JP2016101610A - Machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining device capable of reducing vibrations generated between a workpiece and a tool during machine, in the machining device carrying out mechanical machining.SOLUTION: A machining device 1 holds a long-shaped workpiece 5 made from metallic material while the workpiece is bent along a long shaft on a fixed base 3, and makes a tool 13 act to the workpiece, thereby performing mechanical machining. The machining device 1 has a pair of end portion holding tools 41 for holding the workpiece 5 by parts separated from each other, and an intermediate holding tool 42 for holding the workpiece 5 by parts between the pair of the end portion holding tools 41. Preferably, the pair of the end portion holding tools 41 and the intermediate holding tool 42 apply force opposite to each other on the workpiece 5 to bend the workpiece 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a processing apparatus, and more particularly to a processing apparatus that performs machining on a workpiece held on a fixed base.

  When a metal product is manufactured through welding, a weld bead is formed at the weld. The generated weld bead is often removed by cutting, polishing, or the like for the purpose of avoiding interference with other members.

  For example, when manufacturing an axle housing used for housing a rear axle of a large vehicle such as a truck, as described in Patent Documents 1 and 2, a main body portion that is divided into two parts is formed. While joining by welding, another member called a triangular plate is attached by welding (refer FIG. 2). Thereafter, the weld bead is removed by cutting at the welded portion of the joint portion of the main body and the attachment portion of the triangular plate.

JP 7-328765 A JP 2010-247765 A

  When cutting a projection such as a weld bead in a workpiece made of metal as described above, in order to accurately cut the portion where the projection is formed, the workpiece is placed on a fixed base. The vibration (chatter vibration) generated during cutting between the workpiece and the cutting tool is required to be as small as possible. When chatter vibration is generated, there is a possibility that processing accuracy may be reduced, or a component of the processing apparatus such as a cutting tool may be damaged. When machining is performed by moving a tool with respect to the workpiece, such as polishing and cutting, as well as cutting, the vibration of the workpiece often affects the machining accuracy.

  When fixing a workpiece, conventionally, the workpiece is generally placed on a fixed base, and a workpiece including both ends is fixed using a holding device fixed to the fixed base, such as a clamp device or a chuck device. Several places were pressed toward the fixed base from above. However, in this case, it is difficult to sufficiently suppress the vibration of the workpiece during processing.

  The problem to be solved by the present invention is to provide a machining apparatus capable of reducing vibration generated between a workpiece and a tool during machining in a machining apparatus that performs machining.

  In order to solve the above-mentioned problems, a processing apparatus according to the present invention holds a long workpiece made of a metal material in a state of being bent along a long axis on a fixed base, and performs machining. The gist is to do.

  Here, the said processing apparatus hold | maintains the said workpiece in the site | part between a pair of edge holders which hold | maintain the said workpiece in the site | part which mutually separated, and a pair of said edge holders. It is preferable that the pair of end holders and the intermediate holder bend the workpiece by applying forces in opposite directions to the workpiece. .

  In this case, the pair of end holders may apply an upward force to the workpiece, and the midway holder may apply a downward force to the workpiece.

  Further, the processing device is a processing device for processing a workpiece having a plate-like portion at a midway portion, and the midway holding tool places the plate-like portion of the workpiece between the fixed base and the workpiece. It is good that it is a clamp device which holds by pinching.

  The tool may be a cutting tool.

  According to the machining apparatus according to the above invention, the workpiece is held in a bent state, and thus a reaction force opposite to the bending direction is generated on the workpiece. Since the external force and the reaction force applied to bend the workpiece are balanced, the workpiece in the bent state is stably held. Thereby, even if a tool moves in the state which contacted the surface of the workpiece during machining, it becomes difficult for a workpiece to generate vibration.

  Here, the processing apparatus includes a pair of end holders that hold the workpieces at sites separated from each other, and a midway holder that holds the workpieces at a site between the pair of end holders , And a pair of end holders and intermediate holders effectively deflect the workpiece by applying forces in opposite directions to the workpiece. Can be held stably.

