog is attached to the decaying that galvanometer protective glass surface also results in laser energy input.
In order to keep micro- oxygen environment in print procedure inside molding cavity, it is common practice to before printing starts first
It opens vacuum pump and vacuum pumping is carried out to molding cavity, inside cavity to be formed is closed vacuum pump close to after vacuum, then opened
It opens intake valve and is filled with the inert gases such as argon gas to inside cavity.Until molding cavity internal pressure reaches 25mbar-30mbar's
When slight positive pressure state, intake valve is closed, air outlet valve is opened, is outwardly vented using pressure difference, until molding cavity internal pressure drops
It as low as 10mbar-15mbar, is at this moment again turned on intake valve and is filled with argon gas, until molding cavity internal pressure reaches 25mbar-
The slight positive pressure state of 30mbar, so circulation carry out gas displacement oxygen content inside molding cavity and are reduced to as defined in printing
It is horizontal.
During building micro- oxygen atmosphere, if molding cavity air-tightness is poor to will cause two consequences: first is that vacuum
Molding cavity can not be evacuated to close to vacuum state by pump, and inside cavity still has more oxygen when subsequent gases being caused to be replaced,
And then extend the gas displacement time, to increase the consumption of inert gas；Second is that in print procedure external environment
Oxygen can enter inside molding cavity, destroy printing atmosphere, reduce the Forming Quality of part.
Measurement airtight cavity air-tightness is mainly using helium mass analyzer in practice, but helium mass analyzer can only be to equipment
Single-point leak rate is detected, and can not comprehensively be assessed the whole air-tightness of equipment, and due to molding cavity volume compared with
Greatly, it when carrying out single-point air-leakage test using helium mass analyzer is likely to that leakage point can not be detected, so as to cause to cavity air-tightness
False judgment.
Summary of the invention
The invention mainly solves the technical problem of providing a kind of air tightness detection system of SLM device molding cavity and its
Method solves the problems, such as leakage point missing inspection when helium mass analyzer carries out single-point air-leakage test, and can be to equipment forming cavity
The whole air-tightness of body is effectively assessed.
The technical scheme adopted by the invention is that: a kind of air tightness detection system of SLM device molding cavity, including epicoele
Body, lower chamber, pressure sensor, temperature sensor, air inlet pressure sensor, intake solenoid valve, outlet solenoid valve, vacuum electromagnetic
Valve, vacuum pump, programmable logic controller (PLC), industrial personal computer, touch screen, wherein connection between the upper cavity, lower chamber；It is described
Inert gas inleting pipe road passes through intake solenoid valve and lower chamber connection, is equipped with air inlet pressure sensor on air inlet pipeline, uses
To measure admission pressure；The lower chamber is equipped with pressure sensor and temperature sensor, is respectively used for measuring the pressure of cavity
And temperature value；The outlet solenoid valve and vacuum solenoid are installed on upper cavity top, vacuum pump by vacuum solenoid with it is upper
Cavity connection；The pressure sensor, temperature sensor, outlet solenoid valve, vacuum solenoid, vacuum pump are and programmable logic
Controller is connected, and programmable logic controller (PLC) and touch screen are connected with industrial personal computer.
Further, pass through pipeline connection between the upper cavity, lower chamber.
Further, the pressure sensor and temperature sensor are installed on lower chamber by G1/2 screw thread, are twined on screw thread
There is unsintered tape.
Another technical solution of the present invention is: a kind of air-leakage test side for SLM device molding cavity
Method includes the following steps:
1) pressure maintaining detects；
2) vacuum detecting；
3) gas circuit detects；
4) all of above test and sensor reading filtering processing are run；
5) pressure, temperature sensor reading filtering processing.
Further, specifically comprise the following steps:
(1) pressure maintaining is tested
(1) pressure maintaining testing button is put on the touchscreen, it is formal to open pressure maintaining testing process.PLC judges chamber pressure first
Whether value is less than or equal to 7mbar, if it is, directly opening intake solenoid valve is filled with inert gas until chamber pressure value is greater than
Equal to 15mbar, otherwise needs first to open outlet solenoid valve, open air inlet electromagnetism until chamber pressure value is down to 7mbar again
Valve.
(2) the pressure maintaining testing process timing since intake solenoid valve close moment, while every cavity pressure of 1 second record
Then force value and temperature value calculate the initial pressure that the maximum value in preceding 10 pressure values is tested as pressure maintaining.
(3) when molding cavity pressure value is less than or equal to 7mbar, pressure maintaining test terminates, the time of record pressure maintaining test.
