Circular knitting machine with latch detector

Abstract

The knitting machine is provided with latch detector means including primary and secondary sensor means for detecting a latch improperly positioned in a closed position and for signaling when such a condition occurs. A trigger lever (30) having a free inner end (31) is normally positioned in an operative latch detecting position (FIG. 3) immediately below the path of travel of the hooked upper ends (10) of the needles N so that a latch (11) in the proper open position will not engage and trip the trigger lever (30) while a latch (11) in an improper closed position will engage and trip the trigger lever (30). A tension spring (45) is provided to immediately move the trigger lever (30) to the inoperative position (FIG. 4) with the inner free end (31) outwardly and away from the path of travel of the needles N upon being engaged by a latch in an improper closed position. The primary sensor means includes a ground bracket (56) positioned to be engaged by the tension spring ( 45) as soon as the trigger lever (30) is engaged. The secondary sensor means includes a ground stop pin (53) positioned to be engaged by the outer end of the trigger lever (30) when in a fully inoperative position.

Description

BACKGROUND OF THE INVENTION

It is generally known to provide needle latch detectors on circular knitting machines for indicating the improper positioning of the latches, which condition usually occurs when a stitch loop is not present on the needle to move the latch to an open position. However, the prior known types of latch detectors have not been widely used because they are expensive and/or difficult to maintain in the proper operative position because vibration from the knitting machine will frequently trip the latch detector. Also, if the sensitivity of the latch detector is set to prevent false detection, there is a possibility of damage to the needle latch when it engages the latch detector.

The latch detector of our above-noted copending application operates to signal the detection of a closed latch when the outermost end of the trigger lever engages a sensor to complete an electrical ground contact and stop the knitting machine. In some instances lint can build up on the sensor and prevent an electrical contact from being made with the trigger lever. Also, the electrical ground contact is not completed until the trigger lever is moved into engagement with the sensor so that the stopping of the machine is slightly delayed after a closed latch is detected.

SUMMARY OF THE INVENTION

With the foregoing in mind, it is an object of the present invention to provide a circular knitting machine with a latch detector which is inexpensive, is not subject to false indication of closed latches from vibration of the knitting machine, does not cause damage to the needle latches during operation, reduces the possibility of being rendered inoperative because of the presence of lint buildup, and operates to immediately signal the detection of an improperly closed latch.

In accordance with the present invention, the latch detector includes primary and secondary sensor means for detecting a latch improperly positioned in a closed position. The latch detector comprises a trigger lever having a free end normally positioned in an operative latch detecting position immediately below the path of travel of the upper hooked ends of the needles so that latches in the proper open position do not engage the free end of the trigger lever while latches in an improper closed position will engage and initially move the free end of the trigger lever in the direction of movement and away from the path of travel of the needles. The trigger lever is pivotally mounted intermediate its ends and is normally positioned against a stop member with resilient means being provided to normally urge the trigger lever into engagement with the stop means. A spring extends above the trigger lever and is operable to immediately move the free end of the trigger lever to an inoperative position outwardly of and away from the path of travel of the needles upon engagement by a latch in an improper closed position.

The primary sensor means includes a ground bracket extending over and partially around the spring so that an electrical ground contact is immediately established between the ground bracket and the spring as soon as the trigger lever is engaged by a closed latch, and before it reaches its outermost position. The action of the spring moving into and out of engagement with the ground bracket provides a wiping function which prevents a buildup of lint between the spring and the ground bracket.

The secondary sensor means includes a ground stop pin positioned to be engaged by the outer end of the trigger lever when the free end of the trigger lever is moved to a fully inoperative position. The primary and secondary sensor means both form part of an electrical circuit operable to signal the detection of a latch in improperly positioned closed position. The secondary sensor means operates to signal the detection of a latch in improperly closed position if the primary sensor means fails to make electrical contact between the spring and the ground bracket.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages will appear as the description proceeds when taken in connection with the accompanying drawings, in which

FIG. 1 is a fragmentary plan view of a portion of the latch ring and sinker head of a circular knitting machine and showing the latch detector associated therewith;

FIG. 2 is a vertical sectional view of the latch ring, sinker head and upper end portion of the needle cylinder and showing the latch detector associated therewith;

