Gap adjusting mechanism for rolls on a roll stand used in the extrusion forming of a sheet product

A roll stand for use in the extrusion forming of a sheet product from a flowable material having a main frame supporting first and second rolls between which there is a first gap through which at least one sheet layer passes during sheet product formation. A first adjusting mechanism moves the first roll relative to the second roll so as to vary a dimension of the first gap. The first adjusting mechanism has a first element that is moved by a first actuator that is: a) maintained on the apparatus; b) engageable by a hand of an operator; and c) manually movable through an operator's hand to thereby cause repositioning of the first roll.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to extruded sheets and, more particularly, to an apparatus for continuously forming a sheet product using a roll stand with cooperating rolls between which material passes during the sheet product formation process.

2. Background Art

Extruded sheets are formed from many different materials, with many different thicknesses, and with different layer constructions. An extruded sheet may be formed by itself or combined with one or more other sheet layers that are concurrently formed, or combined after formation.

In a typical apparatus for extrusion forming sheet products, a roll stand is placed downstream of an extruder assembly with an associated sheet die. Flowable material is delivered through the sheet die to a nip/lamination location between adjacent rolls on the roll stand. The applied material is advanced through a gap between the adjacent rolls defined at the nip/lamination location from where it may be routed between one or more additional roll pairs before it arrives at a downstream accumulation location at which the sheet product may be rolled, stacked, packaged, staged, or otherwise handled or processed.

In one exemplary roll stand, there is a roll that cooperates with two adjacent rolls, with the rolls cooperating to facilitate layer, and ultimately sheet product, formation. The gaps between adjacent rolls must be variable to allow an apparatus to have the flexibility to make layers of different thicknesses and products with potentially different combinations of sheet layers that may have thicknesses varying over a significant range.

Such apparatus may be integrated into a line wherein multiple products with different constitution and/or thickness may be serially produced. Accordingly, it is important that the system operator have the ability to readily and accurately adjust the roll gaps to those appropriate for a particular run.

Given that gap control may be required at a number of different locations, it is also important that the mechanisms for varying the gap be reliable in operation and economically feasible.

Heretofore, gap adjusting mechanisms have varied significantly in terms of their complexity, reliability, and accuracy. At one end of the spectrum, it is known to incorporate relatively simple adjusting mechanisms that are operated using a conventional wrench. The system operator is required to have on hand the requisite tooling/wrench that is moved from location to location on the apparatus to make the necessary adjustments. Since a substantial force may be required to turn the wrench to effect adjustments, operators will commonly use a separate, elongate extender bar that can be grasped and manipulated to provide more leverage.

Additionally, since the gap between adjacent rolls is commonly adjusted through separate mechanisms at the spaced ends of the roll, the operator is often required to make incremental adjustments, going back and forth between the ends until the desired gap is established.

Another drawback with this type of setup is that it is difficult for the operator to determine when the desired gap is actually arrived at. Such a determination may involve using a separate measuring instrument. In the event that the gap is not consistent and of the desired dimension, resulting sheet product may be compromised in terms of quality or could even be unusable, in which event a substantial amount of product may have to be scrapped.

Another known adjusting mechanism incorporates conventional block and tackle components to selectively raise and lower one or more rolls relative to another roll to control gap. While this type of system avoids the requirement that necessary separate tooling be kept on hand, the adjustments made using these types of components may be relatively crude. Again, the difficulty in precisely setting a desired gap and identifying the same without onerous measurements, exists with this design.

As an alternative, it is known to use motorized mechanical devices and/or servohydraulic mechanisms to reposition the rolls to set the gap. As mentioned, these mechanisms can get very complex and expensive and require a power supply.

In one form, a separate actuator is required to be kept on hand to be moved separately to each of the mechanisms that is required to be operated for adjustment of the gap. Since these mechanisms are capable of relatively quickly changing the gap dimensions, the operator may have to change operating directions, one or more times, to compensate for an overrun during the adjustment process.

Still further, these designs require that operators contend with the aforementioned problem of accurately identifying when a desired gap has been established.

With some of the power operated mechanisms, the operating drive will be a separately powered component that must be moved to a number of adjusting mechanisms to individually operate them. In the event that such drives are powered pneumatically or through an electrical lead from a supply, the operator will be required to reposition the drive without entangling the supply lines and the system components.

While the above devices have a number of drawbacks, the industry has continued to use them because there is lacking any substitute that addresses all of the issues relating to cost, convenience, reliability, and accuracy.

