Reading arrangement for a dobby

A dobby with a mechanical reading device for a control card having perforated and nonperforated portions therein according to a pattern. The reading needle of the reading device of the pattern card has yielding elements for the purpose of reducing the impact force of the reading needle onto the pattern card.

FIELD OF THE INVENTION 
The invention relates to a reading arrangement for a fast-running dobby 
having a reading needle of a mechanical reading device engaging the 
nonperforated or perforated portions of a pattern card. 
BACKGROUND OF THE INVENTION 
To control dobbies, pattern cards with nonperforated or perforated portions 
are used which are read by needles of a control mechanism. The movement of 
the reading needle toward the pattern card is done with the aid of gravity 
or in fast-running machines with pretensioned springs or special drive 
parts. Upon increasing the operating speed, the time which is available 
for reading is reduced. The reading needles are moved forwardly faster and 
hit with greater speed the nonperforated parts, and in time can result in 
fatique distortions in the pattern card, for example deformations and 
breakage of the nonperforated parts and eventually cause control errors. 
By reinforcing the pattern card, a stiffening thereof would result and 
would make same heavier and bulky. The needle mass can be reduced only in 
as much as the durability of the needle is not affected. A direct and 
purposeful control of the movement of the needle leads to time losses 
during the course of the control operation and also causes vibrations in 
the needle. 
The purpose of the invention is a simple structure of a reading device for 
a dobby which permits an increase in the operating speed thereof. 
This is inventively achieved in a reading arrangement of the abovementioned 
type by providing an element which yields in axial direction of the 
reading needle and is arranged either on the reading needle or on the 
pattern card. 
With this arrangement, the nonresilient mass portion of the reading needle 
which directly engages the card can be reduced by reducing the respective 
needle length to the movement requirements into the pattern card. The 
needle portion which is necessary for transmitting the reading result is 
movably connected in axial direction to a base part. The yielding effect 
can be assured by an elastic deformation or by relative movement against a 
frictional resistance and the latter can be applied as an additional 
arrangement parallel to the first one. It is important that the entire 
needle length is reduced when the needle strikes a nonperforated portion 
of the pattern card and that prior to the next following reading of the 
pattern card and during an indexing of the pattern card the original 
length is again achieved.

