Flat knitting machine

Abstract: A flat knitting machine which can carry out changes in the knock-over timing and changes in the amount of elevation of a knitting needle (14) has a knock-over plate (11) provided at its extreme end with a loop pressing plate (17) having an end edge (29) in contact with a knitting yarn. The knock-over plate (11) is inserted into the bottom of a needle groove (8) in the head portion (9) of a needle bed (1) so that the knock-over plate (11) can be slidably moved in the direction of forward and backward movement of the needle (14). Furthermore, a knock-over plate cam (27) for operating the knock-over plate (11) and in engagement with the knock-over plate is provided on a carriage (24), and the knock-over plate (11) is moved forwards and backwards by the cam (27).

Description: The present invention relates to a flat knitting machine in which a needle at the time of knitting knitted fabrics can adjust the timing of its elevating stroke and a knock-over for drawing a new loop from an old loop. In a needle bed of a flat knitting machine, needle plates are inserted into parallel grooves in a needle bed base plate, needle grooves are formed between the needle plates adjacent to each other, and needles are slidably inserted into the needle grooves. A sinker is locked at one extreme end of the needle bed base plate at the same pitch and the same phase as that of the needle plate and is connected by a sinker wire. A knitting yarn supporting wire is secured to a tooth mouth (a centre line of the confronting needle beds) parallel with the extreme end of the needle bed base plate, and the needle, fed with a yarn at a raised position, moves down while engaging the knitting yarn with a hook, and contacts the knitting yarn supporting wire passing through the old loop at a knock-over position. The amount by which the needle is raised for receiving the feed of the knitting yarn determines the position at which a latch of the raised needle escapes from the old loop engaged with a shank and an extreme end of the latch is moved up by a predetermined amount from the position at which it escapes from the old loop. This position is a position at which the latch can be surely moved away from the old loop. Accordingly, this position can be suitably selected to control the amount the needle is raised. When the next new stitch is formed, timing of the knock-over of the knitting yarn in the form of a loop engaged with a hook of the needle which moves backwards in the needle groove is different in dependence on the position where the needle contacts the knitting yarn supporting wire. The timing is fast when the knitting yarn supporting wire is positioned at the extreme end of the needle bed and slow as it enters from the head of the needle bed. Timing of this knock-over varies with the kind of knitting yarn, the thickness of the yarn and the like, and it is desirable to adjust the knock-over timing whenever these factors change. It has been contemplated that in order to change the position of the knitting yarn supporting wire, a plurality of small holes through which the knitting yarn supporting wire is inserted are provided in a sinker to which the knitting yarn supporting wire is secured, so that the position of insertion of the knitting yarn supporting wire is suitably changed. However, according to this method, adjustment of the timing of the knock-over is carried out stepwise and is not carried out continuously. Furthermore, it takes time to change the position of the knitting yarn supporting wire. DE-C-388816 describes a flat knitting machine for knitting tubular goods wherein specially shaped needle guides are provided. FR-A-335947 describes a lever-operated system for the guided movement of needles in a rectilinear knitting machine. The present applicant's own earlier patent EP-A-0441565 describes a flat knitting machine having the facility for adjusting knock-over timing when knitting. DE-A-3241153 describes various means for guiding the needles of a knitting machine, involving the use of specially shaped guides. It is an object of the present invention to provide a flat knitting machine which can continuously carry out changing of the timing of a rising stroke of a needle and/or of knock-over. According to the present invention, there is provided a flat knitting machine comprising a needle bed having needle grooves therein for the forward and backward movement of needles set in said needle grooves, characterised in that a knock-over plate provided with a loop pressing plate having an end edge in contact with a knitting yarn at its extreme end is mounted in the bottom of the needle groove at a head portion of the needle bed so that the knock-over plate can be slidably moved in the direction of forward and backward movement of the needle. A knock-over plate cam for operating the knock-over plate and in engagement with the knock-over plate is preferably provided on a carriage so that the knock-over plate is moved forwards and backwards by the cam. Furthermore, the position of the knock-over plate cam is preferably movable so that the amount of movement of the knock-over plate which is in engagement with the cam can be varied. The knock-over plate inserted in the bottom of the needle groove of the head portion of the needle bed may be inserted into the bottom