JP2022537469A - Control method for weft insertion mechanism of gripper loom - Google Patents

Abstract

A method for controlling a weft insertion mechanism of a gripper loom in which a carrying gripper and a drawing gripper are alternately driven by a pair of toothed wheels (W) within a shed formed between the warp yarns, the carrying gripper and the drawing The grippers are driven by a pair of toothed wheels (W) via corresponding flexible straps (B) supporting one end of each, each strap (B) being attached to the body of the strap (B). Engaged in each toothed wheel (W) by a series of longitudinally formed slots and held in close contact with a portion of the toothed wheel (W) by a guide slide (S), the operation of the weft insertion mechanism is , monitored by the central controller of the loom. The control method comprises: a. continuously detecting the surface temperature (Ti) of the strap (B) at rest and the surface temperature of the strap (B) during operation of the loom; b. Parameters describing the behavior of the loom based on the surface temperature of the strap (B) at rest (Ti), the surface temperature under friction (Tf), the difference between those surface temperatures (ΔT), and the change over time. and c. comparing each parameter representing the operation of the loom with a predetermined threshold; d. Including sending a warning message to the operator or sending a command message to the central controller of the loom when the values of two different groups of parameters exceed the reference thresholds. [Selection drawing] Fig. 1

Description

The present invention relates to a method for controlling the weft insertion mechanism of a gripper loom. In particular, the present invention continuously monitors the wear and working condition of various components of the weft insertion mechanism based on predetermined parameters, and if these parameters are not met, the weft insertion mechanism and/or suggesting remedial measures to replace components of the mechanism subject to wear.

As known to those skilled in the art and schematically illustrated in FIG. 1, the weft insertion mechanism of a gripper loom comprises a pair of grippers (a carrying gripper and a drawing gripper) moving from opposite sides of the loom. , these grippers provide weft insertion into the shed through mutual weft exchange occurring in the center of the shed. The reciprocating motion of the carrying and drawing grippers is symmetrically controlled by two flexible straps B at one end where each gripper is fixed. Reciprocating motion for each of the two straps is provided by respective toothed wheels W, the teeth of which mesh within a continuous slot F formed along the central portion of the strap B. As shown in FIG. Reciprocating rotary motion to the toothed wheel W is imparted by the loom electric main motor. The continuous rotary motion of the motor is conveniently converted to reciprocating rotary motion via kinematic mechanisms of different types of construction which are not relevant for the purposes of the present invention.

Precise meshing between each toothed wheel W and each flexible strap B (a gripper fixed at one end of each strap) is provided by two guide slides S for each toothed wheel. . In practice, the guide slide S is conveniently aligned radially with respect to the axis of rotation of the associated toothed wheel W, and about the mesh of the toothed wheel with a predetermined angular width, the strap In the geometrically correct meshing position between the slots F in B and the teeth of the toothed wheel W, the strap B is bent and held tightly against the toothed wheel. The angular width of such toothing is calculated so that the force exerted by the wheel W on the strap B does not cause excessively high local stresses in the teeth of the wheel W, and when the gripper is out of the shed, The free ends of the straps B are directed towards the lower area of the loom.

In the contact area between the surface of the bent strap B and the corresponding sliding surface of the guide slide S, a radial centrifugal force is generated. This centrifugal force is composed of a static component due to the bending stiffness of the strap B and a dynamic component due to the high speed rotation of the strap B around the axis of the toothed wheel W. Such centrifugal force produces a corresponding frictional force that is a function of the coefficient of friction of the materials forming the strap B and the guide slide S, the set position of the guide slide S relative to the axis of the wheel W, and the sliding speed. This frictional force causes the surfaces of the guide slide S and strap B to come into contact with each other and be progressively heated. A further sliding phenomenon, which itself contributes to the overheating of strap B, occurs between the side edges of strap B and metal guide hooks located along the shed, causing strap B to move in the desired direction. By guiding it through the shed, it is possible to retain the strap B back in its straight configuration.

