Patent Description:
While the present invention is not necessarily limited to tire uniformity machines, it does have particular applicability to such machines. Such tire uniformity machines commonly include an upper rim and a lower rim disposed in opposed relationship with the lower rim being movable toward and away from the upper rim.

The lower rim is initially disposed at the level of a conveyor and receives each tire to be tested from the conveyor with the tire bead seated on the rim, following which the rim and tire are elevated and the opposite bead of the tire engages the upper rim. To that end, the lower rim generally carries a centering cone engageable with a central recess in the upper rim so as to accurately position the rims with respect to each other.

Once the tire is positioned and inflated, the upper rim is rotated at a predetermined speed and a load wheel is moved into and out of engagement with the tire tread so as to load the tire, simulating actual operating conditions. A number of sensing and testing apparatus are usually associated with these machines in order to measure various characteristics of the tire under such simulated operational conditions.

Precision is, of course, of paramount importance in any testing procedure, and proper seating of the tire is, therefore, critical to the accurate testing in this procedure. Moreover, the problem of attaining this precision is compounded in the usual tire manufacturing facility because tires are presented to the testing machine conveyor on a more or less continuous basis and having test requirements at a variety of different bead width spacings, often from one tire to the next. Inasmuch as it is desirable to provide means for accommodating these different bead width spacings, it becomes necessary to somehow adjust the gap between the upper and lower rims.

The most basic method of changing bead width spacings is to manufacture rims having a specific fixed bead width spacing. The rims are then changed to accommodate different bead width spacings. Another practice common to the prior art has been to adjust the bead width by removing the cones from the socket in the lower rim assembly and replacing them with ones of different lengths. In that fashion, the spacing between the upper and lower rims, when the unit is closed, can be adjusted. Obviously, however, both methods are time consuming and not really practical in a production scenario where the operation is intended to be substantially continuous and down time is to be avoided.

Another prior art solution to this problem is to provide for raising the lower rim until the space between the upper and lower rims is less than the required bead width spacing, inflating the tire and then lowering the lower rim to the required bead width spacing. This is accomplished by a series of sensors and control devices which will sense the width of the tire and adjust to the desired rim spacing. The difficulty with this approach is primarily a lack of speed and, in a production setting, it is desirable to be able to make the adjustment quickly so as to not interfere with the production line operation.

One attempt at solving the aforementioned problems is disclosed in <CIT> entitled Bead Width Adjusting Apparatus For Tire Uniformity Machines, which discloses a chuck assembly according to the preamble of claim <NUM>. This prior art configuration is presented in <FIG> where a bead width adjusting apparatus is designated generally by the numeral <NUM> and is carried by a tire uniformity machine, a portion of which is designated by a frame <NUM>. The apparatus <NUM> receives a tire designated by capital letter T which has opposed beads, each of which is designated by capital letter B, which form an inner diameter of the tire wherein the apparatus <NUM> engages the opposed beads and seals the tire for inflation, testing, and inspection. The tire is delivered to the apparatus <NUM> by a conveyor table (not shown).

The apparatus <NUM> includes an upper chuck assembly <NUM> positioned above the conveyor table (not shown) and a lower chuck assembly <NUM> positioned beneath the table, wherein the table has an opening therethrough which the lower chuck assembly <NUM> may extend into and retract from as needed to engage the tire T when it is positioned immediately above the chuck assembly <NUM>.

