JPS63182543A - Correcting method for measurement error of tire uniformity machine - Google Patents

Abstract

PURPOSE:To reduce the labor and time by correcting a measurement error by electric processing when a uniformity value regarding the riding comfort of a tire is measured. CONSTITUTION:When a two-axis load cell A is fitted deviating by an angle theta, a reference tire T is fitted to the unformity machine first and an error component X is found from X={¦LFD1¦-¦LFD2¦}/2 based upon LFD1 at the time of the forward rotation of the tire T and LFD2 at the time of the backward rotation. At this time, a radial force F is already known, so an angle theta of rotation is found from sintheta/2=X/F and set in a setter 10; and a tire T to be inspected is fitted to the uniformity machine and while an electric signal corresponding to theta is applied from the setter 10 to a function converter multiplier 11, electric signals ER from cells A and B are supplied to the multiplier 11 to perform processing of (ER) (sintheta/2) polarity. Then the electric signal EL of a lateral force is further added by an adder 12 and the obtained electric signal E'L is inputted to a uniformity arithmetic device 9 to correct the error.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to uniformity (L) related to the riding comfort of tires.
The present invention relates to a method for correcting measurement errors in a tire uniformity machine that measures tire uniformity values.

(Prior Art) Uniformity machines for measuring tire uniformity are known, for example, as described in Japanese Patent Publication No. 51-2157 and Japanese Patent Application No. 57-179456 and the drawings.

In the conventional uniformity machine, two two-axis force detection load cells (hereinafter referred to as "two-axis load cells") are installed at both ends of the support shaft of the road wheel, which is a substitute road surface. -ial direction force and lateral direction force are both detected.

The two-axis load cells are installed on the Uniformity machine as precisely as possible to prevent interference between the radial and lateral forces detected by the two two-axis load cells, but due to machining. , or there may be slight errors in the installation process.

Fluctuation component of the force in the radial direction (Radial Force
Variation (hereinafter abbreviated as rRFVj) and variation component of lateral force (Lateral F
orce Variation+hereinafter abbreviated as rLFV
J) focuses on the fluctuation component, so even if the above-mentioned interference is added a little and its absolute value changes slightly, the influence on the fluctuation component is extremely small, so the interference can be practically ignored.

However, the lateral force (Lateral Force+
Hereinafter, abbreviated as [LFj], the integral average of lateral force (
Lateral Force Deviation,
Hereinafter abbreviated as "LFDJ", Conicity (Co
nicity) and Plystee
r) is directly affected by said interference.

That is, in the tire uniformity machine shown in FIG. 3, a tire shaft 1 rotatably supports a tire T, and a road wheel shaft 4 rotatably supports a road wheel 2, which is a substitute road surface, via a hair ring 3. , are arranged parallel to each other, and both ends 4a and 4b of the road wheel shaft 4 are supported by biaxial load cells A and B via bins 5a and 5b.

Then, the rotating tire T and the circumferential surfaces of the road wheel 2 are brought into pressure contact with each other with a predetermined force F, and each biaxial load cell A,
Detect the radial force and lateral force acting on B.

Specifically, as shown in FIG. 4, the electric signal output eR corresponding to the radial force detected by one of the two-axis load cells A
A is stabilized by the stability multiplier 7, and the electrical signal output eLA corresponding to the lateral force is also stabilized by the stability multiplier 7, resulting in an electrical signal E RA +ELA.

In the same way, each force detected by the other two-axis load cell B is also stabilized via stability multipliers 7, 7, and an electric signal E
It becomes RB + ELB.

The electric signal E RA r E RB of the radial force is input to the adder 8 , becomes an electric signal ER, and is input to the uniformity calculation device 9 . Further, the electrical signal B LA + E LB of the lateral force is also input to the adder 8 , becomes the electrical signal EL, and is input to the uniformity calculation device 9 .

Then, by this uniformity calculation device 9, the RFV
, LFV, LFD, conicity, plysteer, etc., are calculated. This uniformity value is used as a reference value for correcting non-uniformity of the tire T. Therefore, this uniformity value is required to be accurate and error-free.

