The present invention relates to a linear actuator, and in particular, to a linear actuator that can be used in a manufacturing apparatus requiring a highly accurate and high-speed reciprocating mechanism, such as a tufting machine.
Conventionally, for example, a tufting machine forms a loop with a thread in a base fabric by reciprocating up and down a needle bar to which, on the same straight line, many needles are attached and reciprocating the needle bar along the axis of the needle bar.
In general, for example, an eccentric crank mechanism is used as a mechanism for reciprocating the needle bar up and down. On the other hand, as a mechanism for reciprocating the needle bar in the axial direction, for example, an actuator combining a servo motor and a ball screw has been used (see JP 2014-29057 A).
However, in an actuator using a servo motor, even if the needle bar is attempted to be reciprocated at a predetermined speed in the axial direction, there is a problem chat when the speed is increased, the needle bar cannot reach a predetermined position and the servo motor stops.
In short, although speeding up of the reciprocating movement of the needle bar in the vertical direction is already achieved, speeding up of the reciprocating movement of the needle bar in the axial direction has a limit, and the ability of the tufting machine has not been fully exhibited.
In addition, since the ball screw for converting rotational movement of the servo motor into reciprocating movement is likely to be worn and has low durability, attempting to secure the desired movement accuracy needs to replace the ball screw in a short period of time, so that the maintenance takes time and effort.
In view of the above problems, the present invention has an object to provide a linear actuator that is driven with high accuracy and high speed and that does not take time and effort in maintenance, and a tufting machine using the linear actuator.
To solve the above problem, the linear actuator according to the present invention has a configuration that includes: a casing being tubular; a magnet unit configured to sandwich both side surfaces at least facing each other of a magnet mounting plate with a magnet, the magnet unit supported to be configured to reciprocate along an axial direction in the casing; and a coil unit arranged to face the magnet of the magnet unit. Based on magnetization and demagnetization of the coil unit, the magnet unit reciprocates between the coil units.
According to the present invention, the magnet mounting plate of the linear actuator can be reciprocated with high accuracy and high speed by magnetic force. Therefore, for example, the productivity of the tufting machine can be increased.
In addition, since a ball screw with low durability is not used, there is no need for replacing the ball screw due to deterioration, the maintenance period is made longer, and the maintenance does not take time and effort.
As an embodiment of the present invention, the magnet mounting plate may have an inverted T-shape in cross section.
According to the present embodiment, the magnet unit can be supported via the horizontal board of the magnet mounting plate. Therefore, a highly accurate and high-speed linear actuator can be obtained by performing a stable reciprocating motion.
As another embodiment of the present invention, the magnet mounting plate may have an I-shape in cross section. According to the present embodiment, a linear actuator with a small number of components and assembly man-hours can be obtained.
As another embodiment of the present invention, the magnet mounting plate may have an H-shape in cross section.
According to the present embodiment, since magnets can be attached to a large number of surfaces, a linear actuator having a large driving force can be obtained.
As a different embodiment of the present invention, the coil unit may have a cooling fin arranged on an outward surface.
According to the present embodiment, the heat generated by the coil unit can be efficiently discharged and cooled, and problems due to heat generation can be avoided.
The tufting machine according to the present invention is configured as a drive source for reciprocating the needle bar in the axial direction.
According to the present invention, the magnet mounting plate of the linear actuator can be reciprocated with high accuracy and high speed by magnetic force. Therefore, a tufting machine with high productivity can be obtained.
In addition, since a ball screw with low durability is not used, a tufting machine can be obtained in which there is no need for replacing the ball screw due to deterioration, the maintenance period is made longer, and the maintenance does not take time and effort.
As a different embodiment of the present invention, a plurality of needle bars may be arranged in parallel.
According to the present embodiment, there is an effect that a tufting machine capable of producing a carpet having a complicated pattern with high productivity can be obtained.
An embodiment of a linear actuator according to the present invention will be described with reference to the accompanying drawings of
It should be noted that the linear actuator 10 according to the present embodiment can be applied to a tufting machine 60 described below, for example, as shown in
As shown in
As shown in
It should be noted that needless to say, the casing 20 is not limited to the above-described shape, may be formed by combining shape steels, and the outer shape can be changed as necessary.