of the needle groove so that the contact end edge of the loop pressing plate provided at the extreme end of the plate protrudes beyond the needle bed base plate. Accordingly, the forward and backward movement of the knock-over plate may cause the knock-over plate to be brought into contact with a knock-over plate butt provided integrally with the knock-over plate, so as to change the position of contact of the end edge with the knitting yarn. One embodiment of apparatus according to the present invention will now be described by way of example and with reference to the drawings. In the drawings: Fig. 1 shows the apparatus of the present invention. Fig. 1a is a longitudinal sectional view and Fig. 1b is a plan view. Fig. 2 is a plan view of a cam provided on a carriage. Fig. 3 shows a knock-over plate. Fig. 3a is a plan view, Fig. 3b is a front view, and Fig. 3c is a side view. Figs. 4a to 4e are longitudinal sectional views of a needle bed, successively showing the process of upward and downward movement of a needle and a knock-over plate. Fig. 1 shows an example in which the present invention is applied to a needle bed 1. The bed 1 is one bed of a two-bed machine, only one side of a centre line X-X extending between the two confronting needle beds being shown. Needle plates 4 are inserted into needle plate grooves 3 juxtaposed on a base plate 2 of the needle bed 1, and a wire 7 is inserted between a notch 5 in the base plate 2 and a notch 6 in the needle plate 4 so that they are fixed. Needle grooves 8 are formed between every two needle plates 4 and 4 adjacent to each other. Guide recesses 12 each having a knock-over plate 11 slidably mounted therein are provided in the bottom 10 of the needle grooves 8 in the head portion 9 of the needle bed, that is, in the upper surface of the needle bed base plate 2. Needles 14 are inserted on the same plane as an upper surface 13 of the knock-over plates 11 which is flush with the bottom 10 of the needle grooves when the knock-over plates 11 are inserted in the guide recesses 12. As shown in Fig. 3, each knock-over plate 11 has a butt 16 at the tail portion of a flat plate-like stem 15 on which the needle 14 is placed and has a square loop pressing plate 17 at the head portion thereof. Each knock-over plate 11 is slidably fitted in its guide recess 12 in the needle bed base plate 2 so that the loop pressing plate 17 protrudes to a position protruding slightly beyond the head portion 9 of the needle bed base plate 2, that is to a position in the vicinity of the end edge of a sinker 18. Each sinker 18 is fitted partly into a sinker groove 19 provided at the same pitch and the same phase as the corresponding needle groove 3 at the extreme end of the head portion of the needle bed base plate 2, and a hook 20 provided at the end of the sinker 18 is locked into a notch 21 in the needle bed base plate 2 and is connected and fixed thereto by a wire 22. Reference numeral 23 denotes a band which passes through the juxtaposed needle plates 4,4, ... in order to prevent the needles 14 from slipping out. Reference numeral 24 denotes a carriage which has cams 26 for operating needle jacks 25 and cams 27 in engagement with the butts 16 of the knock-over plates 11. When the knitted fabric is knitted by the above apparatus, to what extent the outer end edge 29 of the loop pressing plate 17 of the knock-over plate 11 is moved forward from the needle bed base plate 2 is first determined by considering the kind of yarn 28 to be used and its characteristics and properties. The forward movement of the loop pressing plate 17 is carried out in such a manner that the knock-over plate 11 is slidably moved via the butt 16 of the knock-over plate 11 by means of the knock-over plate cam 27. The mount of sliding movement is determined by the shape of the knock-over plate cam 27 on the carriage 24. Accordingly, a change in the forward position of the loop pressing plate 17 of the knock-over plate 11 is carried out by changing the knock-over plate cam 27. Since the knock-over plate cam 27 guides the butt 16 while holding the butt 16 on both sides thereof, the loop pressing plate 17 moved forward by the knock-over plate cam 27 is accurately positioned. Fig. 2 shows the arrangement of cams on the carriage 24. The cam 26 for operating the needle 14 has a known construction in which knitting cams 31 and 32 and a guard cam 33 are arranged at both sides of and on the top of a rising cam 30. The knock-over plate cam 27 is arranged at a position above the needle operating cam 26. The knock-over plate cam 27 is provided with fixed cams 34 and 35 in the centre and the upper and lower portion, and movable cams 36 and 37 which move up and down in an inverted - V shape are provided on both wings of the fixed cam 34. A passage 38 for the knock-over plate butt 16 is formed between cams 36, 34 and 37 and the cam 35. As the carriage 24 moves from right to left in Fig. 2 at the time of knitting of the knitted fabric, a hook 40 of the needle 14 is moved up and down by a needle butt 39 which is guided by the raising cam 30, the guard cam 33 and the knitting cam 32. At the same time, the butt 16 of the knock-over plate 11 moves within the passage 38. When the needle 14 is moved forward by the rising cam 30, the butt 16 is pulled down by following an oblique surface 41 of