Amf Reece, Inc.

Rudy Papajewski

Gerd Papajewski

A counter-weighted eccentric or crank is clamped to an end of the upper drive shaft. A link is pivoted between the eccentric and an end of a short leg on a V-shaped rocker. The base of the V-shaped rocker is pivoted on a fixed pin. The long arm of the V-shaped rocker is connected to a needle bar to drive the needle bar up and down. The movement of the needle bar carries a main needle and thread through a workpiece to make stitches in the cloth.

Needle bar drive for a buttonhole sewing machine

A main cam of a buttonhole sewing machine has four cams connected together in an assembly which includes a drive disk switch spring. A worm hub and a drive disk are connected together. A shifter mechanism has right and left shifter arms and springs which periodically capture and release the drive disk switch spring. The drive disk and worm hub are driven by a worm gear on the main drive shaft. One of the shifter arms holds the switch spring in a detent, disengaging the switch spring from the drive disk while the buttonhole sewing machine sews bight stitches along a first side of the buttonhole site in a workpiece. The workpiece is clamped between a clamping plate and a clamp. The clamping plate moves in steps while the needle is up. When the clamping plate reaches the end of the intended buttonhole a shift plate is moved, moving the shift arms, releasing the switch spring from the first switch arm and positioning the second switch arm for capturing the switch spring. The switch spring engages the drive disk and drives the cam until the switch spring is captured in the second arm. While the switch spring is moving the multiple cams, the feed cam disengages the feed and a barring cam and follower move the clamp plate laterally to form large barring stitches at the end of the buttonhole site.

Main cam for a buttonhole sewing machine

A grooved barrel cam is mounted on a needle bar drive shaft. As the last step, after stitching is completed and power is removed, an engaging arm inserts a follower pin into the cam. A knife cam follower lever drives a knife drive shaft and a knife driving lever. The knife driving lever drives a knife holder downward. A connector at a middle of the knife holder maintains the holder vertical. A knife is secured at the bottom of the knife holder. The cam and a tension spring angularly return the cam follower lever, the shaft and the knife lever and lift the holder, when the cut has been completed. A compression spring around the knife drive shaft moves the follower away from the cam once the engaging arm has released the follower. Engaging the knife cam follower and operating the knife driving mechanism on the last revolution after the clutch is released helps exhaust the kinetic energy of the sewing machine before bringing the machine to a stop.

Knife mechanism drive for a buttonhole sewing machine

A feed mechanism for a buttonhole sewing machine has a movable plate with a clamped piece of cloth. A rack is formed on a rearward extension of the plate. A pinion engages the rack, and a large gear is fixed to the pinion. An upper driving gear drives the large gear and is fixed to a vertical stub shaft which extends through the base of the sewing machine. A lower driving gear is mounted on the lower end of the vertical stub shaft beneath the work-supporting surface. A longitudinally shiftable horizontal shaft is mounted beneath the vertical stub shaft. A left bevel gear and a right bevel gear are keyed to the shiftable shaft. The shaft may be shifted so that either one or the other bevel gear engages the gear on the vertical stub shaft, or to an intermediate position in which the bevel gears are disengaged. The horizontal shaft is driven by a ratchet mechanism. In operation, the horizontal shaft is shifted so that the right bevel gear drives the lower driving gear and bight stitches are formed along a first side of a buttonhole. The bevel gears are disengaged and tack stitches are made at the second end of the buttonhole. The left bevel gear engages the lower driving gear, moving the plate and feeding the cloth back while bight stitches are made along the second side of the buttonhole. The bevel gears are disengaged for forming tack stitches at the first end of the buttonhole.

Growing community of inventors

Stutensee, Germany

Rudy Papajewski