CN201335704Y - Minor-caliber target type flow sensor processed by plastic molding process and household gas meter - Google Patents
Minor-caliber target type flow sensor processed by plastic molding process and household gas meter Download PDFInfo
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- CN201335704Y CN201335704Y CNU2009200385653U CN200920038565U CN201335704Y CN 201335704 Y CN201335704 Y CN 201335704Y CN U2009200385653 U CNU2009200385653 U CN U2009200385653U CN 200920038565 U CN200920038565 U CN 200920038565U CN 201335704 Y CN201335704 Y CN 201335704Y
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Abstract
The utility model discloses a fluid flow sensor, particularly discloses a minor-caliber target type flow sensor processed by plastic molding process and also discloses a household gas meter with the target type flow sensor. According to the provided technical scheme, the minor-caliber target type flow sensor processed by plastic molding process comprises a base cover casing arranged on a measuring straight pipe and connected into a whole with the measuring straight pipe, wherein, a tubular sensor socket is spliced in the base cover casing, a force sensor is fixed on the sensor socket, a target slice is arranged at the bottom end of a target rod of the force sensor, the target surface of the target slice is perpendicular to the axial line of the measuring straight pipe, and a positioning fixing device for the force sensor is arranged between the outer wall of the force sensor and the inner wall of the sensor socket. The utility model has the advantages of lower manufacturing cost, high anti-vibration and anti-interference capability, simple and convenient operation, easy installation, free maintenance, fault self-detection and low running cost.
Description
Technical field
The utility model discloses a kind of flow sensor, especially a kind of small-bore target type flow transducer of plastics molding process processing the invention also discloses a kind of domestic gas meter with this target-type flow sensor.
Background technology
Target type meter is a kind of differential pressure flowmeter, and it is in the history of the existing many decades of industrial Application and Development.It is a measuring instrument electronic, pneumatic unit combination instrument in electronic, the pneumatic target flow transmitter of the exploitation seventies in 20th century in China.Because force transducer directly adopted the dynamic balance mechanism of differential pressure transmitter at that time, target type meter is the flow instrument that grows up along with the measurement that presses for solution high viscosity, low reynolds number fluid in the commercial production sixties.It can be converted into acting force to target by a target plate dynamic pressure that fluid is entrained, again through detecting the size of the suffered acting force of target plate, thereby obtains flow rate corresponding and flow.Thisly measure the method for flow by the applicating fluid dynamic pressure, simple in structure with it, be applicable to the fluid of high viscosity, low reynolds number and contain molecule fluid the survey reason and be widely used.
Conventional target formula flowmeter performance is analyzed.
Because conventional target is carried out the conversion process of flow signal and output signal by lever force equilibrium principle or vector balance of mechanism principle, so show many unsatisfactory defectives in actual applications.Easily drift about as zero-bit, measuring accuracy is low, leverage poor reliability etc.Because not good the tying down of dynamic balance mechanism performance, many advantages of target type meter itself also fail effectively to be brought into play, and the user does not eliminate yet to the bad impression of old target type meter so far, is specially:
1) because to constitute original paper (as envelope film, the detecting amplifier) temperature influence of vector mechanism and converting unit bigger, the therefore higher medium temperature of ability not, serviceability temperature is generally less than 150 ℃.
2) because pneumatic transmitter, the transducer itself of pneumatic target vibrate, therefore need the dress damping unit to use, and, influence stabilization when experiencing the pressure medium fluctuation when instrument, very easily aggravating vibration when impacting.
3) electric target electro-magnetic feedback system, input amplifier are subject to the external magnetic field influence, generally require external magnetic field intensity less than 400A/m.
4) become and to send part to adopt vector mechanism, have a large amount of moving elements, distortion easy to wear can not long-term stable operation, precision low (be generally ± more than 1.5%), and the adjustment workload is big and complicated, it is high to require.
5) require the pipe vibration frequency should be less than 25Hz, double amplitude should be less than 0.1mm, to the fluctuation pressure of pipeline internal medium impact, the temperature shock sensitivity, put into operation that it is high to require, need bypass duct, the erected cost height, maintenance is big.
6) bore generally below 200mm, is not suitable for big Calibration, and usable range is restricted.
7) owing to the restriction of self structure, generally between 8～80N, promptly measured medium should not surpass 80N to the impulsive force of target to the flowmeter field of load, should be less than 8N yet.Again because F ∝ V
2, so range ratio is about 3: 1.
8), influenced the popularization of target type meter in actual production greatly just because of the existence of above defective.Particularly nearly ten years, because in the appearance of measuring novel instrument, the application of target type meter is more existing to be reduced day by day.
And intelligent target type meter of new generation, though microelectric technique and computer technology are applied to signal converter and display part, the afflux amount, temperature, pressure detection function adopt advanced singlechip technology and force transducer in one, sensing member is no movable member, and is simple in structure firm; Anti-vibration, impurity, interference performance are strong, have easy and simple to handlely, install easily, and be non-maintaining, fault self-checking, a series of characteristics such as operating cost is low.But it is simple inadequately still to be in structure for the target type meter of bore below 15mm, can not test the high shortcoming of tiny flow quantity and cost.
Summary of the invention
One of the purpose of this utility model is to overcome the deficiencies in the prior art, provide a kind of and can test tiny flow quantity, manufacturing cost is lower, anti-vibration, impurity, interference performance are strong, easy and simple to handle, install easily, non-maintaining, the small-bore target type flow transducer of the plastics molding process processing that fault self-checking and operating cost are low.
Another purpose of the present utility model then provides a kind of domestic gas meter with this target-type flow sensor.