SUMMARY OF THE INVENTION

In one form, the invention is directed to a roll stand for use in the extrusion forming of a sheet product from a flowable material. The roll stand has a main frame and a plurality of rolls, including at least first and second rolls between which there is a first gap through which at least one sheet layer passes during sheet product formation. The first and second rolls each has spaced end supports through which the first and second rolls are maintained operatively positioned upon the main frame for movement respectively around first and second substantially parallel axes. The roll stand further includes a first adjusting mechanism through which the first roll can be moved relative to the second roll so as to vary a dimension of the first gap to accommodate sheet layers of different thickness. The first adjusting mechanism has a first element that is movable to cause repositioning of one of the end supports on the first roll and a first actuator for causing movement of the first element. The first actuator is maintained on the apparatus, engageable by a hand of an operator, and manually movable through an operator's hand in a first predetermined manner to cause incremental movement of the first element. This movement causes repositioning of the one of the end supports on the first roll, and thereby the first roll, relative to the second roll to change the dimension of the first gap.

In one form, the first actuator has first and second states. With the first actuator in the first state, movement of the first actuator in the first predetermined manner causes the one of the end supports on the first roll to move to increase the dimension of the first gap. With the first actuator in the second state, movement of the first actuator in the first predetermined manner causes the one of the end supports on the first roll to move to decrease the dimension of the first gap.

In one form, the first adjusting mechanism includes a first ratchet mechanism. The first actuator is movable in a predetermined manner in first and second opposite directions. With the first actuator in the first state the ratchet mechanism operates to cause the first actuator to move the first element to reposition the one end support to increase the dimension of the first gap as the first actuator is moved in the first direction, and allows the first actuator to be moved in the second direction without causing repositioning of the one end support. With the first actuator in the second state, the ratchet mechanism operates to allow the first actuator to be moved in the first direction without causing repositioning of the one end support, and causes the first actuator to move the first element to reposition the one end support so as to decrease the dimension of the first gap as the first actuator is moved in the second direction.

In one form, the first element is mounted for movement around a vertically extending axis and the first and second axes are substantially horizontal.

In one form, the roll stand has an upstream end, a downstream end and spaced sides. The first actuator has a first elongate handle that is graspable by a user's hand to operate the first actuator. The first elongate handle has a length that is alignable in a direction extending between the upstream and downstream ends of the roll stand to be stored so as not to project significantly away from the sides of the roll stand.

In one form, the first element is movable around an operating axis to cause repositioning of the one end support. The first actuator is keyed to the first element so that the first element follows movement of the first actuator around the operating axis.

In one form, the first actuator is captively blocked between parts of the first element and one of the end supports on the first roll that are spaced from each other along the operating axis.

In one form, there is a threaded support with a first set of threads on one of the end supports on the second roll and the first element has a second set of threads. As the first element is turned around the operating axis the first element shifts relative to the threaded support along the operating axis.

In one form, the one end support on the first roll has a bearing pad with a surface and the first element has a bearing surface that acts against the surface on the bearing pad as the one end support on the first roll is repositioned relative to the one end support on the second roll.

In one form, the one end support on the second roll is at all times fixed in relationship to the main frame.

In one form, the roll stand includes a second adjusting mechanism that cooperates between the other spaced end supports on the first and second rolls in substantially the same manner that the first adjusting mechanism cooperates between the one spaced end support on the first roll and the one spaced end support on the second roll.

In one form, the roll stand further includes a third roll with spaced end supports through which the third roll is maintained operatively positioned upon the main frame for movement around a third axis that is substantially parallel to the first and second axes. Another adjusting mechanism cooperates between the one spaced end support on the second roll and one of the spaced end supports on the third roll in substantially the same manner that the first adjusting mechanism cooperates between the one spaced end support on the first roll and the one spaced end support on the second roll, to thereby selectively vary a dimension of a second gap between the first and third rolls through which at least one sheet layer passes during sheet product formation.

In one form, the roll stand assembly is combined with an extruder assembly with a sheet die through which flowable material is delivered to a nip location between the first and second rolls.

In one form, the first element on the roll stand has a stepped outer diameter with first and second axially spaced portions. An annular surface between the axially spaced portions defines the part of the first element that blocks the first actuator. The first axially spaced portion of the first element is keyed to the first actuator.

In one form, the second axially spaced portion defines a bearing surface that acts against the one spaced end support on the second roll as the one end support on the first roll is repositioned relative to the one end support on the second roll.

