Flat knitting machine and electric power saving control method of flat knitting machine

Abstract

 A flat knitting machine (2), having a pair of front and rear needle beds (4, 6) one of which is caused to rack freely with respect to the other needle bed (4, 6) by a servomotor (14), is provided with a brake (16) for inhibiting a racking motion of the needle bed (4, 6). Slide force that is applied from a knitted fabric or carriage (10) to the needle bed (4, 6) is obtained based on knitting data of the knitted fabric. When the obtained slide force is equal to or lower than a first predetermined value and the needle bed (4, 6) is not caused to rack by the servomotor (14), excitation of the servomotor (14) is canceled and the brake (16) is turned on.

Description

[0001] The present invention relates to a flat knitting machine, and particularly to the control of a racking motion of a needle bed.

[0002] A flat knitting machine has a pair of front and rear needle beds, one of which racks freely with respect to the other needle bed. The range for moving stitches can be expanded and a variety of knitted fabrics can be knitted by allowing the needle beds to rack with each other. In this case, the racking motions of the needle beds are controlled by a servomotor, which is also used as a servo brake when the needle beds are caused not to rack. However, when using the servomotor as a servo brake, the coil of the servomotor needs to be excited, requiring electric power. On the other hand, a large portions of knitting courses of a knitted fabric (strokes of a carriage), for example, approximately 80% of the knitting courses depending on the knitted fabrics, are courses where the racking motions of the needle beds do not take place.

[0003] In the courses where the racking motions of the needle beds do not take place, the brake of the servomotor (servo brake) is turned off, and the needle beds are fixed using other brake. However, after giving due consideration to this point, the inventor of the present invention had discovered that slide force is sometimes applied from the knitted fabric or the carriage to the needle beds, and that, when applying a brake, there is a possibility that the needle beds move undesirably even in the courses where the racking motions do not take place. In addition, the application of a brake cannot return the needle beds to the original position after the needle beds move. Consequently, knitting continues while the needle beds are placed in a position different from that of knitting data. The servo brake, however, can return the needle beds to the original position. Therefore, conditions under which the servo brake and the other brake are switched need to be taken into consideration.

[0004] With regard to a robot and the like, there is known a robot that is provided with a brake other than that of a servomotor, wherein the servomotor is turned off and the brake is turned on during a period of time in which the shaft is not driven by the servomotor (Patent Document 1: JP2000-308990A). By doing so, the servomotor does not have to be excited, saving the electric power. However, in the case of a flat knitting machine, when switching from the servomotor to the brake only because the shaft is not driven using the servomotor or the racking motions are not performed, the abovementioned force from the knitted fabric or the carriage could undesirably move the needle beds.

[0005] An object of the present invention is to prevent the careless movement of the needle beds and at the same time reduce the frequency of use of a servomotor as a servo brake when racking the needle beds, in order to save electric power.

[0006] The present invention is a flat knitting machine that has at least one pair of front and rear needle beds, at least one of the needle beds being caused to rack freely with respect to the other needle bed along a longitudinal direction of the needle beds by a servomotor used for racking and also used as a servo brake, and that knits a knitted fabric by operating needles of the needle beds by means of a carriage that reciprocates on the at least one pair of front and rear needle beds, the flat knitting machine being provided with: a brake for inhibiting a racking motion of the needle bed that racks freely; and a slide force calculator for obtaining slide force applied from the knitted fabric or the carriage to the needle bed that racks freely, based on knitting data of the knitted fabric. Here, the slide force is force that is applied from a section other than the servomotor to rack the needle beds, and causes the needle beds to move undesirably. The flat knitting machine also has an output interface for canceling excitation of the servomotor and turning the brake on when the obtained slide force is equal to or lower than a first predetermined value and the needle bed is not caused to rack by the servomotor, and for exciting the servomotor and turning the brake off when the obtained slide force exceeds the first predetermined value and the needle bed is caused to rack by the servomotor.

