BAND SAW MACHINE THAT CAN DETECT THE TENSION OF THE SAW BAND

Abstract

Band saw machine (1), which comprises: a base (10) having a straight column (11), an upper wheel housing (12) connected to the straight column (11), and a lower wheel housing (13) connected to the straight column (11) and spaced from the upper wheel housing (12); a saw unit (20) having an upper axle (21) arranged vertically movable in the upper wheel housing (12), an upper wheel (22) rotatably connected to the upper axle (21), a lower axle (23) arranged in the lower wheel housing (13), a lower wheel (24) rotatably connected to the lower axle (23), and a saw band (25) wound around the upper wheel (22) and the lower wheel (24); a tension adjustment unit (30) arranged on the base (10) and connected to the upper axis (21) for pushing the upper axis (21) upward; and a stress detector (40) arranged on the upper axis (21) and detecting a slight deformation of the upper axis (21).

Description

BACKGROUND OF THE INVENTION 1. Technical field

[0001] The present invention relates to a band saw machine and, more particularly, to a vertical band saw machine that can accurately detect the tension of a saw blade. 2. State of the art

[0002] Before using a vertical band saw to saw a workpiece, the operator must adjust the saw blade of the vertical band saw to an appropriate tension. If the saw blade tension is too high, the saw blade is likely to break during sawing, but if the saw blade tension is insufficient, the problem of a saw line being uneven or the saw blade loosening may occur. On the other hand, the saw blade needs to be adjusted to different tensions depending on the size of the saw blades or the materials being processed. For example, a workpiece to be sawn may be made of cast iron with higher hardness or aluminum alloy with lower hardness.

[0003] As far as the inventor is aware, the current band saw machine cannot accurately detect the tension of the saw blade, making it difficult for the operator to adjust the saw blade to the correct tension for sawing. Therefore, the design of the current band saw machine is not perfect and there is still room for improvement. DE102013204636 A1 discloses a guard device of a band saw machine having a tension adjustment device with a movable base connected to a driven wheel for adjusting the tension of a saw blade that rotates around the driven wheel. US2016236291 A1 discloses a system for controlling the feed rate of a band saw having a saw blade guided around a drive wheel and a tension adjustment mechanism for adjusting the tension on the saw blade by changing the distance between them. CN208840610 U discloses a vertical saw with a saw blade tension display.A saw blade clamping device for adjusting the height of the driven saw blade and a tension indicator are arranged on a frame. CN201697842 U discloses a saw blade clamping system applied to a fatigue strength tester for band saw machines and band saw blades. The system includes a guide rail arranged on a base frame. A shaft is arranged on one side of the guide rail on the base frame.A saw blade is mounted on the shaft; a slide carriage capable of linearly reciprocating sliding on the guide rail is mounted on the guide rail; one end of the slide carriage is connected to the saw blade; the other end of the slide carriage is connected with a screw; a spring is fitted onto the screw; the other end of the screw is provided with a handle; a tension sensor is mounted in the slide carriage; and the tension sensor is connected to a digital display instrument capable of displaying the tension value. SUMMARY OF THE INVENTION

[0004] It is a primary object of the present invention to provide a band saw machine that can effectively and accurately detect the tension of a saw blade to facilitate an operator in adjusting the saw blade to a correct tension.

[0005] To achieve the above object, the band saw machine of the present invention comprises a base, a saw unit, a tension adjustment unit, and a tension detector. The base has a straight column, an upper wheel housing connected to the straight column, and a lower wheel housing connected to the straight column and spaced from the upper wheel housing. The saw unit includes an upper axle vertically movably disposed in the upper wheel housing, an upper wheel rotatably connected to the upper axle, a lower axle disposed in the lower wheel housing, a lower wheel rotatably connected to the lower axle, and a saw band wound around the upper wheel and the lower wheel. The tension adjustment unit is disposed in the base and connected to the upper axle to urge the upper axle upward.The tension detector is located on the upper axle and detects slight deformation of the upper axle. In one aspect, the upper wheel housing includes an adjustment base provided with a threaded hole. The tension adjustment unit includes a lifting block attached to the upper axle and an adjustment screw that is screwed to the threaded hole of the adjustment base and pushes the lifting block upward to adjust the tension of the saw blade.

[0006] In particular, the tension adjustment unit further includes a compression spring that is slid onto the adjustment screw and protrudes above an upper end of the adjustment screw. The adjustment screw pushes the lifting block upward through the compression spring to generate a buffer force.

[0007] In particular, the adjusting screw is connected to a stop block. The compression spring is pushed onto the adjusting screw and rests with both ends on the lifting block and the stop block, respectively.

