Background technology
When punching machine is forged towards work, need air operated friction clutch (PneumaticFriction Clutch is hereinafter to be referred as PFC) friction pair can export enough big moment of torsion M
q〉=M
a, otherwise the generation of air operated friction clutch rubbing surface is skidded and vexed car accident is taken place.Provide suitable air pressure to satisfy M for the air operated friction clutch cylinder by electric proportional pressure valve
q〉=M
aThe operate as normal requirement, must know M in advance obviously
aSize.
At present in all punching machines at home and abroad, no matter workpiece deformation needs air operated friction clutch to transmit great moment of torsion M at every turn
a(upset force that carries out the 1st work step as the gear hot forging often only is 1/3 of the 2nd a work step finish-forging power, the required M of corresponding the 1st work step
A1Less than the 2nd work step 1/2), but each air operated friction clutch cylinder all advances maximum air pressure p
Max, correspondingly the air operated friction clutch moment of torsion that can provide always is maximal value M
Qmax, not only caused the waste of compressed air energy but also made the exhaust noise of air operated friction clutch increase pollution grows worse environment, therefore the invention provides the method that a kind of size of the moment of torsion to the required transmission of air operated friction clutch is carried out on-line measurement.And discussed in detail and how to have detected the moment of torsion M that obtains the required transmission of air operated friction clutch by this measurement mechanism
a, air operated friction clutch is again how according to M
aSize, enough big moment of torsion M is provided
qThe needs that the work of satisfying is out of shape.
Because the complicacy of plastic history and punching machine is brought when big difficulty to Theoretical Calculation, adopts the method for online actual measurement to determine M here for this reason
aSize, usually the useful torque sensor of method of testing of actual moment of torsion is directly measured, is used load sensor to measure, use motor current to measure indirectly indirectly and utilizes the slide block range to measure four kinds of methods indirectly on the air operated friction clutch axle, and this paper discusses respectively these four kinds of methods earlier.
1. torque sensor direct measuring method
The sensor of directly measuring moment of torsion on the rotation axis has following two types:
A. strain-type torque sensor:
Adopt resistance strain gage mechanical strain to be converted to the electric signal that is proportional to moment of torsion.Because its output signal from the rotating shaft, device is complicated, or poor reliability or cost are too high, use inconvenience.
B. torsion angle phase-difference type torque sensor
Torque measurement principle as JCZ type torque rotary speed sensor is exactly the phase-difference type principle, promptly two signal gear are installed at the two ends of elastic shaft, one group of signal coil respectively is housed above two gears, the magnetic cylinder all is housed in signal coil, form the magnetoelectricity signal generator with signal gear.When signal gear is rotated with elastic shaft, because the tooth top of signal gear and the bottom of the inswept magnetic cylinder of tooth paddy alternate cycle, make air-gap permeance produce periodic the variation, the magnetic flux of coil inside also produces cyclical variation, makes the ac signal that generates the near sinusoidal ripple in the coil.When elastic shaft is turned round, will produce torsional deflection, two groups of phase differential between the ac signal are changed, in regime of elastic deformation, the absolute value that phase differential changes is directly proportional with the size of torque.
The industry spot environment that forging and pressing are produced is abominable, and should not carry out the destructive transient equilibrium (as sensor installation on bent axle and annex thereof) of handling (as in polishing, boring etc. on the bent axle) and destroying bent axle to the bent axle of punching machine, therefore, the method for the moment of torsion on the above-mentioned direct measurement rotation axis is used difficulty in punching machine air operated friction clutch torsion-testing.
2. load sensor is measured torque method indirectly
Installing on punching machine and using load sensor all is eaily, and the load sensor of installation then can be measured moment of torsion on the air operated friction clutch axle and the variation relation of time on the PFCB-82 type punching machine air operated friction clutch of Xi'an Communications University's mould and plastic working research institute and detent comprehensive intelligent testing table (as shown in Figure 1).Fig. 2 is the situation of installed load sensor on this experiment table, two boss about the holder of detent has, and at a side installed load sensor, the power of the output by measuring load sensor is by torque arithmetic formula M
a=F * L indirect calculation obtains acting on the moment of torsion on the air operated friction clutch axle.
