Measuring and testing – Tire – tread or roadway
Reexamination Certificate
2001-03-20
2003-06-24
Williams, Hezron (Department: 2855)
Measuring and testing
Tire, tread or roadway
C073S146200, C073S146500
Reexamination Certificate
active
06581448
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a snug fitting apparatus for a tire assembly having a tire fitted to a disk wheel for use in automobiles and the like and, more particularly to an apparatus for making the fit between the tire and the disk wheel rim tight.
The tire assembly made by fitting the tire to the disk wheel and being filled with air exhibits slight unbalance in mass distribution due to variation in the tire dimensions, rigidity, weight distribution, true circle accuracy of the disk wheel, and the state of fit between both of the components, which causes vibration and adversely affects riding comfort and maneuverability when a vehicle is driven. Therefore, various measures are taken to solve the problem of the unbalance.
Here, the state of fit between the tire and wheel is settled when air is injected to inflate the tire to a specified shape at the time of assembling the tire.
However, in some cases the air injection only is not sufficient to produce a snug and stabilized state of fit, and unbalance may result. Therefore, a process of correcting the incomplete fit between tire and rim is employed in which a lateral force that can occur during actual vehicle run is applied in advance to the tire assembly to make the fit between tire and rim snug.
As a means for applying the lateral force to the tire assembly, one is proposed (Japanese patent publication No. Sho-64-3683) in which a large diameter drum of normal-and-reverse rotation type with a slip angle is pressed against the ground contact surface of the tire and rotated. The main point of the work of fitting together the wheel and tire is to bring about a normally fit state of the tire assembly with the dummy load before the tire assembly is brought to a stabilized state with the actual load. However, it is generally known through experience that what is practically necessary is not the fit state according to the design theory but a stabilized fit state brought about with the actual load of the vehicle. However, curvature of the roller of the prior art for applying the lateral force is very sharp in comparison with the flatness of the road surface. As a result, the load is not distributed evenly, the pressing force is dispersed around the tire contact area, and the pressing force to the fitting surface is very different from that with the actual vehicle. Moreover, the stresses in the tire is constantly similar to those produced when the tire negotiates a projection on the ground. This sometimes results in that the pressing force does not act on the wheel-tire fit interface.
Another problem with the prior art is a necessity of a device to give swinging motions to the tire so that the lateral force is applied to one and the opposite sides of the tire by turns, which increases the overall size of the correction apparatus.
Therefore, an apparatus has been proposed in a Japanese utility model publication No. 2553192 that is compact, simple, and effective to simulate the actual load very closely by making the pressing surface for applying the lateral force very similar to the ground surface on which the actual vehicle runs. The apparatus is constituted to perform a snug fitting process by pressing the ground contact area of the rotating tire assembly to apply a lateral force to that area. The apparatus comprises a plurality of rollers arranged side by side close to each other with a slip angle to form a set (or a group) of pressing rollers. The rollers as a single set (or a single group) are pressed against the ground contact surface of the tire assembly.
With the above constitution, since the group of pressing rollers is constituted with the plurality of rollers arranged side by side close to each other, a wide pressing surface is formed which is similar to the ground surface on which the actual vehicle runs, and the similar load to that in actual situation acts on the ground contact surface of the tire assembly. Another advantage is that since gaps of a certain size are produced among the rollers, the pressing surface becomes irregular to some extent and is very similar to the irregular road surface, and similar loads to that occurring when the actual vehicle runs act on the tire assembly.
As described above, the snug fitting process apparatus has been proposed with which the ground contact surface moving along its entire circumference of the tire assembly is pressed to improve the snugly fit state between the wheel and tire so that the vibration due to non-uniform fit state between the rim and tire is prevented from occurring. However, since such a process is applied under constant conditions on production lines, the effect of the snug fitting process must be checked appropriately.
The checking work is conventionally made as follows: Samples are taken at specified quantity intervals of the products and the uniformity in the fit state is checked with a uniformity checking machine to determine acceptability of the degree of uniformity. However, such a checking method has the following problems.
First, the uniformity checking machine presses a drum of an outside diameter as large as about 850 mm against the ground contact surface of the tire assembly and measures the magnitude of variation in the radial force (RFV), the magnitude of variation in the lateral force (LFV), and the magnitude of the force in the tangential direction (TFV) of the tire, and the machine is large-sized and expensive. From another aspect, the most important factor in the snug fitting process is the magnitude of the RFV on which the riding comfort and maneuverability largely depend. Therefore, although the uniformity checking machine detects variations in various forces with high accuracy, the measurements can be said superfluous and too much time is taken to obtain the results.
Second, since the check is performed by sampling, the processed state cannot be assured for all the products and the quality is assured only roughly and therefore, reliability is not sufficient. Another problem is that when the RFV value exceeds a specified value, clear determination cannot be made whether the problem is limited to the sampled product or related to the entire quantity, and repeated sampling is required.
Third, since the operator takes a sample at appropriate quantity intervals, transfers it, attaches it to the uniformity checking machine, and tests it in succession, the operator cannot help relying on manual work and bears a heavy work load.
SUMMARY OF THE INVENTION
This invention provides a snug fitting process apparatus for a tire assembly having a disk wheel and a tire fitted thereto, characterized by comprising;
a rotary drive device for rotary-driving the tire assembly supported on a work holding section,
a first pressing member for performing a snug fitting process by pressing the ground contact surface of the tire assembly,
a second pressing member for coming into pressing contact with the ground contact surface of the tire assembly to receive the radial reactional force of the ground contact surface,
a transfer device for transferring each of the first and second pressing members between a pressing contact position where the pressing member is in pressing contact with the ground contact surface of the tire assembly and a position where the pressing member is released from the pressing contact,
a pressure detecting means for detecting the reactional force received with the second pressing member in the state of pressing contact, and
a process control means for performing in succession; the process of snug fitting by moving the first pressing member with the transfer device and pressing the first pressing member against the ground contact surface of the tire assembly being rotated with the rotary drive device, and the process of measuring the variation in the reactional force with the pressure detecting means by moving the second pressing member with the transfer device and pressing the second pressing member against the ground contact surface of the tire assembly being rotated with the rotary drive device; and performing a
Kawaguchi Takehiro
Kimbara Toshiyuki
Takeda Junichi
Central Motor Wheel Co., Ltd.
Darby & Darby
Jenkins Jermaine
Williams Hezron
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