However, as shown in FIG. 5, if the biaxial load cell A is mounted with a deviation of an angle θ, the value will be inaccurate.

That is, the radial force F from the tire T is applied to the road wheel 2.
When the force acts on the center in the middle direction, the force is applied to the pins 5a+5b by F/2, respectively. Assuming that load cell 8 is installed rotated by θ degrees, and load cell B is installed correctly, a force of F/2 is acting on the center pin 5a of load cell A. Nevertheless, as shown in Figure 5, radial force F/2・cosθ □ (1) Lateral force
F/2·sinθ □(2) occurs. Therefore,
The sum of the forces detected by the two-axis load cells A and B is, and if the two-axis load cell A is installed correctly, the radial force is F - (51 compared to the lateral force 0 - +61) (1+cosθ)-(1c
osθ) □ +71 It can be said that there is an interference (error) of -5inθ □ (8) as a lateral force.

In order to reduce these interferences, at present, only one of the two two-axis load cells is slightly rotated, and a component due to the rotation angle is intentionally generated and corrected.

In other words, (i) the lateral force when the tire is tested in the forward direction (rotating the tire clockwise with the serial number side up) and (ii) the lateral force when the tire is tested in the reverse direction (the tire serial number side facing down). This method takes advantage of the property of tires that the magnitude (absolute value) and direction of the lateral force are the same when the tire is rotated counterclockwise) and the magnitude is the same, but only the direction is reversed.

Specifically, by actually using the tire, we measured the LFD under forward rotation front and reverse rotation conditions, and slightly adjusted the N[Iil biaxial load cell so that the absolute values of the two FDs were equal. It was rotating.

Specifically, if there are two 2-axis load cells A and B, (a) 2-axis load cell A is installed correctly and 2
When the axial load cell B is installed rotated in the θ° plane (b) When the 2-axis load cell A is installed rotated in the θ° plane and the 2-axis load cell B is installed correctly (c) 2 Axial load cell A is θ°, biaxial load cell B is α
°It is possible that it is installed with several rotations, but (
In the case of b), the two-axis load cell B is rotated approximately in the −θ° plane to reduce interference. Also, in the case of (b) and (c), the two-axis load cell B is approximately -θ.

θ+α.

Or ~□ rotated to reduce interference.

(Problem to be Solved by the Invention) The above-mentioned load cell correction work involves rotating the two-axis load cell little by little through repeated tests, and adjusting the LF of the forward rotation front and reverse rotation side.
Adjustments were made until D was the same, which took a considerable amount of time and effort.

Therefore, the present invention has developed a tire uniformity measuring machine that can easily obtain highly accurate tire uniformity by installing a two-axis load cell to correct the error through electrical processing rather than mechanically. The purpose is to provide an error correction method.

(Means for Solving Problems) The present invention is characterized in that both ends of either a tire shaft that rotatably supports a tire or a road wheel shaft that rotatably supports a road wheel are A tire that is supported by an axial load cell, presses the circumferential surfaces of a rotating tire and a road wheel, detects tire radial force and lateral force using the two-axis load cell, and calculates tire uniformity from the detected values. The lateral force LF1, or its integral average LPD I, detected by measuring a tire forward rotation table using a uniformity machine and using a reference tire in advance,
From the lateral force LP2 detected in the measurement of the reverse side, or its integral average LF (12), the error component X of the lateral force is determined as or, and the error component X and the radial force applied in the measurement are From F, the correction coefficient β is determined as β=□. Next, the lateral force LP and the radial force F are detected using the tire to be inspected, and the correction coefficient β is used to determine the tire to be inspected. The point is to find the true lateral force LP of the tire as LF=LF-β·F.

(Function) To explain the present invention in detail, the conventional two-axis load cell installation position correction work involves rotating the two-axis load cell, which is caused by a radial force having a magnitude and direction of F. When acting on a two-axis load cell, the angle (-θ°)
is the same as changing F to F cos (-θ) for the radial force and generating F·sin (-θ) for the lateral force by applying F to the two-axis load cell.