FIG. 3 is an isometric view of the latch detector and indicating the path of travel of the latch needles adjacent the outer free end of the trigger lever, with the trigger lever being positioned to detect a closed latch;

FIG. 4 is a view similar to FIG. 3 but illustrating the trigger lever in "tripped" position;

FIG. 5 is a transverse sectional view taken along the line 5--5 in FIG. 3;

FIG. 6 is a fragmentary longitudinal sectional view taken along the line 6--6 in FIG. 3; and

FIG. 7 is a fragmentary longitudinal sectional view taken along the line 7--7 in FIG. 4.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

The circular knitting machine is illustrated as being of the type normally employed in knitting socks and the like and includes a single knitting station. However it is to be understood that the latch detector means may be employed on other types of knitting machines having multiple knitting stations with a latch detector positioned adjacent each or selected ones of the knitting stations. The knitting machine includes a rotating circle of needles N and each of the needles includes an upper hooked end 10 with a pivoted latch 11 movable between open and closed positions. As illustrated in FIGS. 1 and 2, yarn feed fingers 12 are supported for movement into and out of yarn feeding position in a throat opening 13 in a latch ring 14. The yarn feed fingers 12 operate to selectively feed yarns, such as indicated at Y in FIG. 2, to the needles as they are raised and lowered, as indicated by the dash-dot line in FIG. 2, with rotation of the needle cylinder 15. The needles are raised and lowered by conventional cams, not shown, in the conventional and well-known manner.

A sinker bed 17 is supported on the upper end of the needle cylinder 15 and supports sinkers 20 for radial sliding movement between the needles N and the movement of the sinkers 20 is controlled by conventional cams in a sinker cap 21. As the needles N approach the yarn feed fingers Y, they are maintained in a position with the prior knit loops holding the latches 11 in a fully open position. Just prior to the point that the yarn Y is fed to the needles, the needles are further raised to a "shed" level where the prior stitch loops pass below the level of the lower tips of the latches 11 so that the latch remains open but is free to pivot to the closed position.

As the yarn Y is fed into the upper hooked ends 10 of the needles, and they are lowered by the stitch cam in the conventional manner, as indicated in dash-dot lines in FIG. 2, the latches move to a closed position and the needles are drawn down to stitch drawing level below the throats of the sinkers 20 so that the prior stitch loops are shed or cast off and a new knit loop is formed by the yarn Y. The needles are then raised so that the just formed stitch loop is drawn down the shank of the needle and pivots the latch 11 back to the open position.

The latch detector means includes a trigger lever 30 including a free inner, somewhat hooked end 31. Support means is provided for supporting the trigger lever 30 for pivotal movement intermediate its ends, as indicated at 32, and the inner free end 31 of the trigger lever 30 is normally positioned in the operative latch detecting position shown in solid lines in FIG. 1 and illustrated in FIG. 3. In this operative latch detecting position, the inner free end 31 of the trigger lever 30 is positioned immediately below the path of travel of the upper hooked ends 10 of the needles N so that a latch 11 in the proper open position does not engage the free end 31 of the trigger lever 30.

The support means also includes a horizontal support plate 35 which is supported for adjustment adjacent the sinker cap 21 and on the upper end of a support post 36 (FIG. 2), the lower end of which is fixed on the knitting machine. An adjustment slot 37 is provided in the plate 35 (FIg. 1) and a screw 40 penetrates the slot 37 and is threadably embedded in the upper end of the post 36.

Stop means, in the form of a vertical pin 42, is fixed on its lower end in the support plate 35 and extends upwardly adjacent one side of the trigger lever 30 to limit pivotal movement of the trigger lever 30 in a counterclockwise direction (FIGS. 1 and 6). The pin 42 also determines the position of the trigger lever 30 when in an operative latch detecting position, as shown in solid lines in FIG. 1 and in FIG. 3.

Resilient means, in the form of a tension spring 45, is operable to normally urge the trigger lever 30 into engagement with the stop pin 42 and maintain the trigger lever 30 in the operative latch detecting position. The tension spring 45 is supported at its inner end on a spring perch pin 46 which is fixed in the inner end portion of the trigger lever 30 and the outer end of the tension spring 45 is supported on a spring perch pin 47, the lower end of which is fixed in eccentric relationship on the upper surface of a disc 48. The disc 48 is fixed in eccentric position on the upper end of an adjustment bolt 50. The adjustment bolt 50 is threaded through the support plate 35 and is provided with a lock nut 49, for maintaining the adjusted position of the disc 48, for purposes to be presently described.