3. torque method on the indirect measurement axis of motor current
Punching machine is generally driven by threephase asynchronous, when moment of torsion required on the air operated friction clutch axle is big more, the then corresponding required output torque of motor is also big more, can extrapolate M on the air operated friction clutch axle indirectly by the measurement result to motor output torque like this
aBy the operation logic of asynchronous motor as can be known, the electric current in the rotor winding has produced the electromagnetic torque that acts on the motor rotor under the effect of rotating magnetic field.Learned as can be known by motor, the average electromagnetic torque M of motor is:
M=K·Φ
m·I
2·cosΦ
2(N·m)(1)
In the formula: K-with the coefficient of electric motor structure relating to parameters, be called moment coefficient;
Φ
mThe every utmost point magnetic flux of-air gap (Wb);
I
2-rotor winding phase current (A);
Cos Φ
2The power factor of-rotor winding
Can find out the every utmost point magnetic flux phi of the size of asynchronous motor electromagnetic torque M and air gap by formula (1)
m, rotor phase current I
2And the power factor cos Φ of rotor
2Be directly proportional.But because this concerns more complicated, and in actual production, the revolutional slip of motor was very little when motor turned round in normal range, its air-gap flux Φ
mCan be considered ratings, power factor cos Φ
2≈ 1, like this size of electromagnetic torque M only with rotor current I
2Be directly proportional.But,, after respectively amount is carried out amounting to of the number of turn, the number of phases and rotor-position rotor, can obtain stator current according to the equivalent circuit of motor because rotor current is not easy to measure
, rotor amounts to electric current
Exciting current with motor
Relation:
In the formula
k
iBe the electrorheological ratio, can be by calculating or the experiment acquisition.Asynchronous motor in the normal range of operation from the zero load to the nominal load, exciting current
Variation also very little, can be considered definite value basically.Therefore by formula (1) and (2) as can be known, the electromagnetic torque of motor and stator current have certain proportionate relationship, can be by the electric current of a certain phase in the measurement motor stator, and the electromagnetism that record motor is indirectly exported torque.Find that through a large amount of experiments on experiment table the size of current of motor is not only relevant with its output torque, and relevant with technology type, so the present invention does not adopt the method to obtain M
aValue.
4. slide block range indirect measurement method:
The moment of torsion M of the required transmission of air operated friction clutch of punching machine in the reality
aRequired power and Deformation Height are determined when making workpiece produce distortion by its slide block by mould, the device of automatic detection forging towards deformation force and Deformation Height is installed on some punching machine in commercial production reality, like this, the moment of torsion M that just can obtain to act on the bent axle with the size of these two kinds of signals
Ra
M
Ra=Pm
q (3)
P is the workpiece deformation power (N) that affacts on the slide block in the formula, m
qThe equivalent arm of force (m) for toggle.
The moment of torsion M that on online known bent axle, acts on
Ra, the moment of torsion M of required transmission on the air operated friction clutch axle correspondingly
aShould be
In the formula i be the axle of air operated friction clutch to the ratio of gear of bent axle, η be the air operated friction clutch axle to the transmission efficiency between the bent axle, to one-level gear drive η=0.97, secondary gear transmission η=0.94.
Embodiment
As previously mentioned, make the moment of torsion M of air operated friction clutch friction pair output
qCan satisfy the requirement of workpiece deformation, the moment of torsion M that required air operated friction clutch rubbing surface transmits in the time of just must knowing this workpiece deformation
a, could realize M like this according to the required transmission of air operated friction clutch
a, by intelligentized pneumatic system so that the moment of torsion that the air operated friction clutch friction pair can be exported satisfy: M
q〉=M
a, realize that adaptively reliable, high-effect, oligosaprobic forging is towards processing.The present invention comes to determine M for information about according to the actual processing of punching machine
aValue.Obtain M
aMethod a lot, the present invention only just adopts slide block range characteristic to obtain M
aThe method of value study.As the required torque M that obtains bent axle by the range characteristic on the slide block
RaAfter, can determine M by formula easily
aValue, for this reason, the present invention is only with regard to M
RaBe how to determine to study.
