US3618548A

US3618548A - Multiple height-adjusting mechanisms for tubular-bed-sewing machines

Info

Publication number: US3618548A
Application number: US27279A
Authority: US
Inventors: Russell A Fritts
Original assignee: Singer Co
Current assignee: SSMC Inc
Priority date: 1970-04-10
Filing date: 1970-04-10
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

A mechanism for raising or lowering a sewing machine relatively to a support base selectively to orient the machine for sewing tubular or flat work. Adjustment of the machine elevation is accomplished by providing a manually operable lifting mechanism that resiliently supports the sewing machine in an elevated position. The mechanism includes a lift spring disposed in a vertical tubular member secured to the support base for operably coacting in a controllable manner with a mating sleeve secured to the sewing machine frame thereby permitting the operator to place the machine in the desired sewing position. One form of manual control of the lifting mechanism includes a manually influenced locking finger carried on one of the mating parts for register with any one of a plurality of discrete elevations. Another form disclosed provides a friction shoe to permit selection of an infinite variety of selected sewing machine levels. Also disclosed is a hinged auxiliary work support which extends the work-supporting surface in the sewing machine elevation for sewing flat work and which is automatically lowered when the sewing machine is shifted into an elevation for facilitating the sewing of tubular articles.

Description

United States Patent [72] Inventor Russell A. Fritts Phoenix, Md. [211 Appl. No. 27,279 [22] Filed Apr. 10, 1970 [45] Patented Nov. 9, 1971 [73] Assignee The Singer Company New York, N.Y.

[54] MULTIPLE HEIGHT-ADJUSTING MECHANISMS FOR TUBULAR-BED-SEWING MACHINES 5 Claims, 7 Drawing Figs.

[52] US. 112/258, 312/29 [51] Int. Cl D05b 75/00 [50] Field of Search 112/258, 260, 217.1, 63; 312/21, 29, 30, 25

[56] References Cited UNITED STATES PATENTS 2,179,770 11/1939 Wieck 112/260 2,575,045 11/1951 Chason.... 312/29 2,738,248 3/1956 Berker..... 312/29 2,790,689 4/1957 l-lubbell... 312/21 3,468,589 9/1969 Maynard 1l2/217.l X FOREIGN PATENTS 1,121,914 1/1962 Germany Primary Examiner-Jordan Franklin Assistant Examiner-George H. Krizmanich Attorneys-Marshall .I. Breen, Chester A. Williams, Jr. and

Robert E. Smith ABSTRACT: A mechanism for raising or lowering a sewing machine relatively to a support base selectively to orient the machine for sewing tubular or flat work. Adjustment of the machine elevation is accomplished by providing a manually operable lifting mechanism that resiliently supports the sewing machine in an elevated position. The mechanism includes a lift spring disposed in a vertical tubular member secured to the support base for operably coacting in a controllable manner with a mating sleeve secured to the sewing machine frame thereby permitting the operator to place the machine in the desired sewing position. One form of manual control of the lifting mechanism includes a manually influenced locking finger carried on one of the mating parts for register with any one of a plurality of discrete elevations. Another form disclosed provides a friction shoe to permit selection of an infinite variety of selected sewing machine levels. Also disclosed is a hinged auxiliary work support which extends the worksupporting surface in the sewing machine elevation for sewing flat work and which is automatically lowered when the sewing machine is shifted into an elevation for facilitating the sewing of tubular articles.

PATENTEDNHV SIB?! 3518.548

SHEET 1 OF 3 INVENTOR.

Russell A. Frit'rs BY WITNESS AT TORNE Y PATENTEI] NOV 9197i SHEET 2 [IF 3 INVENTQR. Russell, A. Frl'r'rs TTORNE Y Fig. 7

WITNESS MULTIPLE HEIGHT-ADJUSTING MECHANISMS FOR TUBULAR-BED-SEWING MACHINES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to sewing machines and, more particularly, to sewing machines of the tubular-bed variety wherein there is provided novel means to make the tubularbed machine usable either for flat bed or tubular-bed sewing and to facilitate using the machine in a standard dropheadtype cabinet or as a portable table top machine.