(4) slip of molding cavity is calculated.When calculating, consider to carry out temperature-compensating to pressure measurements, according to reason
Think equation of gas state pV=nRT (wherein, p is pressure, and V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant),
Cavity internal pressure value is p when test starts1, temperature T1, pressure value is p in test process lumen body, and temperature T ignores leakage
The amount of the influence of amount, cavity volume and inside cavity gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1.It calculates
When slip, linear fit is carried out to the pressure and temp data sequence acquired in pressure maintaining test process using least square method, is obtained
To the slope of straight line be exactly slip of the molding cavity under state of pressure keeping, formula is as follows:
(5) judge that molding cavity pressure maintaining tests whether qualification.
(2) vacuum test
(1) vacuum test button is put on the touchscreen, it is formal to open vacuum test process.First turn on vacuum pump and vacuum
Solenoid valve carries out vacuum pumping to molding cavity, until cavity internal pressure value is less than or equal to -960mbar.
(2) the vacuum test process timing since vacuum pump close moment, while every chamber pressure value of 1 second record
And temperature value, then calculate initial pressure of the minimum value as vacuum test in preceding 10 pressure values.
(3) when reaching 30 minutes the vacuum test time, chamber pressure value this moment is recorded.
(4) slip of molding cavity is calculated.When calculating, consider to carry out temperature-compensating to pressure measurements, according to reason
Think equation of gas state pV=nRT (wherein, p is pressure, and V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant),
Cavity internal pressure value is p when test starts1, temperature T1, pressure value is p in test process lumen body, and temperature T ignores leakage
The amount of the influence of amount, cavity volume and inside cavity gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1.It calculates
When slip, linear fit is carried out to the pressure and temp data sequence acquired during vacuum test using least square method, is obtained
To the slope of straight line be exactly the slip of molding cavity under vacuum conditions, formula is as follows:
(5) judge whether molding cavity vacuum test is qualified.
(3) gas circuit is tested
(1) gas circuit testing button, formal opening gas circuit testing process are put on the touchscreen.First determining whether chamber pressure value is
It is no to be less than or equal to -700mbar, if it is, opening intake solenoid valve is filled with inert gas, record cavity internal pressure value from -
600mbar rises to the time required for -100mbar, otherwise needs to open vacuum pump and vacuum solenoid, to molding cavity into
Row vacuum pumping is until cavity internal pressure value is less than or equal to -700mbar.When cavity internal pressure value is more than or equal to 0mbar, close
Close intake solenoid valve.
(2) judge that molding cavity gas circuit tests whether qualification.
(4) all of above test is run
Above three process is successively run according to the sequence of pressure maintaining test, vacuum test, gas circuit test.
(5) pressure, temperature sensor reading filtering processing
In order to guarantee the stabilization of pressure and temperature sensor reading, the influence of various noise signals is removed, using second order bar
Special Butterworth low-pass filter is filtered pressure and temperature sensor reading, and the transmission function of filter is as follows:
Wherein ωcIndicate the cutoff frequency of Butterworth LPF.In order to determine the cutoff frequency of filter, first
The reading of unfiltered front sensor is acquired, spectrum analysis then is carried out to it using MATLAB, determines noise signal and pressure temperature
The crest frequency of analog signals is spent, final coutoff frequency just takes suitable value between two crest frequencies.
In general, the contemplated technical solution of the present invention has the advantage that compared with prior art
(1) all testing process are all made of PLC control, realize the automation of whole process test, can significantly subtract
The labor intensity of light work personnel improves the efficiency of detection.
(2) the contemplated technical solution of the present invention can make assessment to the whole air-tightness of SLM device molding cavity, keep away
Having exempted from the leak detection of helium mass analyzer single-point possibly can not detect the defect of leakage point, and operating process is simple, and cost is relatively low.
(3) the contemplated technical solution of the present invention being capable of pressure maintaining air-tightness to SLM device molding cavity, vacuum-tightness
And gas circuit fluency makes comprehensive evaluation.
(4) during actual test, due to the testing time is longer and the temperature change of molding cavity ambient enviroment compared with
Greatly, therefore to the measurement result of pressure there is large effect.In this regard, contemplated technical method of the invention is according to perfect gas shape
State equation has carried out temperature-compensating to the measurement result of pressure, has modified the error that temperature change is brought, improves the standard of test
Exactness.