[0007] Furthermore, the present invention is a method for performing electric power saving control on a flat knitting machine that has at least one pair of front and rear needle beds, at least one of the needle beds being caused to rack freely with respect to the other needle bed along a longitudinal direction of the needle beds by a servomotor used for racking and also used as a servo brake, and that knits a knitted fabric by operating needles of the needle beds by means of a carriage that reciprocates on the at least one pair of front and rear needle beds, wherein the flat knitting machine further has a brake for inhibiting a racking motion of the needle bed that racks freely, and the electric power saving control method executes: a step of obtaining slide force applied from the knitted fabric or the carriage to the needle bed that racks freely, based on knitting data of the knitted fabric; and a step of canceling excitation of the servomotor and turning the brake on when the obtained slide force is equal to or lower than a first predetermined value and the needle bed is not caused to rack by the servomotor, and of exciting the servomotor and turning the brake off when the obtained slide force exceeds the first predetermined value and the needle bed is caused to rack by the servomotor.
In this specification, the descriptions of the flat knitting machine are applied directly to the electric power saving control method of the flat knitting machine, and, conversely, the descriptions of the electric power saving control method of the flat knitting machine are applied directly to the flat knitting machine.

[0008] The present invention obtains the slide force that is applied from the knitted fabric or the carriage to the needle bed that racks freely. In the present invention, the slide force is obtained in order to determine whether to apply the brake from the servomotor or from the other brake, specifically to determine whether or not the undesirable movement of the needle beds can be prevented by restricting the slide force using the other brake. Therefore, the slide force may be obtained accurately enough to make such determination. When the obtained slide force is equal to or lower than the first predetermined value and the needle beds are not caused to rack by the servomotor, the excitation of the servomotor is canceled and the brake is turned on, so that when applying a brake, the excitation of the servomotor is canceled and the electric power consumption can be reduced. When the slide force exceeds the first predetermined value and the needle beds are caused to rack by the servomotor, the servomotor is excited and the brake is turned off. Therefore, the servomotor is always excited, if necessary. Because the flat knitting machine switches between the servomotor and the other brake based on the knitting data, the needle beds can be controlled proactively. In other words, not only is it possible to determine at each point whether applying a brake from the servomotor is appropriate or applying a brake from the other brake is appropriate, but also the conditions of the next course and the one after the next course can be predicted, thus more legitimate control can be performed. Switching between the brakes can be executed in units of courses or in the middle of a course. For example, in a section within a course where the slide force is equal to or above the first predetermined value, the servomotor may be used as the brake. In the other sections within the course, the brake other than the servomotor may be used.

[0009] The slide force can be obtained based on the knitting data by using a device other than the flat knitting machine, such as a knit design system. Whether the obtained slide force is equal to or lower than the first predetermined value, as well as whether the needle beds are caused to rack by the servomotor or not, can be determined based on the knitting data by using the knit design system. Therefore, the knit design system may be used for determining whether to apply a brake from the servomotor or the other brake, and storing the determination in the flat knitting machine, and the output interface of the flat knitting machine may be used for switching between the application of a brake from the servomotor and the application of a brake from the other brake.

[0010] The brake is, preferably, a brake that is activated in a non-excitation state by being turned off by supply of current and turned on by canceling the supply of current. In this manner, the electric power is not consumed when the brake is turned on, and therefore the electric power can be saved.
More preferably, the flat knitting machine further has a sensor such as a strain gauge to measure the slide force. The output interface inhibits the cancelation of the excitation of the servomotor and turns the brake off when the slide force obtained by the sensor is equal to or above a second predetermined value. The slide force that acts on the needle beds can be obtained based on the knitting data. The strain gauge that monitors the force applied to the needle beds can obtain the slide force that is actually applied to the needle beds, so as to be cope with a situation where an unexpected load occurs. The second predetermined value and the first predetermined value may be the same or different. For example, the second predetermined value is greater than the first predetermined value when the control based on the knitting data is considered as a general rule and the control by the sensor as backup safety means.