2. Description of the Prior Art The prior art is cognizant of both flat-bed sewing machines and free arm or tubular-bed machines in which the work-supporting bed of the machine is cantilevered to accommodate a tubular article for stitching thereon.

It is known to provide auxiliary work supports or sewing machine bed extensions which may be applied to a tubularbed sewing machine to augment the raised work-supporting area of the tubular bed in order to facilitate sewing flat articles. While these bed extensions may be used with portable sewing machines, a disadvantage of this means of conversion between flat and tubular-bed arrangement is that the sewing machine always retains the high center of gravity and resultive diminished stability of a tubular-bed machine.

There also exist in the prior art, elaborate sewing-machinesupporting arrangements associated with sewing-machinesupporting cabinets whereby the elevation of a sewing machine may be changed relatively to the cabinet top. These known sewing-machine-supporting structures cannot accommodate flat-bed sewing machines, and, therefore, they comprise special cabinet facilities usable with tubular-bed sewing machines. Since the known cabinets for tubular-bed machines have not been universal, they compound the problems of marketing and inventory by requiring that two separate lines of cabinets must be available.

SUMMARY OF THE INVENTION The present invention overcomes the above-discussed prior art deficiencies by providing a novel mechanism accommodated in the sewing machine and in a base which remains a part of the sewing machine frame assembly for making a tubular-bed sewing machine convertible between flat-bed and tubular bed. The mechanism comprises a compression coil-lift spring disposed in a vertical tube secured to a bracket fastened in a machine-receiving well formed in a flat-bed base member. The vertical tube and the spring are received in a mating sleeve secured to the arm casting of the machine. The machine releasably may be held at a desired elevation for flatbed sewing or tubular-bed sewing, as well as positions intermediate the latter two sewing levels. To accomplish this, there is provided a manually operable, cam-actuated latching finger disposed for register with a selected one of a plurality of vertically spaced apertures formed in the vertical tube each of which corresponds to a predetermined sewing level of the machine. To extend the number of sewing levels available to the operator there may be provided either singularly or in combination with the latching finger, a clamp member that is carried by the mating sleeve and disposed to frictionally engage the vertical tube thereby to hold the sewing machine at a selected one of an infinite number of sewing levels. In one embodiment of this invention there is provided means to avoid the objectionable feature of having to raise the machine to an elevation that may make the machine unstable and particularly so when using the machine as a portable. Such means comprises a work-supporting panel that hingedly is secured adjacent the top on a lateral edge of the flat-bed base and that porting panel arrangement, there may be provided a two-piece flat-bed base construction wherein a portion of the base adjacent to the sewing machine stitch-forming instrumentalities, may be detached and removed from the machine-mounting base portion which carries the lifting mechanism. The latter arrangement allows the operator readily to convert from a flat-bed sewing level to a tubular-bed sewing level and vice versa with a minimum amount of effort on the part of the operator and avoids the necessity of having to raise the machine appreciably for tubular-bed sewing.

Since the flat-bed base member used with this invention may take the same dimensions as the covered base portion of any conventional flat-bed sewing machine, the sewing machine of this invention may be accommodated in any cabinet which is capable of accommodating a regular flat-bed machine and, therefore, there is no necessity for maintaining inventories of special cabinets for tubular-bed sewing machines. The flat-bed base member also readies the sewing machine for use as a portable unit.

Accordingly, it is a primary object of the present invention to provide a tubular-bed sewing machine with novel and improved means to permit selective location of the machine work-supporting bed at any one of a plurality of desired sewing levels.

Another object of this invention is to provide a novel and improved lifting mechanism for a tubular-bed sewing machine, which mechanism readily makes the machine convertible between flat-bed and tubular-bed sewing.

A further object of the present invention is to provide a novel and improved lifting mechanism for a tubular-bed sewing machine, comprising operator-actuated, positive locking means for placing the machine at a selected one of a plurality of predetermined sewing levels.

A further object of the present invention is to provide a novel and improved lifting mechanism for a tubular-bed sewing machine comprising releasable clamping means for locating the machine in any one of an infinite number of sewing levels and adapted for use independent of, or in combination with, the positive locking means.