(5) pressure and temperature sensor is sampled in test process, after the completion of test, using least square method and
The data sequence that The Ideal-Gas Equation obtains sampling is fitted, to obtain the slip of molding cavity.This programme
Take full advantage of the data in test process, it is thus possible to obtain accurate slip result.
(6) the contemplated scheme of the present invention using Butterworth LPF to the reading of pressure and temperature sensor into
It has gone filtering processing, and has proposed the method for spectrum analysis rapidly and accurately to determine the cutoff frequency of filter, this is effectively
The influence for eliminating each noise like improves the accuracy of sensor reading, for test result accuracy established it is solid
Basis.
Detailed description of the invention
Fig. 1 is the flow chart of the pressure maintaining test of the embodiment of the present invention.
Fig. 2 is the flow chart of the vacuum test of the embodiment of the present invention.
Fig. 3 is the flow chart of the gas circuit test of the embodiment of the present invention.
Fig. 4 is the system structure diagram of the SLM device molding cavity air-leakage test of the embodiment of the present invention.
Specific embodiment
In order to more specifically describe the present invention, with reference to the accompanying drawing and embodiment, the present invention is carried out specifically
It is bright.
Referring to Fig. 4, a kind of system for SLM device molding cavity air-leakage test, including 4 He of forming cavity upper and lower cavities
5, chamber pressure sensor 8, cavity temperature sensor 9, air inlet pressure sensor 7, intake solenoid valve 6, outlet solenoid valve 3, true
Empty solenoid valve 2, vacuum pump 1, programmable logic controller (PLC) (PLC) 11, industrial personal computer 12, touch screen 13, wherein
Pass through 10 connection of pipeline between forming cavity upper cavity 4 and lower chamber 5；
Inert gas inleting pipe road passes through intake solenoid valve 6 and 5 connection of lower chamber, is equipped with pressure sensing on air inlet pipeline
Device 7, for measuring admission pressure；
Lower chamber 5 is equipped with pressure sensor 8 and temperature sensor 9, is respectively used for measuring the pressure and temperature value of cavity.
Pressure sensor 8 and temperature sensor 9 are installed on lower chamber 5 by G1/2 screw thread, and unsintered tape is tied on screw thread；
Outlet solenoid valve 3 and vacuum solenoid 2 are mounted on 4 top of upper cavity, vacuum pump 1 by vacuum solenoid 2 with it is upper
4 connection of cavity；
Pressure sensor 8, temperature sensor 9, vacuum solenoid 2, outlet solenoid valve 3, intake solenoid valve 6, vacuum pump 1 are equal
It is connected with PLC11, PLC11 and touch screen 13 are connected with industrial personal computer 12.
Referring to Fig.1, Fig. 2, Fig. 3, the air-tightness detection method for SLM device molding cavity, including pressure maintaining inspection
Survey, gas circuit detection, runs all of above test and sensor reading filtering processing at vacuum detecting, is formed using a kind of SLM device
The air tightness detection system of cavity, specifically comprises the following steps:
(1) pressure maintaining is tested
(1) pressure maintaining testing button is put on touch screen 13, it is formal to open pressure maintaining testing process.PLC11 judges cavity first
Whether pressure value is less than or equal to 7mbar, if it is, directly opening intake solenoid valve 6 is filled with inert gas until chamber pressure
Value be more than or equal to 15mbar, otherwise need first to open outlet solenoid valve 3, opened again until chamber pressure value is down to 7mbar into
Pneumoelectric magnet valve 6.
(2) the pressure maintaining testing process timing since 6 close moment of intake solenoid valve, while every cavity of 1 second record
Then pressure value and temperature value calculate the initial pressure that the maximum value in preceding 10 pressure values is tested as pressure maintaining.
(3) when molding cavity pressure value is less than or equal to 7mbar, pressure maintaining test terminates, the time of record pressure maintaining test.
(4) slip of molding cavity is calculated.When calculating, consider to carry out temperature-compensating to pressure measurements, according to reason
Think equation of gas state pV=nRT (wherein, p is pressure, and V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant),
Cavity internal pressure value is p when test starts1, temperature T1, pressure value is p in test process lumen body, and temperature T ignores leakage
The amount of the influence of amount, cavity volume and inside cavity gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1.It calculates
When slip, linear fit is carried out to the pressure and temp data sequence acquired in pressure maintaining test process using least square method, is obtained
To the slope of straight line be exactly slip of the molding cavity under state of pressure keeping, formula is as follows:
(5) judge that molding cavity pressure maintaining tests whether qualification.