Due to the high running speed of the weaving loom or the incorrect adjustment position of the guide slide S, the heat energy dissipated increases and as a result the temperature of both the strap B and the guide slide S rises. If the temperature of the guide slide S is too high, the polymeric material of which the strap is constructed will age prematurely, leading to premature wear and tear and a significant reduction in life. Wear of the strap B also adversely affects other components of the weft insertion mechanism, both upstream and downstream of the strap. Upstream, strap wear leads to imprecise engagement with the teeth of the toothed wheel W, leading to a set play that triggers an impact event on the toothed wheel W on each reversal of the same rotational direction. Downstream, on the other hand, strap wear means less accurate guiding of the gripper, and the number of weft exchange errors between the carrying and drawing grippers, as well as accelerating the wear of the gripper itself. to increase

Current control methods for weft insertion mechanisms in gripper looms do not take into account the interdependence between each component as described above, and each component subject to wear as described above, i.e. toothed It merely monitors the state of wear of the wheels W, flexible straps B, and grippers both statistically and by direct observation, and replaces them when it is determined that their useful life has ended.

However, the wear of each component of the weft insertion mechanism is determined by multiple simultaneous factors and is neither a regular phenomenon nor uniform from one component to another. Therefore, in the prior art, evaluating when it is appropriate to replace excessively worn parts is a very delicate process, based on the appearance of the various parts of the weft insertion mechanism and the type and frequency of weaving errors that have occurred. , requires the intervention of a professional and experienced fabric operator who can assess the remaining service life of the various parts of the weft insertion mechanism. Premature replacement of the components of the weft insertion mechanism obviously entails wasted resources and economic damage. On the other hand, long-term use under conditions of excessive wear entails a significant risk of breakage which can damage the textile being processed or the loom member itself.

Accordingly, the problem to be solved by the present invention is to quickly warn the operator of the possible failure of the weft insertion mechanism and to carry out adjustments or replace components so as to avoid the occurrence of accelerated wear phenomena. To provide an automatic control of the actual wear of the components of the weft insertion mechanism of a gripper loom by avoiding accidental breakage of said components during weaving operations.

Because of this task, the first object of the invention is a sufficiently simple and industrially feasible technique, which is of particular importance for assessing the quality of the actual working conditions of the weft insertion mechanism of a gripper loom. To define control parameters that can be effectively monitored in a systematic manner.

A second object of the present invention is to provide a control method for a weft insertion mechanism of a gripper loom suitable for handling fluctuations in the control parameters under different working conditions of the loom, comprising: To provide a method for distinguishing between failures requiring intervention to adjust elements and failures requiring replacement of one or more components of said weft insertion mechanism that have reached critical wear conditions. .

Finally, a third object of the present invention is to provide an apparatus and control method that can be integrated that provides direct sensing of the degree of wear of the various components of the weft insertion mechanism.

This problem and these objects are achieved by a method for controlling the weft insertion mechanism of a gripper loom having the features defined in claim 1. Other preferred features of the control method are defined in the dependent claims.

However, further features and advantages of the method for controlling the weft insertion mechanism of a gripper loom according to the invention are the following of the preferred embodiment thereof, given by way of non-limiting example only and illustrated in the accompanying drawings. It will become clearer from the detailed description.

1 is a schematic front view of a gripper loom showing the essential components of the weft insertion mechanism of the gripper loom described in the introductory part of the description; FIG. 1 is a perspective view of a guide slide of a gripper loom according to the invention; FIG. Figure 3 is a top view of the guide slide of Figure 2, showing a perspective view of its internal cooling coils; 1 is a perspective view of a cooling circuit supplying guide slides for gripper straps in a gripper loom according to the invention; FIG.

As a result of the studies and experimental evaluations carried out, for various reasons already indicated in the introductory part of this description, an important component of the weft insertion mechanism of a gripper loom is the flexible strap that drives the movement of the gripper. I have come to the conclusion that I can definitely find it in B.

Furthermore, in experimental tests conducted by the applicant, among the several possible parameters that characterize the actual use of strap B, the surface temperature as described above affects the friction of strap B against the respective guide slides. We have found that the surface temperature of strap B is the most important one, considering that it is directly related. The frictional conditions on which the straps act are the main variable working parameters of the loom, especially
- loom running speed - workroom temperature - play between straps and guide slides - improper strap setting - improper loom adjustment.