Still yet another object of the present invention is to provide in combination with the lifting means for controlled elevation of a tubular-bed sewing machine, a novel and improved means for extending the versatility of such a machine for use in a cabinet or as a portable.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the functions, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of a sewing machine base member and a portion of a sewing machine frame taken substantially through the main ann shaft axis of a tubular-bed sewing machine embodying the present invention;

FIG. 2 is a cross-sectional view taken substantially on the line 2-2 of FIG. 1;

FIG. 3 is an enlarged perspective view of a portion of the novel lifting mechanism incorporated in the sewing machine of FIG. 1;

FIG. 4 is an enlarged elevational view of a portion of the lifting mechanism of FIG. 3;

FIG. 5 is a perspective view of the parts illustrated in FIG. 3

automatically drops when the machine is raised from flat bed but showing a modified form of mechanism for releasably to an elevated sewing level thereby providing the necessary clearance for tubular-bed sewing. This latter feature precludes the necessity of raising the machine to its maximum elevation when tubular-bed sewing is desired, thus enhancing the stability of the machine. As an alternative to the hinged work-supholding the sewing machine at a desired sewing level;

FIG. 6 is a perspective view of a sewing machine having this invention applied thereto and illustrating a further modification of the present invention particularly useful as a portable table-top sewing machine, and

FIG. 7 represents a cross-sectional view taken transversely of the sewing machine of FIG. 1 and illustrating the manner in which the sewing machine base member is accommodated in a sewing machine cabinet.

DESCRlPTION OF THE PREFERRED EMBODIMENTS Referring now to the accompanying drawings wherein like reference numerals designate similar parts throughout the various views, a preferred embodiment of the present invention is herein disclosed as embodied in a sewing machine of tubular-bed variety having a bed substantially like that forming the subject matter of U.S. Pat. No. 3,344,762, granted Oct. 3, 1967 to Jan Szostak et al. It will be apparent from the following detailed description that the disclosed novel lifting mechanism is capable of use with substantially all types of tubular-bed machines and that the presently disclosed machine merely illustrates a preferred embodiment. The present application describes the details of the sewing machine only to the extent necessary for a complete and thorough understanding of the present invention.

As best seen in FIG. 1, the sewing machine 10 has a vertical standard 11 rising at one end of a free work-supporting arm or tubular bed generally designated 12 that provides the worksupporting surface and carries the lower stitch-forming instrumentalities and feed mechanism. As mentioned before, the tubular bed 12 may comprise a configuration like that disclosed in the Szostak, U.S. Pat. No. 3,344,762. A bracket arm 13 overlying the bed 12 extends from the standard 11 and terminates in a head 14 (See FIG. 6.) overhanging the bed 12 in the usual manner.

As shown in FIG. 1 and 7, the fiat-bed base 15 is intended to be assembled as a permanent part of the sewing machine and, although, as will be described in detail hereinbelow, the sewing machine frame may be shifted in elevation relatively to the base 15, the base will remain associated therewith. The base 15 may be fonned with sockets 16 along the rear wall 17 thereof, each to accommodate a mounting pin 18 associated with a conventional hinge 19 carried along the rear edge of a sewing machine accommodating cutout 20 in the table top 21 of any conventional sewing machine cabinet 22. The front wall 23 of the base 15 may rest upon a hinged front panel 24 of the cabinet table top when the sewing machine is in sewing position in the cabinet. To lower the sewing machine into a stored position in the cabinet beneath the table top, the machine and base 15 are first tipped back slightly, the hinged front panel is turned up, and then the machine and base 15 are turned forwardly and downwardly into the dotted-line position as shown in FIG. 7. This mode of accommodation of a sewing machine into what is termed a drophead" cabinet is conventional and most cabinets for flat-bed sewing machines utilize this arrangement. The present invention, therefore, makes machines which are convertible between flat and tubular bed perfectly compatible with existing conventional sewing machine cabinets.