(2) vacuum test
(1) vacuum test button is put on touch screen 13, it is formal to open vacuum test process.First turn on 1 He of vacuum pump
Vacuum solenoid 2 carries out vacuum pumping to molding cavity 4 and 5, until cavity internal pressure value is less than or equal to -960mbar.
(2) the vacuum test process timing since 1 close moment of vacuum pump, while every chamber pressure of 1 second record
Then value and temperature value calculate initial pressure of the minimum value as vacuum test in preceding 10 pressure values.
(3) when reaching 30 minutes the vacuum test time, chamber pressure value this moment is recorded.
(4) slip of molding cavity is calculated.When calculating, consider to carry out temperature-compensating to pressure measurements, according to reason
Think equation of gas state pV=nRT (wherein, p is pressure, and V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant),
Cavity internal pressure value is p when test starts1, temperature T1, pressure value is p in test process lumen body, and temperature T ignores leakage
The amount of the influence of amount, cavity volume and inside cavity gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1.It calculates
When slip, linear fit is carried out to the pressure and temp data sequence acquired during vacuum test using least square method, is obtained
To the slope of straight line be exactly the slip of molding cavity under vacuum conditions, formula is as follows:
(5) judge whether molding cavity vacuum test is qualified.
(3) gas circuit is tested
(1) gas circuit testing button, formal opening gas circuit testing process are put on touch screen 13.First determine whether chamber pressure value
Whether be less than or equal to -700mbar, if it is, opening intake solenoid valve 6 is filled with inert gas, record cavity internal pressure value from -
600mbar rises to the time required for -100mbar, otherwise needs to open vacuum pump 1 and vacuum solenoid 2, to molding cavity
4 and 5 carry out vacuum pumping until cavity internal pressure value is less than or equal to -700mbar.When cavity internal pressure value is more than or equal to
When 0mbar, intake solenoid valve 6 is closed.
(2) judge that molding cavity gas circuit tests whether qualification.
(4) all of above test is run
Above three process is successively run according to the sequence of pressure maintaining test, vacuum test, gas circuit test.
(5) pressure, temperature sensor reading filtering processing
In order to guarantee the stabilization of pressure sensor 8 and the reading of temperature sensor 9, the influence of various noise signals is removed, is adopted
Pressure and temperature sensor reading is filtered with second order Butterworth LPF, the following institute of the transmission function of filter
Show:
Wherein ωcIndicate the cutoff frequency of Butterworth LPF.In order to determine the cutoff frequency of filter, first
The reading of unfiltered front sensor is acquired, spectrum analysis then is carried out to it using MATLAB, determines noise signal and pressure temperature
The crest frequency of analog signals is spent, final coutoff frequency just takes suitable value between two crest frequencies.
In conclusion compared with prior art, the present invention structure is simple and convenient to operate, it can be to SLM device molding cavity
Air-tightness make and comprehensively and accurately assessing.
Technical solution of the present invention and beneficial effect is described in detail in above-described specific embodiment, ability
The technical staff in domain is readily appreciated that the foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to restrict the invention, all
It is any modification, supplementary, and equivalent replacement etc. done in spirit of the invention, should be included in protection of the invention
Within the scope of.
Claims (8)
1. a kind of air tightness detection system of SLM device molding cavity, which is characterized in that passed including upper cavity, lower chamber, pressure
Sensor, air inlet pressure sensor, intake solenoid valve, outlet solenoid valve, vacuum solenoid, vacuum pump, may be programmed temperature sensor
Logic controller, industrial personal computer, touch screen, wherein
Connection between the upper cavity, lower chamber；The inert gas inleting pipe road passes through intake solenoid valve and lower chamber connection,
Air inlet pressure sensor is installed, for measuring admission pressure on air inlet pipeline；
The lower chamber is equipped with pressure sensor and temperature sensor, is respectively used for measuring the pressure and temperature value of cavity；
The outlet solenoid valve and vacuum solenoid are installed on upper cavity top, and vacuum pump is joined by vacuum solenoid and upper cavity
It is logical；
The pressure sensor, temperature sensor, outlet solenoid valve, vacuum solenoid, vacuum pump are and Programmable logical controller
Device is connected, and programmable logic controller (PLC) and touch screen are connected with industrial personal computer.
2. a kind of air tightness detection system of SLM device molding cavity according to claim 1, which is characterized in that described
Pass through pipeline connection between upper cavity, lower chamber.