The technical scheme that provides according to the utility model, the small-bore target type flow transducer of described plastics molding process processing, be included in and measure the base case that is connected with its one on the straight tube, be connected to the sensor socket of tubulose in base case interpolation, be fixed with force transducer on the sensor socket, the target bar bottom of force transducer is provided with the target sheet, the target surface of described target sheet and the axis normal of measuring straight tube, between force transducer outer wall and sensor socket inwall, be provided with the device for positioning and securing of force transducer, and the target sheet is to be that raw material is injected and molded on the target bar by plastics molding process with plastics, and the target sheet is that integral type is connected with the target bar.
The interior axially bored line of base case and the endoporus axis normal of measuring straight tube.The diameter of bore of measuring straight tube is 5～25mm.Described device for positioning and securing is included in the positioning convex that the force transducer outer wall is provided with, and offers one section detent that cooperates with positioning convex at the sensor socket inwall, the tack coat that covering is fixed as one positioning convex and sensor socket above positioning convex.The axis of measuring straight tube is horizontally through the target center of target sheet.The top ends left and right sides of base case is provided with the laterally outwardly directed lug of installing down, be provided with in the sensor socket outer wall left and right sides and lug be installed on laterally outwardly directed, and it is consistent with last installation lug width that lug is installed down.Sensor socket top end opening place buckle closure has gland bonnet.
Domestic gas meter with small-bore target type flow transducer of above-mentioned plastics molding process processing, it comprises the air inlet solenoid valve that links to each other with draft tube, the outlet side of air inlet solenoid valve connects the inlet end of air inlet jar, the outlet side of air inlet jar is opened on the air inlet pot sidewall that is higher than air inlet jar inner chamber bottom, the outlet side of air inlet jar connects the inlet end of measuring straight tube, measure the base case that is connected with its one on the straight tube, be connected to the sensor socket of tubulose in base case interpolation, be fixed with force transducer on the sensor socket, the target bar bottom of force transducer is provided with the target sheet, the target surface of described target sheet and the axis normal of measuring straight tube, between force transducer outer wall and sensor socket inwall, be provided with the device for positioning and securing of force transducer, the outlet side of measuring straight tube is connected out the inlet end of gas tank, the inlet end that goes out gas tank is opened on the pot sidewall of giving vent to anger that is higher than gas tank inner chamber bottom, the outlet side that goes out gas tank is opened on the tank of giving vent to anger that is higher than gas tank inner chamber bottom, and the outlet side that goes out gas tank is connected with escape pipe.
Draft tube is perpendicular to measuring straight tube, and escape pipe is perpendicular to measuring straight tube, and draft tube and escape pipe be arranged in parallel, and the centre distance of draft tube center line and escape pipe center line is 110～150mm.The centre distance of draft tube center line and escape pipe center line is 130mm.
The utlity model has and can test that tiny flow quantity, manufacturing cost are lower, advantage such as anti-vibration, impurity, strong, easy and simple to handle, the easy installation of interference performance, non-maintaining, fault self-checking and operating cost are low.
Description of drawings
Fig. 1 is the one-piece construction synoptic diagram of the small-bore target type flow transducer of plastics molding process processing.
Fig. 2 is the A-A cut-open view of Fig. 1.
Fig. 3 is the domestic gas meter one-piece construction synoptic diagram with small-bore target type flow transducer of plastics molding process processing.
Fig. 4 is a use principle block diagram of the present utility model.
Embodiment
The utility model is described in further detail below in conjunction with concrete drawings and Examples.
As shown in Figure 1: the small-bore target type flow transducer of this plastics molding process processing, be included in and measure the base case 2 that is connected with its one on the straight tube 1, in base case 2, be plugged with the sensor socket 6 of tubulose, be fixed with force transducer 3 on the sensor socket 6, target bar 4 bottoms of force transducer 3 are provided with target sheet 5, the target surface of described target sheet 5 and the axis normal of measuring straight tube 1, between force transducer 3 outer walls and sensor socket 6 inwalls, be provided with the device for positioning and securing of force transducer 3, and target sheet 5 is to be that raw material is injected and molded on the target bar 4 by plastics molding process with plastics, and target sheet 5 is connected for integral type with target bar 4.
The interior axially bored line of base case 2 and the endoporus axis normal of measuring straight tube 1.The diameter of bore of measuring straight tube 1 is 5～25mm.Described device for positioning and securing is included in the positioning convex 7 that force transducer 3 outer walls are provided with, offer one section detent 8 that cooperates with positioning convex 7 at sensor socket 6 inwalls, above positioning convex 7, cover the tack coat 12 that positioning convex 7 and sensor socket 6 are fixed as one.The axis of measuring straight tube 1 is horizontally through the target center of target sheet 5.The top ends left and right sides of base case 2 is provided with the laterally outwardly directed lug 9 of installing down, be provided with in the sensor socket 6 outer wall left and right sides and lug 10 be installed on laterally outwardly directed, and it is consistent with last installation lug 10 width that lug 9 is installed down.Sensor socket 6 top end opening place buckle closures have gland bonnet 11.