The device (being designated hereinafter simply as device for measuring force) that can detect automatically and show the workpiece deformation power that acts on the slide block has been installed on some punching machine in industrial reality.Present this device for measuring force has two kinds of way of outputs, and a kind of is only to export and to show maximum workpiece deformation power P
m, another kind is the size of exportable different deformation force P constantly, and provides maximal value, promptly exportable and demonstration P-t numerical value and curve.For this reason, the present invention is at first known but device for measuring force only can be exported maximum workpiece deformation power P to technology type
mSituation under how to obtain M
RaStudy, obtain M under the situation to known P-t successively then
RaValue discuss.
1. the relation of the moment of torsion of air operated friction clutch and air pressure size
The front has been narrated in the punching machine course of work, how to obtain the moment of torsion M on the air operated friction clutch axle online
aMethod.At known M
aSize after, ensuing problem is exactly to allow the friction pair of air operated friction clutch that enough big moment of torsion M can be provided
q, make M
q〉=M
a, skid otherwise will rubbing surface take place in the workpiece deformation process, friction material wearing and tearing, overheated, even serious " vexed car " accident takes place.But if no matter M
aSize, all get maximal value M when working at every turn
Q maxThough reliable operation can cause the waste of great compressed air energy as previously mentioned, this is the deficiency that present air operated friction clutch air-channel system exists, and also the present invention will improve part just.
Consider to have fricting movement resistance moment of torsion in the course of work, for operate as normal M
q〉=M
a, but for energy-conservation again can not be a lot of greatly, be defined in here when carrying out the moment of torsion Based Intelligent Control and get:
M
q=βM
a (5)
β is defined as the air operated friction clutch coefficient of torque reserve in the formula.It is to consider the moment of torsion M that can transmit between the air operated friction clutch friction pair
qBe subjected under the situations such as variation of the stability of fluctuation, the friction factor of air operated friction clutch cylinder internal gas pressure, true rubbing contact area the air operated friction clutch operate as normal being obtained.Here get 1.1≤β≤1.3, the application gets β=1.2.
To the air operated friction clutch friction pair, the moment of torsion M that it can be exported
qShould be
M
q=mμqF
0R
μ (6)
In the formula, m is the rubbing surface number, and μ is a friction factor, to the common employed friction material of punching machine and to mill element μ=0.3~0.4.R
μBe equivalent friction radius of facing, F
0Be the single-sided friction area, q is the specific pressure on the rubbing surface, and the total snap-in force Q that acts on this rubbing surface is
Q=qF
0 (7)
Q is normally produced by the piston in the cylinder, and piston is to rely on compressed air-driven, and ought establish the air operated friction clutch piston area like this is S, and pressurized air pressure is p, when the friction ignored between piston and the cylinder, can get:
Q=pS (8)
Because μ, F, R in formula (6) and the formula (8)
μAnd very difficult artificial adjusting of S, so as can be known by formula (5), in order to make M
qCan follow M
aAnd change, can only be by regulating the size of air pressure p.The size of air pressure p in this application, air pressure p relies on the online adjusting of electric proportion magnetic valve in this article, thereby comes the detection feedback debug results to constitute closed-loop system by baroceptor.
Usually the friction pair form of air operated friction clutch has disc type and two kinds of the formulas of inserting of floating.The unsteady formula version of inserting that PFC-B-82 type testing table among the application adopts, its friction torque that can produce is
M
q=2μqzF
iR
μ (9)
In the formula: z is the number of inserting that floats;
F
iIt is a monolateral friction area of floating and inserting.
That is to say, this kind floated inlay fast structure, have following formula
F
0=zF
i (10)
m=2 (11)
Can get by formula (7)~(11):
M
q=2μpSR
μ (12)
In experiment of the present invention, air operated friction clutch and Pneumatic friction detent PFB rubbing surface are of a size of z=10, R
μ=0.210m, μ=0.3~0.35, F
i=7.7117 * 10
-3m
2, S
B=0.2366m
2, S
C=0.2686m
2S wherein
B, S
CBe respectively the area of air operated friction clutch and PFB piston.