3. a kind of air tightness detection system of SLM device molding cavity according to claim 1, which is characterized in that described
Pressure sensor and temperature sensor are installed on lower chamber by G1/2 screw thread, and unsintered tape is tied on screw thread.
4. the detection side of the air tightness detection system of SLM device molding cavity described in any claim in claims 1 to 3
Method, which comprises the steps of:
1) pressure maintaining detects；
2) vacuum detecting；
3) gas circuit detects；
4) all of above test and sensor reading filtering processing are run；
5) pressure, temperature sensor reading filtering processing.
5. a kind of detection method of the air tightness detection system of SLM device molding cavity according to claim 4, feature
It is, the step 1) specifically includes:
(a) pressure maintaining testing button is put on the touchscreen, it is formal to open pressure maintaining testing process；
PLC first judges whether chamber pressure value is less than or equal to 7mbar, if it is, directly open intake solenoid valve be filled with it is lazy
Property gas until chamber pressure value be more than or equal to 15mbar, otherwise need first to open outlet solenoid valve, chamber pressure value be down to
Intake solenoid valve is opened until 7mbar again；
(b) the pressure maintaining testing process timing since intake solenoid valve close moment, while every chamber pressure value of 1 second record
And temperature value, then calculate the initial pressure that the maximum value in preceding 10 pressure values is tested as pressure maintaining；
(c) when molding cavity pressure value is less than or equal to 7mbar, pressure maintaining test terminates, the time of record pressure maintaining test；
(d) slip of molding cavity is calculated；
When calculating, consider to carry out temperature-compensating to pressure measurements, according to The Ideal-Gas Equation pV=nRT (wherein, p
For pressure, V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant), cavity internal pressure value is p when test starts1, temperature
Degree is T1, pressure value is p in test process lumen body, and temperature T ignores the influence of amount of leakage, cavity volume and inside cavity
The amount of gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1；When calculating slip, using least square method to guarantor
The pressure and temp data sequence acquired in pressure test process carries out linear fit, and the slope of obtained straight line is exactly that molding cavity exists
Slip under state of pressure keeping, formula are as follows:
(e) judge that molding cavity pressure maintaining tests whether qualification.
6. a kind of detection method of the air tightness detection system of SLM device molding cavity according to claim 4, feature
It is, the step 2) specifically includes:
(a) vacuum test button is put on the touchscreen, it is formal to open vacuum test process；First turn on vacuum pump and vacuum electromagnetic
Valve carries out vacuum pumping to molding cavity, until cavity internal pressure value is less than or equal to -960mbar；
(b) the vacuum test process timing since vacuum pump close moment, while every 1 second chamber pressure value of record and temperature
Then angle value calculates initial pressure of the minimum value as vacuum test in preceding 10 pressure values；
(c) when reaching 30 minutes the vacuum test time, chamber pressure value this moment is recorded；
(d) slip of molding cavity is calculated；When calculating, consider to carry out temperature-compensating to pressure measurements, according to ideal gas
Body state equation pV=nRT (wherein, p is pressure, and V is volume, and T is temperature, and n is the amount of gaseous matter, and R is constant), test
Cavity internal pressure value is p when beginning1, temperature T1, pressure value is p in test process lumen body, and temperature T ignores amount of leakage
It influences, the amount of cavity volume and inside cavity gaseous matter is constant, then the pressure after temperature-compensating is p=p1T/T1；Calculate leakage
When rate, linear fit is carried out to the pressure and temp data sequence acquired during vacuum test using least square method, is obtained
The slope of straight line is exactly the slip of molding cavity under vacuum conditions, and formula is as follows:
(e) judge whether molding cavity vacuum test is qualified.
7. a kind of detection method of the air tightness detection system of SLM device molding cavity according to claim 4, feature
It is, the step 3) specifically includes:
(a) gas circuit testing button, formal opening gas circuit testing process are put on the touchscreen；
First determine whether chamber pressure value is less than or equal to -700mbar, if it is, opening intake solenoid valve is filled with indifferent gas
Body records cavity internal pressure value and from -600mbar rises to the time required for -100mbar, otherwise need to open vacuum pump and
Vacuum solenoid carries out vacuum pumping to molding cavity until cavity internal pressure value is less than or equal to -700mbar；When in cavity
When pressure value is more than or equal to 0mbar, intake solenoid valve is closed；
(b) judge that molding cavity gas circuit tests whether qualification.