The present invention provides a lifting mechanism for raising the tubular bed 12 of a sewing machine relatively to the flat-bed base 15 to a higher elevation in which tubular work may be placed on the bed 12 of the sewing machine. The fiatbed base 15 is arranged to provide a well 26 to accommodate the bed of the sewing machine. The machine is supported for movement relative to the base 15 by means of a bracket 27 secured by screws 28 to the flat-bed casting 15. The bracket 27 comprises a horizontal lower support member 29 and car ries a predetermined location for reasons described hereinafter, a substantially hollow vertically disposed tube or support post 30 that, in turn, carries a compression coil-lift spring 31 therein. The tube 30 includes a blind bore 32 of which the extremity contacts and supports the lower end of the spring 31. The lower solid end of the tube 30 is received in the boss 33 formed integral with the support 29 and is secured thereto by suitable conventional means such as a nut and washer shown at 34. The bracket 27 also has threaded thereto a guide pin 35 that is arranged to be received in an opening or notch 36 formed in a boss 37 attached to the machine standard, as best shown in FIG. 2, for restraining lateral and endwise movement of the machine when located in one of its elevated positions. The tube 30 and the spring 31 are located on the bracket so that when the machine is assembled to the flat-bed base 15 they are received in a mating sleeve or tubular member 38 secured in a suitable manner to the machine frame in the standard 1 1. As best shown in FIG. 3, the sleeve 38 carries at its upper end a cross pin 39 extending diagonally between opposing wall surfaces. The cross pin 39 passes through and supports a spring-abutment member 40 located within the sleeve 38 for register with the upper free end of the lift spring 31. The upper free end of the vertical tube 30 is formed with a pair of opposing upwardly open-ended slots 41-40 that extend axially down from the top of the tube for a predetermined distance. With the machine arranged relatively to the fiat-bed base 15 in a position suitable for flat-bed sewing, the work-supporting surface of the machine will be disposed such that it lies in the same horizontal plane as the surrounding top surface of the base. This position is shown in FIG. 1 by the solid-line representation of the machine. With the machine so disposed, the lift spring 31 is compressed and the cross pin 39 is in register with the slots 41-40 abutting the bottom of each of the slots which corresponds to a location of the machine for flat-bed sewing. The lift spring 31 exerts an upward force on the abutment member 40 that is transferred to the machine frame thereby tending to elevate the machine. To secure the machine in its flat-bed sewing level there is provided an operator-actuated locking construction and arrangement generally designated 42. This construction and arrangement, as best shown in FIG. 3 and FIG. 4, includes a manually operable lift-release lever 43 secured by a setscrew 44 or the like to one end of a shaft 45 that extends in a direction parallel to the main arm shaft 46 of the sewing machine 10. As shown, the lever comprises an elongated curved member that is located external of the machine standard 11 at the right side thereof (as viewed by the operator), but it will be apparent that the lever may take other forms or shapes, such as a knob, and also may be located at another location deemed accessible to the operator other than as illustrated.

The shaft 45 is supported in the

extended arms

47 and 48 of a substantially U-shaped bracket 49 that is located to the right (as viewed from the front of the machine) of the usual vertical shaft for operably connecting the bed shaft (not shown) with the main arm shaft and is fastened to the machine frame by means of a screw 50. The other end of the shaft 45 has keyed thereto a cam member 51 having a cam finger 52 mounted for turning movement therewith. Also secured for movement with the shaft 45 is a substantially horizontal link 53, one end of which is fastened to the shaft 45 between the cam member 51 and the arm 48 of the bracket 49 and the other end thereof carrying a pin 54 slidably guided in an upper slot 55 formed in a vertically disposed link 56 carried for limited sliding movement adjacent the arm 48 of the bracket 49. The shaft 45 normally is biased in a clockwise direction as shown by the arrow in FIG. 3 for disposing a locking member 57 in operable engagement with the mating sleeve 38 and the vertical tube 30. The angular orientation of the shaft 45 and its associated parts is accomplished by means of a helical torsion spring 58 disposed about the shaft 45 between the

arms

47 and 48 of the bracket 49. The spring 58 is maintained in a compressed position for proper biasing of the shaft 45 by the

collars

59 and 60 which are located on either side of the spring. The

collars

59 and 60 are secured to the shaft 45 in a conventional manner such as by setscrews 61 (only one being shown).