[0011] It is preferred that the slide force calculator obtain the slide force applied from the carriage to the needle bed that racks freely, based on a travel speed of the carriage and the number of selected needles. The higher the number of selected needles, the greater the force applied from the carriage to the needle bed. The higher the travel speed of the carriage, the greater the force applied from the carriage to the needle bed. Thus, the slide force can be obtained based on the travel speed of the carriage and the number of selected needles.
It is particularly preferred that the slide force calculator obtain the slide force applied from the knitted fabric to the needle bed that racks freely, based on the number of pitches of the racking motion of the needle bed that racks freely, and the number of threads extending between the front and rear needle beds. The number of threads extending between the front and rear needle beds represents a degree in which the front and rear needle beds are connected to each other by the threads, and the number of pitches of the racking motion represents force by which individual strings cause the needle beds to rack. The force by which the knitted fabric causes the needle beds to rack can be obtained from the number of pitches of the racking motion of the needle bed that racks freely, and the number of threads extending between the front and rear needle beds.

[0012] More preferably, the flat knitting machine is provided with a correction unit for comparing slide force measured from a value of an excitation current of the servomotor or from an output torque of the servomotor when exciting the servomotor to knit the knitted fabric, with the slide force obtained based on the knitting data by the slide force calculator, and for changing the first predetermined value when the measured slide force is different from the slide force obtained based on the knitting data by a predetermined condition or more.

[0013] When the flat knitting machine is cold upon startup, slide force greater than the slide force obtained based on the knitting data might act on the needle beds. Even when a needle groove of the flat knitting machine is full of dust, slide force greater than the slide force obtained based on the knitting data might act on the needle beds. On the other hand, when the flat knitting machine starts knitting and becomes warm after a while, and when the needle groove is clean, slide force smaller than the slide force obtained based on the knitting data acts on the needle beds.

[0014] For instance, the flat knitting machine starts knitting, the servomotor is excited and the maximum number of selected needles is used for knitting approximately 1 to 2 courses, and, meanwhile, the slide force applied from the needle beds to the servomotor is measured. The speed of the carriage may be made, for example, constant or changed between various speeds. The slide force applied to the needle beds can be measured from the value of the excitation current of the servomotor or the output torque of the servomotor. Subsequently, for example, the ratio or difference between the measured slide force and the slide force calculated based on the knitting data is obtained. When this ratio is 1 or equal to or greater than the predetermined condition, or when the absolute value of the difference is equal to or greater than the predetermined condition, the first predetermined value related to the slide force obtained from the knitting data is changed. For example, when the measured slide force is greater than the slide force obtained from the knitting data by the predetermined condition or more, the first predetermined value is set small.

[0015] 

FIG. 1 is a schematic plan view of a flat knitting machine of an embodiment;

FIG. 2 is a block diagram of an electric power saving controller of the embodiment;

FIG. 3 is a diagram schematically showing slide force applied from a carriage to needle beds; and

FIG. 4 is a diagram schematically showing slide force applied from threads to the needle beds.

[0016] Best embodiment for carrying out the present invention is described hereinafter. The scope of the present invention should be interpreted on the basis of the fact that the descriptions of the patent claims can be changed based on the well-known technologies.

[0017] A flat knitting machine 2 of the embodiment is shown in FIGS. 1 to 4. In FIG. 1, reference numeral 4 represents a front needle bed and 6 a rear needle bed, each of which has a number of needles. A trick gap 8 is provided between the needle beds 4, 6. Here, the rear needle bed 6 racks freely in a horizontal direction shown in FIG. 1, whereas the front needle bed 4 is fixed; however, both of the needle beds may rack freely. The present invention may be applied to a flat knitting machine that has top, bottom, front and rear needle beds or four needle beds provided with transfer member beds. In this case, the four needle beds may be divided into front and rear needle beds, and the two needle beds on either the front side or the rear side may rack.