In one form, the roll stand further includes a gap dimension measuring assembly with a gap dimension display. The gap dimension measuring assembly has a housing fixed to the main frame and a displacement measuring tip that engages the first roll, is repositioned relative to the housing as the first roll is moved, and thereby causes the gap dimension display to indicate degree of displacement of the first roll.

In another form, the invention is directed to a method of adjusting a gap between adjacent and cooperating first and second rolls on a roll stand to which a flowable material is supplied to continuously form a sheet product from at least one sheet layer that moves between the first and second rolls during formation of a sheet product. The method includes the step of providing a first adjusting mechanism having a first actuator that is inseparably maintained as part of the roll stand, includes a handle, and is movable in a predetermined manner. The method further includes the step of a hand grasping the handle and, through the hand grasped handle, moving the first actuator in the predetermined manner to vary the dimension of the gap.

In one form, the step of providing a first adjusting mechanism involves providing a first adjusting mechanism with a first actuator having first and second states. The method further involves the steps of placing the first actuator in the first state, wherein the step of moving the first actuator in the predetermined manner causes the dimension of the gap to increase, placing the first actuator in the second state, and moving the first actuator in the second state in the predetermined manner to thereby cause the dimension of the gap to decrease.

In one form, the roll stand has upstream and downstream ends. The handle has an elongate shape with a length. The method further involves placing the first actuator in a stored position, wherein the length of the handle aligns in a direction extending between the upstream and downstream ends of the roll stand, after a selected gap dimension is established.

In one form, a second adjusting mechanism is provided that is substantially the same as the first adjusting mechanism and operable in conjunction with the first adjusting mechanism to control the dimension of the gap.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen inFIG. 1, the invention is directed to a roll stand10for use in an extrusion forming apparatus12. The extrusion forming apparatus12consists of at least the roll stand10and an extrusion assembly14with a sheet die16through which flowable material is delivered to the roll stand wherein it is processed into at least one sheet layer that makes up a sheet product, or is part of a composite sheet product. The roll stand10has a plurality of rolls, and at least first and second rolls18,20in the plurality, that cooperate to process a sheet layer or layers. The rolls18,20have a gap therebetween through which the sheet material passes during the formation process.

At least one adjusting mechanism22, and in most cases a plurality of adjusting mechanisms22, is provided to adjust a gap between the rolls18,20and any other cooperating roll pair.

The apparatus12is shown schematically inFIG. 1since it is intended to encompass extrusion forming apparatus12with components that vary significantly in terms of their construction and operation. The only thing that is critical to the present invention is the provision of at least two rolls18,20that are movable towards and away from each other to control dimension of a gap therebetween to facilitate formation of a sheet layer that makes up, or is part of, a sheet product.

One more specific exemplary form of the apparatus12is shown inFIG. 2. In this embodiment, the extruder assembly14is upstream of the roll stand10and causes flowable material to be delivered from the sheet die16to a nip/lamination location24between the rolls18,20. The completed sheet product is directed from the roll stand10to a collection location26at which it is re-formed, stored, packaged, staged or otherwise handled.

The roll stand10consists of a main frame28that supports the first and second rolls18,20, together with a third roll30. The rolls18,20,30are mounted to the main frame28for rotation around axes34,32,36, respectively, that are substantially parallel to each other and horizontally oriented with respect to a subjacent support38for the entire apparatus12. The main frame28will typically be mounted upon a sub-frame40through which the main frame28and the associated rolls18,20,30can be translated in an upstream and downstream direction towards and away from the sheet die16. It is not necessary to know the details of the construction of the sub-frame40to understand the present invention, and thus a detailed description thereof will be omitted herein.

The roll20is mounted to the main frame28for pivoting movement about its axis32by spaced end supports42,44, mounted one each upon spaced, main frame sidewalls46,48, respectively. The end supports42,44are fixedly mounted to the main frame28so that the roll20is at all times at a fixed vertical height.

The first roll18is maintained operatively positioned upon the main frame28through spaced end supports50,52that are respectively guided in vertical paths by cooperating rails54,56on the main frame sidewalls46,48, respectively. The third roll30is operatively maintained on the main frame28through like end supports58,60that respectively cooperate with the rails54,56, in like fashion.

Through this arrangement, the first roll18can be moved guidingly, selectively upwardly and downwardly relative to the second roll20, to thereby change the dimensions of the gap62therebetween. The roll30is similarly movable vertically upwardly and downwardly relative to the roll20to adjust the dimensions of a separate gap64between the rolls18,30.