Applicants believe that the surface temperature of the strap, and the gradient of said surface temperature over time, when accurately and continuously monitored, is the ideal temperature to be used to solve the problem underlying the present invention. We have the insight that it can be a parameter. Based on this insight, the present invention was conceived.

(Surface temperature measurement of strap)
In order to use the surface temperature of the gripper straps as an evaluation parameter for the quality of the actual working conditions of the entire weft insertion system, first, in the immediate vicinity of each strap B, preferably the highest temperature in the strap path. It is necessary to measure the temperature at the point where the temperature of the strap is the highest due to frictional forces. As a matter of fact, by measuring the strap temperature at the locations defined above, it is possible to detect the actual maximum variation of the strap's local temperature, which for the purposes of the present invention is of most importance. is more important than the strap mean temperature, whose variation over time would not be useful to provide as much information.

From this point of view, the preferred position is where the strap B enters the upper guide slide S, i.e. where the strap switches from a curvilinear configuration tightly attached to the control wheel W to the straight configuration assumed in the shed. Expediently, said temperature is measured by placing a temperature sensor 1 on the wall of the guide slide S which is in contact with the running strap B, as close as possible to the contact area of said wall with the strap B. . Considering here the intimate mechanical sliding contact between the strap B and the guide slide S, and considering that the guide slide S is made of a metallic material with high thermal conductivity, the guide slide Assume that the temperature of S is approximately equal to the surface temperature of strap B at the same location. These two observations therefore suggest that the temperature difference between the strap B and the guide slide S at the above positions is negligible.

Therefore, the sensor 1 repeatedly senses the surface temperature of the strap B under friction conditions (hereinafter referred to as Tf), and for each of the two straps B working simultaneously in the loom, the temperature Tf collected during the weaving operation. Information about is sent to the loom central controller and stored for further processing.

Similarly, there is a need to sense the resting temperature (hereafter Ti) of strap B, which is directly related to the friction of the weaving process and not due to general overheating of individual looms or weaving chambers. Used as a baseline for evaluating the temperature rise of strap B. However, the limited area of strap B which is not directly affected by the frictional phenomenon to the sliding of said strap guide is inevitably affected by the temperature rise of the surrounding area under friction, so that said temperature Direct detection is virtually impossible.

In accordance with the present invention, in order to achieve a reliable measurement of the surface temperature at rest Ti of strap B, this temperature is assumed to correspond, to a reasonable approximation, to room temperature in the vicinity of the strap working area. It is assumed. However, direct measurement of room temperature varies over a localized high range depending on how close the loom is to the "hot" member, making it difficult to identify the precise location where this temperature can be significantly sensed. It's not easy, it's not practical because it makes it difficult. According to a feature of the present invention, the temperature of the lubricating oil contained in the tank of the loom and its change over time are measured indirectly by controlling the effect on the heat phase of the loom. It is believed to be more effective and convenient to use as a direct indicator of phase and as an indirect indicator of local room temperature.

Therefore, assuming the temperature of the lubricating oil before starting the weaving operation as the initial room temperature and as the resting surface temperature Ti of the strap B, any subsequent changes in the lubricating oil temperature under running conditions are taken into account. It is believed that the corresponding changes in room temperature are measured with sufficient accuracy, based on the individual machine placed in, so that the resting surface temperature Ti of strap B is measured with sufficient accuracy. With this selection, the strap B temperature increment value can be automatically corrected from the effects caused by any changes in the local room temperature.

The temperature data collected in this way are processed in the loom's central controller to provide important parameters of the working condition of the weft insertion mechanism, such as the following key parameters.
-Ti: surface temperature of the strap at rest -Tf: surface temperature of the strap under friction -ΔT = (Tf-Ti): increase in surface temperature of the strap under friction during the initial transition period -G: initial transition The slope of the temperature rise from Ti to Tf over time versus time - ΔTd: increase in ΔT value during routine processing - Gm: temperature normalized to a predetermined reference room temperature during extended working periods slope of Tf

(reference baseline value and reference threshold)
The above parameter values were detected experimentally on a test loom in which the weft insertion mechanism was formed by a new component fully installed in the loom after an initial run-in period during which mechanical settling of the various components occurred. be. In this way, a theoretical reference baseline value is established which is believed to be optimal for each of the parameters considered above.

