JPH08289987A - Bearing bushing with plurality of bearing locations for movable bearing of cylindrical rod of sewing machine, especially needle bar or arm shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the mass of a supporting part for a sewing machine needle bar with less structural expense. SOLUTION: A bearing bush is the one provided with plural bearing positions for movablly supporting a sewing machine round bar, especially a needle bar or an arm shaft and is provided with a pipe 24 stored in a housing 18, a first bearing position 33 formed at one end of the tube 24 and the second bearing position 34 arranged in the free end of the tube 24. In the needle bar 15 in this case, a bending moment works by radial force which works in the outer parts of the bearing places 33 and 34 and also in the second bearing place 34 adjacently and also stress owing to edge pressure occurs in the second bearing place 34. The bearing bush is the one where the second bearing place 34 is formed as an elastically deformation possible bearing part 28 having deformation property to be adaptable in accordance with the bending moment in order to reduce edge pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing bush according to the general concept of claim 1.

[0002]

2. Description of the Prior Art From West German Patent Specification 3119567, a bearing bush is known, in which a raising and lowering needle bar is supported on a bush arranged on the machine head. This configuration makes it possible to support the needle bar on both sides with the radial force caused by the crank mechanism used in the usual way. This requires, on the one hand, a long needle bar of relatively large mass and, on the other hand, the individual bushings to be fixed in alignment with the machine head during manufacture.

From Swiss Patent Specification 192550,
It is known to make needle bars of sewing machines very short and thus of low mass and to support them with a single bearing bush. Of course, here there is the difficulty of absorbing the radial force exerted by the crank mechanism on the needle bar under wear which is as low as possible. This difficulty is due to the bending moment acting on the needle bar, which has bearing points where the bushes receiving the needle bars are located relatively close to each other and which is located near the point of action of the radial force. Based on receiving a significant edge pressure.

For example, 3000 revolutions or 3000 minutes per minute
In sewing machines that operate at higher rotational speeds than stitches, there is an additional difficulty in lubricating the bearing point that guides the needle bar in order to avoid pinching sliding of the needle bar at the bearing point in any case. This further entails the need for structural measures to prevent lubricant spillage at the needle bar bearing.

[0005]

DISCLOSURE OF THE INVENTION The present invention makes it possible to reduce the mass of the bearing part of the sewing machine needle bar described at the beginning with a small structural expense while avoiding the above-mentioned difficulties. Is to

[0006]

This problem is solved by the features described in the characteristic part of the bearing part according to the superordinate concept of claim 1. A bearing bush is thereby provided in which the bearing point to which the edge pressure is applied is elastically deformable and can follow the deflection of the guided rod. As a result, it is possible to reduce the generated edge pressure or to achieve a slightly mutually variable pressure distribution inward of the bearing point. This, on the other hand, makes it possible to reduce the structural length of the bearing point or to make the bearing point a large load capacity. By means of the bearing bush according to the characterizing feature of claim 2, a suitable and easily machined, low-cost material for the bearing location is described, which material at the same time allows the sewing machine to operate without interruption with a minimum of lubricant. enable.

The features of claims 3 to 5 lead to an embodiment which is manufactured stably and at low cost.
The structure of the cross-section reducing portion according to the characteristic part of claim 6 leads to that the elastically deformable bearing portion follows the deflection of the needle bar even with a relatively low radial force. The features of claim 7 lead to an effective and easily manufacturable embodiment of the cross-section reduction.

According to the features of claim 8, the bearing part can additionally be fitted at the point of the outlet of the rod. At the same time, the sharp edges effectively prevent unwanted molecules and unwanted lubricants from entering the bearing bush. The features of claims 9 and 10 enable other advantageous configurations of the bearing bush. Reference is made to the documents mentioned at the outset regarding the arrangement and configuration of the friction edges. Further, a self-aligning bearing formed by an elastically deformable slide bearing or an outer spherical form that can be crimped onto a shaft is a Dr. techn.
Otto Gersdorfer, Bohmann I
ndustrie-und Fachverlag, 1
Special magazine "Das GLEIT LAGER" issued by 954
It is known from the description on pages 27 to 30 of the above.

ISBN 3-8023-0493-4,
Vogel Buchverlag magazine "Mode"
2 of "rne Waelzlargertechnik"
From pages 75 to 277 it is known how a uniform pressure distribution can be achieved in a rolling bearing part of defined shape. On the contrary, the invention provides to achieve a uniform pressure distribution in the bearing by means of a special configuration.

Other features, advantages and details of the invention will become apparent from the following description of two embodiments, based on the drawings.

[0011]

1 shows a sewing machine 1 comprising a base 2 and an arm 3 fixed to the base 2, the arm ending with a sewing machine head 4. A bearing bush 5 is disposed on the sewing machine head 4, and an upper shaft 6 is rotatably supported on the bearing bush 5. The upper shaft 6 is provided with a crank 7 at an end which ends at the sewing machine head 4, and the crank 7 does not contact the bearing bush 5. The upper shaft 6 is integrated with an adjusting ring 8 that comes into contact with the edge of the bearing bush 5. The upper shaft 6 is fixed in the axial direction in association with another bearing (not shown).