Before describing in detail the structure of the inventive adjusting mechanisms22, one prior art adjusting mechanism, as described generally in the Background Art portion hereinabove, will now be described with respect toFIGS. 3-6.

InFIGS. 3-6, two cooperating rolls R1, R2are shown between which a gap G is established. The roll R1has an end support ES1, with the roll R2having a corresponding end support ES2through which the rolls R1, R2are respectively supported for rotation around parallel axes. Between the end supports ES1, ES2, an adjusting mechanism AM is provided. The adjusting mechanism AM has a housing66within which a jack arrangement is provided including a vertically translatable piston68that is operated by a gear70that is advanced in rotation by a worm drive72. The drive72has an exposed, stub shaft74with a polygonally-shaped end76to accommodate a power drive tool that is keyed to turn therewith.

With this arrangement, rotation of the shaft74in one direction elevates the piston68to increase the dimension of the gap G. Rotation in the opposite direction reduces the dimension of the gap G.

As noted above, this mechanism is relatively complicated and expensive in terms of its construction. The gearing within the housing66may be prone to failure and wear and must be kept lubricated, which is facilitated by the provision of a zerk fitting78. Since a corresponding adjusting mechanism AM is required at each of potentially multiple locations, the problems inherent to the design, notably maintenance, expense, etc., are multiplied.

Additionally, it is difficult to make fine adjustments of the gap dimension with this type of mechanism. Further, it is difficult to determine without a separate measurement tool, precisely what gap has been generated. Again, this inconvenience is experienced at every location where such an adjusting mechanism AM is provided.

The inventive structure will be described in further detail with respect toFIGS. 7-15, taken in conjunction withFIGS. 1 and 2.

With the three rolls18,20,30shown, four adjusting mechanisms22,22′,22″,22′″ are incorporated into the roll stand10to precisely adjust the dimension of the separate gaps62,64. The adjusting mechanisms22,22′,22″,22′″ are substantially the same in construction and thus detailed description will be limited herein to one exemplary adjusting mechanism22that cooperates between the end supports42,50on the rolls20,18, respectively.

The adjusting mechanism22consists of a first element80that cooperates with a support82. The support82has a mounting base84that nests within a complementarily-shaped, undercut receptacle86at the top88of the end support42. The mounting base84is maintained in the receptacle by fasteners90.

The support82has a set of external threads92that mate with internal threads94on the first element80. By turning the first element80around an operating axis96, that extends substantially vertically, the first element80is caused to shift vertically upwardly or downwardly therealong, depending upon the direction of turning.

A bearing pad98is secured at the bottom100of the end support50. The first element80has a bearing surface102that acts against a downwardly facing surface104on the bearing pad98as the first element80is turned to advance the bearing surface102vertically upwardly so as to reposition the end support50on the roll18upwardly relative to the end support42on the roll20so as to thereby increase the dimension of the gap62.

To turn the first element80, an actuator110is provided. The actuator110consists of a head112, that cooperates with the first element80, and an elongate handle114with a length extending in the direction of the double-headed arrow116.

The head112has a driving component117that is keyed to the first element80so that the first element80can be turned around the operating axis96by a corresponding movement of the component117on the head112as imparted through movement of the handle114.

More particularly, the first element80has a stepped outer diameter118with first and second axially spaced portions120,122. The first axially spaced portion120has a polygonal shape that can be translated along the axis96into a correspondingly-shaped receptacle124on the component117, or any other shape that will be keyed with the portion120so that the portion120will follow movement of the driving component117around the axis96.

The second portion122on the first element defines the aforementioned bearing surface102.

With the first element80threaded onto the support82, the actuator head112is captively blocked between parts of the first element80and the end mount42, that are spaced from each other along the operating axis96. More specifically, the blocking part on the first element80is an annular surface/shoulder126between the axially spaced portions120,122. The top88of the end support42performs the blocking function in the axially opposite direction.

To avoid binding between the actuator110and the end support42, a holding ring128is fixed at the end130of the first element80so that the actuator head112remains consistently at the same axial location with respect to the first portion120of the first element80. Even though the holding ring128blocks downward axial movement of the actuator110and thereby prevents the actuator head112from shifting downwardly to against the top88of the end support42, the top88will be considered for purpose of description herein to block axial movement of the actuator head112since, in the absence of the ring128, the end support42performs this function.