  In this case, according to the configuration in which the pair of end holders applies an upward force to the workpiece, and the midway holder applies the downward force to the workpiece, the tool is moved from above to the workpiece. It is possible to effectively suppress vertical vibrations when processing is applied to the surface.

  Further, when the processing apparatus is for processing a workpiece having a plate-like portion at a midway portion, the intermediate holding tool holds the plate-like portion of the workpiece between the fixed base and the clamp. According to the structure which is an apparatus, since the midway part of a workpiece can be firmly pressed and fixed with respect to a fixed base, the vibration at the time of a process can be prevented effectively.

  In addition, when the tool is a cutting tool, in general, vibration is often applied to the work piece during cutting, but this vibration can be obtained by bending and holding the work piece as described above. Can be effectively suppressed, and high processing accuracy can be obtained.

It is a perspective view showing the cutting device concerning one embodiment of the present invention. In the said cutting device, it is an enlarged view which shows the to-be-processed object vicinity. It is a figure which expands and shows the trunk | drum vicinity further. In the figure, a part of the wall surface in front of the trunk is cut out. It is explanatory drawing which shows the bending of a to-be-processed object, (a) shows the case where a middle part is bent below, (b) has shown the case where a middle part is bent upwards. It is a figure which shows the measurement position of the deflection amount in an Example. It is a figure which shows the measurement result of bending amount.

  Hereinafter, a processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Outline of cutting device]
1-3, the outline of the cutting apparatus 1 is shown as a processing apparatus concerning one Embodiment of this invention. The cutting apparatus 1 performs cutting of the surface of the workpiece 5 installed on the fixed base 3.

  The fixed base 3 is provided with a holder 4 including a pair of end holders 41 and a set of four intermediate holders 42. Although details of the holder 4 will be described later, it plays a role of stably holding the workpiece 5 placed on the fixed base 3.

  The cutting apparatus 1 has two robot arms 10a and 10b. Each of the robot arms 10a and 10b has six axes, and each axis is driven by a servo motor (11 or the like).

  Spindle motors 12 are attached to the tips of the two robot arms 10a and 10b, and a cutting tool 13 such as a face mill cutter is coupled to the output shaft of each spindle motor 12. In the two robot arms 10a and 10b, the first robot arm 10a cuts the right half area of the workpiece 5, and the second robot arm 10b cuts the left half area of the workpiece 5. Thus, according to each movable range, the different area | region of the workpiece 5 can be cut, and the whole area | region of the workpiece 5 can be cut in cooperation.

  Further, in the present cutting apparatus 1, a shape measuring device 14 is disposed adjacent to the spindle motor 12 at the tip of one of the two robot arms 10a and 10b (the first robot arm 10a in FIG. 1). It may be attached. The shape measuring device 14 measures the shape of the metal surface by optical measurement. For example, the shape measuring device 14 emits a line-shaped laser beam to the surface of the workpiece 5 and measures a distance on a two-dimensional surface by an optical cutting method. A measurement device that performs the above can be exemplified. The cutting device 1 is further provided with a control unit (not shown) that controls the movement of the robot arms 10a and 10b, the rotation of the spindle motor 12, and the measurement by the shape measuring device 14.

[Workpiece]
A workpiece 5 to be cut using the cutting device 1 according to the present embodiment has a protrusion 54 to be removed, a central portion can be fixed by a clamping device, and can be pushed up at both ends. As long as it is a long object made of a simple metal material, it does not matter. The workpiece 5 may have a cylindrical part in part or in whole. Examples of the protrusion 54 to be removed include a weld bead, a so-called burr, and material distortion.