The crank 7 is provided with a pivot 10 fixed by a set screw 9, and the pivot 10 is formed integrally with the protrusion 11. A pivot 10 extending parallel to the upper shaft 6 forms the end of the articulating arm 13,
It is surrounded by bearings 12 with play. The free end of the articulating arm 13 is formed as a fork-shaped part 14, which holds the needle bar 15 by means of its fork-shaped part. The needle bar 15 made of metal, for example steel or aluminum, has an equal diameter d over its entire length. Pin 16 extending parallel to upper shaft 4 on needle bar 15
Is fixed by a sex crew 17, and the set screw 17 is supported with a clearance in a hole (not shown) of the fork-shaped portion 14. The sewing machine head 4 is formed as a housing 18 having a hole, and a bearing bush 19 is fixed to the housing 18. The fixing is by means of a decomposable screw connection by means of a set screw arranged in the housing 18 or an adhesive connection by the use of a suitable adhesive. The bearing bush 19 accordingly has a cylindrical jacket 20 and a bearing bore 21 of diameter d1 in which the needle bar 15 is movably supported in the axial direction with little play.

The needle bar 15 is fixed integrally with the needle 23 through the bearing bush 19 and at the end 22 facing the base plate 2. The configuration in which the needle bar 23 is supported by the bearing bush 19 is
When the upper shaft 6 rotates, the needle bar 15 can be moved up and down without the forks 14 or the pins 16 coming into contact with the bearing bush 19. The construction described is of course conventional and the Swiss patent specification 19255 mentioned at the outset.
It is known from No. 0.

Next, the structure of the bearing bush 19 will be described in detail with reference to FIGS. 4 and 7. The cylindrical jacket 20 is made of metal,
For example, a tube 24 made of bronze or steel, the tube having a chamfer 25 at one end. The tube 24 is formed with a stepless outer shape D. Drilling 26 at the free end of tube 24
Is provided at one end 27 of the bearing portion 28 at its free end.
Are housed and fixed. The bearing portion 28 is made of an elastically deformable material, preferably polyamide (PA), polyoxymethylene (POM) or polyether ether ketone (P).
It is made of an elastically deformable material such as EEK). The letters in parentheses are internationally used abbreviations for the synthetic resins. Such synthetic resins are BASE, Du P
Manufacturers such as ont and ICI provide the market with a predetermined product name.

The free end of the bearing portion 28 is provided with a chamfer 29, which ends in a pointed edge 30. Chamfer 29
Is followed by a rounded transition 31, which transitions into a semi-circular notch 32. The end 27 continues from here. The notch 32 is a cross-section reduction, so that the deformability of the part of the bearing part 28 protruding from the tube 24 due to the force acting in the radial direction is favored or facilitated. A plurality of bearing parts are formed by the configuration described,
That is, the bearing bush 19 has a first bearing point 33 and the bearing part 28 has a second bearing point 34.

FIGS. 5 and 6 show a modified bearing part, the reference numerals corresponding to said parts being provided with an "a". In the deformed bearing bush 19a, the bearing portion 28
A is formed with a sharp edge 30a, which results in a reduced diameter d2 here with respect to the diameter d1. The operation method of the bearing bush 19 will be described based on FIGS. 7 to 9. In Figures 8 and 9, the graphically represented components are represented by the previously used symbols and the subscript "c".

While the sewing machine 1 is in operation, the needle bar 15 moves up and down. At that time, the connecting arm 13 transmits the varying tension and pressure acting on the needle bar 15 to thrust and radial forces, on the connecting arm 13. For the following description, the radial force is important, which causes the needle bar 15 to undergo a bending moment. The curved needle bar 15 in FIG. 8 is shown diagrammatically by a line 35 indicated by a dash-dotted line.

The radial force F1 causes reaction forces F2 and F3 in the bearing bush 19c (FIG. 8). Thus, at the outer edge of the bearing bush 19, that is, the first and second
A pressure p is generated at the outer ends of the bearing portions 33, 34 of (FIG. 7). In the literature, the pressure generated at the bearing edge is called the "edge pressure". The generation of such edge pressure is represented by the principle representation shown in the diagram of the pressure p generated over the length of the bearing point 34 in FIG.
To this end, the flexure needle bar 15 and the bearing part 28 crimped thereto are shown with the part of the bearing bush 19 exaggerated.
And are shown. The distribution of the pressure generated in a known bearing bush in the form of a bush indicated by the dashed line in the diagram is shown in contrast with the bearing bush 15 according to the invention. Maximum pressure p1 for bearing bushes according to the state of the art
Occurs.