With the control method of the present invention set up on one particular loom, these reference baseline values are taken during the initial run-in period (again, after the first break-in period, the weft insertion mechanism with new components refined through a self-learning process (performed by This defines a set of actual reference baseline values specific to said particular loom.

Similarly, based on experimental data, a set of reference thresholds has been defined for the parameters above which either components showing signs of significant wear should be replaced or the parameter under consideration may fall below the thresholds. Measures must be taken, such as gradually reducing the weaving speed to a value that reduces it.

(adjustment and replacement)
The control method of the present invention can send a warning message to the user and/or to the central controller of the loom based on the comparison between said parameters and their associated reference baseline values and reference threshold values. , can be directed to modify its behavior. For example, such a message may, in a first step, instruct the loom to gradually decrease the weaving speed, or to replace worn components, or to make mechanical adjustments to different components. The operator may simply be advised to check. In the event of advanced component wear, the central controller of the loom either directly progressively limits the weaving speed of the loom, or prevents restarting of the machine after a first stop for other reasons, Alternatively, the loom may be stopped.

In particular, according to another aspect of the method of the present invention, a first group of parameters relating to the surface temperature of strap B (e.g., Tf, ΔT, ΔTd) exceed their threshold values, while the surface temperature of strap B If the second group of parameters (e.g., G, Gm) relating to gradients over time do not exceed their threshold values, it is considered indicative of reaching a critical wear condition for one or more components of the weft insertion mechanism, in this respect is sent to the operator.

On the other hand, if both groups of parameters above exceed their thresholds, the malfunction is assumed to be dependent on improper mechanical adjustment of the component and a corresponding message is sent to the operator.

Also, the control method of the present invention provides for direct monitoring of the wear status of individual components of the weft insertion mechanism from one or more devices (preferably either optical, electrical, electronic or electromagnetic). Other information may be easily integrated. This additional information is related to the surface temperature of the gripper strap B in order to provide the operator with more accurate information regarding the particular component of the weft insertion mechanism that has reached critical wear and needs to be replaced. It may be coordinated with the above.

(Forced cooling of strap surface temperature)
The control method according to the invention further provides a direct cooling intervention when the surface temperature Tf under friction of the strap B approaches a reference threshold, reducing the temperature of the guide slide S in the area of contact with the strap B to reduce or limit and remove the heat generated by friction through the circulation of coolant fluid within the same guide slide, thereby avoiding the occurrence of accelerated damage to the strap B due to overheating.

Such forced cooling may be permanent if the increase in temperature Tf is essentially due to room temperature increase. On the other hand, if the excessively high temperature Tf is due to mechanical adjustment problems or problems with the use of worn components, forced cooling may be temporary, said adjustment/replacement: For example, it must be postponed to complete the weaving operation of the article. In this way, thanks to said forced cooling, the work can be completed without interruption while the strap B is kept in exactly the safe condition.

FIG. 4 is a simplified diagram of the cooling circuit of the guide slide S of the strap for the gripper loom. A coolant fluid is circulated within the guide slide S to remove some of the heat generated by friction between the outer surface of the strap and the guide slide itself. A conveniently sized pump 2 located downstream of the tank 3 pushes the refrigerant fluid into the guide slide S. Energy exchange between the two components in contact leads to an increase in the temperature of the coolant fluid, but allows the temperature of the guide slide S to decrease. For this reason, the cooling fluid is conveyed through one or more static heat sinks 4 (or other active device for dissipating heat) to reduce its temperature before being re-entered the tank.

The internal structure of the guide slide S with such a cooling device has one or more channels 5 for internal circulation through which the coolant fluid flows, as shown in FIG. The metallic material of the body of the guide slide S further facilitates heat dissipation to the external environment and heat exchange with the refrigerant fluid.