  Here, the axle housing 5 is treated as an example of the workpiece. The axle housing 5 is used for a rear axle portion of a large vehicle such as a truck, and houses an axle, a differential gear, and the like. As shown in FIG. 2, the axle housing 5 has a body portion 51 and a cylindrical portion 52 as main body portions. The body 51 is formed by bending a steel plate into a semi-cylindrical shape (substantially U-shaped or substantially U-shaped in cross section) and bulging into a substantially annular shape, and accommodates a differential gear. Both surfaces of the body portion 51 are plate-like end surfaces 51a having a substantially annular shape, and the edge 51b of the steel plate is exposed inside the annular shape. And the hollow cylindrical part 52 by which an axle shaft is penetrated is formed in the radial direction both sides of the trunk | drum 51. As shown in FIG. A substantially triangular triangular plate 53 is attached to the gap formed between the body portion 51 and the tubular portion 52.

  The main body of the axle housing 5 is manufactured from two divided members. That is, by manufacturing two split members obtained by dividing the annular shape of the trunk portion 51 and the cylindrical shape of the cylindrical portion 52 in half, the end edges of the two split members are butted at the cylindrical portion 52 and welded. A body portion is formed. Thereafter, the triangular plate 53 is disposed at a portion between the trunk portion 51 and the cylindrical portion 52, and the portion between the main body portion and the triangular plate 53 is welded.

  The axle housing 5 formed in this way has a weld bead 54 at a joint between the two divided members and a portion between the main body and the triangular plate 53. These weld beads 54 need to be removed as flat as possible from the viewpoint of preventing interference with members attached to the axle housing 5 in a later step. Therefore, these welding beads 54 are cut using the cutting device 1 according to the present embodiment.

[Holder configuration and workpiece holding]
Here, the details of the holder 4 that holds the workpiece 5 on the fixed base 3 will be described. As described above, the holder 4 includes a pair of end holders 41 and a pair of midway holders 42.

  The end holder 41 is fixed on the fixed base 3 at a position where the end of the cylindrical portion 52 of the axle housing 5 which is a workpiece is disposed. Each end holder 41 has an end holding recess 41a on the upper side. The end holding recess 41 a is a concave structure cut into a curved shape or a substantially V shape that is substantially the same as or slightly larger than a part of the outer shape of the cylindrical portion 52 of the axle housing 5. The cylindrical portion 52 can be placed in contact. The height of the end holding recess 41a from the fixed base 3 is determined so as to push up the cylindrical portion 52 of the axle housing 5 placed on the fixed base 3. The fixing base 3 is provided with a stepped portion 31 that is higher than the surface to which the end holder 41 is fixed in order to place the barrel housing 51 of the axle housing as appropriate.

  Each of the set of midway holders 42 includes a clamp device, specifically, a swing clamp. In each halfway holding tool 42, a base 42 a is fixed on the fixing base 3 at a position inside the annular shape of the body 51 of the axle housing 5. And the edge 51b of one end surface 51a of the trunk | drum 51 of the axle housing 5 is pressed and hold | maintained toward the fixed base 3 with the press part 42b connected with the base 42a so that space | interval adjustment is possible. The four halfway holders 42 are arranged substantially axisymmetrically with respect to the center of the body portion 51.

  The axle housing 5 placed on the fixed base 3 is held with the ends of the cylindrical portions 52 at both ends being applied with force by the end holder 41 upward. The midway body 51 is held by the midway holding tool 42 in a state where a force is applied downward. As described above, the force is applied in the reverse direction in the vertical direction by the end holder 41 and the midway holder 42, so that the axle housing 5 is bent (curved) at the end and downward at the middle. A) state. If bending is shown extremely, it will become like Fig.4 (a).

  In the axle housing 5 bent in this way, a reaction force works due to the elasticity of the metal material (steel plate). As shown in FIG. 4A, the reaction force Fr acts in the direction opposite to the bending direction of the axle housing 5, that is, in the direction of lifting the midway portion upward. The magnitude of the reaction force Fr is balanced with the external force Fe applied to the axle housing 5 by the end holder 41 and the midway holder 42.