The locking member 57 includes a latch finger 62 extending outwardly in an upward direction from the main body thereof for register with an aperture 63 fon'ned in the wall of the mating sleeve 38. Also fonned with the main body in substantially right-angle relation relative to the latch finger 62 and extend ing outwardly therefrom in a downward direction is a clamp finger 64 adapted for clamping engagement with a clamping shoe 65 carried in a complemental apertured boss 66 formed with, or secured to, the mating sleeve 38 by means of the screws 67, as best shown in FIG. 4. The clamp shoe 65 is provided on the surface located adjacent the vertical tube 30 with a coating 68 of suitable material such as polyurethane for increasing the friction between and thus, the normal holding force exerted by the clamp shoe 65 on the adjoining tube wall when the former is disposed in operable engagement with the tube 30. The member 57 is shiftable on pivot stud 69 integral with a unitary support member 70 constrained for limited sliding movement in a substantially horizontal direction on the arm 48 of the bracket 49 by means of a stud 71 extending laterally from the arm 48 into register with a horizontal slot 72 provided at the lower end of the member 70. The member 70 supports the locking member 57 such that an abutment stud 73 integral with the member and located below and forwardly of the pivot stud 69 (as viewed from the front of the machine and as best shown in FIG. 4) is disposed for cooperative engagement with the clamp finger 64 in a manner to be described hereinafter. A torsion spring 74 having

spring arms

75 and 76 is mounted about a screw 77 threaded into the bracket arm 48 with the end of the spring arm 75 being secured in an aperture 78 of the bracket arm 48 and the end of the spring arm 76 resiliently engaging an edge 79 of the support member 70. The spring 74 is constructed and arranged to bias the member 70 against the adjacent surface of the bracket arm 48 and toward the mating sleeve 38. With the member 70 so disposed the stud 71 locates in the rearrnost portion of the slot 72 as viewed from the front of the machine such that the adjacent portion of the member 70, which takes the form of a cam projection 80, is urged against a first raised or forward upper cam edge surface 81 formed on an abutment member 83 integral with, and extending laterally of, the sliding link 56. A second cam edge surface 82 is formed on the lateral abutment member 83 located directly below and to the rear of the first surface 81. The surface 82 functions to define the extent of permissible inward movement of the support member 70 toward the mating sleeve 38 when the vertical link 56 is located in its raised or upper position shown by the dotted-line configuration thereof in FIG. 4. This latter positioning of the link 56 is accomplished by turning the release lever 43 in a clockwise direction as viewed in FIG. 4 relatively to its normal position. The path of sliding movement of the link 56 is in a vertical direction only and is restricted thereto by means of the coaction of the pin 54 with the slot 55 and the cooperation between a pin 84 which extends laterally from the bracket arm 48 in vertical alignment with the pin 54, and a lower vertical slot 85 formed in the link 56.

To properly locate the vertical tube 30 during assembly of the support bracket to the machine and to prevent turning movement of the machine relative to the flat-bed base support, there is provided a resiliently mounted latch pin 86 disposed in slidable register with an axial groove 87 of predetermined length formed at the lower end in the outer surface of the vertical tube 30. The pin 86 is carried in a support block 88 and extends through an aperture 89 formed in the wall of the mating sleeve 38 at its lower end. As the machine is elevated to a desired sewing level, the pin 86 remains in register with the groove 87 thereby to prevent undesirable turning movement of the machine relative to the support bracket 17. The support block 88 is carried at one end of an angle-shaped lever 90 that is pivoted to the machine frame by means of a headed fulcrum screw 91 and resiliently is biased by a spring 92 such that the pin 86 constantly is urged in a direction for register with the aperture 89 and thus the groove 87. The free end of the lever 90 extends laterally from the machine bed so that it is conveniently accessible to the operator. When assembling the machine to the flat-bed base it may be necessary to locate the pin 86 so that it does not extend into the hollow mating sleeve and interfere with assembly of the mating sleeve and the vertical tube. Toward this end, the operator merely urges the free or accessible end of the lever 90 in a direction opposing the bias of the spring 92.