On the other hand, the bearing bush 1 according to the present invention
9 adapts or follows the respective bending moment, that is, the bending of the needle bar 15, and the bearing portion 28 elastically deforms.
As a result, a reduction of the pressure p generated in the edge region of the second bearing point 34 is achieved, which pressure is
The maximum pressure p2 is reached. Correspondingly, the bearing bush 19 according to the invention has a relatively low edge pressure. As a result, the reduction of the pressure p in the edge region of the second bearing point 34 leads to a pressure distribution over the length of the bearing point which varies less than in the case of known bearing bushes. Thereby, the bearing bushes according to the invention lead to a high load capacity in equal size, or on the contrary a bearing bush of equal load capacity can be made smaller.

Of particular importance is the shape of the bearing portion 28 due to the reduction in cross-section, ie the bearing portion 28 due to the notches 32 and the sharp edges 30. On the one hand, the notch 32 and the pointed edge 30 favor the deformability of the bearing part 28 on the one hand, and on the other hand the edge 30 acts as an elastic sealing member for sealing the needle bar 15. 5 and 6 another configuration of the edge in the bearing portion 28a is shown, the edge configuration being referred to herein as the edge 30a. The bearing portion 28a has the same structure as the bearing portion 2a.
Corresponds to 8. From FIG. 5 it is clear that the edge 30a extends over the diameter d2 when the needle bar 15 is not in the bearing bush 19a. The diameter d2 indicates a reduced diameter with respect to the diameter d1.

In another embodiment, the bearing bush 5 is likewise provided on the side facing the crank 7 with a resilient bearing part 28 or 28.
a. In this example of use illustrated in FIG. 9, the rotational force F4 acts on the arm 6 which generates reaction forces F5 and F6 in the bearing bush 5. The arm shaft 6c receives a bending moment. The curved upper shaft 6a in FIG. 9 is schematically represented by a line 36 represented by a dashed line. Also in this usage example, the bearing bush 28 or 28
The special design of a makes the bearing bush 5 deformable and at the same time suitable for a tight closure.

[Brief description of drawings]

FIG. 1 is a front view of a sewing machine.

FIG. 2 is an enlarged sectional view of a sewing machine head.

3 is a view of the sewing machine head taken along arrow III in FIG. 2;

FIG. 4 is an enlarged sectional view of a bearing bush.

FIG. 5 is a cross-sectional view of one end of a deformed bearing bush.

6 is a diagram showing a state where a needle bar is inserted into the end of the bearing bush shown in FIG.

FIG. 7 is a pressure distribution diagram of the bearing bush end deformed by bending.

FIG. 8 is a schematic view of a needle bar bearing portion.

FIG. 9 is a schematic view of an arm shaft bearing portion.

[Description of sign]

 1 Sewing machine 6 Upper shaft 15 Needle bar 18 Housing 24 Tube 28 Bearing part 28a Bearing part 33 First bearing part 34 Second bearing part 34a Second bearing part F1 Radial force F2 Radial force F3 Radial force

Claims (10)

[Claims] 1. A round bar of a sewing machine, in particular a needle bar or an arm shaft as a bearing bush with a plurality of bearing points for movable bearings, a pipe (24) housed in a housing (18), A first bearing point (33) formed at one end of the pipe (24)
A second bearing part (3) provided at the free end of the pipe (24)
4) and the needle bar (15; 6) is provided at the bearing point (3
In the bearing bush, a bending moment is generated by a radial force acting outside the third bearing portion (34) and adjacent to the second bearing portion (34), and a stress due to an edge pressure is generated in the second bearing portion (34), The second bearing part (34; 34a) is formed as an elastically deformable bearing part (28; 28a) having a deformability adaptable to the bending moment for reducing the edge pressure. The bearing bush described above. 2. The bearing portion (28; 28a) comprises a needle bar (1).
5; 6) bearing elastically deformable synthetic resin (PO
The bearing bush according to claim 1, which is formed of M; PA; PEEK). 3. A bearing bush according to claim 2, wherein the tube (24) has a stepless diameter (D). 4. Bearing bush according to claim 1, wherein the tube (24) is made of metal (bronze; steel). 5. The tube (24) comprises a bearing part (28; 28).
Bearing bush according to any one of claims 1 to 4, having a bore (26) for fixing and accommodating a). 6. Bearing bush according to claim 1, wherein the bearing part (28; 28 a) has a cross-section reduction (32; 29) which favors deformability. 7. Bearing bush according to claim 6, characterized in that the cross-section reduction has a ring-shaped notch (32). 8. A bearing portion (28; 28) having a reduced cross section.
Bearing bush according to claim 6 or 7, characterized in that it has a pointed edge (30; 30a) in a). 9. The rim (30a) has a reduced inner diameter (d2) prior to the insertion of the needle bar (15; 6).
Bearing bush described. 10. Bearing points (33, 34; 33, 34)
Bearing bush according to any one of claims 1 to 9, wherein the needle bars (15; 6) extending through a) are formed with the same diameter (d) over their entire length.