The coolant fluid may be specially selected for this application, using a dedicated suitable cooling circuit, or, if available, using the loom's lubricating oil circulation system. The channel may be diverted towards the guide slide to be cooled. The choice between these two cooling mechanisms obviously also depends on the required cooling mechanism performance.

Especially when the temperature of the lubricating oil of the loom (usually averaging 55-65°C) is too high for said cooling, i.e. when the reference threshold of the surface temperature Tf under friction of the strap B is less than 55°C. , By combining the guide slide S and the Peltier cell, the temperature of the guide slide S is lowered by using the negative thermoelectric effect, and the role of lowering the temperature of the hot side of the Peltier cell is left to the cooling circuit, lubricating oil It is possible to use the main circuit of as a cooling source.

In effect, electrically powering the Peltier cell results in heat flow from one side of the cell being cooled to the opposite side of the cell being heated. The "cold side" of the cell is the side in contact with the main body of the guide slide S in order to absorb some of the heat generated by friction with the strap B. Cooling. The heat removed from the cold side is transferred back to the "hot side" in addition to the heat generated by the Joule effect of the Peltier cell itself.

Therefore, in this case as well, it is necessary to apply a heat dissipation mechanism to ensure the integrity of the Peltier cell itself. This heat dissipation mechanism is provided in a cooling circuit that uses the lubricating oil of the loom as a coolant fluid. An advantage of this solution is that the cooling effect of the Peltier cell makes it possible to lower the temperature of the guide slide S compared to the temperatures achievable with conventional mechanisms. Moreover, since the generated heat is removed from the guide slides S at high temperatures, the oil in the forced lubrication circuit of the loom is at a higher temperature than normally desired for the surface temperature Tf under friction of the straps B. can be used as a refrigerant fluid without

From the foregoing description, it will be apparent how the present invention fully achieves all its intended purposes. In practice, the surface temperature of the strap has proven to be a parameter that is likely to be monitored as a control parameter for the actual working condition of the strap B. This parameter is also of particular importance in efficiently and timely highlighting abnormal working conditions of the loom, whether due to incorrect adjustment or the use of excessively worn parts. The first object of the invention is thereby fully achieved.

Furthermore, by processing additional control parameters related to the slope of the change over time of the above-mentioned basic control parameters, and using said parameters in the control means, the control means can detect wear of said components. When integrated into a special device, it provides the operator with specific indications of the components to be replaced and guides the operator towards adjustment or replacement of the components of the weft insertion mechanism. to select the type of intervention to be performed. Thereby, the second and third objects of the present invention are also fully achieved.

However, the present invention should not be considered limited to the particular configurations described above, which are merely exemplary embodiments thereof, and may be modified to the fullest extent within the scope of those skilled in the art without departing from the scope of the present invention. , and different variations are possible, defined solely by the following claims.

Claims (12)