8. a kind of detection method of the air tightness detection system of SLM device molding cavity according to claim 4, feature
It is, the step 5) specifically includes:
In order to guarantee the stabilization of pressure and temperature sensor reading, the influence of various noise signals is removed, is irrigated using second order Bart
This low-pass filter is filtered pressure and temperature sensor reading, and the transmission function of filter is as follows:
Wherein ωcIndicate the cutoff frequency of Butterworth LPF；In order to determine the cutoff frequency of filter, acquire first
Then the reading of unfiltered front sensor carries out spectrum analysis to it using MATLAB, determines noise signal and pressure and temp mould
The crest frequency of analog quantity signal, final coutoff frequency just take suitable value between two crest frequencies.
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| CN201810900882.5A CN109000863A (en) | 2018-08-09 | 2018-08-09 | A kind of air tightness detection system and its detection method of SLM device molding cavity |
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| CN201810900882.5A CN109000863A (en) | 2018-08-09 | 2018-08-09 | A kind of air tightness detection system and its detection method of SLM device molding cavity |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN110361130A (en) * | 2019-07-25 | 2019-10-22 | 新奥（中国）燃气投资有限公司 | A kind of pressure detecting system and its application method |
| CN110553152A (en) * | 2019-09-06 | 2019-12-10 | 郑州畅威物联网科技有限公司 | Pressure maintaining detection method and system for gas conveying pipe network |
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| CN112710440A (en) * | 2020-12-21 | 2021-04-27 | 宁波旭升汽车技术股份有限公司 | Air detection machine leakage detection method with temperature compensation |
| CN112847138A (en) * | 2021-04-25 | 2021-05-28 | 杭州众硅电子科技有限公司 | Polishing head detection device and method for detecting air tightness of cavity and sensor effectiveness |
| CN113280986A (en) * | 2021-04-17 | 2021-08-20 | 山西潞安太阳能科技有限责任公司 | Method for detecting leakage rate of furnace tube vacuum pump |
| CN114160970A (en) * | 2021-12-01 | 2022-03-11 | 上海航天设备制造总厂有限公司 | 3D prints shaping and detects sharing galvanometer integrated device |
| CN115287926A (en) * | 2022-08-01 | 2022-11-04 | 湖北三江航天江北机械工程有限公司 | Energy-saving mechanism and energy-saving method of stranding machine |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109580126A (en) * | 2019-01-18 | 2019-04-05 | 楚天科技股份有限公司 | A kind of integrity detection system and method for freeze dryer filter |
| CN110361130A (en) * | 2019-07-25 | 2019-10-22 | 新奥（中国）燃气投资有限公司 | A kind of pressure detecting system and its application method |
| CN110553152A (en) * | 2019-09-06 | 2019-12-10 | 郑州畅威物联网科技有限公司 | Pressure maintaining detection method and system for gas conveying pipe network |
| CN112484935A (en) * | 2020-10-27 | 2021-03-12 | 潍柴动力股份有限公司 | Leak detection system and method for vehicle hydrogen filling |
| CN112484935B (en) * | 2020-10-27 | 2023-09-19 | 潍柴动力股份有限公司 | System and method for detecting leakage of hydrogen filling of vehicle |
| CN112710440B (en) * | 2020-12-21 | 2022-12-27 | 宁波旭升集团股份有限公司 | Air detection machine leakage detection method with temperature compensation |
| CN112710440A (en) * | 2020-12-21 | 2021-04-27 | 宁波旭升汽车技术股份有限公司 | Air detection machine leakage detection method with temperature compensation |
| CN113280986A (en) * | 2021-04-17 | 2021-08-20 | 山西潞安太阳能科技有限责任公司 | Method for detecting leakage rate of furnace tube vacuum pump |
| CN113280986B (en) * | 2021-04-17 | 2023-05-12 | 山西潞安太阳能科技有限责任公司 | Method for detecting leakage rate of furnace tube vacuum pump |
| CN112847138A (en) * | 2021-04-25 | 2021-05-28 | 杭州众硅电子科技有限公司 | Polishing head detection device and method for detecting air tightness of cavity and sensor effectiveness |
| CN114160970A (en) * | 2021-12-01 | 2022-03-11 | 上海航天设备制造总厂有限公司 | 3D prints shaping and detects sharing galvanometer integrated device |
| CN114160970B (en) * | 2021-12-01 | 2023-11-24 | 上海航天设备制造总厂有限公司 | 3D prints shaping and detects shared mirror integrated device that shakes |
| CN115287926A (en) * | 2022-08-01 | 2022-11-04 | 湖北三江航天江北机械工程有限公司 | Energy-saving mechanism and energy-saving method of stranding machine |
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