US3570427A

US3570427A - Top feed means for sewing machines

Info

Publication number: US3570427A
Application number: US838550A
Authority: US
Inventors: Herbert Wenz; Heinrich Berg
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1969-07-02
Filing date: 1969-07-02
Publication date: 1971-03-16
Anticipated expiration: 1988-03-16
Also published as: DE2031437A1; GB1271175A

Abstract

Top feed means for sewing machines having a presser foot and a spring biased top feed foot linked to a feeding and raising drive and connected with a carrier on the presser bar, which top feed foot is connected to a link connected with the feeding mechanism and joined with the carrier by a lever connected with the raising elements, which is pivotally supported by the carrier and reaches below a roller element that is arranged on the top feed foot.

Description

United States Patent Herbert Wenz;

Heinrich Berg, Kaiserslautern, Palatinate, Germany July 2, 1969 Mar. 1 6, 197 1 GM. Pfaff AG Kaiserslautern, Palatinate, Germany Inventors Appl. No. Filed Patented Assignee TOP FEED MEANS FOR SEWING MACHINES 4 Claims, 2 Drawing Figs.

U.S. Cl 112/212 Int. Cl D05b 27/04 Field of Search 112/212, 207

[56] References Cited UNITED STATES PATENTS 488,964 12/1892 Dolloff 112/207 1,129,854 3/1915 Dahl l12/212X 3,009,432 11/1961 Reeber et al 112/212 Primary Examiner-Richard J. Scanlan, Jr. Attorney Robert H. Jacob l 42- x24 17 2 0 j 0 1 O 1 O i a;

Patented March 16, 1971 INVENTOR.

1951985197 VIII 11w BY Y P/OVBIWG- TOP FEED MEANS FOR SEWING MAQIIINIES BACKGROUND OF THE INVENTION The invention relates to the feed means for sewing machines. More in particular, the invention is concerned with a top feed means or device for sewing machines having a presser foot and a top feeding foot, each of which is connected by connecting links with a forward feeding and a raising drive means and with a support or carrier connected to the presser bar.

In known devices of this type undesirable oscillation phenomena arise as a result of high operating velocities which are caused by the return impact of the top feed foot upon the material beingsewn, or upon the lower material feed dog, and by the mass forces of the movable parts. The top feed or presser foot then is raised up from the material from time to time during its forward feeding phase. As a result, the material can then no longer be evenly fed or transported.

In order to reduce the inertia forces or momentum, an arrangement has becomeknown where the connection between the presser bar and the top feed foot is made by a feed joint. This joint arrangement, however, is very costly if faultless guiding is to be insured.

Furthermore, in the known arrangement a spring is provided in a sleeve between the presser bar and the needle bar. As a result of the small space between the feeding joint and the head of the machine, the spring may only be of small structural height. In that case however, only a small path is available for the spring so that it is necessary to select a spring having a relatively steep characteristic. This, in turn, results in that with sewing material of different thickness the pressure at any time upon the top feed foot is of different magnitude. Thus, it is necessary to readjust the spring tension as the thickness of the material changes.

SUMMARY OF THE INVENTION In order to eliminate these shortcomings, it is an object of the invention to provide a top feedmeans wherethe mass being moved is still further reduced as compared to known arrangements.

In accordance with the invention, this problem is solved in that the top feed foot is connected to a link that is connected with the forward feed gear and linked to the support or carrier, while furthermore a lever connected with the raising gear, rockably supported on the carrier reaches below a rolling body provided on the top feed foot.

1 In order to avoid a complicated guide means for the top feed foot an arrangement can be employed where the spring presses a ball that is limited in its lateral movement by an abutment surface upon a pressure surface provided upon the top feed foot.

In accordance with a further object of the invention the spring can be arranged within the presser foot bar. In this manner there results a spacially advantageous accommodation of the spring, and simultaneously the use of a spring having a relatively long path of movement is made possible.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the invention is illustrated in the accompanying drawing, in which:

FIG. I is a front perspective view of a sewing machine provided with the top feeding means in accordance with the invention; and

IFIG. 2 is an enlarged illustration of the top feeding means, partly in section.

DESCRIPTION OF THE INVENTION In the housing I of the sewing machine a presser foot bar 2 provided with a bore 3 is journaled at the lower end of which a carrier 4 is threadedly secured. The carrier 4 is provided with a rearwardly extending arm 5, and in addition it supports the presser foot 6.

In the housing I of the machine there is furthermore journaled an arm shaft 7, which drives the needle bar 3 with the needle 9 in a known manner by way of driving elements (not illustrated). Besides, an eccentric III as well as an eccentric II are mounted upon the arm shaft 7.

The eccentric III is encompassed by the eccentric bar I2 upon which is journaled a sliding block 14 guided in the ad justable sliding track member 13. The direction of the guiding path of the adjustable track 13 is adjusted by means of a setting shaft 15 journaled in the housing, with a manual lever I6 (FIG. l) the connection of which with the setting shaft is not illustrated. The setting lever 16 extends from the housing I. By means of the setting shaft the magnitude and direction of the feeding movement of the lower feed dog 18 extending through the stitch plate 17 is determined.

