JP3373166B2 - Circular saw cutting machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a circular saw cutting machine, and more particularly, to a circular saw cutting machine for preventing chatter vibration generated when cutting a metal work material. 2. Description of the Related Art Conventionally, this kind of circular saw cutting machine has a low speed,
In order to rotate the circular saw with high torque, the rotation of the electric motor is reduced and transmitted to the main shaft via a pulley and a gear mechanism provided in the gear box, and the circular saw is protruded from one end of the main shaft gear box. , And the metal work is cut by rotating the spindle at low speed and high torque.
Since the circular saw uses the gear mechanism in the rotation transmitting portion as described above, there is a backlash of the gear. Therefore, at the start of cutting for each cut by the circular saw and at the end of cutting, when the number of teeth involved in cutting Zi is in the range of 0 to 1.0, when the saw teeth bite into and out of the work material, the gears are cut. Rotational fluctuation corresponding to backlash occurs. Further, even when Zi is large, there are cases where regenerative chattering, which is self-excited vibration in the main body feed direction, and coupled chattering accompanied by fluctuation in rotation of the main shaft. Due to such fluctuations in the gear rotation, chatter vibration occurs in the circular saw, and the cutting accuracy is deteriorated, and the life of the circular saw is shortened due to damage and chipping of the cutting edge.
Furthermore, the working environment was deteriorated by the vibration noise. As a circular saw cutting machine for preventing such fluctuations in the rotation of gears, for example, as shown in Japanese Utility Model Publication No. Sho 62-28334, holding pieces are provided on both sides of a circular saw, and a hydraulic cylinder is operated on one of the holding pieces. There is known an apparatus in which a frictional force is applied before starting the cutting, thereby starting the cutting while removing the backlash of the power system, and releasing the frictional force by a timer halfway. In another circular saw cutting machine, as shown in Japanese Utility Model Publication No. 7-48339, a control shaft is directly connected via a gear to a main shaft to which the circular saw is attached, and a brake device is provided on the control shaft. This circular saw cutting machine is
From the start of cutting by the circular saw to the end of cutting, the backlash of the drive system gears is suppressed while the braking force is electrically controlled by an electromagnetic proportional valve to eliminate chatter vibration of the circular saw during cutting. ing. [0004] However, in the case of the above-mentioned circular saw cutting machine, at the beginning and end of cutting, a braking force is applied to the drive system to forcibly remove the backlash of the gear. The cutting is performed while losing the cutting power. Therefore, there is a problem that the mechanical structure becomes complicated and an electric control configuration is also required, so that the machine becomes expensive and maintenance work becomes complicated. SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and can eliminate chatter vibration of a circular saw during cutting to increase cutting accuracy, extend the life of the circular saw, and suppress noise generation at low cost. It is an object to provide a circular saw cutting machine. [0006] In order to achieve the above object, a structural feature of the first aspect of the present invention is that a rotation of an electric motor is transmitted to a main shaft, and a circle attached to one end of the main shaft. In a circular saw cutting machine that performs cutting with a saw, a constrained mesh gear train is configured by arranging three or more odd number of intermediate gears that mesh with a main shaft gear fixed to the main shaft and rotate simultaneously, and The rotation of the electric motor is input to one of the intermediate gears, and at least one of the intermediate gears is made movable. By applying a load to at least one of the movable intermediate gears, the backlash of the restricted meshing gear train is increased. When the outside diameter of the circular saw is D (mm), the number of revolutions is N (rpm), and the cutting force per tooth, which is the tangential component, is F (kgf), With backlash removed The sum of the main shaft conversion inertia moment including the major axis of each axis in conjunction ^{J (kgf · m · sec 2} ) is, J ≧ F × (D /
2) / [1000 × 250 × (N / 60) ² ]. According to the first aspect of the present invention, a flywheel having a necessary and sufficient moment of inertia is attached to a shaft of at least one of the intermediate gears constituting the restricted meshing gear train and is movable. By applying a load to the intermediate gears, the backlash of each gear constituting the constrained meshing gear train is eliminated, and the sum J (kgf · m · se
c ² ) is F × (D / 2) / [1000 × 250 × (N /
60) ² ] or more. As described above, by eliminating the backlash of the circular saw drive system and increasing the sum J of the spindle equivalent inertia moments, the start and end of cutting of the work material by the circular saw cutting machine in which rotation fluctuations are likely to occur. In a region where the number Zi of teeth involved in cutting is 1.0 or less, rotation fluctuation can be suppressed. In other words, the rotation fluctuation of the main spindle becomes small with respect to the cutting force F applied to the main spindle due to the intermittent cutting resistance, and the vibration attenuation of the machine body of the cutting machine becomes larger. Is suppressed, and the accuracy of the cut surface and the life of the blade can be greatly improved. Also,
Increasing the moment of inertia can also suppress the occurrence of regenerative chatter vibration or coupled chatter vibration that occurs when the number of teeth Zi involved in cutting is large. [0009] The basis of the above-described spindle converted inertia moment J will be described. As is well known, the following equation 1 holds for the moment of inertia J (kgf · m · sec ² ). T = J × dω / dt where T (kgf · m) is a torque and ω
= 2π · (N / 60) (rad / sec) is the angular velocity of rotation, and dω / dt (rad / sec ² ) is the angular acceleration. The maximum force per blade when the saw blade cuts the workpiece is F
(Kgf), the fluctuation torque T is as shown in Expression 2. T = F × (D / 2) / 1000 where D (mm) is the outer diameter of the circular saw.
