Abstract:
Methods and apparatus for determining an angular location on a round object during a current operation in order to facilitate positioning the object for subsequent operation. At a first station, an angular location identifying feature is sensed, and an angle at which a predetermined desired angular location is located with respect to the feature is determined. At a second station, the feature is sensed, the object is indexed from the feature in an amount equal to the angle, and the object is marked at the relocated predetermined desired angular location. Another method eliminates the marking step at the second station, and the subsequent operation is performed instead. Apparatus comprises a first station means and a second station means. The first station means includes means for sensing an angular location identifying feature on the object and measurement means for determining an angle at which a predetermined desired angular location on the object is located with respect to the feature. Second station means includes sensing means for sensing the feature, indexing means for indexing from the feature in an amount equal to the angle, and marking means for marking the object at the relocated desired location.
Abstract:
Steering pull to which a vehicle is subjected due to tire non-uniformity is measured accurately even in the presence of wind. An anemometer mounted in proximity of and in positionally fixed relation to the vehicle measures the speed and direction of wind apparent to the vehicle. Those measurements are used by a computer to determine a wind correction quantity which is subtracted from the steering pull measured at the steering wheel.
Abstract:
An object is positioned in fixed relation to a measuring axis without regard to centering the object on the axis and at least one series of data samples correlated to the distance between the measuring axis and a series of points located at angularly spaced intervals on at least one surface feature of the object are generated and stored. To determine the center of a first surface feature, the corresponding series of samples is analyzed to identify samples therein corresponding to points lying on a maximum inscribed circle whose center corresponds to that of the surface feature. To measure a second surface feature of an object with reference to the center of a first surface feature thereof, a first signal and a second signal correlated to the distance between the measuring axis and points on the first surface feature and second surface feature, respectively are generated. The center of the first surface feature is then determined to define a vector indicating the positional offset between the measuring axis and that center. The second signal is then adjusted in accordance with that vector to provide a coordinate-corrected signal to be used as a basis for a centered measurement.
Abstract:
An apparatus and method for imposing a desired average radial load force on a tire by calculating the current average force between the tire and a loadwheel based on the average radial force and radial distance between the tire and a loadwheel over the last previous complete revolution of the tire, the spring constant of the tire and the current radial distance between the tire and the loadwheel. The calculated average force value is applied as a feedback signal to the loadwheel position controller in order to achieve the desired average radial load. The spring constant of the tire may be determined from the change in force per unit distance as the tire is loaded or programmed as a constant to be applied for testing all tires of a given type.
Abstract:
A tire uniformity inspection machine is calibrated by applying to at least one force measuring channel thereof a signal which simulates the application of a force of a magnitude greater than any force actually applied to the machine during calibration. That signal, which is preferably of a magnitude appropriate to simulate the largest forces encountered during actual tire testing, can be generated by connecting the channel, preferably at its input, to an energy source through an impedance. The response of the channel to the signal is measured and a calibration factor is determined based on that response. Such calibration factor accounts for the actual behavior of the channel more truely than prior art calibration techniques which relied solely upon the relatively small signal excitation conditions achievable by applying a relatively small actual force to the machine. Thus, the invention affords tire uniformity measurements of improved accuracy.
Abstract:
The mass of a tire/wheel assembly is altered to apply a static imbalance to the assembly in a manner which reduces the overall tendency of the assembly to cause vibration in the plane perpendicular to its axis of rotation when in use. The applied imbalance, combined with any static imbalance initially inherent in the tire/wheel assembly, results in a desired net static imbalance oriented so as to induce a centrifugal force which opposes, and therefore tends to cancel, at least one component, such as the first order harmonic, of radial force variation characterizing the assembly. The magnitude of the net static imbalance is limited and is preferably selected to substantially equal the lesser of either: (a) a predetermined maximum limit, or (b) the amount of static imbalance required to generate at a designated highway speed a centrifugal force whose magnitude substantially equals that of the aforementioned radial force variation component.
Abstract:
Apparatus and methods for use in measuring the uniformity of a body such as a tire, wheel or the like wherein a waveform related to the uniformity of the body is digitally sampled to acquire a series of data samples, each of which is correlated with a respective physical location on the body. According to a first aspect of the invention, a non-repetitive error component of the waveform is corrected for by sampling the same location on the body at two different times and determining the difference between the corresponding data samples. A part of the total difference is allocated to each of the data samples in the series according to a predetermined methematical function which at least approximately describes the non-repetitive component of the waveform. The part of the difference allocated to each sample is then subtracted from it to obtain a corrected series of data sample. According to a second aspect of the invention, the maximum, minimum and/or peak-to-peak values of the waveform are more accurately determined by relating selected extreme data samples and one or more data samples adjacent thereto to a polynomial function of at least second order. The function is then evaluated at the location where its first derivative equals zero to determine a more accurate and repeatable approximation of a maximum, minimum or peak-to-peak value of the waveform. According to yet another aspect of the present invention the first and second aspects above are practiced in conjunction with one another.
Abstract:
Apparatus for inflating tires to a test pressure. The apparatus includes a shop supply of air and a regulated supply of air. A valve system is used to connect the tire to the shop supply to seat the bead on the test rim; to exhaust the air from the tire to bring the pressure in the tire to approximately the test pressure; and to the regulated supply to bring the air in the tire to the preselected test level. The difference between the actual test pressure and the desired test pressure is measured and that difference is used to control the pressure regulator so as to correct the test pressure in the next succeeding tire.
Abstract:
Method of inflating tires wherein the tires are inflated to a bead seat pressure and thereafter the pressure is reduced without deflating the tires through the valve.