A method for controlling a weft insertion mechanism of a gripper loom, wherein a carrying gripper and a drawing gripper are alternately driven by a pair of toothed wheels (W) in a shed formed between the warp threads, comprising:
said carrying gripper and said drawing gripper are driven by said pair of toothed wheels (W) via corresponding flexible straps (B) supporting one end of each;
Each strap (B) is meshed with a respective toothed wheel (W) by means of a series of slots longitudinally formed in the body of the strap (B), and by a guide slide (S) of said toothed wheel (W). It is held in close contact with a part,
operation of the weft insertion mechanism is monitored by a central controller of the gripper loom;
The control method is
a. sensing the surface temperature of the flexible strap (B) at rest (Ti) and the surface temperature under friction (Tf) during operation of the gripper loom;
b. of the gripper loom based on the resting surface temperature (Ti) of the strap (B), the surface temperature under friction (Tf), the difference between those surface temperatures (ΔT), and the change over time. calculating parameters representing the motion;
including
The room temperature near the work area of the strap (B) is measured as the surface temperature (Ti) of the strap (B) at rest, and the room temperature is the lubricating oil in the lubricating oil tank mounted on the gripper loom. is indirectly sensed as the temperature of
The control method further includes:
c. comparing said parameters representing the operation of said gripper loom with respective predetermined threshold values;
d. Exceeding said threshold,
i. a first group of parameters related to the surface temperature of said strap (B); and ii. a second group of parameters related to the gradient of the surface temperature change over time of said strap (B);
the steps considered separately in
e. 1 of said weft insertion mechanism if the actual value of said parameter of said first group of parameters exceeds the respective threshold and the actual value of said parameter of said second group of parameters does not exceed respective threshold. sending a warning message to an operator indicating the reaching of a critical wear condition of said component, or sending a command message indicating said reaching to a central controller of said gripper loom;
f. mechanical adjustment of a component of the weft insertion mechanism when the actual value of the parameter of the first group of parameters and the actual value of the parameter of the second group of parameters exceed their respective threshold values. sending a warning message to an operator indicating a possible error, or sending a command message indicating the possibility to the central controller of the gripper loom;
A method of controlling a weft insertion mechanism of a gripper loom, comprising: A first group of parameters describing the operation of said gripper loom are:
i. Tf: surface temperature under friction of said strap;
ii. ΔT=(Tf−Ti): increase in surface temperature (Tf) under friction of said strap (B) during the initial transition period;
iii. ΔTd: increase in surface temperature (Tf) under friction of said strap (B) during daily operation;
A control method for a weft insertion mechanism of a gripper loom according to claim 1. A second group of parameters describing the operation of said gripper loom are:
iv. G: the slope of the change over time of the surface temperature (Tf) under friction of said strap (B) during the initial transition period;
v. Gm: Gradient of change over time of surface temperature (Tf) under friction of said strap (B) during an extended operating period of treatment, wherein said surface temperature (Tf) is normalized at a predetermined reference room temperature. is
3. A control method for a weft insertion mechanism of a gripper loom according to claim 1 or 2. The surface temperature (Tf) under friction of each strap (B) is the position of said guide slide (S) in contact with said strap (B) at the position where said strap (B) enters said guide slide (S). 2. A method for controlling a weft insertion mechanism of a gripper loom according to claim 1, wherein the temperature is detected by measuring the temperature of the upper wall of the gripper loom. A parameter representing the operation of the gripper loom was experimentally sensed after an initial run-in period on a test loom constructed with new components in which the weft insertion mechanism was fully mounted on the gripper loom, whereby 5. A method of controlling a weft insertion mechanism of a gripper loom according to claim 4, wherein the established values are taken as reference optimum values for each of said considered parameters. 6. A method of controlling a weft insertion mechanism of a gripper loom according to claim 5, further comprising a device for monitoring the state of wear of one or more individual components of said weft insertion mechanism. further comprising forced cooling of at least one guide slide (S) of said strap (B) when the surface temperature (Tf) under friction of said strap (B) exceeds a predetermined threshold temperature; A control method for a weft insertion mechanism of a gripper loom according to any one of claims 1 to 6. 8. The method of controlling a weft insertion mechanism of a gripper loom according to claim 7, wherein loom lubricating oil is used as a coolant fluid in said forced cooling step. In the forced cooling step, a Peltier cell is used, the cold side of the Peltier cell is brought into contact with the guide slide (S) to be cooled, and the hot side of the Peltier cell is used with loom lubricating oil as a refrigerant liquid. 9. The method for controlling a weft insertion device of a gripper loom according to claim 8, wherein the weft insertion device of a gripper loom is cooled by When the surface temperature of the strap (B) exceeds a first predetermined threshold, the gripper continues until the surface temperature under friction (Tf) of the strap (B) drops below the first threshold. The automatic control method for a gripper loom according to any one of claims 1 to 9, wherein the weaving speed of the loom is reduced stepwise. 11. The method of automatically controlling a gripper loom according to claim 10, wherein the gripper loom is prevented from restarting after an initial stop when the surface temperature of the strap (B) exceeds a second predetermined threshold. 12. The method of automatically controlling a gripper loom according to claim 11, wherein the gripper loom is stopped when the surface temperature of the strap (B) exceeds a predetermined third threshold.

Images