LONATI, Ettore (Via Sott'acqua 32, Botticino, I-25080, IT)
LONATI, Fausto (Via Mediana 15, Brescia, I-25128, IT)
LONATI, Tiberio (Via Sera 24, Brescia, I-25121, IT)
LONATI, Ettore (Via Sott'acqua 32, Botticino, I-25080, IT)
LONATI, Fausto (Via Mediana 15, Brescia, I-25128, IT)
CLAIMS
1. A method for determining automatically the offset angle between the needle cylinder zero and the encoder zero, in a circular knitting machine for hosiery or other articles, characterized in that it comprises the steps of: - detecting, by means of an encoder (11), the rotation of the needle cylinder (1) and sending a detection signal (a) to an electronic processing unit (10);
- detecting, by means of a proximity sensor (7), a detectable area (6) which is defined at the lateral surface of the needle cylinder (1), said detectable area affecting an odd number of needles (2), the central needle with respect to said detectable area (6) being identified as the reference needle and constituting the needle cylinder zero;
- determining, by means of said electronic processing unit (10), the angle of rotation of the needle cylinder (1) covered starting from the detection signal of said encoder (11), defined as encoder zero, to the needle cylinder zero, defined by the signal sent by said proximity sensor (7).
2. The method according to claim 1, characterized in that said detectable area is provided by a recess or a raised portion (6) formed on the lateral surface of the needle cylinder (1). 3. The method according to claim 1, characterized in that said rotation angle of the needle cylinder (1) constitutes the offset angle of the needle cylinder zero with respect to the encoder zero.
4. The method according to one or more of the preceding claims, characterized in that said proximity sensor (7) is arranged at said recess or raised portion (6) which is provided on the lateral surface of the needle cylinder (1), said proximity sensor (7) being mounted on the supporting structure (8) of the circular knitting machine for hosiery or other articles.
5. A device for detecting the offset angle of the needle cylinder zero with respect to the encoder zero in a circular knitting machine for hosiery or other articles, comprising at least one proximity sensor (7) which is adapted to be arranged at a detectable area (6) which is defined on the lateral surface of the needle cylinder (1) of a circular knitting machine for hosiery or other articles, said proximity sensor being connected to an electronic processing unit (10), to which an encoder (11) of said needle cylinder (1) is further connected.
6. The device according to claim 5, characterized in that said proximity sensor (7) is oriented radially with respect to the needle cylinder
(1).
7. The device according to claims 5 and 6, characterized in that said detectable area is constituted by a recess or raised portion (6) provided on the lateral surface of the needle cylinder (1).
8. The device according to one or more of the preceding claims, characterized in that said recess or raised portion (6) has such an extent as to affect an odd number of needles (2), the central needle with respect to said recess or raised portion (6) being identified as reference needle and constituting the needle cylinder zero.
9. The device according to one or more of the preceding claims, characterized in that said encoder (11) is rigidly coupled to said needle cylinder (1). 10. A circular knitting machine for hosiery or other articles, characterized in that it comprises a device according to one or more of claims 5 to 9. |
METHOD FOR DETERMINING AUTOMATICALLY THE OFFSET ANGLE BETWEEN THE NEEDLE CYLINDER ZERO AND THE ENCODER ZERO IN A CIRCULAR KNITTING MACHINE FOR HOSIERY OR OTHER ARTICLES Technical Field
The present invention relates to a method for automatically determining the offset angle between the needle cylinder zero and the encoder zero in a circular knitting machine for hosiery or other articles. Background Art As is known, circular knitting machines for hosiery or other articles comprise at least one needle cylinder, which has a vertical axis and has, on its lateral surface, a plurality of axial slots within each of which there is a needle and, below such needle, a selector. The needle and the selector are provided generally with at least one heel, which protrudes from the lateral surface of the needle cylinder and can engage paths defined by corresponding actuation cams which face the lateral surface of the needle cylinder.
The paths defined by the actuation cams of the needles and of the selectors are shaped so as to produce, as a consequence of the rotation of the needle cylinder about its own axis with respect to such actuation cams, a movement of the needles and of the selectors along the corresponding axial slot to form knitting on the part of the needles.