As best seen in <FIG> and <FIG>, a dual piston cylinder designated generally by the numeral <NUM> is connected to and supports the lower chuck assembly <NUM>. The dual piston cylinder <NUM> includes a cylinder housing <NUM> which provides for a hydraulic fluid port <NUM> that receives hydraulic fluid so as to operate pistons maintained within the piston cylinder <NUM>. In particular, the dual piston cylinder includes an inner piston cylinder <NUM> from which axially extends an inner piston rod <NUM>. The cylinder housing <NUM> forms an outer chamber <NUM> which slidably receives an outer piston cylinder <NUM> from which extends an outer piston rod <NUM>. The outer piston rod <NUM> is annularly maintained within the outer chamber <NUM>. The outer piston cylinder forms an inner chamber <NUM> in which the inner piston cylinder <NUM> and the inner piston rod <NUM> are slidably received and axially movable therein. The outer chamber <NUM> also forms an inner chamber seat <NUM> upon which the inner piston cylinder <NUM> rests. The inner chamber <NUM> also provides an inner chamber seal <NUM> axially removed from the inner chamber seat <NUM>. The seat <NUM> and the seal <NUM> define a stroke which allows for extension and retraction of the inner piston rod <NUM> with respect to the outer chamber <NUM>. In other words, as hydraulic fluid fills the dual piston cylinder, the hydraulic fluid first engages the inner piston cylinder <NUM> so as to move it axially upward. Sometime after the inner piston cylinder begins to move, the hydraulic fluid fills the dual piston cylinder in such a manner so as to move the outer piston cylinder <NUM> and the attached outer piston rod <NUM> axially upward. As will be discussed in detail later, this action by the inner piston rod and outer piston rod serves to raise the lower chuck assembly <NUM> so as to engage the tire.

The inner piston rod <NUM> includes an axially extending stem <NUM> which extends from a stem ledge <NUM>. The stem <NUM> may include or provide a threaded end <NUM> opposite the stem ledge <NUM>.

Referring back to <FIG>, it can be seen that the lower chuck assembly <NUM> includes an outer spindle apparatus <NUM> secured to the outer piston rod <NUM> at one end, wherein the opposed end of the spindle apparatus <NUM> is connected to a lower rim <NUM>. The lower rim <NUM> provides for a radially extending lip <NUM> which seals the lower bead of the tire when the assemblies are brought together. Rotatably received within the outer spindle apparatus <NUM> is an inner spindle apparatus <NUM> which is biasingly secured to the inner piston rod <NUM> and in particular to the stem <NUM>. Extending axially from the inner spindle apparatus <NUM>, at an end opposite the stem <NUM>, is an elongate nose cone shaft <NUM>, which has a tapered nose <NUM>, which axially moves and rotates with the inner spindle apparatus. The nose cone shaft <NUM> has an axial cone opening <NUM> therethrough. A base seat <NUM> extends radially inward from an inner surface of the nose cone shaft <NUM> that forms the cone opening <NUM>. The base seat <NUM> provides a stem opening <NUM> that slidably receives the stem <NUM>. As best seen in the detailed drawing <FIG>, a fastener <NUM> connects to the threaded end <NUM> so as to secure the inner piston rod <NUM> to the inner spindle apparatus <NUM>. In the embodiment shown, a spring <NUM> may be interposed between a lower surface of the fastener <NUM> and the base seat <NUM>.

At an end of the inner spindle apparatus <NUM> positioned opposite the lower rim <NUM> an end bore <NUM> may be provided. The end bore <NUM> may include an axial end bore surface <NUM> from which substantially perpendicularly extends an end bore sidewall <NUM>. A spacer <NUM> may be carried by the inner piston rod's stem ledge <NUM>. The spacer <NUM> provides for a spacer ledge <NUM>. A seal <NUM> may annularly extend between an outer radial surface of the spacer and the end bore sidewall <NUM>. A thrust bearing <NUM> may be positioned between the end bore surface <NUM> and the spacer ledge <NUM>.

A plug with a grease zerk <NUM> is received in the cone opening <NUM>. An area <NUM>' in the opening between the zerk <NUM> and the base seat <NUM> is filled with grease so as to lubricate the slidable movement of the stem <NUM> in the stem opening <NUM>. The nose cone shaft also has cross-lube holes <NUM> in selected locations so that grease may be fluidly transferred between the area <NUM>' and an outer surface of the nose cone shaft <NUM>.

The inner chuck assembly <NUM> and the nose cone <NUM> are axially aligned with the upper chuck assembly <NUM>. The upper chuck assembly <NUM> includes a body section <NUM> with a recess <NUM> axially aligned to receive the nose cone <NUM>. Those skilled in the art will appreciate that an air supply is connected through the recess <NUM> and flows into the tire T for inflation thereof. The body section <NUM> provides for an upper rim <NUM> that engages and seals the upper bead of the tire when the chuck assemblies are brought together.