  In this way, the external force Fe that deflects the axle housing 5 and the reaction force Fr exerted in the opposite direction to the external force Fe are balanced, so that the axle housing 5 is stably held at a predetermined position on the fixed base 3. . As a result, when the cutting tool 13 is brought into contact with the surface of the axle housing 5 from above and cutting is performed, even if the cutting tool 13 rotates, the axle housing 5 does not easily vibrate (chatter vibration). As a result, it is possible to suppress a decrease in machining accuracy due to vibration of the axle housing 5. For example, when cutting the weld bead 54 on the surface of the axle housing 5, the fixing is performed by simply pressing the axle housing 5 from above or by pressing from both ends of the cylindrical portion 52 toward the center. Higher surface smoothness can be achieved compared to cases.

  As described above, the direction in which the workpiece including the axle housing 5 is bent is not limited to the direction in which the end portion is bent upward and the midway portion is bent downward, but the cutting tool 13 contacts the workpiece 5. By bending along the direction in which the workpiece is cut, it is possible to effectively suppress the workpiece 5 from vibrating along that direction as the cutting tool 13 moves. That is, when the cutting tool 13 performs cutting from above the workpiece 5 as described above, the vibration in the vertical direction associated with the cutting is effectively generated by bending the axle housing 5 along the vertical direction. Can be suppressed.

  As the bending in the vertical direction, there are a case where the middle part is bent as shown in FIG. 4 (a) and a case where the middle part is raised as shown in FIG. 4 (b). Even in this case, the effect of suppressing the vibration in the vertical direction can be obtained. When the workpiece has a cylindrical portion 52 at both ends, like the axle housing 5, and has a plate-like portion such as an end face 51a in the middle, as described above, It is excellent in holding stability that the both ends are raised and bent in the direction of lowering the midway portion. This is because the plate-like part existing in the middle part such as the end face 51a is easily sandwiched between the fixing base 3 by the clamping device and held while being pressed against the fixing base 3, while the cylindrical part is Although it is relatively difficult to hold the end portion while being pushed down toward the fixed base 3 by a clamp device or the like, the end portion is placed and pushed up from below by using a holding tool such as the above-mentioned end portion holding tool 41. This is because it is easy to hold.

  In this way, by fixing the workpiece 5 using the reaction force, a smaller external force is applied than when the end portion or midway portion of the workpiece 5 is simply pressed against the fixing base from above and fixed. As a result, the vibration of the workpiece 5 during processing can be effectively suppressed. For this reason, the holder 4 having a simple configuration can be used for fixing the workpiece 5. In particular, when a swing clamp is used as the midway holding member 42 for fixing the axle housing 5, if the swing clamp is arranged in a well-balanced manner inside the trunk portion 51 as described above, a pneumatic clamp is used instead of a hydraulic clamp. The vibration at the time of cutting the weld bead 54 with the cutting tool 13 can be sufficiently suppressed (see the following example). The pneumatic swing clamp is inferior in output as compared with the hydraulic one, but has a simple configuration and excellent handleability.

  What is necessary is just to select suitably the amount of bending of the to-be-processed object 5 in the range which can generate | occur | produce sufficient reaction force and can eliminate bending after removing the holder 4. FIG. For example, when the workpiece 5 is an axle housing 5 made of a steel plate, the amount of deflection is preferably about 0.1 to 0.3% of the total length at the maximum portion. In addition, the specific structure and installation site of the end holder 41 and the intermediate holder 42 are installed by separating the pair of end holders 41 from each other, and the intermediate holder between the end holders 41. What is necessary is just to select suitably according to the shape of the to-be-processed object 5, the direction of bending, etc., as long as 42 can be installed and the force of the mutually opposite direction can be applied to the to-be-processed object 5.

  The amount of bending when the axle housing was bent using the end holder and the intermediate holder and the influence on the machining accuracy were actually examined.