As shown in Figure 2: flowmeter with small-bore target type flow transducer of above-mentioned plastics molding process processing, it comprises the air inlet solenoid valve 14 that links to each other with draft tube 13, the outlet side of air inlet solenoid valve 14 connects the inlet end of air inlet jar 15, the outlet side of air inlet jar 15 is opened on air inlet jar 15 sidewalls that are higher than air inlet jar 15 inner chamber bottoms, the outlet side of air inlet jar 15 connects the inlet end of measuring straight tube 1, measure the base case 2 that is connected with its one on the straight tube 1, in base case 2, be plugged with the sensor socket 6 of tubulose, be fixed with force transducer 3 on the sensor socket 6, target bar 4 bottoms of force transducer 3 are provided with target sheet 5, the target surface of described target sheet 5 and the axis normal of measuring straight tube 1, between force transducer 3 outer walls and sensor socket 6 inwalls, be provided with the device for positioning and securing of force transducer 3, the outlet side of measuring straight tube 1 is connected out the inlet end of gas tank 16, the inlet end that goes out gas tank 16 is opened in and is higher than the going out on gas tank 16 sidewalls of gas tank 16 inner chamber bottoms, the outlet side that goes out gas tank 16 is opened in and is higher than the going out on gas tank 16 tank bodies of gas tank 16 inner chamber bottoms, and the outlet side that goes out gas tank 16 is connected with escape pipe 17.
(1) air inlet jar 15, the effect that goes out gas tank 16: when medium by solenoid valve, the air inlet jar 15 of flowing through, target type meter, when going out gas tank 16, air inlet jar 15, go out gas tank 16 not only play the effect that is communicated with the target type meter measuring tube also play with the contaminant removal in the fluid at the air inlet jar, go out the effect in the gas tank, the measuring tube passage that has prevented target type meter causes the inaccurate of measurement because of the impurity in the fluid, even the obstruction of measuring tube and damage target type meter influence and measure.
(2) the target plate material of target type meter so far both at home and abroad still by stainless steel through metal processing and make, and with screw or be threaded in the target bar, with being connected of measuring tube it is installed in the measuring tube by removing flange.And the target sheet 5 of the utility model small-bore target type flow transducer is to be that raw material is injected and molded in the target sheet on the target bar 4 by plastics molding process with plastics, with target bar 4 be one.Its superiority is:
1. target sheet 5 manufacture crafts are simple, can make by stainless steel through the microminiature plastics target sheet 5 that with small-bore target type flow transducer be complementary of metal difficult processing to make.
2. need not carry out connection with target bar 4, and be connected the direction in the back insertion measuring tube with target bar 4, the position, accuracy, degree of accuracy all is better than the target of split and the requirement of target bar 4 artificial connections.
3. so owing to adopt plastics forming technique just can make the microminiature plastics target sheet 5 that is complementary with small-bore target type flow transducer easily.Just can make the small-bore target type flow meter, just can the micrometer low discharge.
(3) measure the base case 2 that is connected with its one on the straight tube 1 and force transducer socket 6, force transducer 3 and detent 8 connected the all-in-one-piece pattern by positioning convex 7 by fluid sealant, make entire target formula flowmeter structure more simple, and whole instrument do not have moving element, also make whole instrument not have the parts wear distortion, be not subjected to pressure medium fluctuation shock effect, the energy long-term stable operation has reduced the target type meter failure rate.
(4) owing to adopted the plastics target sheet 5 of plastic shaping to be injection molded into one with target bar 4, its area, volume are connected little than stainless steel target sheet with the target bar, but therefore its stressed target surface does not diminish, because plastics target sheet has saved area and the volume that is connected the part of usefulness with the target bar.During area when the slotting target mouth on measuring straight tube 1 is connected with target bar 4 greater than target sheet 5, the area volume that is connected with the target bar owing to the traditional target sheet of target sheet 5 and target bar 4 injection moulding all-in-one-piece area-volume ratios is little, so it is also less relatively to insert the area of target mouth, thereby kept away face because of inserting the big measuring accuracy that influences target type meter of target open area.Simplified simultaneously to installation target sheet is connected with the target bar and removed the loaded down with trivial details step that flange is connected with measuring tube.
(5) domestic gas meter of the small-bore target type flow transducer of the small-bore target type flow transducer of plastic shaping of the present utility model and plastic shaping, its whole parts are made by plastics forming technique, have: the advantage of high precision, high complexity, high consistance, high productivity, low consumption, low price.
Therefore, the utlity model has following advantage:
(1) material of original usefulness is steel, and material is used plastics instead now.
(2) production efficiency height is compared through metal processing with adopting stainless steel, produces same or a plurality of plastic parts and adopts the one-shot forming of mould energy, and throughput rate can be several times, tens times or hundred times of metal working (machining) efficiency.
(3) high precision is with below the plastic part precision Gao Keda 0.01mm of plastic shaping, usually between 0.01～0.001mm.
(4) high consistance is used the repetition deviation of the plastic part size of plastic shaping, and is repeated deviation of weight: can be lower than 0.5%.
(5) best bright finish, the surfaceness that can reach with the plastic part of plastic shaping: the Ra parameter value usually can be between 0.025～0.8 μ m.
(6) low consumption with the raw-material utilization factor height of plastic part of plastic shaping, is adopted the way of stainless steel through metal processing, blank 40% or manyly all can become scrap by work in-process.
(7) high complexity can plastic shaping become complicated integral type parts.
(8) low price is tens times even hundred times of plastic shaping part processing expense with adopting stainless steel through the part cost of metal processing.
(9) the plastics selection is wide, can select suitable plastic machine-shaping for use according to characteristics, character and the operating mode of fluid.
Be not difficult in sum to find, the domestic gas meter of the small-bore target type flow transducer of plastic shaping of the present utility model and the small-bore target type flow transducer of plastic shaping is being inherited and is being developed on the basis of original survey reason principle, by utilization new material, new technology, new design, new construction, had in essence different with traditional target type meter.Filled up the blank that target type meter is measured simultaneously aspect little caliber, tiny flow quantity.