Due to this torque fluctuation, the rotation speed of the main shaft is changed to the angular acceleration d.
f / dt. When the related factors are made dimensionless by using the above equations (1) and (2), the following equation (3) is obtained. K = F × (D / 2) / [1000 × J × (N
/ 60) ² ] where K is a constant. In the above equation 3, by setting the constant K to an appropriate value, the following equation 4 is obtained. J ≧ F × (D / 2) / [1000 × K × (N
/ 60) ² ] That is, by determining an appropriate value as the constant K, the moment of inertia J can be made to satisfy Equation 4. In this case, the rotational fluctuation of the gear due to the cutting force is reduced. Does not occur. Here, as a result of various cutting tests, it has been clarified that if K = 250 or more and the moment of inertia is in the relationship of Equation 4, the rotation fluctuation of the gear due to cutting is eliminated. In the present application, K = 250 is adopted as the limit value. An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 are a partially cutaway front view, a cross-sectional view (along the line II-II in FIG. 1) and a cross-sectional view (III-III in FIG. 1) of the swing type circular saw cutting machine according to the embodiment.
(Line direction). This circular saw cutting machine is
A box-shaped machine base 11 is provided, and the machine base 11 is rotatably supported by a support base 12 at a lower right position. Machine 1
A box-shaped gear box 20 is placed and fixed on the upper part of the gear box 1. The gearbox 20 includes a front wall 20a and a rear wall 20.
b, has a hollow shape surrounded by a right side wall 20c, a left side wall 20d, a top wall 20e, and a bottom wall 20f, and has a working chamber R filled with lubricating oil. The direction is viewed from the front of the table 11).
As shown in FIG. 2, the rear side wall 20b is provided with a space S extending from the left end to a position substantially at the intermediate position, and the space S is interposed between the rear wall 20b and the front wall 20b1. Wall 2
0b2. At a position on the left of the center of the gear box 20,
There are formed through holes 21a and 21b penetrating the front wall portion 20b1 and the rear wall portion 20b2 of the rear side wall 20b in the front-rear direction.
A mounting hole 21c is provided at an extension position of 1b. The drive shaft 22 is inserted through the through-holes 21a, 21b and the mounting hole 21c.
c is supported via a bearing so as to be rotatable and immovable in the axial direction. One end of the drive shaft 22 has a rear wall 20b.
, A pulley 24 is fixed to the protruding portion, and a drive shaft gear 23 is fixed to a portion inside the working chamber R 1. At a position near the right side wall 20c of the gear box 20, a through hole 25a penetrating through the front side wall 20a in the front-rear direction.
And a mounting hole 25b is formed on the front side of the rear wall 20b. The main shaft 26 is supported by the through-hole 25a and the mounting hole 25b via a bearing so as to be rotatable and immovable in the axial direction. One end of the main shaft 26 slightly protrudes forward from the front wall 20a, and the protruding portion has a flange 28.
, The circular saw 27 is fixed. Also, the spindle 26
The main shaft gear 29 is fixed to a portion inside the working chamber R. The drive shaft 2 in the gear box 20
2 and the intermediate position of the main shaft 26 in the front-rear direction.
a through hole 31a and the front wall 2 of the rear wall 20b.