[0008] In another aspect, the band saw machine further comprises a drive motor disposed in the lower wheel and having an output shaft, a first pulley coaxially connected to the upper wheel, a second pulley coaxially connected to the output shaft, and a belt wound around the first pulley and the second pulley. Thus, the drive motor can rotate the lower wheel via the belt and the two pulleys, thus driving the saw blade for the sawing operation.

[0009] In another aspect, the band saw machine further includes a display unit disposed on the base and a control chip electrically connected to the tension detector, which controls the display unit to display tension information of the saw blade according to the slight deformation detected by the tension detector. Thus, the operator can conveniently adjust the tension adjustment unit via the display unit to adjust the tension of the saw blade.

[0010] The indicator unit may, in particular, consist of one or more indicator lights. The control chip controls the indicator light to turn on or off depending on the slight deformation detected by the tension detector, thereby indicating whether the saw blade tension is set to a desired value.

[0011] In another aspect, the control chip is electrically connected to the voltage detector via a wired connection. If the voltage detector is installed at other locations on the band saw machine, the signal detected by the voltage detector can be wirelessly transmitted to the control chip.

[0012] Further advantages and features of the present invention will be fully understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numerals designate like structural components. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a band saw machine of the present invention. Fig. 2 is similar to Fig. 1 and shows the opened housing covers of the upper and lower wheel housings. Fig. 3 is an enlarged view of Fig. 2, in which the upper wheel and the saw blade are omitted. Fig. 4 is a partial sectional view of Fig. 2. Fig. 5 is an enlarged view of Fig. 2. Fig. Figure 6 is a block diagram of the signal connection of the voltage detector. DETAILED DESCRIPTION OF THE INVENTION

[0013] The Fig. The band saw machine 1 of the present invention shown in Figures 1 to 5 comprises a base 10, a saw unit 20, a tension adjustment unit 30, and a tension detector 40.

[0014] The base 10 comprises a straight column 11, an upper wheel housing 12 and a lower wheel housing 13. The straight column 11 is hollow and is connected to the upper wheel housing 12 and the lower wheel housing 13. Fig. 1 serves as a direction indicator. The upper and lower wheel housings 12, 13 are connected to the right side of the straight column 11 and are vertically spaced from each other. The upper wheel housing 12 has a lower opening 121, and the lower wheel housing 13 has an upper opening 131. The lower opening 121 is located directly above the upper opening 131. The upper and lower wheel housings 12, 13 each have a housing cover 122, 132 pivotally connected to the straight column 11. Fig. 2. shows the opened housing covers 122, 132. As in Fig. 3 and Fig. As shown in Figure 4, the upper wheel housing 12 has a chamber 14 inside. An adjustment base 15 is fixed to an inner wall of the chamber 14 and provided with a threaded hole 151. Note that, in this embodiment, the adjustment base 15 is arranged inside the upper wheel housing 12 by way of example. In some cases, the adjustment base 15 may be connected to the outside of the upper wheel housing 12, not being limited to this embodiment.

[0015] As in the Fig. 2, Fig. 4 and Fig. 5, the saw unit 20 comprises an upper axle 21, an upper wheel 22, a lower axle 23, a lower wheel 24, and a saw blade 25. The upper axle 21 is vertically movable within the upper wheel housing 12. The upper wheel 22 is considered a driven wheel in this embodiment, comprising a wheel portion 221, six spokes 222, and a shaft portion 223. Two opposite ends of the spokes 222 are connected to the wheel portion 221 and the shaft portion 223. The shaft portion 223 is supported on the upper axle 21 via a bearing, so that the upper wheel 22 is rotatably mounted on the upper axle 21. The lower axle 23 is disposed within the lower wheel housing 13. The lower wheel 24 is used as a drive wheel, and the lower wheel 24 is rotatably mounted on the lower axle 23. The saw blade 25 is mounted around the upper wheel 22 and the lower wheel 24.The left side of the saw blade 25 is located on the right side of the straight column 11 and is covered by a cover plate 111. The right side of the saw blade 25 passes through the lower opening 121 of the upper wheel housing 12 and the upper opening 131 of the lower wheel housing 13. When the lower wheel 24 is rotated, the saw blade 25 is moved for sawing.

[0016] As in Fig. 5, the band saw machine 1 in this embodiment is equipped with a drive motor 51, a first pulley 52, a second pulley 53 and a belt 54 to rotate the lower wheel 24.

[0017] The drive motor 51 is installed in the lower wheel housing 13 and provided with an output shaft 511. The first pulley 52 is coaxially connected to the lower wheel 24. The second pulley 53 is coaxially connected to the output shaft 511. The belt 54 is mounted around the first and second pulleys 52, 53. When the drive motor 51 is started, the drive motor 51 drives the lower wheel 24 in rotation via the first and second pulleys 52, 53 and the belt 54. In some cases, the output shaft 511 of the drive motor 51 can be regarded as the lower axle 23, so that the first and second pulleys 52, 53 and the belt 54 can be omitted.