The small-bore target type flow meter connects after the outside relevant device, with reference to Fig. 3, can realize following function: target plate stressed passes to force transducer through the target bar and converts the electric signal that the electric signal that is directly proportional with square of flow velocity will be directly proportional with square of flow velocity to by force transducer again and carry out the AD conversion, handles the back by Single Chip Microcomputer (SCM) system and shows flow value.Temperature sensor is measured the temperature of medium in real time, utilizes scm managing system online to the Media density temperature and pressure compensation, has guaranteed the accuracy of the family expenses flowmeter measurement of small-bore target type flow transducer.The RS485 interface is used for communicating with on-the-spot table tool; Adopt concentrator and realizations remote autos such as communication network such as GPRS, dialing in real time or call and check meter.And the IC-card interface is the message exchange between IC-card and the equipment, to the mutual authentication between holder, card, the interfacing equipment and the encryption of data.Keypress function mainly comprises: button shows that accumulative total purchases tolerance, the last time and purchase tolerance, and residue tolerance, shows calibrating function, instantaneous delivery, accumulation flow etc.Display: the content that the display button function is included, and the flow value of user when using combustion gas.Power supply: be equipped with direct supply or AC power by actual conditions.
Above-mentioned small-bore target type flow transducer can make by the following method:
Embodiment 1:
With the fluororesin is that raw material is made small-bore target type flow transducer, make after molding, mould and die preheating, lock pin, fusion-cast, cooling, die sinking and each operation of loosing core, the concrete following polytetrafluoroethylene (PTFE) of injection molding process is the mobile fluororesin of non-hot melt.The mobile fluororesin of hot melt is except that perfluoroethylene-propylene (FEP), also have tetrafluoroethene and perfluoroalkyl vinyl ether co-polymer (PFA), Kynoar (PVDF), polyvinyl fluoride (PVF), polychlorotrifluoroethylene (PCTFE), ethene and TFE copolymer (ETFE), ethene and chlorotrifluoroethylene (ECTFE) etc.
The FPA processing and forming also can claim the processing of soluble poly tetrafluoroethene.Its processing characteristics is as follows:
The PFA resin has translucent pellet (extrusion molding, injection molding moulding), powder (coating and rotational forming), form such as dispersion liquid (flood and be coated with formable layer).Being divided into I type PFA by the melt mass flow rate size---melt mass flow rate 7～18g/ (10min) mainly is used as the clad of the semi-conductive chip carrier of injection mo(u)lding, pipe adapter and extrusion moulding tubing, electric wire etc.; II type PFA---melt mass flow rate 1～3g/ (10min), suitable extrusion molding straight tube, sheet material, inner lining material, transfer molding has stress cracking resistance preferably.
The machining feature of PFA and the processing characteristics of FEP are basic identical, and thermal stability is better than FEP, and forming temperature also needs high about 20 ℃.But the melt viscosity of PFA is bigger than FEP, and heat-processing equipment need have good anti-corrosion.
Extrusion molding
The technology of PFA extrusion molding and equipment can with technology and the Device-General of FEP, but forming temperature need improve.PFA also exist take place the fusion fragmentation critical shear rate---to I type PFA is 50s
-1, II type PFA is 3s
-1The melt strength of PFA is big, and is bigger than the melt length growth rate of FEP, can take bigger draw ratio when moulding tubule and monofilament, can reach about 170 as the tubing ratio of drawing (DDR) of PFA.
Injection mo(u)lding
The melt viscosity of 360 ℃ of following PFA is about 1 times of FEP melt, should adopt the less I type resin of melt viscosity, and injection speed can not be too fast, otherwise easily produces the phenomenon of broken shape of the not bright and clean similar fusion in surface even sur-face peeling.The mixing material of the screw-type injection molding machine that plasticizing capacity commonly used is big is even, the material that stagnates is few, and it is rapid that mould is transmitted pressure, but screw rod, machine barrel and the mould etc. that contact with the PFA molten resin all need be made of corrosion-resistant stainless steel.
The screw design of PFA can be with the such compression-type screw rod of FEP.The head of screw rod must have the structure (retaining ring etc.) of prevention molten resin reverse flow, but this class screw rod exists resin to be detained the shortcoming that produces heat ageing, therefore need to adopt plasticizing hair style screw rod avoid it, other has melting effect to reach advantages such as wearing and tearing with barrel wall are few well.
Injector is annotated the bore of mouth and is wanted big, and well heater and temperature regulator should be able to reach 430 ℃, and corresponding electrical power density is 6.7W/cm
2, injection speed should be slow, in order to avoid lamination appears in product surface.The diameter in injection mould notes road should be greater than annotating the mouth flow diameter, and the diameter of runner is relevant with product wall thickness, the above person of wall thickness 13mm, and flow diameter is got 1/2 of its wall thickness; Wall thickness is below 13mm, and then flow diameter should be greater than 1/2 of wall thickness.The cast gate of injection mould should be lacked and avoid adopting pin-point gate greatly.The speed of the injection mo(u)lding of PFA should be slow, and pressure is 21～55MPa, and forming temperature sees Table 1.
