Patent Application
20180133766
The present disclosure generally relates to plate roll bending machines and, more particularly, to plate roll bending machines having hydraulic cylinders.
The present disclosure relates roll bending machines having three or four rolls, which are well known in the metal fabricating industry for rolling metal plate into cylinders, obrounds and cone shapes. A traditional roll bending machine 100 is shown in
As is known, the output voltage of a rectilinear displacement transducer sensor will change with wear and scratches. In the particular application of a roll bending machine, lubricants and contaminants in the operating environment of the machine may also find their way into the sensor and, particularly, along a sliding interface between a resistive strip and a sensor tip, which will further degrade sensor life, accuracy and performance. Wear and scratches can also be caused by shock and vibration caused by rolling steel plates. Temperature is also a factor that can affect sensor performance and accuracy. Though contained within a housing and somewhat protected by mounting position, rectilinear displacement transducers used in roll bending machine applications are known to be prone to damage.
Similarly, string encoders, which are often also referred to as pull wire or pull rope encoders, are known to be relatively more reliable than potentiometer-based transducers in that they use a string 110 or 110′ that can deflect or bend out of the way of a falling object. However, these strings are necessarily exposed such that a falling object hitting the string can cause a temporary change in feedback information and cause unwanted movement of the roll, which may cause a defect in the part being rolled. Resolution of string encoders is such that rolls can be leveled or set parallel to the gripping rolls within a tolerance of 1 mm.
In one aspect, the disclosure relates to a hydraulic roll bending machine, which includes a frame and a hydraulic cylinder. The hydraulic cylinder includes a housing forming a bore and a plunger slidably and sealably disposed within the bore of the housing, the plunger being connected to a rod extending past one end of the housing such that motion of the plunger within the bore of the housing causes the rod to extend or retract relative to the housing. The first end of the hydraulic cylinder is connected to the frame. A bending roll is rotatably connected to a second end of the hydraulic cylinder such that extension or retraction of the rod changes a height of the bending roll relative to the frame. A hydraulic system that includes a valve is disposed to provide pressurized hydraulic fluid on at least one side of the plunger within the bore of the housing. A controller operates to provide a command signal to the valve. A sensor is integrated with the hydraulic cylinder. The sensor is integrated within the bore of the housing and disposed to sense a distance of the plunger relative to one end of the housing and to provide a signal indicative of the distance to the controller.
In another aspect, the disclosure describes a hydraulic roll bending machine for bending metal plates. The machine includes a controller, and upper and lower gripping rolls rotatably and drivably mounted on a frame. A plate to be bent is arranged to pass between the upper and lower gripping rolls. A height of at least one of the upper and lower gripping rolls relative to the frame is adjustable by two cylinders. A bending roll is also rotatably mounted on the frame through two additional cylinders operating to adjust a height of first and second ends of the bending roll relative to the frame independently and in response to command signals provided by the controller. The controller is programmed and operates to adjust a position of each of the two cylinders and the two additional cylinders independently and based on a respective position signal provided by a sensor disposed in each of the two cylinders and the two additional cylinders. The respective position signal is provided by a respective sensor that is entirely disposed within the respective one of the two cylinders and the two additional cylinders.
The present disclosure generally relates to improvements in the positioning of metal working equipment using a sensor arrangement that is associated with a hydraulic actuator of the machine. The sensor arrangement is advantageously resistant to wear and to accuracy degradation because of vibration, debris and wear. A plate roll bending machine is shown and discussed herein for illustration.
Accordingly, a hydraulic roll bending machine 200 in accordance with the disclosure is shown in
A sectioned view through hydraulic cylinder 215, which is also representative of the structures of cylinder 220 but at different internal and external diameters and stroke length, is shown in
As shown, the plunger 216 has an outer diameter 330 that is larger than diameter 330′ of the rod 210 such that hydraulic pressure present on either side of the plunger 216 within the internal chamber 306 of the housing 208 will cause the plunger 216 to move and push or pull the rod 210 relative to the housing 208. Hydraulic oil or fluid is provided on either side of the plunger 216 by hydraulic passages 308 and 310, which are controlled by a valve 312. The valve 312 and its fluid connections to passages 308 and 310 are associated with a leader block 314.
In the illustrated embodiment, the cylinder 220 fully encloses a position sensing and feedback arrangement, which is embodied as a non-contacting magnetic transducer. More specifically, the cylinder 220 includes a magnetic, micro-pulse linear transducer 332 that is mounted on the cylinder cap or leader block 314. The transducer 332 includes a sensing rod 334 that is connected to a sensor housing 316 and extends into the bore 302 of the housing 208 concentrically relative to the rod 210. The rod 210 has a blind bore 335 extending therethrough in aligned relation to the sensing rod 334 and at a clearance therewith such that the rod 210 can move relative to the housing 208 as previously described without interfering with the sensing rod 334. Micropulse linear transducers are available in a number of resolutions from 0.002 to 0.1 mm. In the illustrated embodiment, a micropulse linear transducer having a 0.04 mm resolution is utilized, which during operation of the machine 200 provides a non-linearity specification of plus or minus 0.08 mm and a repeatability specification of plus or minus 0.08 mm.
Use of the micropulse linear transducer 332 provides a positioning accuracy potential that is at least six times better than can be expected with a string transducer. Micropulse linear transducers are also known as magneto-restrictive linear position sensors. The position data from such transducers represents the absolute distance between a magnet and the head end of the measuring rod 334. To achieve this arrangement, a magnet 340 is mounted in a bore 344 formed at the inner end 318 of the rod 210. The magnet 340 thus moves along with the rod 210 as the sensor rod 334 remains connected to the leader block 314. Magnet 340 is sandwiched between two non-magnetic spacers 342 and 343 and held in place in bore 344 by retaining ring 345. Other contactless linear measurement devices such as one based upon an inductive principal or one based on a Hall Effect principle could be used in place of the micropulse linear transducer 332.
During operation, as the position of the rod 210 changes with respect to the leader block 314, the magnetic field created by the magnet 340 as it traverses the sensing rod 334 will change as the distance of the magnet 340 changes with respect to a stem 41 of the sensing rod. This change in magnetic field will be sensed by the transducer 332, which will continuously provide a signal indicative of the absolute position or the change in position, as appropriate, to an electronic controller that controls operation of the valve 312. In such a control arrangement, a closed loop control scheme can be implemented to more accurately and quickly command the cylinder 220 to assume a desired extension or retraction in the position of the rod 210 relative to the housing 208 and, thus, the frame 202.
In reference now to
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