This conversion can be processed electrically without mechanically rotating the two-axis load cell.

In other words, the rotation angle θ is a freely selectable setting value.
is generated electrically, and sinθ,
After converting to cos θ, (a) for radial force, multiply the force F by cos θ, and (b) for lateral force, add F multiplied by sin θ.

This electrical processing is equivalent to mechanically rotating the biaxial load cell by θ degrees.

Therefore, if this θ is known, electrical processing can be performed.

By the way, from the above equation (8), if the error component X of the lateral force caused by the interference of the lateral force (the error component X of the lateral force due to the mounting error when actually using the tire) is found, it can be expressed as follows.Here, the radial force F is Since this is known, the correction coefficient β can be found from equation (9). (Determining β is equivalent to finding θ.) Therefore, in order to find the correction coefficient β, the error component It is important to know that this error component X can be determined by measuring the forward and reverse sides of the tire.

That is, the lateral force when the tire is tested in the normal rotation table,
The magnitude and direction of the lateral force when a tire is tested in reverse can be determined from the tire's property that the magnitude is the same but only the direction is reversed.

That is, for example, if the tire's true forward rotation sad poem LFD 1 is +
Assuming that the weight is 11 kg and the error component of the two-axis load cell is +2 kg, the actual measured value is L for normal rotation.
FDl − (+11 kg) + (+ 2 kg) = +
When 13kg is reversed, LFD2-(41kg)+(+2
kg) --9 kg.

Therefore, the error component X is It is required as.

Therefore, the error component X can be determined in advance by measurement, and the correction coefficient β can be determined from the above-mentioned formula 001 using F at that time.

Since this correction coefficient β is caused by an error in mounting the two-axis load cell, it is applied to all tires to be inspected as a value specific to the uniformity machine.

Therefore, the error component X of the lateral force when measuring the tested tire is X=β・F from formula 00), and the true lateral force LP is: UF=LP−X =LF−β・F (12) however,
■ is the measured lateral force of the tire to be inspected, and F is the radial force of the tire to be inspected.

In the above explanation, LFD was used to obtain X, but L
The same applies if P is used.

Furthermore, although β is equivalent to θ, correction can also be made using θ.

That is, it is equivalent in the present invention to obtain and correct θ as θ −5in−′ −−(13) F from the equation (GO).

(Example) The present invention will be explained in detail below.

The tire uniformity machine body used in the method of the present invention is:
Since it is the same as the conventional one, it will be explained with reference to FIG.

In FIG. 3, a tire T is assembled into a precision rim (not shown) and rotatably mounted on a tire rotation shaft 1. As shown in FIG. Road wheel 2 which is a substitute road surface corresponding to tire T
is rotatably attached to the road wheel shaft 4 via the hair ring 3.

Both ends 4a and 4b of the road wheel shaft 4 are bins 5a,
5b is fixed to the biaxial load cells A and B, and the biaxial load cells A and B are fixed to the carriage 6 with bolts (not shown).

In the tire uniformity machine, the tire rotating shaft 1 is rotated by an electric motor (not shown), and the carriage 6 is moved toward the tire by an appropriate moving means (not shown) to apply a predetermined load (radial force) to the tire T. After giving , the tire rotation axis 1
The distance between the axis of the wheel and the axis of the road wheel axis 4 is fixed constant, and the radial force and lateral force accompanying the rotation of the tire T are
It is detected and analyzed by axial load cells A and B.

Figure 1 is a circuit diagram of the uniformity machine, which includes a stabilization and addition circuit for the output signals of the two-axis load cells A and B for detecting radial force and lateral force of the uniformity machine, and a uniformity calculation device that calculates the uniformity value. Indicated.

The electric signal output eRA corresponding to the radial force detected by the two-axis load cell A is stabilized by the stabilizer 7, and the electric signal output eLA corresponding to the lateral force is also stabilized by the stability amplifier 7. and the electrical signals E RA , E
Becomes LA.

Similarly, the force detected by the two-axis load cell B is also stabilized and becomes electrical signals E Re and E LB.

