Electronic servo powered pilot release mechanism

Abstract

In a roller-style feed mechanism, a feed roll is opened and closed for the purpose of pilot release using a direct-coupled servo motor as opposed to pneumatic or hydraulic cylinders. The electronically controlled servo motor drives a rotating shaft with eccentric cams that interact with cam followers causing the feed rollers separate for pilot release. The cam followers produce a force sufficient to overcome nip pressure when separating the feed rollers during pilot release. The electronically controlled servo motor is preferably operative to sense the point where the cams contact the cam followers after the upper feed roller is closed on the feed material, and automatically sense resistance to determine where the upper roll begins to lift so as to compensate for different material thicknesses.

Claims

1. A feed mechanism adapted to deliver coiled or rolled flat material having a thickness into a press or other piece of equipment, comprising: an upper feed roller and a lower feed roller; a feed motor causing the upper and lower rollers to rotate about parallel, spaced-apart axes to advance a feed material through the feed mechanism; an electronically controlled servo motor driving a rotating shaft that is parallel and spaced apart from the axes of the upper and lower feed rollers; opposing cams mounted on the rotating shaft that interact with opposing cam followers coupled to one of the feed rollers, such that when the shaft is rotated in a first direction by the servo motor, the upper feed roller is lifted for pilot release, and when the shaft is rotated in an opposing direction by the servo motor, the upper feed roller is closed on the feed material; wherein the electronically controlled servo motor is operative to sense resistance to determine where the upper roll begins to lift to automatically compensate for different material thicknesses; and wherein the electronically controlled servo motor is operative to sense the point where the cams contact the cam followers after the upper feed roller is closed on the feed material such that the amount of lift is precise and consistent regardless of material thickness.

2. The feed mechanism of claim 1, including at least one device causing the feed rollers to apply a consistent, predetermined pressure against the feed material; and wherein the cam followers produce a force sufficient to overcome the pressure applied by the device when separating the feed rollers during pilot release.

3. The feed mechanism of claim 2, wherein the device is a pneumatic cylinder.

4. The feed mechanism of claim 1, wherein the upper roller is mounted in a support frame; and the cam followers move the support frame upwardly to separate the upper roller from the lower roller for pilot release.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a section view of a typical feed mechanism; and

(2) FIG. 2 is an oblique view of a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) The invention relates to a system and method, as shown in FIG. 2, wherein a feed roll 211 is opened and closed for the purpose of pilot release using a direct-coupled servo motor 221. Servo motor 221 drives a shaft 223 with eccentric lobes 225. The lobes 225 work against cam followers 227 mounted on upper roll support frame 207, causing the feed roll 211 to lift off of the material strip for pilot release. While only one lobe 225 and follower 227 are clearly visible in FIG. 2, it will be appreciated that a corresponding lobe/follower set is provided on the left side of the support frame, simultaneously driven by the same shaft 223.

(4) This invention provides many advantages. Modern servo technology eliminates the delays resulting from the use of solenoid operated directional control valves and the movement of compressed air or fluid. The approach also eliminates the inefficiency and losses associated with existing systems, as well as the cost of expelling large quantities of compressed air into the atmosphere or the heat losses that result from the use of inefficient fluid power as well as the high maintenance costs that go along with those systems. The invention also eliminates the need for any mechanical adjustment by the operator to optimize the precision and effectiveness of the release. This allows the use of the cylinders to provide a wide opening of the roll for the purpose of inserting new material into the feed even if the leading edge of the new strip is significantly deformed as a result of mishandling.

(5) In accordance with the invention, a cam mechanism is used to lift and lower a movable roll a precise amount to release the material strip, thereby allowing pilot pins to align it. In contrast to the prior-art system of FIG. 1, the invention eliminates the repeated, alternating application and removal of pneumatic pressure to cause the cylinder to extend and retract to open and close the feed roll. Instead, a controlled pneumatic pressure is applied constantly to the cylinder to keep the roll closed and to control the feed roll nip pressure. The opening and closing of the feed roll for pilot release is caused by the rotation of the cam mounted on the cam shaft and coupled to and controlled by a servo motor.

(6) The cam applies force against a cam follower that is mounted in the upper roll support frame in a way that causes it to overcome the cylinder force and to open the feed roll. When the cam is rotated by the servo motor in the opposite direction the cylinder forces the closure the feed roll. The rotation of the shaft and cams is minimized and optimized by using the drive control technology to sense resistance and determine the correct position where the roll begins to lift. Using this technology allows the elimination of any mechanical adjustment to compensate for different material thickness.

(7) The invention also does not require manual mechanical adjustment of the cams or cam followers to compensate for different strip thickness, as in the prior. Instead, the invention uses the servo drive and control technology to sense the point where the cam contacts the cam follower after the upper feed roller is closed on the material strip. This ensures that there is no wasted motion required to reach the point of roller lift. The amount of lift is precise and consistent, regardless of strip thickness. The prior art requires that a manual adjustment be made by the operator to initialize the mechanism each time there is a change in strip thickness. If the adjustment is not made correctly each time there is a change in strip thickness, the roll lift distance will vary or, if the change in material thickness is substantial, it might not even lift the roller at all. This invention overcomes those limitations as well.