Table 1
| The position | Temperature |
| Machine barrel | 315 |
| Machine barrel | 330 |
| Machine barrel | 370 |
| Annotate mouth | 370 |
| Resin | 340 |
| Mould | 150 |
Injection mo(u)lding temperature and goods size, product wall thickness and resin factor such as residence time in machine barrel is relevant, if the residence time is long, then gets lower forming temperature in order to avoid heat ageing.Injection speed is fast, near cast gate or the thinnest position of goods lamination appears easily; Otherwise, if the injection speed of thick article is slow excessively, then also undulatory flow cracks can appear on the surface.Injection pressure is too high, and the meeting residual stress ftractures near cast gate in goods, but high to the goods injection pressure Etech that leaves welded side seam.Usually injection pressure is 20～60MPa, and the rotational speed of screw rod is not more than 50r/min.Mold temperature is relevant with mobile distance and the product wall thickness of molten resin in mould, and thick article is got 150 ℃, and general goods are 230～260 ℃, and good mould temperature insulated heat measure should be arranged.The product molding cycle about wall thickness 3mm is 30～40s.The wall of goods is long more thick more cool time, and molding cycle is also long more.Produce flat trace and pin hole for not making, enough dwell times should be arranged because of shrinking.
PFA fusant density 1.495g/cm
3, cooling back extrudate density 2.15g/cm
3, therefore be chilled to solid-state 30% the volume change that has from molten.The molding shrinkage of PFA goods is relevant with wall thickness, and wall thickness is that the shrinkage factor of 5mm is 3.2% usually, and 10mm's is 3.5%, and 15mm's is 5.2%, and 20mm's is 5.5%.Goods be higher than carry out annealing in process certain hour (handling 15min) under 5～10 ℃ of the actual serviceability temperatures as the 3mm wall thickness after slowly cooling again, can stablize the product size when using.
PFA is the same with other plastics, and thin-gage goods is difficult to injection mo(u)lding, especially to the PFA of high melt viscosity, if the wall thickness of goods will be former thereby be difficult to injection mo(u)lding because of filling material deficiency etc. less than 2.5mm.
Transfer molding
The PFA transfer molding is that the molten resin of seasoning in batch can is pressed into temperature by plunger is in 200 ℃ the mould, cooling and demolding under pressure.The molding cycle of transfer molding is longer, is suitable for that processing dimension is big, precision is higher and goods that quantity is few; Backing layer as large-scale valve, pump case, flowmeter and pipe adapter etc.
PFA II type resin commonly used is made transfer molding.One of its advantage is can in time replenish material when the material cooling is shunk in the mould, and the differential contraction stress that makes it is little during than injection mo(u)lding.When feed supplement if the mould temperature control more than fusing point, promptly uses mobile less II type resin that favorable surface quality is also arranged.
The little 10MPa of the comparable injection pressure of plunger pressure during transfer molding, transmitting Mo Mowen is about 200 ℃.The PFA resin will heat 3～4h in material-storage jar, add patrix temperature cool time, and the molding cycle of transfer molding is significantly greater than injection moulding and extrusion molding, and the material heated time is long aging easily simultaneously, is the weak point of transfer molding method.
Powder coating
Coat at material surfaces such as metal, potteries that fluororesin cannot not bring stickingly, premium properties such as lubricated and anti-corrosion.Basically the electrostatic spray with FTFE is identical.But because of PFA resin energy melt-flow, so its coating is the continuous film of free of pinholes.
The PFA resin of spraying usefulness is the powder of particle diameter 30 μ m, is suitable for static and is coated with thermopnore dipping and is coated with.The PFA powdery paints is the controlled spheroidal particle of particle diameter, compare with the PFA powdered resin of general usefulness, its apparent density is big, one time coated can obtain the continuous coated of the thick free of pinholes of 50 μ m, final coating thickness can reach 0.8mm, voltage during electrostatic spraying is got 10～30kV, films after the spraying in 370 ℃ of sintering temperature 30min.
Rotational forming
Rotational forming claims rotation molding again, and the thickness of its product is much thicker than powder coating.Drop into after control size of product and the PFA resin weighing of thickness and be rotated in the pattern, heat, allow resin fusion on die wall, become the inside surface of mould while rotate with powdery; After treating the complete fusion of resin, mould takes out in heating furnace, again the cooling curing demoulding under rotation.
Rotoforming should container molding, storage tank, T type pipe, elbow and the hollow product that is difficult to moulding with coating and lining method.
The advantage of rotational forming is that mould is simple, should produce large-scale and measure few goods, and the scope of design of product size is wide, wall thickness change is adjusted easily, raw-material loss is few, little, the easy demoulding of internal stress goods; Shortcoming is that molding cycle is long, the smooth finish of the poor dimensional precision of goods, inside surface is poor, remakes relatively difficulty etc. of secondary processing.
Sweat soldering
PFA and FEP can melt-flow, therefore can hot jet welding and hot bonding, but direct heat fusion pressures such as PFA and FEP film and aluminium foil, glass cloth are integral.PFA also is the hot weld material of infusibility PTFE plastics, and bigger heat seal strength is arranged.
Welding efficient is the ratio of intensity with the intensity of material itself of weld.Used thickness is the FEP of 100～500 μ m and PFA diaphragm when making hot weld material welding PTFE, and the welding efficient of FEP is 50%～70%, and the welding efficient of PFA is up to 65%～85%.360～390 ℃ of temperature during the PFA welding, pressure 0.5～1.0MPa, hot pressing time 10～30min.Can utilize the diaphragm of PFA, thin rod and silk ribbon etc. as the sweat soldering material.
Other forming methods of PFA also have the dip forming of compression forming, blow molding, vacuum forming and dispersion liquid etc., and the forming method with FEP is identical basically.