Circular knitting machines for hosiery or other articles further comprise other elements or devices which cooperate with the needles and/or the selectors in forming the knitting and are stationary as regards rotation about the axis of the needle cylinder, such as for example the selection devices which face the lateral surface of the needle cylinder and can be actuated to actuate the selectors, the thread guides which are arranged in preset regions around the axis of the needle cylinder and can be actuated to provide the needles with the threads to be knitted, movable cams which can
be moved into an active position so as to engage the heels of the needles or of the selectors only for specific patterns, and other elements required for the operation of the machine, such as for example the actuation cams of the sinkers, et cetera. For correct operation of the machine, these devices and elements which co-operate with the needles and/or with the selectors in forming the knitting must be actuated in relation to a precise position of the needle with which they must interact.
For this reason, circular knitting machines for hosiery or other articles are provided with an electronic unit which, by means of an encoder connected to the needle cylinder as regards rotation about its axis, constantly controls the rotation of the needle cylinder about its axis.
To allow the electronic unit to know the angular position of each needle and therefore of each selector during the rotation of the needle cylinder about its own axis, it is necessary to preset a reference needle on the needle cylinder which constitute the needle cylinder zero, and to know the angular offset of this needle cylinder zero with respect to the encoder zero.
In order to determine the offset angle between the needle cylinder zero and the encoder zero, a manual procedure is performed which consists substantially in applying a reference to the supporting structure of the machine or to an element of the machine that is rigidly jointly coupled thereto, and a reference at the needle selected as needle cylinder zero in such a position as to allow, during the rotation of the needle cylinder about its own axis, to align these two references. The needle cylinder is then actuated with a rotary motion about its own axis, activating the encoder and stopping the machine when the two references are aligned. The angle detected by the electronic unit by means of the encoder, starting from the encoder zero, constitutes the offset angle of the needle cylinder zero with respect to the encoder zero.
This procedure, indeed because it is manual, requires the intervention of an operator, and since it is entrusted to a visual detection of the correct alignment between the two references it may have poor precision.
In order to solve this problem, procedures for self-learning the offset angle between the needle cylinder zero and the encoder zero have been proposed which are based generally on the use of electrical contacts between an element arranged on the needle cylinder and an element arranged on the supporting structure of the machine. However, these techniques have poor reliability, due mainly to the use of an electrical contact which can be in itself scarcely accurate and reliable. Disclosure of the Invention
The aim of the present invention is to solve the problems described above by providing a method for determining automatically the offset angle between the needle cylinder zero and the encoder zero in a circular knitting machine for hosiery or other articles.
Within this aim, an object of the invention is to provide a method which ensures high reliability and precision in determining the offset angle between the needle cylinder zero and the encoder zero.
Another object of the invention is to provide a method which can be performed by means of components which are easily available and easy to install.
Another object of the invention is to provide a method which can be used on single-cylinder circular machines and on double-cylinder circular machines. Still another object of the invention is to provide a device which can implement the method described above.
This aim and these and other objects which will become better apparent hereinafter are achieved by a method for determining automatically the offset angle between the needle cylinder zero and the encoder zero, in a circular knitting machine for hosiery or other articles, characterized in that it
comprises the steps of:
- detecting, by means of an encoder, the rotation of the needle cylinder and sending a detection signal to an electronic processing unit;
- detecting, by means of a proximity sensor, a detectable area which is defined at the lateral surface of the needle cylinder, said detectable area affecting an odd number of needles, the central needle with respect to said detectable area being identified as the reference needle and constituting the needle cylinder zero;
- determining, by means of said electronic processing unit, the angle of rotation of the needle cylinder covered starting from the detection signal of said encoder, defined as encoder zero, to the needle cylinder zero, defined by the signal sent by said proximity sensor. Brief Description of the Drawings
Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the method and the device according to the present invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:
Figure 1 is an axial sectional view of a portion of the needle cylinder, with the device for implementing the method according to the invention;
Figure 2 is a top plan view of a portion of the needle cylinder with the device cited above;
Figure 3 is a schematic view of the needle cylinder with the device according to the present invention; Figure 4 is a view of charts of signals used in the method according to the invention. Ways of carrying out the Invention
With reference to the figures, the invention can be applied to a single- or double-cylinder circular knitting machine for hosiery and the like. In the figures, the reference numeral 1 designates the needle cylinder,
the reference numeral 2 designates a knitting needle with a corresponding heel 3, and the reference numeral 4 designates a needle selector, also provided with a corresponding heel 5.