In operation, the chucking apparatus <NUM> is associated with a control system associated with the tire uniformity machine. The size of the tire and other related information about the tire is received by the control system prior to the tire entering the chucking apparatus. This information is then used to determine the bead width of the received tire. Once the tire is positioned between the upper and lower chuck assemblies, the control system causes hydraulic oil or fluid to flow into the dual piston cylinder <NUM> such that the inner piston extends upwardly. This causes the nose cone to immediately extend upwardly and soon afterward the outer piston rod begins to extend causing the tire to be received on the lower rim <NUM>. As the piston rods <NUM> and <NUM> are extending, sensors associated with the uniformity machine track the movement of the lower chuck assembly <NUM> and feeds that information back to the control system. Next, the lower chuck assembly continues to rise until the nose cone is firmly seated in the recess of the upper chuck assembly. At this time, the hydraulic fluid continues to be directed into the dual piston cylinder until an appropriate force is created between the nose cone and the upper chuck assembly. When the nose cone is firmly seated, the lower rim reaches a predetermined tire inflation position whereupon the tire can be inflated. As the tire is inflated through the recess <NUM>, the control system moves the lower rim via the outer piston rod <NUM> and the inner piston rod <NUM> as needed to the set position as provided in the predetermined information. As a result, the tire is precisely positioned to accommodate different bead width spacings. At this time, any appropriate testing and inspection may take place for the inflated tire.

Once the testing is completed, the fluid is withdrawn from the dual piston cylinder. As this occurs, the fastener <NUM> and associated spring <NUM> pull the elongated nose cone downwardly and a significant force is applied to the inner piston rod <NUM> and the associated biasing components, namely the spring and the thrust bearing <NUM>.

Although the chucking assemblies and apparatus described above are effective, the design and construction of the inner piston rod and associated mechanism for attachment to the nose cone present a number of problems. Specifically, the operational stresses applied to the inner piston rod and associated biasing mechanisms result in breakage of the inner piston rod. Another drawback is believed to be a result of inadequate lubrication reaching areas around the spring <NUM> and the thrust bearing <NUM>. As a result, the spring <NUM> and bearing <NUM> break after extensive use and the broken pieces then result in breakage of the stem. As a result, significant downtime is encountered to replace the inner piston rod and this replacement part is quite expensive. Moreover, to ensure precise positioning of the inner piston rod to the outer piston rod, the inner piston cylinder must be sized with respect to the other components of the dual piston cylinder. As such, if the inner piston cylinder and/or inner piston rod break, the whole dual piston cylinder <NUM> needs to be replaced.

Therefore, there is a need in the art for an inner piston rod utilized within a dual piston cylinder which absorbs stress better, has improved lubrication, and is less prone to breakage, and furthermore which allows for on-site replacement of just the inner piston cylinder, or a portion of the inner piston cylinder, instead of total replacement of the dual piston cylinder.

The matter for which protection is sought is defined in the appended claims. In light of the foregoing, it is an aspect of the present invention is to provide a lower chuck assembly used in a chucking apparatus of a tire uniformity machine comprising a dual piston cylinder having an axially movable outer piston rod, an inner piston rod axially movable with respect to the outer piston rod, the inner piston rod having a stem opening, an inner piston stem detachably received in the stem opening and extending axially from the inner piston rod, and a nose cone shaft having a nose cone opening therethrough which slidably receives the inner piston stem.

These and other features and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings wherein:.

Referring now to <FIG>, it can be seen that a lower chuck assembly is designated generally by the numeral <NUM>. The lower chuck assembly <NUM> may be utilized in the chucking apparatus <NUM> shown in <FIG> and <FIG>. As will be appreciated as the detailed description proceeds, the lower chuck assembly <NUM> has a number of modifications different than the lower chuck assembly <NUM> previously described. Generally, the lower chuck assembly <NUM> and selected components provide for advantages to overcome the deficiencies noted in the prior art chuck assembly discussed above.