The tension spring 45 is also operable to immediately move the free end 31 of the trigger lever 30 to an inoperative position outwardly and away from the path of travel of the needles N upon being engaged by a latch 11 in an improper closed position, as shown in FIG. 4. As indicated in FIG. 3, the right-hand needle N is approaching the free inner end 31 of the trigger lever 30 in an improper closed position and will engage the free end 31 of the trigger lever 30 to immediately "trip" the lever 30. Upon the lever 30 being moved slightly in a clockwise direction, and away from the stop pin 42, the tension spring 45 immediately and quickly moves the lever from the position shown in FIG. 3 to the position shown in FIG. 4 so that the free end of the lever 30 will be moved outwardly and away from the path of travel of the needles to avoid damage to any of the latches. Also, the disc 48 can be rotated to change the position of the outer spring perch pin 47, relative to the pivot point 32, so that the " sensitivity" of the tripping of the trigger lever 30 can be varied to prevent false movement and detection due to vibration of the knitting machine and to vary the amount of impact necessary by the latch 11 to trip the trigger lever 30 so as to insure that the latch is not damaged by the trigger lever.

Sensor means, including primary and secondary sensor means, is provided to be operated by the trigger lever 30 for signaling when the free end 31 of the trigger lever 30 is engaged by an improper closed latch 11 and moved outwardly and away from the path of travel of the needles N. The sensor means includes an electrical insulation block 52 supported on the upper surface of the support plate 35. The forward end of the block 52 is undercut, as best shown in FIGS. 5 and 7, and a ground stop pin 53 is threadably supported in the block 52 and extends downwardly beneath the undercut portion into the horizontal channel formed between the undercut portion and the surface of the plate 35. The lower end of the ground stop pin 53 is thus shielded from the buildup of falling lint.

A nut 54 is provided on the upper portion of the stop pin 53 and a second nut 55 is threaded on the upper end of the stop pin 53 to maintain a ground bracket 56 in position. The ground bracket 56 includes a horizontal portion which extends over the spring 45 and a vertical portion 56a extending beside and partially around the spring 45 (FIG. 5).

An electrical wire 57 is fixed on the ground pin 53 and the ground bracket 56 by the nut 55. The wire 57 is connected to a conventional stop motion, indicated in block form at 58 in FIG. 1. The wire 57 forms a portion of a detector or sensor circuit which is actuated, in the manner described below to turn on a signal light for the operator and/or stop the operation of the knitting machine through the conventional stop motion 58.

When the inner end 31 of the trigger lever 30 is engaged by a closed latch, one side of the spring 45 will immediately engage the vertical portion 56a of the ground bracket 56 and actuate the primary sensor means to operate the stop motion 58, even before the trigger lever 30 is moved to the outermost position shown in FIG. 4. The spring 45 is in stretched condition as it moves laterally and engages the vertical portion 56a, and it is moved to a more relaxed position when the lever 30 is moved back to the set position (FIG. 3) by the operator to restart the machine. This action of the spring 45 against the vertical portion 56a provides a wiping function which prevents a build-up of lint between the spring 45 and the vertical portion 56a of the ground bracket 56. Also, the horizontal portion of the ground bracket 56 prevents lint from falling between the spring 45 and the vertical portion 56a.

Even if lint should build up between the spring 45 and the vertical portion 56a to the point that an electrical contact is not made, the secondary sensor means will operate and the sensor circuit will be completed when the outer end of the trigger lever 30 engages and makes electrical contact with the lower end of the ground stop pin 53, as shown in FIG. 7. The lower end of the stop pin 53 is also protected from a buildup of falling lint because it is positioned in the undercut portion of the block 52. Thus, the sensor circuit is initially actuated by contact of the spring 45 with the vertical portion 56a, and if electrical contact is not completed, because of lint of the like, the sensor circuit will be actuated when the outer end of the lever 30 engages the ground stop pin 53. The initial contact between the side of the spring 45 and the vertical portion 56a of the ground bracket 56 thus provides the primary sensor means while the immediately following contact between the outer end of the trigger lever 30 and the ground stop pin 53 provides the secondary sensor means.