Operation of the combined latching and clamping mechanism shown in FIGS. 1 to 4 and described heretofore, is set forth below. Upward pressure on the lever 43 causes a pivoting motion about the lever shaft 45, forcing the horizontal link 53 to pivot downwardly and the cam finger 52 to be urged in a counterclockwise direction as viewed in FIG. 4. The cam finger 52, in turn, causes the locking member 57 to pivot about the pivot stud 69 causing the clamp finger 64 to contact the abutment stud 73 on the support member 70. The locking member 57 and the support member 70 then pivot together about the stud 71 with the cam projection resting on the forward cam surface 81 of the vertical sliding link 56. At the termination of travel of the locking member 57 and the support member 70 (as shown in solid lines in FIG. 4) the projection 80 rests on the cam surface 81 and the latch finger 62 and the clamp shoe 65 are released to permit movement of the sewing machine in a vertical direction. After slight upward travel of the machine assembly, the lever 43 may be released from the manual grip of the operator. When the machine reaches a predetermined height and upon release of the lever 43, the latch finger 62 will positively lock by dropping into register with a locking aperture 102 formed in the vertical support tube 30, an simultaneously therewith the clamp finger 64 will come into engagement with the clamp shoe 65 which, in turn, will frictionally engage the vertical tube 30. The machine now releasably is secured at a raised sewing level. There may be provided

additional locking apertures

103 and 104, each of which defines a predetermined desired sewing level. In the present embodiment, the

apertures

102 and 104 correspond to flat-bed and maximum elevation for tubular-bed sewing, while aperture 103 corresponds to a position intermediate the latter two, for example, one-third of the maximum elevation.

Should the operator desire to place the machine in a position intermediate the predetermined positions defined by each of the finger-locking

apertures

102, 103, 104, then the operator merely would have to repeat the above operations. However, since there would be no position-defining aperture present in the support tube for receiving the latch finger 62, the clamp finger 64 is not able to apply pressure to the clamp shoe 65 because the latter finger 64 first contacts the abut ment stud 73 of the support member 70, thereby preventing movement of the clamp finger 64 into engagement with the clamp shoe 65. This may be avoided by the operator exerting a downward pressure on the lever 43 secured to the shaft 45 which moves the connecting pin 54 upwardly and thus moves the sliding link 56 into the dotted-line position shown in FIG. 4. This movement changes the contact level of the support member cam projection 80 with the abutment member 83 from the forward cam surface 81 to the lower rearwardly disposed cam surface 82. Thus, the torsion spring 74 now is able to urge the support member 70 and the locking member 57 operably engaged therewith further toward the clamp shoe 65 such that the clamp finger 64 comes into contact with the shoe. Pressure is applied to the tube 30 through the frictional contact surface 68 thereby locking the machine in an intermediate position solely by means of such frictional pressure. The intermediate clamp positions may be released by exerting an upward pressure on the release lever 43.

It is apparent from the foregoing description that the machine may be positively locked in any one of three sewinglevel positions by means of the latching finger 62. The intermediate clamp shoe positions are infinitely variable between the lowermost and uppermost sewing levels. The three predetermined positively locked positions are: (A) Down (locking aperture 102) for flat-bed sewing; (B) substantially one-third of the distance up (locking aperture 103) for tubular'bed sewing, preferably as a portable table-top machine; and (C) up (locking aperture 104) for tubular-bed sewing when the machine and the flat-bed base assembly are placed as a unit into a standard cabinet.

A simplified embodiment of the locking mechanism described heretofore is illustrated in Flg. 5. In this embodiment the latch finger 62 and the mechanism associated for coaction therewith have been eliminated and the sole means required to locate the machine at a desired sewing level comprises a clamp shoe 105 similar to the clamp shoe 65 described above. The clamp member 105 is supported in a bracket 106 that may be formed with or secured to the mating sleeve 38 in a suitable conventional manner. The bracket 106 includes an apertured extended wall 107 for pivotally carrying a release lever carrying shaft 108. The end of the shaft 108 adjacent the clamp shoe 105 has secured thereto by means of a setscrew 109 a sleeve 110 having an eccentric 111 formed at the free end thereof. Rotation of the shaft 108, which may be accomplished by means of lever constructed and arranged like the release lever 43, in an upward or counterclockwise direction as viewed in FIG. causes the eccentric or cam portion 1 11 of the sleeve 107 to turn thereby to apply pressure to the clamp shoe 105 which, in turn, bears pressure against the polyurethane coating disposed on its contact surface for providing a positive grip on the vertical tube 30. Rotation of the shaft 103 is terminated when the eccentric 111 has applied sufficient pressure to the clamp shoe 105 to lock the machine either in an up, down, or intermediate position. To release the clamp shoe pressure exerted on the tube 30, the operator merely needs to reverse the direction of pressure applied, that is, turn the shaft 108 clockwise from its clamp-engaging position as viewed in FIG. 5.