DETAILED DESCRIPTION 
FIG. 8 illustrates a pattern card 1 which is moved by a cylinder 10. The 
pattern card has nonperforated and perforated portions for controlling a 
dobby of a Hattersley system. The two draw hooks which are associated with 
a frame of the weaving machine are identified by the reference numeral 12, 
which draw hooks are pulled out in a patterned manner by the draw knives 
13. The schematically illustrated draw bar 14 provides the connection to 
the frame of the weaving machine. 
Only the reading-in mechanism which is associated with the lower draw hook 
12 will be described hereinafter. The reading needle 5 is loosely 
suspended by means of an eyelet on an auxiliary needle 2 which lies both 
in the radiused path of movement of a vertically movable rod 4 and the 
back and forth movement of a push bar 15. The support needle 16 is 
slidably supported in an eyelet of the auxiliary needle 2 and the lower 
end thereof rests on a vertically movable step bar 17. 
The rod 4 is driven by a two-arm lever 18 which is controlled at one end by 
a rotatably supported cam member 19. 
The push bar 15 is driven in the same manner by a rotatably supported cam 
member 19. 
The reading needle illustrated in FIG. 1 consists of an upper needle part 
50 would around the auxiliary needle 2 and a lower needle part 5 which for 
reading the pattern card 1 directly cooperates therewith. The auxiliary 
needle 2 and needle 5,50 are lifted vertically together by the rod 4 prior 
to an indexing of the pattern card 1. The two parts 5 or 50 of the reading 
needle are guided in the guideways 3 or 30 affixed to not illustrated 
support structure. The connection between the lower part 5 of the needle 
and the upper part 50 consists of a helical spring 55 which is wound out 
of the material of the reading needle. 
If the reading needle 5,50--as is shown in FIG. 1--strikes a nonperforated 
portion of the pattern card 1, the impact of the lower needle part 5 onto 
the pattern card is absorbed by the helical spring portion 55. If the 
reading needle 5,50 is received in a perforation, the spring 55 does not 
influence the needle parts 5,50. 
A spiral spring or a resilient bar 57 can be utilized instead of the 
helical spring. 
In the previously described embodiment, the reading needle does not have a 
damper and, as a result, vibrations can occur. 
FIG. 2 illustrates a reading needle having a damping mechanism. The 
reference numeral 6 identifies the lower part of the needle and the 
reference numeral 60 identifies the upper part of the reading needle. Both 
parts are connected together by a press fit type connection to the 
opposite ends of a helical spring 65. A cage 66 is secured to the upper 
part 60 of the needle and houses the spring 65 therein and is under a 
small amount of initial stress while the lower part 6 of the reading 
needle is axially movably guided in the lower part of the cage. The lower 
part 6 of the needle is slidably received in the guideway 3. The guideway 
of the upper part 60 corresponds to the structure of FIG. 1 and is not 
shown in FIG. 2. 
A pair of flaps 67 are mounted on the lower part of the cage 66, which 
flaps grip around the lower part 6 of the reading needle with a small 
amount of applied pressure. These flaps 67 frictionally dampen any 
vibrations in the reading needle during contact thereof with a 
nonperforated part of the pattern card. The cage 66 with the flaps 67 may 
be made of plastic. Installation of the spring 65 into the cage 
substantially permits a free selection of the dimension of the spring. 
According to FIG. 3, the helical spring can be replaced by at least one 
elastic or flexible block 75 in which is received and secured the 
separated upper parts 70 and lower parts 7 of the reading needle. The 
block material functions as the spring and the spring function can still 
be reinforced by the fastening points 77 for the reading needle parts 
being provided side-by-side due to an overlapping of the two parts 7,70 
and not in an axial direction one below the other. As a result, resilience 
occurs not only through a compression of the material of the block 75 but 
also through a shearing effect in the block material. 
By selectively choosing the material and the dimension of the elastic block 
75, the spring characteristics thereof can be varied. The illustrated bent 
offset 7A in the lower needle part 7 results in the space 78 between the 
part 7 and the lower end of the upper needle part 70 and serves as a 
limitation for the reciprocal motion of the spring. 
In the two further modified embodiments, the yielding element consists of 
an arrangement in which the reading needle is composed of two parts which 
move reciprocally in axial direction under friction action. 
In FIGS. 4 and 5, the lower part of the reading needle is identified by the 
reference numeral 8 and the upper, independent part of the reading needle 
by the reference numeral 80. The lower part 8 slides in the guideway 3 and 
is positioned on a nonperforated portion of the pattern card 1; the upper 
part 80 slides in the guideway 30 and cooperates with the auxiliary needle 
2 which has the part 80 wound therearound. 
A clip 85 is used as the resilient element in the embodiment of FIGS. 4 and 
5 and consists of spring band which is bent to a not quite closed 
rectangle wherein the free end 86 acts as a resilient pressure element. An 
opening 87 is provided in each of the upper and lower wall portions of the 
clip and are adapted to receive and guide the two needle parts 8,80 
therein. The ends of the two needle parts 8,80 are bent and engage the 
outer wall portions of the upper and lower sides of the clip. Reinforced 
by the force of the resilient part 86, the surfaces of the needle parts 
frictionally engage one another within the clip 85. The reading needle is 
held in the illustrated position by this friction force. 
During a lowering of the reading needle onto a nonperforated portion of the 
pattern card 1, the impact forces effect a shifting, starting at a fixed 
threshold frictional value of the lower needle part 8 with respect to the 
upper needle part 80 and causes the peak of these impact forces to be 
absorbed. The maximum sliding path 88 is determined by the position of a 
ring or collar 89 which is pressed onto the lower needle part 8. To index 
the pattern card, the rod 4 lifts along its path of movement toward the 
auxiliary needle 2 and carries therewith the entire reading needle 8,80 by 
engaging the bent end portion of the upper part 80 of the needle until the 
bent end portion of the upper end of the lower part 8 of the reading 
needle engages the guideway 30. A continued movement of the rod 4 will 
cause the lower needle part 8 to be pushed back to the original position 
thereof relative to the upper needle part 80 and the clip 85. 
In the modified embodiment according to FIGS. 6 and 7, the mutually 
adjacent ends of the needle parts 9,90 which are directed toward one 
another are slidably guided in an opening 97 in a block 95 and are bent 
backwardly generally 180.degree. until they lie in the lateral groove 96 
in the block 95 to cause the arrangement to be secured against rotation. 
The bent end of the upper part 90 grips around both the upper and lower 
ends of the block 95 so that a reciprocal relative shifting does not take 
place. The bent end of the lower part 9, however, can slide slightly in 
axial direction of the block. 
When the reading needle hits a nonperforated portion of the pattern card, 
the lower part 9 thereof is pushed back into the block 95 at a certain 
relationship with respect to the impact force. During a subsequent lifting 
of the upper part 90 of the needle by the rod 4, a subsequent impact of 
the needle 9 on the guideway 30 will effect a return of the needle 9,90 to 
its original length. 
The bent end of the lower part 9 of the reading needle rests with an 
initial elastic tension on the base or bottom wall of its respective 
groove 96. This needle end is arranged inclined with respect to the needle 
shaft. As a result, the frictional pressure is reinforced with an 
increasing shortening of the entire needle to cause a progressive braking 
action between the needle 9 and the block 95 when the impact force acts 
onto the needle 9. 
With all of the described modified embodiments, the peak force from the 
impact of the reading needle on the nonperforated portion of the pattern 
card is broken due to the reading needle being shortened under the brake 
effect. 
A further possibility of reducing these impact forces can now consist in 
absorbing a part of these forces by the pattern card. 
For example the pattern card 1 can, in particular at the nonperforated 
portions, be coated with a rubber-elastic mass or a rubber-elastic layer 
can be arranged between the pattern card cylinder and the pattern card 1 
and yields under the impact pressure. The nonperforated portions 
themselves can also consist directly as pins of elastic material. 
A different possibility of weakening the impact pressure consists in the 
pattern cylinder moving during the moment of the impact of the reading 
needle in the same direction with same, however, at a lower speed. 
The difference in movement results in a longer duration of time for 
transmitting the movement energy from the needle to the nonperforated 
portion of the pattern card to cause the peak forces to be reduced without 
timely influencing the reading of a perforated portion of the pattern 
card. 
Although particular preferred embodiments of the invention have been 
disclosed in detail for illustrative purposes, it will be recognized that 
variations or modifications of the disclosed apparatus, including the 
rearrangement of parts, lie within the scope of the present invention.