Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1993-12-06
1995-06-27
Knable, Geoffrey L.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156 96, 156130, 156360, 1564051, 1564066, 156909, B29D 3056
Patent
active
054276365
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns the field of tire recapping for heavy vehicles, using pre-molded and pre-vulcanized treads. More specifically, it concerns a device for measuring the travelling length of the tread during its installation on a casing.
The process entailing recapping of a heavy-weight tire casing by installing a pre-molded, pre-vulcanized tread thereon is well known. After removing what remains of the used tread by machining the casing and putting in place a bonding layer, a new pre-molded, pre-vulcanized tread is put on the tire, followed by vulcanization of this bonding layer, performed, for instance, in an autoclave, this process being designed to ensure the adhesion between the new tread and the casing. It is sometimes necessary to also replace one or several top-reinforcement plies.
To properly assemble the new tread to the casing, the tread length must be slightly shorter than that of the circumference of the casing, and must thus be elongated when it is put on.
Another problem is linked to the use of pre-molded treads incorporating a tread-design spacing. It is desirable that this spacing be taken into account at the point where the two ends of the tread are joined on the casing, so as to prevent defects of uniformity of dynamic performance of the recapped tire.
A conventional procedure for installing a tread on a casing consists in controlling the elongation of the tread when it is placed on the casing as a function of the difference between the measurement of the length of the arc of the casing upon which the tread has been applied and the measurement of the length of the finished tread. This limitation of elongation is intended to allow uniform placement of the tread on the casing with an average elongation initially provided for, so as to achieve, at the end of the installation procedure, a satisfactory connection of the two ends of the tread, while adhering to the tread-design spacing.
These two measurements both relate to the same quantity of material, i.e., the portion of the tread placed on the casing, but to a material not in the same state of deformation. In fact, the arc of the casing at the point where the tread is completed relates to a material which is elongated during its installation; the completed length refers to the original length of the tread in the resting state, i.e., in its non-deformed condition. The variation of the elongation of the treads is produced by a press-roller actuated by a jack. The measurement of the tread arc makes use of an optical coder attached to the drive shaft of the chuck on which the casing is mounted. The measurement of the tread length in its finished state corresponds to the measurement of the travelling length of the tread recorded by a second optical coder fastened to a roller driven in rotation and located near the aforementioned press-roller. Experience shows that this device for measurement of the travelling length of the tread during placement of the tread on the casing does not prove satisfactory, since it is not accurate, and lacks of reproducibility.
To improve the reliability of this measurement of the travelling length of the tread when placed on a casing, U.S. Pat. Des. No. 2,105,765 has proposed monitoring the movement of the free end of the tread as it travels in front of a series of photoelectric cells evenly spaced along a roller-driven feed conveyor. However, this measurement is necessarily discontinuous, and the device is expensive.
The purpose of the invention is a simple device for measurement of the travelling length of the tread during its placement on the casing, and the procedure for use thereof.
This device for measurement of the travelling length of the tread during its placement on a tire casing is characterized by the fact that it measures the movement of a stop pressed lightly against the free end of the tread.
Another feature of this embodiment is the fact that the pressure with which the stop is pressed is supplied by the action of a motor which can generate a substantially constant torque whatever is spee
REFERENCES:
patent: 1315981 (1919-09-01), Morton
patent: 3874974 (1975-04-01), Simmons, Jr.
patent: 5292398 (1994-03-01), Miyamoto et al.
Baccaud Armand
Chabin Veronique
Knable Geoffrey L.
Pneu Laurent
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