Naturally, it will be understood by those skilled in the art that the use of the latch finger 62 along will suffice to achieve a predetermined desired sewing level without the need for the clamp shoe and its associated components for frictionally engaging the support tube 30.

A still further embodiment that substantially increases the versatility of the present invention for use as a cabinetmounted or a table-top machine is shown in FIG. 6. This arrangement comprises a two-piece flat-bed base construction having a left portion 122 detachably connected to the liftmechanism-mounting base portion 123 thereby to facilitate conversion from flat-bed sewing to tubular-bed sewing or vice versa with a minimum amount of effort. The base portion 123 carries the identical raising and lowering mechanism described above relative to the other embodiments. The left, or head end, portion 122 is of a substantially U-shaped configuration and removably is secured to the bed portion 123 by means of a plurality of projecting pins 124 located on the portion 122 for register with corresponding apertures or sockets 125 provided in the base portion 123. It is apparent from FIG. 6 that the bed of the sewing machine illustrated therein differs from that disclosed in FIGS. 1 to 5 inclusive, in that it includes a stabilizing leg 126 rearwardly of the tubular bed 12. The stabilizing leg 126 may take the form of a hollow accessory box having a cover 127 therefor hinged secured at 128 to the stabilizing leg 126 of the bed. The combination of the base construction disclosed in FIG. 6 together with the previously discussed raising and lowering mechanism provides a machine of the tubular-bed type with a substantial amount of versatility that readily adapts the machine for use as a portable table-top machine or for mounting in a standard cabinet. When the machine is used as a portable the operator readily may convert from flat-bed sewing to tubular-bed sewing merely by removing the left base portion 122 and, if deemed necessary, the machine may be raised a slight amount. Thus, the amount of elevation required for tubular-bed sewing is minimized by avoiding the necessity to raise the machine to its maximum elevation.

When the sewing machine of this invention is supported in a conventional cabinet, the amount of elevation required for tubular-bed sewing may be minimized by resort to an ancillary feature illustrated in FIG. 1.

At the end of the flat-bed base opposite from the support bracket there is provided a mechanism that provides for increased clearance between the machine bed 12 and the flatbed base when sewing tubular articles. This mechanism may be, but is not limited to, use with a machine having a tubular bed such as disclosed in the previously mentioned U.S. Pat. No. 3,344,762 and comprises an automatically operable hinged-bed extension door pivotally mounted as at 141 adjacent the top edge of the sewing machine accommodating well of the flat-bed base 15 as shown in FIG. 1. The door 140 automatically drops or tilts down relatively to the horizontal a predetermined amount when the machine is elevated to provide the increased clearance for handling tubular work. For this reason, dropping of the door makes it unnecessary to raise the machine to its maximum permissible elevation when tubular-bed sewing is desired. Toward this end there is provided a rod 142 suitably secured at one end to the hinged door 140 and at its other end secured in a suitable manner to the hookshaped end 143 of pivotally mounted actuating lever 144. The lever 144 pivots substantially about its center on a pin 145 fastened in a boss 146 secured to or integrally formed with the bottom of the flat bed base 15. The pin 145 properly is held in place by means of a screw 147 threaded upward from the bottom of the base 15 into proximate holding relationship with the pin. The opposite end of the lever 144 carries an adjustable-headed screw 148 with the head thereof being disposed for contact with the underside of the machine bed 12. A spring 149 connected between the actuating lever 144 and the door 140 normally biases the door in a downward direction toward the bottom of the flat-bed base. When the machine is located for flat-bed sewing, as shown in solid lines in FIG. 1, the underside of the machine bed 12 contacts the headed-screw 148 thereby urging it and the actuating lever 144 in a downward or clockwise direction. This causes the hooked end 143 of the lever 144 to move the rod 142 upwardly and by reason of the connection between the rod 142 and the door 140, the latter is positioned horizontally, being substantially flush with the surrounding surface of the sewing machine bed. Upon elevating the machine the spring 149 causes the lever 144 to pivot in a counterclockwise direction, thus automatically lowering or tilting the door into a position as shown by the dotted line configuration thereof in FIG. 1.