A through hole 31b penetrating through 0b1 is formed. The intermediate shaft 32 is supported by the through holes 31a and 31b by bearings so as to be rotatable and immovable in the axial direction. An intermediate gear 33 is fixed to the intermediate shaft 32. The intermediate gear 33 is meshed with the drive shaft gear 23 and the main shaft gear 29, respectively, and is used for transmitting power from the drive shaft 22 to the main shaft 26. The drive shaft 22 in the gear box 20
As shown in FIG. 3, a through hole 34a penetrating through the front wall 20a and a through hole 34b penetrating through the front wall portion 20b1 of the rear wall 20b are formed in the lower left position in the front-rear direction.
In the through holes 34a and 34b, a support shaft 35 is supported by bearings so as to be rotatable and immovable in the axial direction. A swing arm 36 is fixed to the support shaft 35 as shown in FIG. Swing arm 36
Is substantially L-shaped when viewed from the front, and the intersection of the L-shaped vertical portion 36a and horizontal portion 36b is fixed to the support shaft 35. The upper end of the vertical portion 36a of the swing arm 36 is connected to the tip of a hydraulic cylinder 37 penetrating at a substantially middle position in the vertical direction of the left side wall 20d. It is rotatable. The horizontal portion 36b of the swing arm 36 is shown in FIG.
As shown in FIG. 5, a middle portion in the front-rear direction is a concave portion 36c cut out from the right end side, and the support shaft 38 is supported at the right end position of the horizontal portion 36b so as to be rotatable and immovable in the axial direction. . An intermediate gear 39 is fixed to the support shaft 38 at the position of the concave portion 36c.
3 and the main shaft gear 29.
The drive shaft gear 23 is one of intermediate gears, and includes an intermediate gear 39, a drive shaft gear 23, a main shaft gear 29 and an intermediate gear 3.
Numerals 3 constitute a constrained meshing gear train that meshes and rotates at the same time by forming a ring. The intermediate gear 39 is used for removing backlash of the restricted meshing gear train. That is, the driving of the hydraulic cylinder 37 causes the support shaft 3
The depth of engagement of the intermediate gear 39 with the drive shaft gear 23 and the main shaft gear 29 is controlled by the angle of the swing arm 36 that rotates about the center 5. In the rotation direction (illustrated, arrow direction) shown in the present embodiment, the rotation of the swing arm 36 shifts the axis of the intermediate gear 39 in a direction away from the other gears, thereby forcing the teeth. The gears are brought into contact with each other to reduce the backlash of the entire gear train to zero, and to apply a necessary pressure to the gears to suppress chatter vibration. Further, the pressure can be easily adjusted by a pressure adjusting valve (not shown) provided in the hydraulic circuit, and the pressure is operated only when necessary by a switching valve. As a result, useless power consumption and gear wear can be suppressed, and backlash can be maintained at zero even when gear wear progresses due to long-term use of the machine. Further, even if the gear has eccentricity or a gear shape error, it is absorbed by expansion and contraction of the hydraulic cylinder, so that an excessive load does not act on the tooth surface and the bearing. Furthermore, since it is not necessary to use a high-precision gear, a cutting machine can be manufactured at low cost. In addition,
When the rotation direction is opposite, the backlash of the entire gear train can be reduced to zero by shifting the moving direction of the intermediate gear 39 in a direction closer to other gears. A mounting portion 41 is provided on the upper surface wall 20e of the gear box 20, and the tip of a rod of a hydraulic cylinder (not shown) fixed to another place on the right side of the circular saw cutting machine is fixed. . The gear box 20 is pushed by the expansion and contraction of the rod of the hydraulic cylinder, and rotates around the support base 12. Also, the gearbox 20
In the vicinity of the lower end of the right side wall 20c, a cutting table 42 for attaching a work material 43 is provided. An acceleration sensor 44 is mounted on the right side of the front end of the upper surface wall 20e of the gear box 20, and detects the acceleration in the feed direction of the gear box 20 near the circular saw 27. An electric motor 45 is provided on the lower left side of the machine base 11.
Is attached. A pulley 46 is fixed to a shaft protruding to the rear side of the electric motor 45, and a belt 47 is wound around the pulley 46 and the pulley 24. Thus, the rotation of the electric motor 45 is transmitted to the main shaft 26 at a reduced speed via the drive shaft 22 and the intermediate shaft 32, and the circular saw 27 is rotated. And gearbox 2
Lubricating oil is filled in 0, and circulates in the working chamber R. (1) Cutting Test Next, the moment of inertia of the pulley 24 attached to the drive shaft 22 is changed into three types (performed by adding a flywheel to the pulley), and the work material 43 is A test was conducted on the effect of suppressing chatter vibration at the beginning of cutting when cutting a piece. Here, the load applied to the intermediate gear 39 by the hydraulic cylinder 37 was 150 kgf. The moment of inertia of the changed pulley 24 (P1 to P3) is shown in Table 1 below.