Due to the controlled guidance of the sliding block 14 in the setting track 13 the end of the eccentric bar 12 supporting the sliding block I4 has imparted to it a lateral movement depending on the inclination of the setting and guiding track 13. This lateral movement of the eccentric barv I2 is transmitted by a link bar 19 by way of a double lever 20 and a link 21 journaled to the stud 22 of a joint, which is carried by a pair of links 23 connected to the arm 5.

The eccentric l1 drives an eccentric bar 24 which by means of a bellcrank lever 25 and a link 26, rocks a lever 28 journaled on an extension 27 of the arm 5 of the carrier 4.

The free arm 30 of the lever 28 provided with a smooth surface 29 extends below a roller member 32 rotatably journaled upon a stud 3I. The stud 31 is secured in the split shank 33 of a top feed foot 35 journaled upon the joint stud 22 by way of an arm 34.

The wall 36 of the shank 33 extending below the support 4 has a pressure surface 37 for a ball 38 which is movable within a conically shaped expansion of a bore 40 in the support 4 that is limited by an abutment surface 39.

The bore 40 constitutes an extensions of the bore 3 provided in the presser bar 2. In the bore 3 a spring 41 is received, one end of which rests against a setting screw 42 threadedly received in the upper end of the presser bar 2 and the other end of which rests against a guiding bolt 43 that is guided in the bores 3 and 40 and biased against the ball 38.

A flat spring or leaf spring 44 secured in the housing I in a known manner presses with its end against a ball 46 disposed in a recess 45 of the setting screw 42. This ball passes on this pressure by way of the presser foot bar 2 to the presser foot 6. This presser foot presses the sewing material against the lower presser material feed dog I8 or against the stitch plate 17.

By turning the setscrew 42 in or out, the pressure of the presser foot 6 upon the material can be changed.

A raising or lifting member 47 is secured to the presser foot bar 2 which has an abutment surface 48 with an abutment 49 for the manual lever 50 rockably secured in the housing I.

The arrangement operates as follows: As the arm shaft 7 rotates, the two eccentrics I0 and II are driven together with the other sewing tools of the machine. The eccentric l1 rocks the bellcrank lever 25 by way of the eccentric bar 24, and the bellcrank lever rocks the lever 28 by way of the link 26. In this manner the arm 30 of lever 28 is raised and lowered.

As the arm 30 is raised, its upper surface 29 also presses the top feed foot 35 upwardly by way of the roller member 32. The raising in this connection takes place against the pressure brought to bear by spring 41 upon the ball 38. When the top feed foot 35 is raised, the material being sewn is pressed only by the pressure of the presser foot 6 which is under the pressure of flat spring 44.

By lowering the arm 30, its surface 29 becomes separated from the roller element 32, as soon as the top feed foot 35 is seated on the material being sewn or on the bottom feed dog I8 under the pressure of spring 41. The presser foot 6 which is under the bias of leaf spring 44 and the top feed foot 35 under the effect of spring 41 now press down together on the material.

Due to the rocking of the eccentric bar 12 caused by the eccentric or cam the sliding block 14 is displaced in the track 13. Depending on the position of this track 13, which can be changed by the manual lever shown in FIG. 1, the double lever is more or less strongly deflected. The top feed foot 35 connected with it by way of link 21 effects correspondingly large feeding movements.

These horizontal movements of the top feed foot 35 are made possible by the roller bearing guidance existing between roller element 32 and the surface 29 as well as also between surface 37 and ball 38 as well between it and the bolt 43. The abutment surface 39 in this connection limits the movement of ball 38 and thereby its relative position with respect to surface 37 and wall 36.

In order to raise the presser foot 6 the manual lever 50 is swung upwardly. The abutment 49 thereby raises the lifting member 47 and the presser bar 2 together with the presser foot 6. Due to the linking of the top feed foot 35 by the pair of links 23, as well as also the linking of the lever 28 to the support 4 that is rigidly connected with the presser bar 2 the top feed foot 35 is thus raised to the same extent.

Having now described out invention with reference to the embodiment illustrated in the drawing, what we desire to protect by letters patent is set forth in the appended claims.

We claim:

1. Top feed means for sewing machine of the type having a housing, a drive shaft in said housing, a presser foot bar movable axially in said housing and supporting a presser foot a first spring disposed in said housing biasing said presser foot bar, a carrier secured to said presser foot bar, a top feed foot and a link connecting said top feed foot with said carrier, a second spring for biasing said top feed foot downwardly, means operably connecting said top feed foot with said drive shaft for imparting feed movements thereto, a lever pivotally connected to said carrier, and means connecting said lever to said drive shaft for imparting rocking movements to said lever, and a roller rotatably supported on said top feed foot, said lever extending below said roller for engaging said roller while executing rocking movements.

2. Top feed means in accordance with claim 1, wherein said second biasing spring and a guiding bolt are in said presser foot bar, an abutment on said top feed foot and a ball intermediate said abutment and said guiding bolt, and said carrier defining a conical surface around said ball.

3. Top feed means in accordance with claim 1 including means operative to apply the pressure of said second spring to said top feed foot, said means comprising a pressure surface on said top feed foot, a ball in engagement with said pressure surface, and an abutment surface proximate said carrier limiting lateral movement of said ball.

4. Top feed means in accordance with claim 3, where said second spring is arranged inside said presser bar.