[0018] A carriage 10 reciprocates on the needle beds 4, 6 in the horizontal direction of FIG. 1. One stroke of the reciprocating motion is referred to as one course or one knitting course. The carriage 10 selects the needles of the needle beds 4, 6 and controls and operates butts of the selected needles by means of a cam. At this moment, slide force acts on the rear needle bed 6 from the carriage 10 through the needles. Reference numeral 12 represents a toothed belt, which is driven by a carriage driving servomotor, not shown. Reference numeral 14 represents a racking servomotor, which is also used as a servo brake to rack the rear needle bed 6. Reference numeral 15 is a sensor for measuring the slide force and is, for example, a strain gauge that is provided on the needle beds or a shaft of the servomotor. Using the strain gauge as the sensor 15 can obtain the slide force even when the servomotor is off. A current sensor for monitoring a value of an excitation current of the servomotor 14 or a sensor for measuring an output torque of the servomotor 14 may be used as the sensor 15, but when the servomotor is off, knitting data are not enough for such sensors cope with the occurrence of an unexpected load.

[0019] Reference numeral 16 represents a brake, which is activated in a non-excitation state. The brake action of this brake is canceled when the brake is excited. The structure of the brake 16 is shown at the bottom left of FIG. 1. Reference numeral 20 represents a shaft, which is provided with unshown screws at a central part thereof and meshes with a nut provided on the rear needle bed 6. When the shaft 20 is rotated by the servomotor 14, the rear needle bed 6 racks horizontally. Reference numeral 22 represents a brake disc, 24 an excitation coil, 26 a spring, and 27 a friction plate. When the coil 24 is excited, the friction plate 27 separates from the brake disc 22, overcoming the repulsion force of the spring 26, whereby the brake application is canceled. When supply of current to the coil 24 is stopped, the friction plate 27 comes into pressure-contact with the brake disc 22 due to the repulsion force of the spring 26, and consequently the brake is turned on. Therefore, no electric power is consumed when the brake is on, but the electric power is consumed when the brake application is canceled.

[0020] A controller 18 of the flat knitting machine stores and analyzes the knitting data, and outputs a control signal of the servomotor 14, a control signal of the brake 16, a movement control signal of the carriage, and control signals of a needle selecting device of the carriage and of the cam. An electric power saving controller 30 of the embodiment is provided within the controller 18.

[0021] In FIG. 2, reference numeral 30 represents the electric power saving controller and 32 a knitting data storage for storing the knitting data of a knitted fabric. The electric power saving controller 30 and the knitting data storage 32 are provided within the controller 18. A knitting data analyzer 34 analyzes the knitting data prior to the execution of each knitting course. The knitting data analyzer 34 foresees the total knitting courses before knitting is started, and analyzes the knitting courses. The knitting data analyzer 34 analyzes a racking state, which is, in other words, the number of pitches of a racking motion of the rear needle bed 6 to the left or right with respect to the front needle bed 4, and the number of extending threads, which is, in other words, the number of threads extending between the front and rear needle beds. A pitch represents a needle interval on the needle beds. A racking state between the front and rear needle beds is stored as an original racking state when, for example, a stitch is formed; however, such data may be ignored. A loop length of a stitch is obtained from the knitting data. If need be, the material, the thickness and the like of the threads are stored as data other than the knitting data. These data are stored in a storage 36.

[0022] A correction unit 37 compares the slide force obtained from the knitting data, with slide force that is measured from the value of the excitation current of the servomotor 14 or the output torque of the servomotor when exciting the servomotor 14 and knitting the knitted fabric. When the measured slide force is different from the slide force obtained from the knitting data by a predetermined condition or more, the correction unit 37 changes a first predetermined value and stores the changed first predetermined value.