Shown in [Table 1] Table 2 below shows the spindle converted inertia moments of the common parts other than the pulley 24. [Table 2] The total spindle converted moment of inertia J obtained from the combination of each of the pulleys (P1 to P3) and the common parts.
s is as shown in Table 3 below. [Table 3] (2) Test Method A circular saw having an outer diameter D of φ280 mm, a thickness of T2.0 mm, a thickness of a base metal of t1.7 mm, and a number of blades of 60 was fixed to the main shaft 26 with a flange having a diameter of φ106 mm. . The work material is a chrome molybdenum steel SCM440H having a diameter of φ60 mm and a hardness of HRC = 30. As the cutting conditions, the feed per tooth was set to Sz = 0.08 mm / constant blade at a rotational speed N ≦ 130 rpm, and the circular saw feed speed f was set to 624 mm / min at a rotational speed higher than that. When the present invention is carried out, the lowest rotational speed Ncr at which no chatter vibration occurs at the beginning of cutting is actually measured.
The calculated Ncr calculated by (K = 250) is shown in Table 4 below. However, in the actual measurement, the presence or absence of chatter vibration was observed at a rotation speed of 10 rpm. However, since the amplitude of the chatter was not large, whether or not chatter vibration occurred at the beginning of cutting was determined by the effective value of the acceleration recorded in the pen recorder. Judgment was made based on the rising slope of. In addition to the chatter vibration accompanied by the rotation fluctuation of the gear backlash, other mechanical vibrations such as impact vibration (without the rotation fluctuation of the backlash) when the saw blade bites into the work material, It always occurs during rotation. [Table 4] (3) Test Results From the above results, the measured value Ncr was slightly smaller than the calculated value Ncr when the moment of inertia was small, but was substantially equal to the calculated value Ncr when the moment of inertia was large. In other words, it was confirmed that the analysis result by Equation 4 was substantially correct. 4 and 5 show examples of the pulley P3 with respect to the relationship between the rotational speed N of the circular saw and the maximum acceleration of vibration (G-rms). The higher the acceleration, the higher the vibration level of the machine body. Figure 4 shows a case where by the hydraulic cylinder 37 to the intermediate gear 39 does not act a load _{F G (F G = 0)} . However, a load due to the weight of the intermediate gear 39 and the swing arm 36 is applied. FIG. 5 shows that the intermediate gear 39 has the hydraulic cylinder 3
7 shows a case in which a load F _{G of} 150 kgf = 150 kgf is applied. As apparent from FIG. 5, when the backlash is removed by applying a load to the intermediate gear 39, the vibration at the start of cutting at a rotation speed higher than the minimum rotation speed is combined with the effect of the increase in the moment of inertia. And other than the beginning of cutting (between cutting when the number of cutting edges Zi exceeds 1)
It can be seen that the method is also very effective in removing chatter vibrations such as reproduction and coupling in a low frequency range. However,
As can be seen from FIG. 1, the intermediate gear 39 has a slight load due to the influence of gravity without applying a load, and the viscous action of the lubricating oil filled in the working chamber R of the gearbox 20. As a result, as shown in FIG. Also, since the rotation speed of the drive shaft 22 is higher than that of the main shaft 26, the pulley 2
Since the diameter of the flywheel attached to the wheel 4 can be reduced and the flywheel is not on the main shaft 26, interference between the wheel and the work material can be avoided, and the effect of reducing the machine weight can be obtained. In the above embodiment, when the tooth profile of the saw blade is special and the cutting force F varies depending on the blade, the maximum value is used. In the actual design, the value of the cutting force F is considered based on the life of the saw blade. Further, when the saw diameter changes, the maximum saw diameter is used as the value of the outer diameter D. Further, any of the intermediate gears may be a drive shaft gear, and a flywheel may be mounted on any of the intermediate gear shafts. Alternatively, a constrained mesh gear train having five or more intermediate gears may be used. However, if the number is more than 7, it is not practical due to problems such as mounting space and cost. In the present invention, the spindle-equivalent moment of inertia J is as shown in Expression 4. The larger the moment of inertia is, the more effective at preventing chatter vibration, but the flywheel is required to increase the moment of inertia. If the wheels are made heavy, it is necessary to increase the rigidity of the cutting machine, and the weight of the cutting machine may become too large. Therefore, in order not to make the moment of inertia too large, it is desirable to add the condition of the following equation 5 in addition to the above equation 4. In calculating the main shaft equivalent inertia moment of each shaft, the shaft itself, pulleys, gears, electric motors, and the like are naturally taken into account. J ≦ 3 ｛F × (D / 2) / [1000 × 25
