Presses – Methods – With heating or cooling
Reexamination Certificate
2002-05-20
2003-12-23
Ostrager, Allen (Department: 3725)
Presses
Methods
With heating or cooling
C100S048000, C100S214000, C100S257000, C384S039000, C384S040000
Reexamination Certificate
active
06666134
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a press machine environment, and, more particularly, to a system for monitoring the gib-slide interface to detect the presence of a clearance therebetween and to initiate a procedure for adjusting the clearance in a controlled manner, using a process that thermally conditions the connection elements which connect the gib to the frame uprights.
2. Description of the Related Art
Mechanical presses of the type performing stamping and drawing operations have a conventional construction comprising a crown and a bed portion configured within a frame structure. A slide supported within the frame is adapted for reciprocating movement toward and away from the bed. The slide is driven by a crankshaft having a connecting arm coupled to the slide. These mechanical presses are widely used for a variety of workpiece operations employing a diverse array of die sets, with the press machine varying substantially in size and available tonnage depending upon its intended use.
In a conventional arrangement, the frame structure is formed and/or integrated with a gib apparatus having a known function and configuration. For example, in a typical machine configuration, the frame includes a set of upright support members (e.g., four) extending between the crown and bed at respective corner locations. Transverse cross-beams are used to provide a connection between a pair of same-side uprights. At the upper portion of each upright, a gib member is employed in a known manner to provide guidance-type bearing support to the slide. For example, the gib member includes an engagement surface that is adapted for full surface-to-surface abutting contact with a corresponding surface on the slide or a coupling piece secured to the slide.
In one gib configuration, the individual gib members are mounted to a respective upright. Although designed as stationary structures, the uprights may nevertheless experience an undesirable bending or outward bowing under certain conditions. For example, this bending may occur at the upper ends of the uprights as the crown expands in response to certain thermal conditions within the machine environment, such as significant variations or increases in temperature. These environmental factors are difficult to avoid and/or overcome because press operations inevitably involve a dynamic confluence of extremely high pressures and temperatures that make it difficult to isolate individual machine components from their effects, particularly with respect to a component as massive as the press crown.
The significance of this bending behavior of the upright is seen in the fact that the attached gib member will move in concert with the upright. In particular, any deflection of the upright causes a simultaneous displacement of the attached gib member, which necessarily rearranges the precise spatial relationship between the gib and slide. Under conditions where the upright bows outwardly (i.e., away from the slide), the concurrent movement of the gib will cause a spatial separation or clearance to develop at the interface between the gib and slide, where previously these components were in abutting engagement with one another in a bearing support relationship.
The absence or diminution in the bearing support provided by the gib to the slide can present various problems. For example, if the slide is inadequately supported, as may arise when certain gib elements experience movement creating an unbalanced support configuration, the slide may deviate from its planned course of travel as it reciprocates between the crown and bed. Malfunctions or misalignments involving the slide can lead to press failure and die damage.
SUMMARY OF THE INVENTION
An adjustment mechanism for use in a press machine environment is used to vary the spatial relationship between the slide and gib member mounted to the press upright. Adjustment of the gib-slide clearance is part of a compensation scheme aimed at (in one embodiment) counteracting the bowed condition of the uprights that may arise from thermal expansion or contraction of the crown portion, causing the clearance between the gib and slide to increase or decrease.
In one form of the invention, the connection bolts that attach the gib to the press upright are adapted for use in combination with an apparatus to thermally condition the bolts. In particular, the thermal process involves selectively heating and/or cooling the bolts in a manner sufficient to induce a corresponding deformation of the bolt, namely, expansion or contraction of the bolt dimensions, respectively. This modification of the bolt geometry has the effect of varying the clearance between the gib and upright, which in turn controls the clearance between the gib and slide.
A sensor is provided to measure a clearance between the gib and slide. A determination is made regarding whether this clearance measurement has exceeded an allowable threshold value. In response to an out-of-bounds determination, a controller is programmed, for example, to induce a suitable expansion of the bolt by directing a fluid flow into sufficient contact with the bolt. The fluid temperature and the extent of fluid immersion experienced by the bolt are tailored to cause an expansion or change of the bolt.
This expansion activity is sufficient to effectuate a desired inward displacement of the gib toward the slide (e.g., via elastic bending of the gib). This gib movement counteracts the prior displacement of the gib resulting from a bow in the upright. The clearance between the gib and slide is therefore substantially restored to a normal condition, e.g., a full close-out. In one form, the thermally-induced bolt expansion is manifested as a change in the longitudinal dimension of the bolt, i.e., axial elongation.
The adjustment mechanism preferably forms part of an automated closed-loop feedback system that dynamically and continuously monitors the gib-slide clearance and appropriately regulates the thermal variations in the connection bolt in accordance with a comparison of the clearance measurement to allowable data values. Adjustment of the gib clearance preferably occurs during a running press cycle.
In another form, an adjustment mechanism comprises, in combination, a deformable, thermally-sensitive connection element that provides a connection between a press upright and a gib member. The connection element, in response to changes in its thermal state, experiences a corresponding deformation that actuatively induces a displacement (e.g., elastic deformation) of the gib sufficient to close-out or reduce the clearance between the gib and slide.
The mechanism further includes a sensor to measure the gib-slide clearance, and a controller to vary the thermal state of the connection element according to the sensor clearance measurement. The system preferably defines an automated, closed-loop feedback configuration offering dynamic and continuous monitoring and adjustment of the gib-slide clearance.
As used herein, thermal activity and other such equivalents referenced herein should be considered as encompassing any treatment, conditioning, or other such process that alters, modifies, or otherwise changes a spatial feature or characteristic of the affected element. In one form, the thermal activity will induce such spatial variation by changing a thermal property of the element, such as temperature. This thermal activity should be understood as including a mechanism both for cooling and heating the target material, i.e., the gib-upright connection element.
In one form, the cooling and heating function may be accomplished using a single fluid source that alternately acts as a coolant and a heating agent depending upon the application. In particular, if a connection bolt is specified for expansion, the bolt will be immersed or otherwise brought into contact with fluid having a temperature above that of the bolt. For this purpose, a temperature sensor may be provided to monitor the temperature of the bolt and generate a temperature measuremen
Bornhorst John B.
Gusching Jim
Knuth Randall J.
Nguyen Jimmy T
Ostrager Allen
The Minster Machine Company
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