[0023] When the flat knitting machine 2 is cold upon startup, slide force greater than the slide force obtained based on the knitting data might act on the rear needle bed 6. Even when a needle groove of the flat knitting machine 2 is full of dust, slide force greater than the slide force obtained based on the knitting data might act on the rear needle bed 6. On the other hand, when the flat knitting machine 2 starts knitting and becomes warm after a while, and when the needle groove is clean, slide force smaller than the slide force obtained based on the knitting data acts on the rear needle bed 6.

[0024] For instance, the flat knitting machine starts knitting, the servomotor is excited and the maximum number of selected needles is used for knitting approximately 1 to 2 courses, and, meanwhile, the slide force applied from the needle beds to the servomotor is measured. The speed of the carriage may be made, for example, constant or changed between various speeds. Note that this knitting does not have to be performed for each knitted fabric. For example, at the beginning, everyday, the knitting may be performed simultaneously with a "loop length routine" for adjusting the cam of the carriage 10 so that the flat knitting machine 2 can knit stitches in sizes corresponding to the knitting data. The slide force applied to the rear needle bed 6 can be measured from the value of the excitation current of the servomotor 14 and the output torque of the servomotor 14. When performing knitting in order to measure the slide force applied from the knitting needles to the servomotor in the beginning of the knitting, idle knitting may be performed in which the needles are moved vertically without using the threads.

[0025] The ratio or difference between the measured slide force and the slide force calculated from the knitting data is obtained. When this ratio is 1 or equal to or greater than the predetermined condition, or when the absolute value of the difference is equal to or greater than the predetermined condition, the first predetermined value related to the slide force obtained from the knitting data is changed. For example, when the measured slide force is greater than the slide force obtained from the knitting data by the predetermined condition or more, the first predetermined value is set small. When, on the other hand, the measured slide force is smaller than the slide force obtained from the knitting data by the predetermined condition or more, the first predetermined value may be set large, or the first predetermined value may not be changed.

[0026] A storage 38 is for storing elements related to the slide force that acts from the carriage 10 onto the rear needle bed 6. The elements include the number of needles selected from the rear needle bed 6 and the speed of the carriage. The slide forces cause the rear needle bed 6 to rack in the horizontal direction and includes slide force acting from the carriage 10 and slide force acting from the knitted fabric. The slide force from the knitted fabric acts on the rear needle bed 6 when the racking motion of the rear needle bed 6 causes a stitch to rack more in the horizontal direction than that in a position where it is formed. This force becomes stronger as the number of threads extending between the front and rear needle beds 4, 6 increases, and the distance in which the stitch racks in the horizontal direction (the number of pitches) increases compared with when the stitch is formed. Moreover, this slide force becomes strong when the tensile force of the threads is high due to a small loop length of the stitch or when the material is thick and hard. In place of the racking distance obtained when the stitch is formed, the current racking distance may simply be used. Slide force calculators 40, 42 convert these data into the slide force acting from the knitted fabric, by means of appropriate tables, maps and functions.

[0027] The slide force calculator 42 calculates the slide force applied from the carriage 10 to the rear needle bed, based on a travel speed of the carriage and the number of needles described above. In other words, the carriage controls the butts of the needles by using a cam, and the butts are pressed against the carriage 10, whereby the slide force is generated. When a state where the impact of the carriage is small (the carriage is inverted or when there are less needles selected) is shifted to a state where a number of needles are selected at a transfer part or the like, the slide force acts drastically, causing the rear needle bed 6 to rack. Similarly, the slide force acts even when the number of needles to be selected changes rapidly in the middle of a course. The higher the travel speed of the carriage is, the greater these slide forces become. A racking command storage 44 stores the presence/absence of a racking command.

[0028] A determination unit 46 adds up the slide forces obtained by the slide force calculator 40, 42. Note that the slide forces have their own orientations. In a racking course and 1 to 2 courses in the front and rear of the racking course, the servomotor 14 is turned on mandatorily and the brake 16 is turned off. When the sum of the slide forces is equal to or lower than the first predetermined value, the servomotor 14 is turned off (cancel the excitation) and the brake 16 is turned on (cancel the excitation) in courses other than the racking course and the 1 to 2 courses in the front and rear of the racking course. Note that the value corrected by the correction unit 37 is used as the first predetermined value. In this manner, information indicating which one of the servomotor 14 and the brake 16 is turned on is stored in units of courses into a storage 48.