(Example)
Specifically, an axle housing 5 having a total length of 1330 mm, an outer diameter of the barrel portion of 395 mm, an outer diameter of the cylindrical portion of 120 mm, a thickness of the barrel portion (distance between outer wall surfaces of both end faces) of 124 mm, and a steel plate thickness of 8 mm, Used as work piece. As shown in FIG. 5, one end of the cylindrical portion 52 of the axle housing 5 is pushed up with a force of 135 kgf using the end holder 41, and four portions of the trunk portion 51 are moved using the swing clamp 42. The axle housing 5 was bent by pressing against the fixed base with a force of 630 kgf. At this time, the fulcrum 7 was provided at a position 140 mm from the center of the body portion 51 and fixed to the fixed base.

  And the dial gauge was arrange | positioned in the position of 245 mm, 365 mm, and 485 mm (280 mm, 160 mm, 40 mm from the edge part of a cylindrical part) on the outer side from the fulcrum, respectively. In this way, the amount of displacement at each position due to bending was measured and used as the amount of bending.

  FIG. 6 shows the measured amount of deflection at each position. According to this, it can be seen that a maximum deflection of 1.5 mm occurs. Further, as shown in the approximate curve in the figure, the amount of deflection is proportional to the distance from the fulcrum. Thereby, as described above, it is understood that the entire axle housing can be bent uniformly by pushing up the end and pushing down the body.

  Further, the weld bead was cut from above using a face mill cutter attached to the robot arm in a state of bending as described above. After cutting, the surface roughness of the part where the cutting was performed was evaluated using a surface roughness standard piece. As a result, the surface roughness (Rmax) was estimated to be equivalent to 12S.

(Comparative example)
The axle housing 5 similar to that used in the above example was fixed on a fixed base without bending. Specifically, tapered center cones were respectively inserted into the hollow portions at both ends of the cylindrical portion 52 of the axle housing 5 from the distal end side and pressed toward the center with a force of 1250 kgf. Further, using a lifting jig provided on the fixed base, the lower end surface 51a of the body portion 51 was pushed up with a force of 780 kgf, and leveling was performed. In this state, the weld bead was cut from above as in the case of the example. The surface roughness (Rmax) of the cut part was estimated to be equivalent to 50 to 100S.

  As described above, it has been found that by holding the axle housing bent, a smooth surface can be obtained by cutting as compared with the case where the axle housing is held without bending.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, the processing apparatus according to the present invention is not limited to a cutting apparatus, and can be a processing apparatus that performs arbitrary machining such as polishing and cutting, and flexes and holds a workpiece as described above. Thus, vibration during processing can be suppressed.

DESCRIPTION OF SYMBOLS 1 Cutting device 10a, 10b Robot arm 11 Servo motor 12 Spindle motor 13 Cutting tool 14 Shape measuring device 3 Fixing base 4 Holding tool 41 End part holding tool 41a End part holding recessed part 42 Midway holding tool (swing clamp)
5 Axle housing (workpiece)
51 trunk 51a end face 51b edge 52 cylindrical part 53 triangular plate 54 weld bead (projection)
Fe External force Fr Reaction force

Claims (5)

  Holding a long workpiece made of a metal material while being bent along the long axis on a fixed base, and moving the tool relative to the workpiece to perform machining. A processing device characterized.   The processing apparatus includes a pair of end holders that hold the workpiece at sites separated from each other, and a midway holder that holds the workpiece at a site between the pair of end holders. The pair of end holders and the midway holder deflect the workpiece by applying forces in opposite directions to the workpiece. Item 2. The processing apparatus according to Item 1.   The pair of end holders applies an upward force to the workpiece, and the midway holder applies a downward force to the workpiece. Processing equipment. The processing device is a processing device for processing a workpiece having a plate-like portion in the middle part,
The processing apparatus according to claim 3, wherein the halfway holding tool is a clamp device that holds the plate-like portion of the workpiece while sandwiching the plate-like portion with the fixed base.   The said tool is a cutting tool, The processing apparatus of any one of Claim 1 to 4 characterized by the above-mentioned.

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