The PVDF processing and forming
Processing characteristics
The fundamental characteristics of PVDF is that good melt processable is arranged, 177 ℃ of its fusing points, and heat decomposition temperature is up to 350 ℃, therefore can moulding in very wide warm territory, suitable processing temperature is 200～250 ℃, and melt viscosity is 0.1～1.0kPas, and molding shrinkage is 2%～3%.Special-purpose special former needn't be adopted, process equipments such as extruder can be made with the stainless steel of nitrated steel and chromium plating usually.Internal stress can be eliminated or reduce to PVDF goods after the processing 80～120 ℃ of following annealing in process after a period of time.PVDF can carry out secondary processing such as welding, bending and cutting easily.
With ABS is that raw material is made small diameter winding pipe flow rate sensor, makes after molding, mould and die preheating, lock pin, fusion-cast, cooling, die sinking and each operation of loosing core, and concrete injection molding process is as follows:
Temperature is set;
Hopper feed mouth: 50～60 ℃; 180～230 ℃ at machine barrel rear portion; 180～240 ° at machine barrel middle part; 210～260 ℃ at machine barrel middle part; 210～280 ℃ of machine barrel front portions; 210～280 ℃ at nozzle; 60～90 ℃ on mould
Injection speed:
1, the processing of plastics
The water-intake rate of ABS is approximately 0.2%～0.8%, for general grade of other ABS, dries by the fire 1～2 hour with 80 ℃ with 80～85 ℃ of bakings 2～4 hours or with drying hopper with baking oven before the processing.For the heat-resisting level ABS that contains the PC component, bake out temperature is suitably heightened to 100 ℃, and concrete drying time can be definite with sky is extruded.The usage ratio of reworked material can not surpass 30%, electroplates level ABS and can not use reworked material.
2, injection machine is selected for use
Can select the standard injection machine (screw slenderness ratio 20: 1, ratio of compression are greater than 2, and injection pressure is greater than 1500bar) of Ramada for use.If adopt Masterbatch or products appearance to require material high, can select the screw rod of little one-level diameter for use.Clamp force is determined according to 4700～6200t/m2, specifically needs to require to decide according to plastic grade and goods.
3, mould and cast gate design
Mold temperature can be made as 60～65 ℃.Flow diameter 6～8mm.The wide about 3mm of cast gate, thickness is the same with goods, and cast gate length is less than 1mm.Wide 4～the 6mm of vent port, thick 0.025～0.05mm.
4, melten gel temperature
Available empty injection is accurately judged.Grade difference, melten gel temperature are also different, and suggestion is set as follows:
The anti-impact level: 220～260 ℃ is good with 250 ℃;
Electroplate level: 250～275 ℃ is good with 270 ℃;
Heat-resisting level: 240～280 ℃ is good with 265 ℃～270 ℃;
Flame retardant grade: 200～240 ℃ is good with 220 ℃～230 ℃;
Transparent stage: 230～260 ℃ is good with 245 ℃;
Glass booster stage: 230 ℃～270 ℃;
For the high goods of surface requirements, adopt higher melten gel temperature and Mo Wen.
5, injection speed
The fire prevention level will be used fast for heat-resisting grade with at a slow speed.Have relatively high expectations as product surface, then will control with the firing rate of high speed and multistage injection moulding.
6, back pressure
Back pressure is low more good more generally speaking, and back pressure commonly used is 5bar, and dye need be with higher back pressure so that colour mixture be even.
7, the hold-up time
Under 265 ℃ temperature, the hold-up time at most can not be above 5～6 minutes in rubber melting cylinder for ABS.Duration of fire resistance is shorter, shuts down as need, should be low to moderate 100 ℃ to design temperature earlier, again with general purpose grade ABS cleaning rubber melting cylinder.Compound after the cleaning will be put into cold water to prevent further decomposition.Change dozen ABS material as need from other plastics, then will use PS, PMMA or PE cleaning rubber melting cylinder earlier.Some ABS goods just has variable color when the demoulding just and no problem after a period of time, this may be overheated or plastics cause at the rubber melting cylinder overstand.
8, the aftertreatment of goods
General ABS goods do not need aftertreatment, have only the level of plating goods to need through baking (70～80 ℃, 2～4 hours) with the passivated surface vestige, and the goods that need to electroplate can not use release agent, and goods will be packed after taking out immediately.
9, the item that will pay special attention to during moulding
The ABS (particularly flame retardant grade) of several grades is arranged, and its melt is very big to the adhesion of screw surface after plasticizing, can decompose after the time is long.When above-mentioned situation occurring, need pull out the wiping examination to screw rod homogenizing zone and compression, and regularly with cleaning screw rods such as PS.
With PVC (Polyvinylchloride) is that raw material is made small diameter winding pipe flow rate sensor, makes after molding, mould and die preheating, lock pin, fusion-cast, cooling, die sinking and each operation of loosing core, and concrete injection molding process is as follows:
(1) PVC (Polyvinylchloride) has certain intensity and anti-flammability, has the superior corrosion resistance energy, the corrosion of acidproof (comprising rare nitric acid), alkali, salt, gas, water etc.Serviceability temperature-40 °～60 °.
(2) winding pipe flow rate sensor of PVC (Polyvinylchloride) material can be used for: the measurement of coal gas, rock gas, oven gas, gas, water etc.
1, PVC (Polyvinylchloride) injection molding process
The processing of plastics was in room temperature after 24 hours, and water absorbing capacity is less than 0.02%, therefore need not dry.As must be dry, can put into 60～70 ℃ heating furnace 3 hours, or 80 ℃ dryer 1～1.5 hour.
2, injection machine is selected for use
UPVC is because melt viscosity is big, easily decomposition, and decomposition product has corrosive attack to iron, and its injection mo(u)lding must special-purpose plasticizing parts and temperature control system.