As shown in
As shown in
As shown in
A guide block 38 is fixed to the upper surface of the casing main body 21. The guide block 38 is engaged with a guide rail 37 attached to the protruding portion 44 of the magnet mounting plate 41. Therefore, the magnet mounting plate 41 slidable in the X-axis direction is regulated in position by the guide block 38, and performs an accurate reciprocating movement. It should be noted that as shown in
As shown in
The magnet mounting plate 41 has an inverted T-shape in cross section in which a vertical board 43 is erected at the center of the upper surface of a horizontal board 42. As shown in
In addition, as shown in
Furthermore, as shown in
It should be noted that the magnet mounting plate 41 is not limited to having an inverted T-shape in cross section, and may have a T-shape in cross section, an I-shape in cross section, or an H-shape in cross section. With an I-shape in cross section, the number of components such as the slide block 46, the assembly man-hour, and the weight can be reduced. In addition, if the magnet has an H-shape in cross section, the magnet can be attached to four places, so that there is an advantage that a high-power linear actuator can be obtained.
As shown in
The assembly of the linear actuator 10 will be described.
The magnet unit 40 mounted on the slide base 47 is inserted from the mounting port 24 of the casing main body 21, and the protruding portion 44 of the magnet mounting plate 41 is protruded from the slide groove 25 and positioned. Then, the slide base 47 is fixed to the bottom surface of the casing main body 21.
Furthermore, the scale base 35 and the guide rail 37 are attached to the upper end edge portion of the protruding portion 44 protruding from the slide groove 25. Next, the detection head 36 is attached to the upper surface of the casing main body 21, and the linear encoder 34 is assembled. Furthermore, the guide block 38 engaged with the guide rail 37 is fixed to the upper surface of the casing main body 21.
A ball screw 33 is fixed to the protruding portion 44, and a coupling shaft 32 inserted through the ball screw 33 is coupled to the rotary encoder 30 via a coupling member 31.
Next, the coil units 50 and 50 are assembled and fixed from the mounting ports 26 and 27 on both sides of the casing main body 21, respectively. Finally, fixing the clamp member 49 to one end side in the X-axis direction of the vertical board 43 of the magnet mounting plate 41 via the mounting ports 26, 27, and 28 of the casing main body 21 (
According to the present embodiment, the magnet unit 40 is positioned and fixed in the casing main body 21, and then the coil units 50 and 50 are assembled from both sides of the casing main body 21. Therefore, a small linear actuator not only excellent in assembly performance but also easy to adjust can be obtained. In particular, since the linear actuator according to the present invention does not require a large mounting area, there is an advantage that it can be mounted even on a tufting machine having a small installation space.
As shown in
Next, as illustrated in
The tufting machine 60 has an approximately portal shape in which a horizontal frame 63 having a U-shape in cross section is bridged between a pair of vertical frames 61 and 62. Then, the linear actuator 10 is attached to the outward surface of the vertical frame 62 out of the outward surfaces of the vertical frames 61 and 62 opposite to each other.
As shown in
The main shaft 70 rotates at a high speed in one direction via a motor and a belt (not shown). Then, the rotational motion of the main shaft 70 causes the needle shaft 80 to alternately rotate in the forward and reverse directions via an eccentric cam mechanism (see
In the eccentric cam mechanism housed in the vertical frame 62, as shown in
As shown in
It should be noted that the push rod 82 is supported via a push rod housing 83 fixed in the horizontal frame 63 described above.
As shown in
On the upper surface of the needle bar 90, as described above, a plurality of sets of a pair of guide brackets 92 and 92 as one set are fixed at predetermined pitches. Two slide bars 93 and 93 are bridged in parallel between the pair of guide brackets 92 and 92. Then, the needle bar carrier 84 is slidably inserted through the two slide bars 93 and 93 as described above. Therefore, the needle bar carrier 84 is not in direct contact with the needle bar 90.
It should be noted that the needle bar 90 has a plurality of needles 91 arranged on the lower surface thereof in one row on the sane straight line, but the needles 91 need not necessarily be arranged in one row. If necessary, for example, the plurality of needles 91 may be arranged in two rows or three rows. In addition, the number of needle bars 90 is not necessarily one, and a plurality of needle bars 90 may be arranged in parallel.
The above-described linear actuator 30 is connected as shewn in the block diagram shown in
That is, the power source 110 is connected to a noise filter 112 via a molded-case circuit-breaker 111. The noise filter 112 is connected to a main driver board 113, and to a sub driver board 115 via an electromagnetic contactor 114. The main driver board 133 connected to the PC 116 is connected to the main shaft position detecting encoder 117 and also connected to the sub driver board 115. The sub driver board 115 includes a regenerative resistor 118 and is connected to the linear actuator 10 via a zero-phase reactor 119.