Numerous alternations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having set forth the nature of this invention, what is claimed herein is:

1. A supporting mechanism for a sewing machine having a frame including a tubular bed comprising, a base member formed with an upwardly open cavity for accommodating the tubular bed of the sewing machine, telescopically interfitting guide members secured one on said base member and one in said sewing machine frame for guiding said sewing machine into a plurality of different elevations relatively to said base member, a lift spring arranged to act between said sewing machine frame and said base member to bias said sewing machine toward the highest elevation relatively to said base member, means for interlocking said guide means in selected relative positions comprising a locking finger shiftably supported on one of said telescopically interfitting guide members, the other of said guide members being formed with a plurality of vertically spaced locking finger accommodating apertures, and manual operating means accessible exteriorly of said sewing machine frame for controlling the position of said locking finger into said apertures to lock said sewing machine at selected discrete sewing levels.

2. A sewing mechanism for a sewing machine as set forth in claim 1 in which said interlocking means comprises a clamp shoe shiftably supported on one of said telescopically interfitting guide means said clamp shoe having a friction surface located adjacent and adapted frictionally to engage the other of said guide members to maintain said sewing machine in any selected one of a range of elevations relatively to said base member.

3. A supporting mechanism for a sewing machine as set forth in claim 1 in which said telescopically interfitting guide members are cylindrical and one is formed with an axial groove and the other carries a pin engageable in said groove to prevent relative turning movement of said sewing machine relatively to said base member.

4. A supporting mechanism for a sewing machine as set forth in claim 1 in which said interlocking means includes both a locking finger and a clamp shoe carried on one of said telescopically interfitting guide members, the other of said guide members being formed with a plurality of vertically spaced locking-finger-accommodating said apertures and movement of said clamp shoe into engagement with the other of said guide members to provide both discrete elevations and a range of elevations into which said sewing machine may be secured relatively to said base member.

5. A supporting mechanism for a sewing machine as set forth in claim l in which said base member cavity is formed larger than the outline of the sewing machine bed accommodated therein and in which a door is hingedly connected to said base member to fill the space between the base member cavity and said sewing machine tubular bed, linkage carried by said base member and operatively connected to said door for influencing the position of said door, means biasing said door into a lowered position, and abutment means on said linkage disposed for engagement by said sewing machine bed in the lowered position of said sewing bed into said base member cavity to raise said door into a position substantially flush with said sewing machine tubular bedv k i i I

Claims

4. A supporting mechanism for a sewing machine as set forth in claim 1 in which said interlocking means incluDes both a locking finger and a clamp shoe carried on one of said telescopically interfitting guide members, the other of said guide members being formed with a plurality of vertically spaced locking-finger-accommodating apertures and in which said manual operating means controls both he position of said locking finger said apertures and movement of said clamp shoe into engagement with the other of said guide members to provide both discrete elevations and a range of elevations into which said sewing machine may be secured relatively to said base member.

5. A supporting mechanism for a sewing machine as set forth in claim 1 in which said base member cavity is formed larger than the outline of the sewing machine bed accommodated therein and in which a door is hingedly connected to said base member to fill the space between the base member cavity and said sewing machine tubular bed, linkage carried by said base member and operatively connected to said door for influencing the position of said door, means biasing said door into a lowered position, and abutment means on said linkage disposed for engagement by said sewing machine bed in the lowered position of said sewing bed into said base member cavity to raise said door into a position substantially flush with said sewing machine tubular bed.