Of course, the needle cylinder 1 is provided with a plurality of needles and selectors 4.
The peculiarity of the invention resides in that it has, at the lateral surface of the needle cylinder 1, an area which can be detected by a proximity sensor 7 which is arranged radially with respect to the needle cylinder 1 at a level which matches the height of the position of the detectable area and is conveniently mounted on a support 8 which is therefore laterally adjacent to the needle cylinder 1 and is mounted on the supporting structure of the machine.
The detectable area cited above is constituted preferably by a recess 6, which is provided in a region of the lateral surface of the needle cylinder 1 which, except for the region affected by the recess 6, has a substantially regular circumferential profile.
As an alternative, the above cited detectable area can be constituted by a raised portion which is provided in a region of the lateral surface of the needle cylinder 1 which, except for the region affected by the raised portion, has a substantially regular circumferential profile. For this reason, although a recess 6 is preferred as a detectable region, as shown, what is stated hereafter with reference to the recess 6 also applies to the alternative which provides a raised portion in replacement of the recess 6.
The proximity sensor 7 is capable of detecting the recess 6 during the rotation of the needle cylinder 1 about its own axis.
Conveniently, the recess 6 has such an angular extent, with reference to the axis of the needle cylinder, that it affects or extends over a region of an odd number of needles 2, so that the needle that is at the center of the recess 6 is identified as the reference needle and constitutes the needle cylinder zero.
The block diagram of Figure 3 illustrates the connection of the proximity sensor 7 to an electronic processing unit 10, which is also connected to an encoder 11 which determines the rotation of the needle cylinder 1 and is rigidly coupled to the needle cylinder 1. The method of use of the device described above is as follows.
The procedure for self-learning the offset angle of the needle cylinder zero with respect to the encoder zero consists substantially in actuating the needle cylinder 1 with a rotary motion about its axis and in detecting, by means of the encoder 11, the rotation of the needle cylinder 1 and, by means of the proximity sensor 7, the passage of the recess 6 at the proximity sensor 7.
The encoder 11 sends to the electronic processing unit 10 a signal, designated by the reference letter "a" in Figure 4, which identifies the encoder zero (zero encoder or zero mark), and the electronic processing unit 10, starting from this signal, detects the extent of the rotation angle of the encoder and therefore of the needle cylinder 1. When the recess 6 arrives at the proximity sensor 7, such sensor sends to the electronic processing unit 10 a signal, designated by the reference letter "b" in Figure 4. The electronic processing unit 10 is thus capable of detecting the rotation angle (corresponding to "c" in Figure 4) of the needle cylinder 1 covered starting from the encoder zero to the needle cylinder zero, which indeed constitutes the offset angle of the needle cylinder zero with respect to the encoder zero.
Therefore, the electronic processing unit 10 learns the exact angular position, around the axis of the needle cylinder 1, of the needle that is located at the needle cylinder zero.
Since the position of all the other needles of the machine with respect to the reference needle, which constitutes the needle cylinder zero, is a design datum and is therefore known, and so is the angular position around the needle cylinder 1 with respect to the position of the proximity sensor 7 of all the other elements that must interact with the needles, since they, too,
are design data, the electronic processing unit 10 knows the exact position of each needle, during the rotation of the needle cylinder 1 about its own axis, as well as the exact position of all the elements of the machine that must cooperate with the needles in the formation of knitting. Therefore, as shown in Figure 4, the encoder sends to the electronic processing unit 10 the signal "a", while the proximity sensor 7 sends, when it detects the presence of the recess 6, the signal "b" and the distance "c" between the encoder zero signal and the signal of the proximity sensor 7 is the offset angle between the encoder zero and the needle cylinder zero. In this manner, the offset angle has been determined automatically, eliminating any error due to manual detection, which is entrusted to the skill and care of the operator.
In practice it has been found that the method and the device according to the present invention fully achieve the intended aim and objects, since they allow to know the exact position of the needle cylinder by determining, in an automated manner with high precision and reliability, the offset angle between the needle cylinder zero and the encoder zero.
The method and the device thus conceived are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may further be replaced with other technically equivalent elements.
In practice, the materials used, as well as the dimensions, may be any according to requirements and to the state of the art.
The disclosures in Italian Patent Application No. MI2006A001487 from which this application claims priority are incorporated herein by reference.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each
element identified by way of example by such reference signs.