0 × (N / 60) ² ]｝ The type of transmitting power from the motor shaft to the drive shaft by a belt is considered to have a substantial backlash because the belt is elastic. Further, the specific configuration of the circular saw cutting machine is not limited to the above-described one, and the present invention is not limited to the swing type but can be similarly applied to a slide type circular saw cutting machine. According to the present invention, the back mesh of the drive system can be completely eliminated by forming a restraining mesh gear train and applying a load to the movable intermediate gear, so that the flywheel can be mounted on the main shaft. The same vibration suppression effect as when the wheels are directly connected can be obtained, and vibration and noise can be reduced at low cost. Such a reduction in vibration and noise can prevent the working environment from deteriorating. Also, by mounting the flywheel on the intermediate shaft with a high rotation speed, the diameter of the flywheel can be made smaller than the method directly connected to the main shaft, and since the flywheel is not on the main shaft, interference between the wheel and the work material In addition to avoidance, the effect of reducing the machine weight can be obtained. Further, the pressurizing force can be easily adjusted by the pressure adjusting valve provided in the hydraulic cylinder circuit. Further, the pressurizing force is applied only at the time of cutting by the switching valve, and the pressurizing force is stopped at the time of idling. Power consumption and gear wear can be reduced. Further, the backlash can be maintained at zero even when the gear wears due to long use. Also, even if the gear has eccentricity or gear shape error,
Since it is absorbed by the expansion and contraction of the hydraulic cylinder, an excessive load does not act on the tooth surface and the bearing. Further, since it is not necessary to use a high-precision gear, a cutting machine can be manufactured at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken front view showing a swing type circular saw cutting machine according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II shown in FIG. FIG. 3 is a sectional view taken along line III-III shown in FIG. FIG. 4 shows the relationship between the rotational speed N of the circular saw and the maximum acceleration of machine body vibration (G-rms) when no load is applied to the intermediate gear of the circular saw cutting machine (pulley P3) by the hydraulic cylinder. It is a graph shown. FIG. 5 shows the relationship between the rotational speed N of the circular saw and the maximum acceleration (G-rms) of vibration of the machine main body when a load by a hydraulic cylinder is applied to the intermediate gear of the circular saw cutting machine (pulley P3). FIG. [Description of Signs] 11: Machine stand, 12: Support stand, 20: Gear box, 22
... Drive shaft, 23 ... Drive shaft gear, 24 ... Pulley, 26 ... Main shaft, 27 ... Circular saw, 29 ... Main shaft gear, 32 ... Intermediate shaft, 33
... Intermediate gear, 35 ... Support shaft, 36 ... Swing arm, 3
7 hydraulic cylinder, 38 support shaft, 39 intermediate gear, 4
DESCRIPTION OF SYMBOLS 1 ... Mounting part, 42 ... Cutting table, 43 ... Work material, 45 ... Electric motor, 46 ... Pulley, 47 ... Belt.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B23D 47/00-47/12 B23D 45/00

Claims (1)

(1) A circular saw cutting machine for transmitting rotation of an electric motor to a main shaft and performing cutting by a circular saw attached to one end of the main shaft, wherein the main shaft fixed to the main shaft is provided. A constrained meshing gear train is formed by arranging three or more odd number of intermediate gears that mesh with each other and rotate at the same time as the gears and the wheels, and input and transmit the rotation of the electric motor to one of the intermediate gears. , At least one of the intermediate gears is movable, and a load is applied to at least one of the movable intermediate gears to remove backlash of the restricted meshing gear train. When the diameter is D (mm), the number of rotations is N (rpm), and the cutting force per tooth, which is the tangential component, is F (kgf), each of the shafts interlocked with the main shaft without backlash. Spindle conversion inertia model including the spindle The sum J (kgf · m · sec ² ) is J ≧ F × (D / 2) / [10
00 × 250 × (N / 60) ² ].