3, mould and cast gate design
Mold temperature can be made as 40 ℃.The length of runner will be lacked, and it is big that diameter is then wanted, and can be delivered to die cavity to reduce the pressure loss and pressurize.Cast gate is short more good more, and it is circular that the cross cutting face is wanted, the minimum 6mm of the diameter of nozzle mouth, and, coning, interior angle becomes 5 °.
It is circular that the cross cutting face of sprue is also wanted, and combines with slag well, connects sprue and cast gate by the tangent plane radius, and diameter can be 7mm.
The radius that cast gate is used circle of contact face shape connects plastic, and is short more good more, and the cross cutting face will be along sliding.
Slag well can prevent that the material that partly solidifies from entering die cavity, and its importance often is left in the basket.
It is correct that want the position of cast gate, and material is flowed on runner smoothly, can not rest in the vestige of wedge angle, fragment and metal, in order to avoid the situation of compression or decompression occurs, should keep runner smooth along slip-stream.Mould is used the stainless steel casting, and the content at least 13% of chromium is best 16%, and Rockwell's hardness has 55 at least, and the hard steel mould can be handled through chromium plating, forms protective effect.After having produced, use and spray oil spraying or siliceous spraying again after gentle alkali lye carefully cleans up die face.
4, melten gel temperature
Available sky is penetrated method tolerance, does not wait by 185～205 ℃.Can learn the accurate melten gel temperature of UPVC from the material smooth degree that penetrates.As material coarse injustice after ejaculation, just prove that material is not homogeneous (plasticizing not enough), expression fixed temperature too low; After penetrating, spume and a large amount of smog of emerging, just represent that temperature is too high.
5, injection speed
It is slow that firing rate is wanted, otherwise undue shearing can make material degrade, and when utilizing UPVC to produce extremely smooth thick article, should adopt multistage injection mold filling speed.
6, screw speed
Should cooperate molding cycle and decide.The screw rod face velocity should not surpass 0.15～0.2m/s
7, back pressure
Can reach 150bar, low more good more, common is 5bar.
8, the hold-up time
Under 200 ℃ temperature, the machine barrel hold-up time at most can not be above 5 minutes.When temperature is 210 ℃, the machine barrel hold-up time just can not be above 3 minutes.
With the polythene PE is that raw material is made small diameter winding pipe flow rate sensor, makes after molding, mould and die preheating, lock pin, fusion-cast, cooling, die sinking and each operation of loosing core, and concrete injection molding process is as follows:
The moulding processability of polythene PE
1, PE is the crystallinity raw material, and hydroscopicity is minimum, is no more than 0.01%, therefore need not to carry out dried before processing.
2, PE molecule connection chain flexibility is good, and acting force is little between key, and melt viscosity is low, and is mobile fabulous, so need not too high pressure during moulding and just can mold thin-walled and grow the flow process goods.
3, the shrinkage factor scope of PE is big, and shrinkage value is big, and directivity is obvious, and the LDPE shrinkage factor is about 1.22%, and the HDPE shrinkage factor is about 1.5%.Therefore easy deformation warpage, the mold cools down condition is very big to the influence of shrinkage factor, so should control mold temperature well, keep cooling evenly, stablize.
4, the crystallizing power height of PE, the temperature of mould has very bigger influence to the crystalline condition of plastic.Mo Wengao, the melt cooling is slow, plastic crystallinity height, intensity is also just high.
5, the fusing point of PE is not high, but specific heat capacity is bigger, still need to consume more heat when therefore plastifying, thus require plasticizing apparatus that bigger heating power will be arranged, so that enhance productivity.
6, the softening range of PE is less, and the easy oxidation of melt, therefore should avoid melt and oxygen to come in contact in processing and forming as far as possible, in order to avoid reduce plastic part quality.
7, the softer and easy demoulding of PE product quality, therefore, can the powerful demoulding when plastic has shallow side groove.
8, the non-Newtonianism of PE melt is not obvious, and the change of shear rate is less to the influence of viscosity, and the PE melt viscosity is subjected to Temperature Influence also less.
9, the cooling velocity of PE melt is slower, therefore fully cooling.Mould should have cooling system preferably.If the PE melt time adopts direct throat-fed in injection, easily increase stress and produce the inhomogeneous and directivity of search and significantly increase distortion, therefore should note selecting the charging aperture parameter.
10, the forming temperature broad of PE, under flow state, a little fluctuation of temperature is to not influence of injection mo(u)lding.
11, the better heat stability of PE, generally no tangible decomposing phenomenon below 300 degree has no impact to quality.
The main condition of molding of PE
Barrel temperature: barrel temperature mainly is relevant with the melt flow rate size with the density of PE height, in addition also with the type and the performance of injection machine, the shape of one-level plastic is relevant.Because PE is the crystal polymer thing, crystal grain will absorb certain heat when fusion, so barrel temperature should be higher than its fusing point 10 degree.Spend in LDPE, barrel temperature is controlled at 140～200 ℃, and the barrel temperature of HDPE is controlled at 220 ℃, and minimum value is got at the barrel rear portion, and front end is got maximal value.
Mold temperature: the mould temperature has considerable influence to the crystalline condition of plastic, Mo Wengao, and melt crystallization degree height, the intensity height, but shrinkage factor also can increase.Usually the mold temperature of LDPE is controlled at 30～45 ℃, and the temperature of HDPE is corresponding high again 10～20 ℃.
Injection pressure: improve the mold filling that injection pressure helps melt, because PE's is mobile fine, therefore except that the thin-wall long and thin goods, should the lower injection pressure of superior selection, generally injection pressure is 50～100MPa.Simple shape.The plastic that wall thickness is bigger, injection pressure can be hanged down, otherwise then high.