Referring now to <FIG>, <FIG>, <FIG>, <FIG>, it can be seen that a dual piston cylinder is designated generally by the numeral <NUM>. The cylinder <NUM> may be utilized with the lower chuck assembly and incorporates most of the same components as in the prior art but some components are configured differently as will be discussed. And the dual piston cylinder is still operative with the upper chuck assembly <NUM> through the lower chuck assembly. In particular, the dual piston cylinder <NUM> provides an inner piston rod <NUM>. A number of the outer components of the dual piston cylinder <NUM> are similar or the same as the dual piston cylinder <NUM>. In particular the cylinder housing <NUM>, the hydraulic fluid port <NUM>, the inner piston cylinder <NUM>, the outer chamber <NUM>, the outer piston cylinder <NUM>, the outer piston rod <NUM>, the inner chamber <NUM>, the inner chamber seat <NUM>, and the inner chamber seal <NUM> are substantially similar in the dual piston cylinder <NUM>, as in the dual piston cylinder <NUM>. Skilled artisans will appreciate that there may be some modifications in the placement of various components, but that the overall operation of the dual piston cylinder <NUM> is similar to that of the dual piston cylinder <NUM> in that it is utilized to elevate the lower chuck assembly <NUM> into operation with the upper chuck assembly <NUM> as described in the background art.

The inner piston rod <NUM> is distinguishable from the inner piston rod <NUM> provided by the prior art configuration. In particular, the rod <NUM> provides for an axial stem opening <NUM>. The opening <NUM> is formed by a stem bore <NUM> which includes a bore radial surface <NUM> from which substantially perpendicularly extends a bore axial surface <NUM>. The bore <NUM> further includes a rod internal surface <NUM> which is provided with internal threads.

Received in the stem opening <NUM> is a field-replaceable inner piston stem designated generally by the numeral <NUM>. The stem <NUM> includes a stem body <NUM> which at one end has a nut end <NUM> which may be threaded. Extending substantially perpendicularly from the stem body <NUM> is a landing surface <NUM> which may be in proximity to the nut end <NUM> and in particular to the lowermost thread, if provided. Extending substantially perpendicularly from the stem body <NUM> is also a collar <NUM> wherein the collar <NUM> fits in the bore radial surface <NUM> and wherein a lower edge <NUM> of the collar <NUM> comes in contact with the bore axial surface <NUM>. Further extending from the collar <NUM> is a threaded shaft <NUM> which is received in the stem bore <NUM> and meshes with the rod internal surface <NUM>.

As best seen in <FIG>, the threaded shaft <NUM> is detachably received in the axial stem opening <NUM> and in particular the rod internal surface <NUM>. This allows for in-field replacement of the inner piston stem <NUM> in the event it becomes damaged or broken during use.

The inner piston stem <NUM> also provides for an axial orifice <NUM> which extends internally through the stem body from the nut end <NUM> to a position just above the collar <NUM>. In some embodiments, a mid-cross bore <NUM> extends transversely through the stem body <NUM> and intersects with the axial orifice <NUM>. And, in some embodiments, a lower-cross bore <NUM> may extend transversely through the stem body <NUM> and also intersects with the axial orifice <NUM>. The lower-cross bore <NUM> is positioned between the mid-cross bore <NUM> and the collar <NUM>. The purpose of the axial orifice <NUM>, the mid-cross bore <NUM>, and the lower-cross bore <NUM> will become apparent as the detailed description proceeds.

Referring now to <FIG>, it can be seen that a nose cone shaft is designated generally by the numeral <NUM>. The shaft <NUM> is similar to the prior art shaft or elongate nose cone <NUM> as described above. However, there are several modifications for use with the inner piston rod <NUM> and other features as will be described. The shaft <NUM> includes a conical nose cone <NUM> at one end. Extending transversely through the conical nose <NUM> is a nose-cross bore <NUM>. Extending axially through the nose cone shaft <NUM> is a nose cone opening <NUM>. The shaft <NUM> provides for an outer wall <NUM> and an inner wall <NUM> which may form the nose cone opening <NUM>. At an end of the opening <NUM> opposite the conical nose <NUM> is an inwardly extending base seat <NUM>. In the embodiment shown, the base seat <NUM> extends substantially perpendicularly inwardly from the inner wall <NUM>.