The electric signals ERA and ERR of the radial force are input to the adder 8, and are input to the uniformity arithmetic unit 9 as an electric signal ER. In addition, the electric signal E LA of the lateral force
+E L[l is also input to the adder 8, and becomes the electrical signal E.

This electric signal EL is corrected by a correction circuit 9'',
The electric signal E L+ becomes the uniformity calculation device 9.
is input. This correction circuit 9' is comprised of a function conversion/multiplier 11, a setting device 10 for setting the rotation angle θ, and the like.

Next, a specific example of the method of the present invention using the above device will be explained.

Now, it is assumed that the two-axis load cell A is installed with a deviation of an angle θ. First, the reference tire T is mounted on a uniformity machine and the error component X of the lateral force is determined.

This error component X is determined from equation (11) from LFD 1 of the reference tire T when it is in the normal rotation and LFD 2 when it is in the reverse rotation. At this time, since the radial force F is known, 00
) is used to find sin θ X F and set the rotation angle θ in the setting device 10.

Next, the tire T to be inspected is attached to the uniformity machine and measurement is started. The measured values of the radial force detected by each of the two-axis load cells A and B are inputted to the uniformity calculation device 9 as an electric signal ER via the adder 8, as described above. The lateral force is converted into an electric signal EL through an adder 8, and at this time, a setting device 10 that sets the rotation angle θ
An electrical signal corresponding to θ is generated and applied to the function conversion multiplier 11. The function conversion multiplier 11 receives the electrical signal E.
An electric signal corresponding to R, that is, radial force F is also added, and the following processing is performed, and the adder 12 adds it to the electric signal EL, which becomes E L+ and is input to the uniformity calculation device 9.

With the above circuit configuration, the error component of the lateral force generated due to the mounting inaccuracy of the two-axis load cells A and B can be reduced to θ
By setting , it is now possible to electrically correct the error.

The above is a specific example using θ based on theory, but
In reality, it is easier to use β in the α0) formula.

That is, as shown in FIG. 2, a correction circuit is incorporated into the uniformity arithmetic unit 9. (a) In terms of electric circuit, it is equivalent to function conversion (sin θ), so it is equivalent to □. ) (b) If you run the forward rotation front and reverse rotation tests several times without manually setting and inputting the error component force after knowing the error component force, the uniformity calculation device will automatically calculate the average value and radius of the error component force. According to the present invention, the directional force can be handled by electrical processing, which reduces the labor and time required for mechanical correction (calibration) during manufacturing, and also facilitates maintenance by eliminating the need for mechanical correction. It is possible to correct machine interference and maintain high machine quality.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a device used in the method of the present invention, Fig. 2 is a modified circuit diagram of Fig. 1, Fig. 3 is an explanatory diagram showing the structure of a tire uniformity machine, Fig. 4 is a conventional circuit diagram, FIG. 5 is an explanatory diagram for explaining the conventional problems. 1... Tire shaft, 2... Road wheel, 4...
Road wheel axis, 9...uniformity calculation device,
T... Tire, A, B... 2-axis load cell.

Claims (1)

[Claims] (1) Both ends of either the tire shaft, which rotatably supports the tire, or the road wheel shaft, which rotatably supports the road wheel, are supported by a two-axis load cell, and both outer peripheries of the rotating tire and road wheel are supported. Using a tire uniformity machine that presses the surfaces, detects tire radial force and lateral force using the two-axis load cell, and calculates tire uniformity from the detected values, use a reference tire in advance to measure the tire. Lateral force LF_1 detected by normal rotation table measurement or its integral average LFD_1
From the lateral force LF_2 detected in the reverse side measurement or its integral average LFD_2, the error component X of the lateral force is calculated as follows: X=(|LF_1|-|LF_2|)/2 Or, From the error component X and the radial force F applied in the measurement, the correction coefficient β is determined as β=X/F. to detect the lateral force @LF@ and the radial force @F@, and use the correction coefficient β to calculate the true lateral force @LF@ of the tested tire as LF=@L
A measurement error correction method for a tire uniformity machine characterized by calculating as F@−β・@F@.