[0018] As in the Fig. 3 and Fig. 4, the tension adjustment unit 30 is arranged on the upper wheel housing 12 of the base 10 and connected to the upper axle 21 to push the upper axle 21 upward so that the upper wheel 22 can push the saw blade 25 upward, thereby adjusting the tension of the saw blade 25. In this embodiment, the tension adjustment unit 30 includes a lifting block 31, an adjusting screw 32, a handwheel 33, and a compression spring 34. The lifting block 31 is vertically movably arranged in the chamber 14 of the upper wheel housing 12 and is fixed to the upper axle 21. The adjusting screw 32 has an upper portion 321 and a threaded portion 322 that is screwed into the threaded hole 151 of the adjustment base 15. A step difference is formed between the upper portion 321 and the threaded portion 322, which is connected to a stop block 35.The compression spring 34 is pushed onto the upper part 321 of the adjusting screw 32 and protrudes beyond the upper part 321. The two ends of the compression spring 34 rest against the lifting block 31 and the stop block 35, respectively. The handwheel 33 is located below the upper wheel housing 12 and is connected to the lower end of the adjusting screw 32. When the handwheel 33 is turned by the operator, the adjusting screw 32 pushes the lifting block 31 and the upper wheel 22 connected to the lifting block 31 upward via the stop block 35 and the compression spring 34. It should be noted that the compression spring 34 is not required. In some cases, the compression spring 34 can be omitted, so that the adjusting screw 32 is directly connected to the lifting block 31. Therefore, it should not be limited to this embodiment.

[0019] The tension detector 40 is used to detect the tension of the saw blade 25 when the saw blade 25 is wound around the upper and lower wheels 22, 24. In this embodiment, the tension detector 40 is a strain gauge. The tension detector 40 is attached to the upper axle 21. When the saw blade 25 is wound around the upper and lower wheels 22, 24, the upper wheel 22 exerts an upward force on the saw blade 25, so that the upper axle 21 is slightly deformed by this force. The tension detector 40 detects a slight deformation of the upper axle 21 and generates a change in the resistance value. At the same time, the tension detector 40 is connected to a control chip 70 (see Fig. 6) is used, which is electrically connected to the voltage detector 40 via a wire connection. The control chip 70 is equipped with a signal amplifier 71 to obtain the change in resistance value. The aforementioned resistance value and the current voltage of the saw blade 25 are in a corresponding relationship. In some cases, a piezoelectric sensor or a capacitive sensor can be used as the voltage detector 40.

[0020] In order to indicate to the operator the tension of the saw band 25 and to inform him whether the current tension is sufficient, a display unit 60 (as shown in Fig.1). The display unit 60 in this embodiment consists of two indicator lamps 61, 62. The two indicator lamps 61, 62 emit red and green light, respectively. When the control chip 70 receives the tension information of the saw blade 25 through the tension detector 40, if the tension of the saw blade 25 is insufficient, the control chip 70 controls the indicator lamp 61, which emits red light, to turn on and controls the indicator lamp 62, which emits green light, to turn off. Conversely, if the tension of the saw blade 25 is sufficient (or correct), the control chip 70 controls the indicator lamp 62, which emits green light, to turn on and controls the indicator lamp 61, which emits red light, to turn off.

[0021] Note that the display unit 60 in this embodiment uses two indicator lamps 61, 62 as an example. However, the display unit 60 may also be an LED that emits light or a screen that can display numerical values. The display unit 60 may also be a virtual indicator light on the screen of a mobile phone, which transmits the voltage detected by the voltage detector 40 to an APP of the mobile phone via a Wi-Fi connection, thereby displaying or turning off the virtual indicator light. Therefore, it should not be limited to this embodiment.

[0022] By the configuration of the band saw machine 1 of the present invention, on the one hand, the operator can adjust the tension of the saw blade 25 through the tension adjustment unit 30, and on the other hand, the operator can obtain the tension information of the saw blade 25 through the tension detector 40 to facilitate the operator to adjust the saw blade 25 to a correct and appropriate tension.

[0023] Since the spokes 222 of the upper wheel 22 and the lower axle 23 can be easily deformed by the tension of the saw blade 25, the tension detector 40 can be attached to the spokes 222 of the upper wheel 22 or the lower axle 23. When the tension detector 40 is attached to the spokes 222 of the upper wheel 22, the tension detector 40 can be electrically connected to the control chip 70 in a wireless connection to facilitate the transmission of the signal to the control chip 70.