At an opposite end of the conical nose <NUM>, the nose cone shaft <NUM> provides for a stem end <NUM>. Extending from the base seat <NUM> through to the stem end <NUM> is a stem opening <NUM>, which is coaxial with the nose cone opening <NUM>, wherein the opening <NUM> slidably and rotatably receives the stem body <NUM> of the inner piston stem <NUM>. Extending axially inwardly from the stem end <NUM> is a spacer sidewall <NUM>. Extending radially inward from the spacer sidewall <NUM> to the stem opening <NUM> is a spacer seat <NUM>.

Extending completely through the nose cone shaft <NUM>, from the outer wall <NUM> to the inner wall <NUM>, may be a shaft lube hole <NUM> which is positioned at about a mid-point between the stem end <NUM> and the conical nose <NUM>. As shown, the shaft lube hole <NUM> extends diametrically through the nose cone shaft, but in some embodiments any number of holes <NUM> may be provided and they may extend in any radial direction. Also extending transversely through the nose cone shaft <NUM> from the outer wall to the inner wall may be a spring lube hole <NUM> which is positioned to be about slightly above the base seat <NUM>. And extending through the nose cone shaft <NUM> in proximity to the stem end <NUM> is a spacer lube hole <NUM> which is positioned to be about slightly below the spacer seat <NUM>. As with the other lube holes <NUM> and <NUM>, the hole <NUM> extends transversely through the nose cone shaft <NUM> from the outer wall to the inner wall <NUM>. And as with the lube hole <NUM>, the lube holes <NUM> and <NUM> may extend diametrically through the nose cone shaft, may be of any number and may extend in any radial direction.

The nose cone shaft <NUM> also provides for lube channels <NUM> on either side thereof. The lube channels <NUM> extend from the shaft lube hole <NUM> to the spring lube hole <NUM> and the spacer lube hole <NUM>. The channels <NUM> are configured to intersect with the openings provided by the holes <NUM>, <NUM>, and <NUM> so as to facilitate the flow of lubricating material on an outer surface of the nose cone shaft <NUM> when it is received in the inner spindle apparatus <NUM> as best seen in the prior art drawing of <FIG>. It will also be appreciated that the channels <NUM> may only intersect with selected lube holes <NUM>, <NUM>, and <NUM>. And in some embodiments the lube channels <NUM> may be in the form of a reduced diameter of the shaft <NUM> so as to be fluidly connected with all of the lube holes <NUM>, <NUM>, and <NUM>.

Received in the nose cone opening <NUM> is a nose cone plug <NUM> which has a plug hole <NUM> extending axially therethrough. Secured to an upper end of the nose cone plug <NUM> is a grease fitting <NUM>, which may also be referred to as a grease zerk. Extending between the plug <NUM> and the fitting <NUM> may be an extension <NUM>. The extension serves to provide easier access to the fitting in the event debris accumulates in the opening <NUM>. Skilled artisans will appreciate that a zerk cap <NUM> may be used to enclose the zerk <NUM> so as to prevent contaminants from entering therein. The cap also prevents the air pressure generated while testing a tire from forcing open the grease zerk and removing grease from the cavity. Prior to operation of the lower chuck assembly, skilled artisans will appreciate that the interior of the nose cone shaft from the plug <NUM> to the base seat <NUM> is filled with lubricating fluid. This is accomplished by filling the interior of the nose cone opening <NUM>, which is sealed by the nose cone plug <NUM>, with lubricating fluid through the fitting <NUM>. As the lubricating fluid is filled within the nose cone shaft it will emanate outwardly from the shaft lube hole <NUM> and the spring lube hole <NUM> into the channels <NUM>. Moreover, it will be appreciated that the lubricating fluid will be received into the axial orifice <NUM> and flow therethrough into the rib-cross bore <NUM> and the lower-cross bore <NUM>. Depending on movement of the nose cone shaft <NUM> and movement of components external and internal to the shaft, the lubricating fluid may also flow in any direction through the various holes, bores, channels, and orifice.