With above-mentioned data substitution formula (12) and get μ=0.31 and can get:
M
qB=0.0308p(N·m) (13)
M
qC=0.0350p(N·m) (14)
As seen the air operated friction clutch to other size still exists
M
qC=kp (15)
That is to say that the interior air pressure size of friction torque size that power clutch can produce and cylinder is directly proportional, by formula (5) and formula (15) as can be known, directly detecting the friction torque M of the required transmission of air operated friction clutch like this
aSituation under, can be according to M
aAnd the size of regulating the cylinder internal gas pressure, thereby reach the purpose of save compressed air.
2. use the slide block range characteristic of online actual measurement to determine M
a
By document as can be known, when known workpiece deformation power P, also can't determine to affact the moment of torsion M on the bent axle
Ra, must know the size of the arm of force, at maximum distortion power P
mOften locate the arm of force and may not get maximal value, relation between the two exists than big-difference different technology.Expect M
RaValue, must know any arm of force length m
qUnder deformation force P, both multiply each other and could obtain M
RaValue, could try to achieve M on the air operated friction clutch axle by formula (4) then
aThe M of any time now
RaValue can't be known and only know P
mValue, how to obtain M
Ra?
Though the P of any time can't obtain, the technology type that punching machine reality is finished is to determine as stamping-out, pull and stretch, hot forging, cold extrusion, and every kind of technology all has its unique range characteristic, especially at known P
mDuring with Deformation Height, the deformation rule of other power constantly can calculate out that the workpiece deformation height here also is known to machining blanks and the mould of determining, so just at already known processes type, P
mAnd under the h situation, just can obtain the M of any time
RaValue can find out that thus there is certain approximation in this method.
For this reason, the present invention discusses the distortion range rule of different process type earlier, and then how research determines M by the distortion range of already known processes
RaAs previously mentioned, because M
RaKnown, by formula (4) as can be known, M
aJust can try to achieve, so how following only research obtains M
Ra
According to document, after the consideration rubbing action, the moment of torsion of the required transmission of the bent axle of punching machine (or eccentric wheel) can be expressed as:
M
Ra(α)=M
L(α)+M
μ(α)
(16)
(18)
M in the formula
L(α) be desired torque, M
μ(α) be friction torque, P (α) is a workpiece deformation power, and μ is a mechanical rotation system friction coefficient, and opposite opened pressing machine μ=0.04~0.05 is to straight side press μ=0.045~0.055, d
A, d
BAnd d
0Be respectively the diameter of connecting rod tip, small end and crankshaft support axle journal.Consider that aforementioned five kinds of typical process constitute by the broken line of Different Slope, have more versatility for making P (α) expression formula, with reference to the discussion of aforementioned each technology range characteristic equation, P (α) can be write as:
P(α)=k(α-a
0)+P
0 (19)
K=(P in the formula
1-P
0)/(a
1-a
0) be the slope of load line segment; (a
0, P
0) and (a
1, P
1) being respectively the coordinate of this line segment two-end-point, this coordinate of 2 is determined by the parameter of each typical process, in concrete solution procedure, needs determine this coordinate of 2 according to technological parameter earlier, could further find the solution then.
For the convenience of subsequent calculations, can make:
(21)
Like this, formula (17) and (18) can be write as respectively:
M
L(α)=P(α)f
1(α)
(22)
M
μ(α)=P(α)f
2(α)
(23)
Again convolution (16) as seen, M
Ra(α) be function, can use a computer easily by formula (16) and (19)~(23) like this and obtain M about α
RaValue (α) also obtains its maximal value.In addition as can be known, for each section of range figure, M by the range figure of each typical process in the pertinent literature
q(α) all continuous, promptly each section all has extreme value to occur, and this extreme value is the maximal value of the moment of torsion of this section.
Because to air operated friction clutch output torque M
qBased Intelligent Control be online in real time, so require fast automaticly P according to online actual measurement gained
mValue and the technology type output M that is finished
RaValue, be convenient to system is controlled.Therefore must the online M that tries to achieve of programming
RaValue, and then obtain M by formula (4)
aValue.
According to technique scheme, the on-line monitoring system of the required transmission moment of torsion of punching machine air operated friction clutch of the present invention adopts computing machine by data acquisition deformation force sensor signal, utilizes the P-t numerical relation of online actual measurement to determine M
RaBe illustrated in figure 4 as the computing machine on-line monitoring and the control system synoptic diagram of the required transmission moment of torsion of punching machine air operated friction clutch.