It should be noted that the main shaft position detecting encoder 117 is, for example, arranged on the outward surface of the vertical frame 62, is connected to the main shaft 70 via a timing pulley and a timing belt (not shown), detects the rotation conditions of the main shaft 70, and the detection result is transmitted to the main driver board 113. Therefore, the PC 110 can check the rotation conditions of the main shaft 70 in real time.
Next, based on
As shown in
When the main shaft 70 rotates in one direction caused by the rotation of a motor (not shown) via a belt, the needle shaft 80 alternately rotates in the forward and reverse directions via the eccentric cam mechanism shown in
It should be noted that in
The needle bar 90 in which the needles 91 are arranged in parallel is supported to be reciprocally movable in the direction perpendicular to the paper surface via the needle bar carrier 84 and the slide bars 93 and 93.
A looper 97 positioned immediately below the needle 91 is attached to a rotatable looper block 96.
A large number of finger portions 95 are arranged in parallel on the finger plate 94. Then, the needles 91 are arranged so as to descend one by one between the adjacent finger portions 95 and 95.
As shown in
Furthermore, as shown in
Thereafter, repeating the same operation completes a carpet having a pattern while forming the loop 104.
In the above-described embodiment, a case has been described in which one linear actuator is attached to one tufting machine and one needle bar is reciprocated in the axial direction. However, the present invention is not limited to this, and for example, a linear actuator may be attached to each of the two vertical frames of a tufting machine, and each of the two needle bars arranged in parallel may be reciprocated in the axial direction.
In addition, in the above-described embodiment, the looper that forms the loop pile is described. However, the present invention is not limited to this, and for example, may be applied to a looper that forms a cut pile or a cut-and-loop pile.
The linear actuator according to the embodiment was attached to an existing tufting machine, the attached machine was driven, and the drive limit was examined.
The main shaft of the existing tufting machine was rotated at a maximum rotational speed of 1142 rpm being the limit value of the tufting machine, and the needle bar was moved up and down. It was confirmed that the reciprocating motion in the axial direction of the needle bar driven by the linear actuator according to the present invention can be followed without any problems.
An actuator formed by combining a servo motor (SGMGV-44DDA21 manufactured by YASKAWA ELECTRIC CORPORATION) and a ball screw (BLK3232-3.6 manufactured by THK) was attached to an existing tufting machine. Then, the attached machine was driven in the same manner as in Example 1. When the rotational speed of the main shaft began to exceed 600 rpm, abnormal noise began to occur, and it was found that the reciprocating motion in the axial direction of the needle bar could not follow the vertical motion of the needle bar.
From the above experiments, it was found that if the linear actuator of the present invention is used, the main shaft can be rotated at a rotational speed at least twice as high as that in the case where the existing actuator is used. Therefore, it was clarified that the productivity of the tufting machine is remarkably improved by using the linear actuator of the present invention.
The linear actuator of the present application was mounted as a needle bar reciprocating drive mechanism on an existing actual tufting machine (model 2.15M×1/10G ICY LOOP machine, serial number No. 185, manufactured by Michishita Iron Works Co., Ltd.). The maximum weaving width dimension of the actual machine was 2.15 meters, and the distance between the needles was 1/10 inch. Then, in order to detect whether the needle maintains repeatability of positioning, that is, whether the needle is greatly displaced from a predetermined position, a linear scale (NSR-LHDAE5A10-001U manufactured by Mitutoyo Corporation) was used.
The rotational speed of the tufting machine was set to 1140 rpm being the maximum allowable rotational speed of the tufting machine.
In addition, the moving amount of the needle was 2.54 mm per pitch. Then, the movement pattern of, while following the needle stroke, moving the needle 4 times by 1 pitch to one side and then moving the needle 4 times by 1 pitch to the opposite side was repeated and experimented.
Furthermore, the lead factor of the linear actuator at a continuous operation time of 6 hours and a rotational speed of 1140 rpm was set to 43%, and the repeatability of positioning was set to ±0.03 mm.
It should be noted that when the needle could not maintain repeatability of positioning of ±0.03 mm, the tufting machine was set to automatically stop.
It should be noted that the load factor refers to the ratio of the driving force necessary to drive the needle bar when the maximum driving force of the linear actuator of the present invention is set to 100%. Normally, the load factor increases as the rotational speed increases.
In addition, the repeatability of positioning refers to a value obtained by a performance evaluation method conforming to JIS B 6192. Specifically, positioning from the same direction at any one point is repeated 7 times, the stop position is measured, and ½ of the maximum difference in reading is obtained. This measurement is performed at the respective positions of the center and approximately both ends of the movement distance, and the maximum value of the obtained values is taken as the measurement value, and the value represented by adding ± sign to the measurement value is referred to as “repeatability of positioning”.