[0029] An output interface 50 monitors the progress of the knitting and reads the data from the storage 48 one course prior to each course to be executed. When the slide force obtained by the sensor 15 is equal to or lower than a second predetermined value, the output interface 50 controls the servomotor 14 and the brake 16 in accordance with the data of the storage 48. When the slide force exceeds the second predetermined value, it is determined that the rear needle bed 6 is in the middle of its racking motion, or that certain force is applied thereto, for some reason, to cause the rear needle bed 6 to rack undesirably. If the latter is the case, the servomotor 14 is turned on and the brake 16 is turned off.

[0030] Steps 1 to 4 of FIG. 3 illustrate how the carriage 10 pushes the rear needle bed 6. When the carriage is inverted and the needles are selected, the butts of the needles are operated and pushed by the carriage, whereby the slide force acts. This force is proportional to the number of needles that are operated by the carriage 10 at the transfer part. When the number of needles to be selected per predetermined length changes, the slide force proportional to the change in the number of needles acts.

[0031] FIG. 4 shows a mechanism of the slide force acting from the knitted fabric. Reference numeral 52 represents a prolongation between the front and rear needle beds 4, 6, 54 a stitch of the front needle bed 4, and 55 a stitch of the rear needle bed 6. As shown in FIG. 4, a stitch 55 racks to the right as viewed from the front, and tensile force of the string applies force that causes the rear needle bed 6 to rack to the left in FIG. 4. This force is proportional to the number of prolongation 52 and to the racking distance obtained when the stitch 55 is formed. The shorter the loop length of the stitch 55 is, the stronger the force. The slide force acting from the knitted fabric can be calculated based on these factors.

[0032] The following effects can be accomplished in the embodiment.

1) When the rear needle bed 6 is unlikely to rack undesirably, the servomotor 14 is turned off and the excitation of the brake 15 is canceled so as to save the electric power.

2) Switch data of the servomotor 14 and the brake 16 can be obtained beforehand based on the knitting data.

3) The slide force that actually acts on the rear needle bed is obtained by the sensor 15. When the slide force is great, the servomotor 14 is turned on.

4) In addition to the slide force acting from the knitted fabric, the slide force acting from the carriage can be controlled.

Note that the components from the knitting data storage 32 to the determination unit 46 shown in FIG. 2 may be provided in a knit design system, which is not shown, and the flat knitting machine 2 may be provided only with the storage 48 and the output interface 50 shown in FIG. 2.

[0033] 

2

Flat knitting machine

4

Front needle bed

6

Rear needle bed

8

Trick gap

10

Carriage

12

Belt

14

Servomotor

15

Sensor

16

Brake

18

Controller

20

Shaft

22

Brake disc

24

Coil

26

Spring

27

Friction plate

30

Electric power saving controller

32

Knitting data storage

34

Knitting data analyzer

36, 38

Storage

40, 42

Slide force calculator

44

Racking command storage

46

Determination unit

47

Correction unit

48

Storage

50

Output interface

52

Prolongation

54, 55

Stitch

Claims

1. A flat knitting machine (2) that has at least one pair of front and rear needle beds (4, 6), at least one of the needle beds (4, 6) being caused to rack freely with respect to the other needle bed (4, 6) along a longitudinal direction of the needle beds (4, 6) by a servomotor (14) used for racking and also used as a servo brake, and that knits a knitted fabric by operating needles of the needle beds (4, 6) by means of a carriage (10) that reciprocates on the at least one pair of front and rear needle beds (4, 6),
the flat knitting machine (2) being characterized by comprising:

a brake (16) for inhibiting a racking motion of the needle bed (4, 6) that racks freely;

a slide force calculator (40, 42) for obtaining slide force applied from the knitted fabric or the carriage (10) to the needle bed (4, 6) that racks freely, based on knitting data of the knitted fabric; and

an output interface (50) for canceling excitation of the servomotor (14) and turning the brake (16) on when the obtained slide force is equal to or lower than a first predetermined value and the needle bed (4, 6) is not caused to rack by the servomotor (14), and for exciting the servomotor (14) and turning the brake (16) off when the obtained slide force exceeds the first predetermined value and the needle bed (4, 6) is caused to rack by the servomotor (14).

2. The flat knitting machine (2) according to claim 1, characterized in that the brake (16) is activated in a non-excitation state by being turned off by supply of current and turned on by canceling the supply of current.

3. The flat knitting machine (2) according to claim 1 or 2, further comprising a sensor (15) for measuring the slide force, characterized in that the output interface (50) inhibits the cancelation of the excitation of the servomotor (14) and turns the brake (16) off when the slide force obtained by the sensor (15) is equal to or above a second predetermined value.

4. The flat knitting machine (2) according to claim 1 or 2, characterized in that the slide force calculator (40, 42) obtains the slide force applied from the carriage (10) to the needle bed (4, 6) that racks freely, based on a travel speed of the carriage (10) and the number of selected needles.

5. The flat knitting machine (2) according to claim 3, characterized in that the slide force calculator (40, 42) obtains the slide force applied from the carriage (10) to the needle bed (4, 6) that racks freely, based on a travel speed of the carriage (10) and the number of selected needles.

6. The flat knitting machine (2) according to claim 4, characterized in that the slide force calculator (40, 42) obtains the slide force applied from the knitted fabric to the needle bed (4, 6) that racks freely, based on the number of pitches of the racking motion of the needle bed (4, 6) that racks freely, and the number of threads extending between the front and rear needle beds (4, 6).

7. The flat knitting machine (2) according to claim 5, characterized in that the slide force calculator (40, 42) obtains the slide force applied from the knitted fabric to the needle bed (4, 6) that racks freely, based on the number of pitches of the racking motion of the needle bed (4, 6) that racks freely, and the number of threads extending between the front and rear needle beds (4, 6).

8. The flat knitting machine (2) according to claim 1 or 2, further comprising a correction unit (47) for comparing slide force measured from a value of an excitation current of the servomotor (14) or from an output torque of the servomotor (14) when exciting the servomotor (14) to knit the knitted fabric, with the slide force obtained based on the knitting data by the slide force calculator (40, 42), and for changing the first predetermined value when the measured slide force is different from the slide force obtained based on the knitting data by a predetermined condition or more.

9. A method for performing electric power saving control on a flat knitting machine (2) that has at least one pair of front and rear needle beds (4, 6), at least one of the needle beds (4, 6) being caused to rack freely with respect to the other needle bed (4, 6) along a longitudinal direction of the needle beds (4, 6) by a servomotor (14) used for racking and also used as a servo brake, and that knits a knitted fabric by operating needles of the needle beds (4, 6) by means of a carriage (10) that reciprocates on the at least one pair of front and rear needle beds (4, 6),
the flat knitting machine (2) further having a brake (16) for inhibiting a racking motion of the needle bed (4, 6) that racks freely, and
the electric power saving control method being characterized by executing:

a step of obtaining slide force applied from the knitted fabric or the carriage (10) to the needle bed (4, 6) that racks freely, based on knitting data of the knitted fabric; and

a step of canceling excitation of the servomotor (14) and turning the brake (16) on when the obtained slide force is equal to or lower than a first predetermined value and the needle bed (4, 6) is not caused to rack by the servomotor (14), and of exciting the servomotor (14) and turning the brake (16) off when the obtained slide force exceeds the first predetermined value and the needle bed (4, 6) is caused to rack by the servomotor (14).

Drawing