[0024] The invention thus described is obviously susceptible of variation in many respects. Such variations are not to be regarded as a departure from the spirit and scope of the invention. All such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

[1] Band saw machine (1), which comprises: a base (10) having a straight column (11), an upper wheel housing (12) connected to the straight column (11), and a lower wheel housing (13) connected to the straight column (11) and spaced from the upper wheel housing (12); a saw unit (20) having an upper axle (21) arranged vertically movable in the upper wheel housing (12), an upper wheel (22) rotatably connected to the upper axle (21), a lower axle (23) arranged in the lower wheel housing (13), a lower wheel (24) rotatably connected to the lower axle (23), and a saw band (25) wound around the upper wheel (22) and the lower wheel (24); a tension adjustment unit (30) arranged on the base (10) and connected to the upper axis (21) for pushing the upper axis (21) upward; and a stress detector (40) arranged on the upper axis (21) and detecting a slight deformation of the upper axis (21). [2] The band saw machine (1) according to claim 1, wherein the upper wheel housing (12) has an adjusting base (15) provided with a threaded hole; the tension adjusting unit (30) has a lifting block (31) fixed to the upper axle (21), and an adjusting screw (32) screwed to the threaded hole of the adjusting base (15) and pushing the lifting block (31) upward. [3] The band saw machine (1) according to claim 2, wherein the tension adjustment unit (30) further comprises a compression spring (34) fitted onto the adjustment screw (32) and projecting beyond an upper end of the adjustment screw (32); and the adjustment screw (32) presses the lifting block (31) to move upward by the compression spring (34). [4] Band saw machine (1) according to claim 3, wherein the adjusting screw (32) is connected to a stop block (35); and the compression spring (34) is pushed onto the adjusting screw (32) and rests with its two ends against the lifting block (31) and the stop block (35), respectively. [5] The band saw machine (1) according to claim 1, further comprising a drive motor (51) disposed in the lower wheel housing (13) and having an output shaft (511), a first pulley (52) coaxially connected to the upper wheel (22), a second pulley (53) coaxially connected to the output shaft (511), and a belt (54) wound around the first pulley (52) and the second pulley (53). [6] Band saw machine (1) according to claim 1, further comprising a drive motor (51) arranged in the lower wheel housing (13) and having an output shaft (511) which is the lower axis (23). [7] The band saw machine (1) according to claim 1, further comprising a display unit and a control chip (70) electrically connected to the tension detector (40) and controlling the display unit to display tension information of the saw band (25) corresponding to the slight deformation detected by the tension detector (40). [8] The band saw machine (1) according to claim 7, wherein the display unit is an indicator lamp (61) arranged in the base (10); the control chip (70) controls the indicator lamp (61) to be turned on or off according to the slight deformation detected by the stress detector (40). [9] Band saw machine (1) according to claim 8, wherein the control chip (70) is electrically connected to the voltage detector (40) via a wire connection. [10] Band saw machine (1), which comprises: a base (10) having a straight column (11), an upper wheel housing (12) connected to the straight column (11), and a lower wheel housing (13) connected to the straight column (11) and spaced from the upper wheel housing (12); a saw unit (20) having an upper axle (21) arranged vertically movable in the upper wheel housing (12), an upper wheel (22) rotatably connected to the upper axle (21) and having a wheel portion (221), a shaft portion (223) and a plurality of spokes (222) connected to the wheel portion (221) and the shaft portion (223), a lower axle (23) arranged in the lower wheel housing (13), a lower wheel (24) rotatably connected to the lower axle (23), and a saw band (25) wound around the upper wheel (22) and the lower wheel (24); a tension adjustment unit (30) arranged on the base (10) and connected to the upper axis (21) for pushing the upper axis (21) upward; and a tension detector (40) arranged on one of the spokes (222) and detecting a slight deformation of the corresponding spoke (222). [11] Band saw machine (1), which comprises: a base (10) having a straight column (11), an upper wheel housing (12) connected to the straight column (11), and a lower wheel housing (13) connected to the straight column (11) and spaced from the upper wheel housing (12); a saw unit (20) having an upper axle (21) arranged vertically movable in the upper wheel housing (12), an upper wheel (22) rotatably connected to the upper axle (21), a lower axle (23) arranged in the lower wheel housing (13), a lower wheel (24) rotatably connected to the lower axle (23), and a saw band (25) wound around the upper wheel (22) and the lower wheel (24); a tension adjustment unit (30) arranged on the base (10) and connected to the upper axis (21) for pushing the upper axis (21) upward; and a stress detector (40) arranged on the lower axis (23) and detecting a slight deformation of the lower axis (23).

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