the cam 35 and is most pulled down when the needle 14 moves up to a substantially tack position of the needle 14. The butt 16 moves within the passage 38 during the time when the needle 14 moves furthest forwards, and then starts to move down as the hook 40 receives the knitting yarn. When the needle 14 starts to move down and moves down to a substantially tack position, the knock-over plate butt 16 is moved upwards by an oblique rising surface 42 on the movable cam 37 so as to move the loop pressing plate forwards 17. By the forward movement of the loop pressing plate 17, the end edge 29 of the loop pressing plate 17 comes into abutment with the old loop 43 engaged with the needle 14 to urge the old loop 43 towards the hook side of the needle 14. Since the knitting yarn 28 fed to the needle 14 is engaged with the hook 40 of the needle 14, the hook 40 passes through the old loop 43 while holding a newly fed knitting yarn 28 and is knocked over. Accordingly, the knock-over position is moved away from the end of the needle bed base plate 2 to assume a forward position. The needle 14 is pulled down by the successive pull-down action of the knitting cam 32, the old loop 43 is knocked over, and the knitting yarn 28 locked at the hook 40 of the needle 14 forms a new loop 44. The above-described knitting processes are shown in Figs. 4a to 4e. The position of the knock-over operation is determined by the position of the end edge 29 of the loop pressing plate 17, and the position of the loop pressing plate 17 is determined by the position of the movable cam 37. Accordingly, it is necessary to adjust in advance the position of the movable cam 37 prior to knitting, in dependence upon the kind of yarn, yarn thickness, etc. of the knitting yarn. By this adjustment, suitable knock-over timing is continuously and optionally obtained. The position at which a top end 45 of a latch of the rising needle 14 is passing through the old loop 43 is lowered by moving back the position of the end edge 29 of the loop pressing plate 17 when the needle 14 moves up as shown in Fig. 4b, and a position of the knock-over is made higher than the position of the former, so that the elevating and lowering stroke of the needle 14 can be lessened. As described in detail hereinbefore, according to the present invention, a knock-over plate provided at its extreme end with a loop pressing plate having an end edge in contact with a knitting yarn is inserted into the bottom of a needle groove of the head portion of a needle bed so that the knock-over plate can be slidably moved in the direction of forward and backward movement of a needle. Therefore, the end edge in contact with the yarn of the knock-over plate with respect to the hook of the needle moved forward when the knitted fabric is knitted can be suitably changed, whereby the knock-over timing can be adjusted and the elevating stroke of the needle can be lessened. The above-described adjustment can be carried out continuously by suitably changing the amount of movement of the knock-over cam.

Claims: A flat knitting machine comprising a needle bed (1) having needle grooves (8) therein for the forward and backward movement of needles (14) set in said needle grooves (8), characterised in that a knock-over plate (11) provided with a loop pressing plate (17) having an end edge (29) in contact with a knitting yarn at its extreme end is mounted in the bottom (10) of the needle groove (8) at a head portion (9) of the needle bed (1) so that the knock-over plate (11) can be slidably moved in the direction of forward and backward movement of the needle (14). A flat knitting machine as claimed in claim 1, characterised in that a guide recess (12) having said knock-over plate (11) slidably mounted therein is provided in the bottom (10) of the needle groove (8) and a needle (14) is inserted on the same plane as an upper surface (13) of the knock-over plate (11) which is flush with the bottom (10) of the needle groove (8) when the knock-over plate (11) is inserted in the guide recess (12). A flat knitting machine as claimed in claim 1 or 2, characterised in that said knock-over plate (11) has a butt (16) at the tail portion of a flat plate-like stem (15) on which the needle (14) is placed and has a substantially square loop pressing plate (17) at a head portion thereof, said knock-over plate being slidably fitted in a guide recess (12) of a needle bed base plate (2) so that the end edge (29) of the loop pressing plate (17) protrudes to a position somewhat beyond the head portion (9) of the needle bed base plate (2) to a position in the vicinity of the end edge of a sinker (18). A flat knitting machine as claimed in any preceding claim, characterised in that a knock-over plate cam (27) in engagement with and controlling movement of the knock-over plate (11) is provided on a carriage (24), and the knock-over plate (11) is moved forwards and backwards by said cam (27). A flat knitting machine as claimed in claim 4, characterised in that the position of the knock-over plate cam (27) is movable so as to vary the amount of movement of the knock-over plate (11) in engagement with the cam (27).

Inventors: YABUTA MASAHIRO, YABUTA, MASAHIRO
Applicants: SHIMA SEIKI MFG, SHIMA SEIKI MFG., LTD.
Application year: 1992
Main classification: D04B7
IPC codes: D04B7, D04B15, D04B35