As previously mentioned, the simulating signal of the deformation force P value of deformation force sensor exportable any time of installing on some punching machine just can obtain the P-t data relationship by A/D data acquisition and computing machine.Consider α=ω t, through time t being converted into the P-α relation and the numerical value that just can obtain after the crank angle concerns α and digital filtering as shown in Figure 5.Just discuss below and how to determine M by Fig. 5
RaSize.
3. corner step delta α's chooses
At first to as [α between the Microcell among Fig. 5
i, α
I+1], α
I+1=α
i+ Δ α, Δ α is for calculating M
RaStep-length, between this Microcell in, establish P and change very I and ignore, thereby can regard constant as, and get the numerical value P that does left side between microcell
i, i.e. P=P (α
i) (α
i≤ α≤α
i+ Δ α).Continuous curve among Fig. 5 just can be by the different ladder (α of height like this
i, P
i) replace, in fact when computing machine obtains curve among Fig. 5 by the A/D card, also be smooth and get by very intensive discrete point.Think the curve (the situation exception that has P-α Presentation Function certainly in control system) that improves arithmetic speed and also can obtain Fig. 5 earlier, when the sampling period of known A/D card Δ t, calculated torque M
RaThe time corner step delta α can choose by following formula:
Δα=ωΔt (24)
Δ α is more little obviously, and degree of accuracy is high more, but the real-time of On-line Control moment of torsion can be subjected to influence to a certain degree, so choosing of Δ α should be taken into account above-mentioned two aspects.
1.M
RaDetermine
By formula (16), (17) and (18), at arbitrary corner α
iThe moment of torsion M of required transmission on the bent axle at place
RaiFor
M
Rai=M
L(α
i)+M
μ(α
i) (25)
M
L(α
i)=P(α
i)f
1(α
i) (26)
M
μ(α
i)=P(α
i)f
2(α
i) (27)
Increase a Δ α then, obtain next corner α
I+1=α
iThe M at+Δ a place
Ra (i+1)Value, carry out successively up to calculating all (0~α
0) the interior M of scope
RaValue, relatively obtain maximal value M then
RmUtilize formula ω t again
i=α
iJust can obtain not t constantly
iMoment of torsion M
RaiValue.The above calculation procedure program of being compiled into can be implemented in line computation, and rapidly provide data for the control system of back.In order to verify this program correctness, the JH23 that is used when still selecting previous exemplary for use-63 type punching machine carries out the force deformation figure of the approximate half sine-wave with typical drawing work is carried out emulation, promptly
P(α)=4×10
5sin2α(N) (0≤α≤90°) (28)
As previously mentioned to this punching machine because of its ram travel s
0=100mm, crank length R=s
0/ 2=50mm, d
0=115mm, d
A=155mm, d
B=120mm, μ=0.045, λ=0.1, Δ α=1 °, ratio of gear I=5.353, one-level gear-driven efficiency η=0.97, ram travel frequency n=50 time/minute, correspondingly crank angular velocity of rotation ω=2 π n/60=5.236 (rad/s).Above-mentioned given data is input in the program of being worked out, can obtains simulation result as shown in Figure 6 and Figure 7, Fig. 6 is the change in torque curve, and Fig. 7 is the deformation force curve.Obtain the required peak torque M of air operated friction clutch axle in the time of can trying to achieve in pressure angle α=53.1 ° (t=0.177s) by Fig. 6
a=3493 (Nm).Can find out M from Fig. 6 and Fig. 7
aMaximal value and moment of occurring of the maximal value of power P be different (maximal values that deformation force P gets at 45 places), therefore can not think maximum distortion power P simply
mThe place is exactly the moment of torsion maximum.
Utilize online actual measurement deformation force numerical value such as force transducer, A/D plate and computing machine and constantly, adopt software can calculate workpiece deformation different moment of torsion M constantly in the stage automatically
Ra, and the different M constantly of output
RaValue and moment of torsion maximal value M
Rm, this method has superperformances such as rapid, reliable, is worth applying aborning.
Finished a series of tests according to the technique scheme applicant, result's proof has reached purpose of the present invention.