A biasing mechanism is designated generally by the numeral <NUM> and may be received on the stem body <NUM>. In particular, the biasing mechanism <NUM> includes a spring <NUM> which may fit around the stem body <NUM>. A locknut <NUM> may be received on the threaded nut end <NUM> so as to hold the spring <NUM> between the locknut and the base seat <NUM>. Positioned between an end of the spring <NUM> and the base seat <NUM> may be a base needle thrust bearing <NUM>. Also provided between the spring <NUM> and the base seat may be a seat bushing <NUM> which is interposed between the needle thrust bearing and the end of the spring <NUM>, wherein the stem body extends through openings provided by the base needle thrust bearing and the spacer. Moreover, it will be appreciated that the needle thrust bearing <NUM> and the seat bushing <NUM> are aligned with the spring lube hole <NUM> and also the mid-cross bore <NUM> of the stem body <NUM>. As a result, the lubricating fluid is purposefully directed into the biasing mechanism <NUM> which undergoes a significant amount of mechanical stress during operation of the lower chuck assembly.

Received in an area formed by the spacer sidewall <NUM> and the spacer seat <NUM> is a spacer needle thrust bearing <NUM>, and a stem spacer <NUM> which may partially enclose the needle thrust bearing. Extending transversely through the stem spacer <NUM> is a spacer cross hole <NUM> which is generally aligned with the lower-cross bore <NUM> and the spacer lube hole <NUM>. This alignment of the cross hole <NUM>, the lower-cross bore <NUM>, and the spacer lube hole <NUM> also delivers a lubricating fluid to an area of significant mechanical stress during operation of the lower chuck assembly. Indeed, the alignment of the lube holes <NUM> and <NUM> with the corresponding cross bores <NUM> and <NUM> facilitate the flow of lubricating fluid from the nose cone opening <NUM> to the exterior of the nose cone shaft <NUM> via the lube channels <NUM>. This alignment facilitates the flow of lubricating fluid in and around the thrust bearing and the spring <NUM>.

As noted previously, in operation, the inner piston stem is threaded into the thread opening of the inner piston rod. The nose cone shaft, which is part of the inner spindle apparatus, is slidably assembled to the stem <NUM> and held in place by the locknut <NUM>. As the inner piston rod <NUM> is extended and retracted with respect to the outer piston rod during the chucking operation, the nose cone shaft is also extended and retracted. In other words, when the inner piston rod is retracted, the spring <NUM> is slightly compressed and these forces are further absorbed by the needle thrust bearing <NUM> and the base needle thrust bearing <NUM>. This extension and retraction of movement of the nose cone shaft facilitates movement of the lubricating fluid between the nose cone opening and the exterior of the nose cone shaft. It will further be appreciated that the nose cone shaft may also be undergoing rotation by the inner spindle apparatus with respect to the outer spindle apparatus. This further facilitates the flow of lubricating fluid therebetween. With the alignment of the cross-bores <NUM> and <NUM> with respect to the lube holes <NUM> and <NUM>, the thrust bearings are adequately lubricated along with the spring <NUM>. This significantly reduces the amount of stress absorbed by the inner piston stem. In the event abnormal stresses are subjected to the inner piston stem and it bends or breaks, the inner piston stem can now be easily replaced in contrast to the configuration of the prior art. This is accomplished by removing the nose cone plug from the nose cone opening <NUM>, evacuating any lubricant that remains, and loosening the locknut <NUM>. The nose cone shaft is then removed, whereupon the broken inner piston stem may be removed. A new inner piston stem can then be installed and the nose cone shaft is re-installed. Skilled artisans will appreciate that this is advantageous in that entire dual piston cylinder does not need to be disassembled from the lower chuck apparatus, thus saving a significant amount of down time of the tire uniformity machine.

Claim 1:
A chuck assembly (<NUM>) suitable to be used as a lower chuck assembly in a chucking apparatus (<NUM>) of a tire uniformity machine, the chuck assembly (<NUM>) comprising:
a dual piston cylinder (<NUM>) having an axially movable outer piston rod (<NUM>), an inner piston rod (<NUM>) axially movable with respect to said outer piston rod (<NUM>);
an inner piston stem (<NUM>) extending axially from said inner piston rod (<NUM>); and
a nose cone shaft (<NUM>) having a nose cone opening (<NUM>) therethrough which slidably receives said inner piston stem (<NUM>);
characterized in that
said inner piston rod (<NUM>) has a stem opening (<NUM>) detachably receiving a threaded shaft (<NUM>) of said inner piston stem (<NUM>).