As a result of the experiment according to Example 2, the carpet production capacity averaged 53 m2/hour.
The reasons why Example 2 has high productivity include a point that the operation of the linear actuator could follow the operation of the maximum allowable rotational speed of 1140 rpm of the tufting machine, and a point, that since the repeatability of positioning was high, the stop time due to thread breakage was shortened.
It should be noted that in the visual observation, the driving state of the linear actuator of the present invention was stable and a surplus capacity was felt. Therefore, it was found that if the rotational speed of the tufting machine can be further increased, the production capacity can be further improved.
A needle bar reciprocating drive mechanism including a servo motor and a ball screw was mounted on the tufting machine used in Example 2.
That is, the needle bar reciprocating drive mechanism drives a servo motor (SGMSV-25DDA21 manufactured by YASKAWA ELECTRIC CORPORATION) with a servo driver (SGDV-120D01A manufactured by YASKAWA ELECTRIC CORPORATION), and reciprocates and drives the needle bar via a ball screw (BLK3232-3.6 manufactured by THK).
It should be noted that when the rotational speed of the tufting machine began to exceed 600 rpm, the needle bar reciprocating drive mechanism including the servo motor and the ball screw could not follow the speed of the tufting machine and could not maintain the repeatability of positioning. Therefore, in Comparative Example 2, the rotational speed of the tufting machine was set to 600 rpm. The other experimental conditions were the same as in Example 2, and the production capacity was measured by performing the drive for 6 hours continuously.
As a result of the experiment according to Comparative Example 2, the carpet production capacity averaged 26 m2/hour.
From the above experimental results, it was found that the case of using the linear actuator of the present invention (Example 2) as a needle bar drive mechanism can operate at a rotational speed of at least twice as much as the rotational speed of the case of using the existing needle bar drive mechanism (Comparative Example 2). As a result, according to the present invention, it was clarified that productivity is not less than doubled.
In addition, it was found that even if the rotational speed of the tufting machine is further increased, it is considered that the linear actuator of the present invention can sufficiently follow, so that productivity can be nade still higher.
In the above-described embodiment, the case of applying the present invention to a tufting machine is described, but needless to say, the present invention may be used for other manufacturing apparatuses.
Number | Date | Country | Kind |
---|---|---|---|
JP2019-073562 | Apr 2019 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
5979344 | Christman, Jr. | Nov 1999 | A |
6283052 | Pratt | Sep 2001 | B1 |
20030005869 | Hicks | Jan 2003 | A1 |
20040025767 | Card et al. | Feb 2004 | A1 |
20050056197 | Card et al. | Mar 2005 | A1 |
20050109253 | Johnston | May 2005 | A1 |
20050204975 | Card et al. | Sep 2005 | A1 |
20060150882 | Johnston | Jul 2006 | A1 |
20060272564 | Card et al. | Dec 2006 | A1 |
20070119356 | Johnston | May 2007 | A1 |
20150091393 | Hayner | Apr 2015 | A1 |
20150091395 | Spivak | Apr 2015 | A1 |
20160305055 | Hall et al. | Oct 2016 | A1 |
20170264146 | Shibata et al. | Sep 2017 | A1 |
20180371663 | Hall et al. | Dec 2018 | A1 |
Number | Date | Country |
---|---|---|
60009357 | Jan 1985 | JP |
03-14976 | Feb 1991 | JP |
06-87449 | Mar 1994 | JP |
10-237755 | Sep 1998 | JP |
11-315465 | Nov 1999 | JP |
2000-14190 | Jan 2000 | JP |
2001-348768 | Dec 2001 | JP |
2006-524753 | Nov 2006 | JP |
2007-89382 | Apr 2007 | JP |
2007-107150 | Apr 2007 | JP |
2007-512451 | May 2007 | JP |
2008-144349 | Jun 2008 | JP |
2008-527199 | Jul 2008 | JP |
2008-200947 | Sep 2008 | JP |
2014-29057 | Feb 2014 | JP |
2016-123213 | Jul 2016 | JP |
2016-178749 | Oct 2016 | JP |
2018-078668 | May 2018 | JP |
WO-9715708 | May 1997 | WO |
Entry |
---|
Hasegawa (JP 60009357 A) English Translation (Year: 1985). |
Extended European Search Report dated May 13, 2020 in corresponding European Patent Application No. 19204881.7. |
Number | Date | Country | |
---|---|---|---|
20200318275 A1 | Oct 2020 | US |