The latch detector means thus provides for detecting a latch improperly positioned in a closed position when it should be in an open position and for signaling when such a condition occurs in the knitting machine. The latch detector means is of simple construction, virtually trouble free in operation and may be operated over a long period of time without being rendered inoperative because of lint buildup. The sensitivity of the latch detecting means may be varied in accordance with the type of machine to which it is applied.

In the drawings and specification there has been set forth the best mode presently contemplated for the practice of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

Claims

1. In a circular knitting machine including a circle of needles mounted for rotation about a fixed axis, each of said needles including an upper hooked end and a pivoted latch movable between open and closed positions, and yarn feed fingers for feeding yarn to said needles as said needles are raised and lowered to form stitch loops, the combination therewith of latch detector means for detecting a latch improperly positioned in a closed position, said latch detector means comprising

(a) a trigger lever including a free end,

(b) means supporting said trigger lever for pivotal movement intermediate its ends and about an axis parallel to said fixed axis of said circle of needles, said free end being normally positioned in an operative latch detecting position immediately below the path of travel of said upper hooked ends of said needles so that a latch in the proper open position does not engage said free end of said trigger lever and while a latch in an improper closed position will engage and move said free end of said trigger lever to an inoperative position wherein said free end is moved in the direction of movement and outwardly away from the path of travel of said needles,

(c) stop means mounted on said supporting means and adapted to engage one side of said trigger lever for normally maintaining said free end of said trigger lever in said detecting position,

(d) a tension spring fixed at one end adjacent said free end of said trigger lever and at the opposite end to said supporting means and so as to extend generally along and above said trigger lever and the pivotal support thereof for urging said trigger lever into engagement with said stop means with said trigger lever in said detecting position, and for immediately moving said free end of said trigger lever to said inoperative position outwardly and away from the path of travel of said needles upon being laterally deflected from said detecting position by a latch in an improper closed position, and wherein said spring moves laterally during such lateral movement of said trigger lever, and

(e) primary sensor means including an electrically conductive member mounted on said supporting means adjacent said spring and operable by engagement with said tension spring upon lateral movement thereof for signaling when said free end of said trigger lever is engaged by a closed latch and moved outwardly and away from the path of travel of said needles.

2. In a circular knitting machine according to claim 1 wherein said primary sensor means comprises a ground bracket extending over and partially around said tension spring, and wherein said tension spring is positioned to wipingly engage and make electrical contact with said ground bracket immediately after said free end of said trigger lever begins to move outwardly and away from the path of travel of said needles, and wherein said primary sensor means further includes electric wire means connected to said ground bracket and forming part of an electrical circuit operable to signal the detection of a latch in improperly closed position.

3. In a circular knitting machine according to claims 1 or 2 wherein said means supporting said trigger lever comprises a support plate pivotally supporting said trigger lever for limited movement in spaced relationship thereabove, and including a spring perch supporting the opposite end of said tension spring on said support plate, and adjustment means for varying the position of said spring perch and the outer end of said tension spring to thereby vary the sensitivity of the tripping of said trigger lever.

4. In a circular knitting machine according to claim 3 wherein said adjustment means comprises a disc supporting said spring perch in eccentric relationship thereon, an adjustment bolt threadably supported in said support plate and supporting said disc in eccentric relationship thereon, and a lock nut on said adjustment bolt for maintaining said adjustment bolt in adjusted position.

5. In a circular knitting machine according to claim 2 including secondary sensor means comprising a ground stop member mounted on said supporting means and against which said trigger lever is engaged when said inner end of said trigger lever is moved to a fully in-operative position outwardly and away from the path of travel of said needles, and wherein said electric wire means is also connected to said ground stop member and forms part of an electrical circuit operable to signal the detection of a latch in improperly positioned closed position, said secondary sensor means being operable if said tension spring and said ground bracket of said primary sensor means fail to make electrical contact.

6. In a circular knitting machine according to claim 5 wherein said means supporting said trigger lever comprises a support plate pivotally supporting said trigger lever for limited movement in spaced relationship thereabove, and said secondary sensor means further comprises an electrical insulation block mounted on said support plate, said block having an undercut portion to define a horizontal channel between said undercut portion and the surface of said support plate, and wherein said ground stop member is positioned within said channel so as to be protected from the buildup of falling lint.