With the described arrangement, the actuator110is at all times maintained on the apparatus12, and more particularly on the roll stand10thereon. The handle114is engageable by the hand of an operator and can be conveniently grasped and manually moved through that hand in a predetermined manner back and forth in an arcuate path, as indicated by the double-headed arrow132inFIG. 7, thereby to turn the first element80in opposite directions around the operating axis96.

By turning the first element80in one direction around the axis96, the first element80, through its threaded cooperation with the support82, is caused to shift upwardly, thereby raising the end support50and thus the roll18associated therewith upwardly relative to the end support42and roll20so as to increase the dimension of the gap62. Turning of the first element80in the opposite direction reverses this movement and thereby reduces the dimension of the gap62.

To allow the gap62to be changed through a substantial dimensional range, without interference between the actuator handle114and the other components on the roll stand10, a ratchet mechanism140is incorporated into the actuator110. The ratchet mechanism140may have a conventional construction, and thus detailed description of the same is unnecessary and does not occur herein. It suffices to say that the ratchet mechanism140incorporates the generally ring-shaped component117, within which the receptacle124is provided, that can be turned with a ratcheting action selectively in opposite directions, relative to a housing144and other components on the head112.

Through a conventional-type, repositionable knob146, the ratchet mechanism140can be reconfigured selectively to change the actuator110between first and second different states wherein the ratcheting occurs in different directions as the handle114is operated. More specifically, with the actuator in a first state, as the actuator110is moved in the predetermined manner back and forth in the path indicated by the arrow132, the first element80is caused to be turned in increments in one direction around the axis96, which causes the end support50to move upwardly relative to the end support42, thereby increasing the dimension of the gap between the rolls18,20. In the second state for the actuator110, movement thereof in the predetermined manner back and forth, as indicated by the arrow132, causes the first element80to be turned oppositely whereby the end support50moves downwardly relative to the end support42, thereby to diminish the dimension of the gap62.

More specifically, with the actuator110in its first state, the ratchet mechanism140operates to cause the actuator110to move the first element80so as to increase the dimension of the gap62as the first actuator is moved in one of the opposite directions, indicated by the arrow132, and allows the actuator110to be moved oppositely thereto without causing any turning of the first element80, and thus without causing any repositioning of the end support50and its associated roll18. In the second state, the same action results, with the first element80turned in an opposite direction.

The ratchet mechanism140also provides a convenient means by which compact storage of the actuator110can be effected with a desired gap dimension having been set. By placing the actuator110in the appropriate state, once the gap dimension has been set, the handle114can be grasped and ratcheted back to a position wherein the length of the handle114is alignable in a direction extending between the upstream and downstream ends of the roll stand10, as shown inFIG. 2. Essentially, the handle114is folded compactly against the side of the roll stand10in a manner that it does not project significantly away from the sides of the roll stand10.

As noted above, all of the adjusting mechanisms22,22′,22″,22′″ can be made to operate in substantially the same manner. For the roll18, the adjusting mechanisms22,22″ are used in conjunction with each other to cooperatively control the gap62. The adjusting mechanisms22′,22′″ cooperate to control the dimension of the gap64.

In the embodiment depicted, the end supports42,44are shown fixed to the main frame28, whereby the gaps62,64are controlled by moving the rolls18,30relative to the roll20. Other arrangements are contemplated.

Further, the adjusting mechanisms22,22′,22″,22′″ could be fixed to their respective cooperating end supports or the parts could alternatively be separable with or without the release of separate fasteners.

To determine the dimensions of the gaps62,64that have been set, a gap dimension measuring assembly150is provided between each of the cooperating end supports that are relatively moved to control gap dimension. The measuring assembly150is shown between the exemplary end supports42,50in each ofFIGS. 8,9,12, and14.

The gap dimension measuring assembly150consists of a housing154, that is fixed to the main frame28. A displacement measuring tip156engages the end support50on the roll18and shifts relative to the housing154in an amount corresponding to the movement of the end support50. This movement is converted to a quantified dimension value that is readable on a display158.

With the above inventive structure, a method of adjusting a gap between adjacent cooperating first and second rolls on a roll stand can be carried out as follows. As shown in block diagram form inFIG. 16, a first adjusting mechanism is provided as shown at block162. The first actuator is inseparably maintained as part of the roll stand, has a handle, and is movable in a predetermined manner. As shown at block164, the handle on the actuator is grasped and thereafter moved in the predetermined manner, as shown in block166, thereby to vary the dimension of a gap between cooperating rolls with which the adjusting mechanism is associated.

The method may be performed with the actuator in the aforementioned first and second states to thereby increase and decrease the gap dimension, depending upon the selected state.