Claims (10)
1, a kind of small-bore target type flow transducer of plastics molding process processing, be included in and measure the base case (2) that straight tube (1) upward is connected with its body, in base case (2), be plugged with the sensor socket (6) of tubulose, be fixed with force transducer (3) on the sensor socket (6), target bar (4) bottom of force transducer (3) is provided with target sheet (5), the target surface of described target sheet (5) and the axis normal of measuring straight tube (1), it is characterized in that: the device for positioning and securing that between force transducer (3) outer wall and sensor socket (6) inwall, is provided with force transducer (3), and target sheet (5) is to be that raw material is injected and molded on the target bar (4) by plastics molding process with plastics, and target sheet (5) is connected for integral type with target bar (4).
2, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1 is characterized in that: the interior axially bored line of base case (2) and the endoporus axis normal of measuring straight tube (1).
3, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1 or 2, it is characterized in that: the diameter of bore of measuring straight tube (1) is 5～25mm.
4, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1, it is characterized in that: described device for positioning and securing is included in the positioning convex (7) that force transducer (3) outer wall is provided with, offer one section detent (8) that cooperates with positioning convex (7) at sensor socket (6) inwall, cover the tack coat (12) that positioning convex (7) and sensor socket (6) are fixed as one in positioning convex (7) top.
5, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1 is characterized in that: the axis of measuring straight tube (1) is horizontally through the target center of target sheet (5).
6, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1, it is characterized in that: the top ends left and right sides of base case (2) is provided with the laterally outwardly directed lug (9) of installing down, be provided with laterally outwardly directed going up in sensor socket (6) the outer wall left and right sides lug (10) is installed, and it is consistent with last installation lug (10) width down lug (9) to be installed.
7, the small-bore target type flow transducer of plastics molding process processing as claimed in claim 1, it is characterized in that: sensor socket (6) top end opening place buckle closure has gland bonnet (11).
8, a kind of domestic gas meter, it is characterized in that: it comprises the air inlet solenoid valve (14) that links to each other with draft tube (13), the outlet side of air inlet solenoid valve (14) connects the inlet end of air inlet jar (15), the outlet side of air inlet jar (15) is opened on air inlet jar (15) sidewall that is higher than air inlet jar (15) inner chamber bottom, the outlet side of air inlet jar (14) connects the inlet end of measuring straight tube (1), measure straight tube (1) and go up the base case (2) that is connected with its one, in base case (2), be plugged with the sensor socket (6) of tubulose, be fixed with force transducer (3) on the sensor socket (6), target bar (4) bottom of force transducer (3) is provided with target sheet (5), the target surface of described target sheet (5) and the axis normal of measuring straight tube (1), between force transducer (3) outer wall and sensor socket (6) inwall, be provided with the device for positioning and securing of force transducer (3), the outlet side of measuring straight tube (1) is connected out the inlet end of gas tank (16), the inlet end that goes out gas tank (16) is opened in and is higher than the going out on gas tank (16) sidewall of gas tank (16) inner chamber bottom, the outlet side that goes out gas tank (16) is opened in and is higher than the going out on gas tank (16) tank body of gas tank (16) inner chamber bottom, and the outlet side that goes out gas tank (16) is connected with escape pipe (17).
9, domestic gas meter as claimed in claim 8, it is characterized in that: draft tube (13) is perpendicular to measuring straight tube (1), escape pipe (17) is perpendicular to measuring straight tube (1), draft tube (13) be arranged in parallel with escape pipe (17), and the centre distance of draft tube (13) center line and escape pipe (17) center line is 110～150mm.
10, domestic gas meter as claimed in claim 9 is characterized in that: the centre distance of draft tube (13) center line and escape pipe (17) center line is 130mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2009200385653U CN201335704Y (en) | 2009-01-06 | 2009-01-06 | Minor-caliber target type flow sensor processed by plastic molding process and household gas meter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2009200385653U CN201335704Y (en) | 2009-01-06 | 2009-01-06 | Minor-caliber target type flow sensor processed by plastic molding process and household gas meter |
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| CN201335704Y true CN201335704Y (en) | 2009-10-28 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103256951A (en) * | 2012-02-20 | 2013-08-21 | 日本皮拉工业株式会社 | Fluid measurement sensor attachment structure |
| CN107389971A (en) * | 2017-07-20 | 2017-11-24 | 清华大学 | A kind of on-line measurement device of On Solids Recirculating Flowrate of Circulating Fluidized Bed |
| CN114103014A (en) * | 2021-11-22 | 2022-03-01 | 广州城市理工学院 | Working method of injection mold |
-
2009
- 2009-01-06 CN CNU2009200385653U patent/CN201335704Y/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103256951A (en) * | 2012-02-20 | 2013-08-21 | 日本皮拉工业株式会社 | Fluid measurement sensor attachment structure |
| CN103256951B (en) * | 2012-02-20 | 2017-08-22 | 日本皮拉工业株式会社 | The mounting structure of fluid measurement sensor |
| CN107389971A (en) * | 2017-07-20 | 2017-11-24 | 清华大学 | A kind of on-line measurement device of On Solids Recirculating Flowrate of Circulating Fluidized Bed |
| CN114103014A (en) * | 2021-11-22 | 2022-03-01 | 广州城市理工学院 | Working method of injection mold |
| CN114103014B (en) * | 2021-11-22 | 2023-10-03 | 广州城市理工学院 | Working method of injection mold |
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