JP5444778B2 - Broaching tool and processing method using broaching tool - Google Patents

Description

  The present invention relates to a broaching tool for cutting a workpiece with a plurality of cutting edges, and in particular, a broach capable of stably cutting a workpiece without vibration and improving the cutting quality of the workpiece. The present invention relates to a machining tool and a machining method using a broaching tool.

  Conventionally, this type of broaching tool is provided with a large number of cutting edges along one direction. In general, the cutting edge heights of these many cutting edges are gradually increased from the front to the rear in the feed direction of the tool (see, for example, Patent Document 1).

  Specifically, the broach 10 shown in FIGS. 17 and 18 can be given as a broach in which a plurality of cutting edges are arranged along the feed direction of the tool. In the broach 10, a plurality of cutting edges 13, 13... Arranged along the tool feeding direction 12 are formed on the upper surface of the tool body 11. In the broach 10, the number of blades that come into contact with the cutting edge and the workpiece during cutting is different. That is, in the example shown in FIG. 18, as shown in FIG. 19, when the horizontal axis is time (movement amount) and the vertical axis is the number of biting blades (pieces), the biting that cuts the workpiece. The number of blades repeats 1 and 2. FIG. 19 shows a case where the width of the workpiece W is 7 mm, for example, and the pitch of the cutting edges 13 is 5 mm, for example.

  The number of cutting edges is 5, the first cutting edge is for rough cutting, the middle cutting edge is for medium cutting, and the last cutting edge is for finishing cutting. When the horizontal axis is time (movement amount), the cutting resistance sum changes stepwise as shown in FIG. 20, and the amount of bending of the workpiece corresponding to the force also changes.

JP 2002-144143 A

  By the way, the broach described in Patent Document 1 and the broach tool shown in FIGS. 17 and 18 have a plurality of cutting edges of the broach arranged in the moving direction of the tool. The number of blades in contact with the object changes. That is, in the case as shown in FIG. 18, when the workpiece is at the position W2, the number of blades in contact with the workpiece is two, and when the workpiece is at the position W1, the workpiece is in contact with the workpiece. The number of blades to be performed is one. For this reason, the first problem is that the workpiece is moved or vibrated as indicated by W3 when pressed by one cutting edge during the cutting process. As a result, cutting with the conventional broach is not stable, and there is a risk of problems in quality after cutting.

  The second problem is that the pressure (contact load) from the workpiece applied to the cutting edge changes, and the position of the machining surface changes. That is, at the position W2 where the two cutting edges are in contact, as shown in FIG. 21A, the two cutting edges are pressed by F1 and F2. On the other hand, at the position W1 where one cutting edge is in contact, as shown in FIG. 21B, the first pressing force F1 passes through the workpiece and is pressed only by the pressing force F2 of the next cutting edge. The As a result, at the position W2, the position of the machining surface is h2, and the position h1 of the machining surface at which one cutting edge is in contact is higher than this. In this way, a height difference of (h1-h2) occurs between the position where the two cutting edges are in contact with the position where the one cutting edge is in contact, and the cutting is less than 1/100 mm. When a cost is required, there arises a problem that the machining accuracy is not stable.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a broaching tool capable of stably performing cutting and stabilizing the accuracy of a cut surface after processing. It is in. Another object of the present invention is to provide a broaching tool that can perform plastic working after cutting and can finish a machined surface smoothly.

  In order to achieve the above object, a broaching tool according to the present invention is a broaching tool in which a plurality of cutting edges are arranged along the tool feed direction, and is applied to the cutting edge on the flank of the cutting edge. It is characterized in that a raised portion that supports the back force of the cutting force is formed. This raised portion has a function of supporting a back component force (a component force acting in a direction perpendicular to the cutting surface during the cutting process) acting from the workpiece during the cutting process. The raised portion is formed so as to be raised along the feeding direction of the tool on the flank, and is preferably constituted by a curved convex surface having no corners with respect to the flank.

  In the broaching tool of the present invention configured as described above, a raised portion is formed on the rear surface of the cutting edge in the tool feed direction, that is, the flank face, so that the cutting edge having the raised portion passes through the workpiece. When this occurs, the cutting surface of the cutting edge comes into contact with the raised portion. Thereby, since the back component force of the workpiece is supported, vibration and movement of the workpiece can be suppressed, and fluctuations in the back component force can be suppressed. Thus, according to the broaching tool, the machining accuracy can be increased because the cutting can be performed in a stable state.

  Moreover, as a preferable specific aspect of the broaching tool according to the present invention, the cutting edge height is sequentially increased toward the rear side in the tool feeding direction, so that continuous cutting is possible. Preferably, each raised portion of the cutting edge is gradually higher than the cutting edge of each cutting edge toward the rear side in the tool feed direction (raised so as to approach the cutting surface). Here, the height of the cutting edge refers to the height from the reference surface (surface formed in the tool feed direction) of the broaching tool, for example, specified by the protruding height of the broaching tool from the surface of the tool body. To do.

  In the broaching tool configured in this way, the height of the cutting edge is gradually increased toward the rear side in the tool feed direction, so that it can be sequentially cut with a plurality of cutting edges. Since the raised portion that rises along with the height gradually increases toward the rear side in the tool feeding direction, it is possible to cut in a stable state with a plurality of cutting edges, and to improve the quality of the cutting process.

  In addition, the amount of increase in the height of each cutting edge is gradually decreased toward the rear side in the tool feed direction, and the amount of increase in the height of each raised portion is directed toward the rear side in the tool feed direction. It is preferable to adjust sequentially. Accordingly, the cutting amount by the cutting blade on the front side to the rear side in the tool feeding direction can be reduced, and a series of processing can be performed from roughing to finishing, and the raised portion is brought into contact with the rear side to cut the cutting surface. Can be plastically processed.

  Furthermore, as another preferable specific aspect of the broaching tool according to the present invention, at least a ridge on the front side in the tool feeding direction among the plurality of ridges is spaced from a cutting surface cut by the cutting edge. It is formed to have. According to the present invention, the raised portions are arranged to face each other so as to have a gap in the cutting surface cut by the cutting edge. Then, the gap between the raised part and the cutting surface is adjusted (the height of the cutting edge and the height of the raised part are adjusted), and the distance between the cutting edge of each cutting edge and the raised part is adjusted to support the back component force. And the pressing force of the raised portion of the cutting surface can be adjusted.

  As another preferred aspect, of the plurality of raised portions, at least a raised portion on the rear side in the tool feed direction is formed so as to contact a cutting surface cut by the cutting edge. Specifically, the height of each raised portion of the cutting edge is equal to or higher than the height that finally contacts the surface of the workpiece. With the broaching tool configured in this way, the cutting surface cut with a plurality of cutting edges can be pressed and plastically processed (plastically flowed) by the raised portion, and the processing surface is finally plastically processed and smoothly It can be processed as a smooth surface. That is, plastic working can be performed by actively using the raised portions.

  As still another preferable aspect, the cutting edge is an oblique blade that obliquely intersects the tool feeding direction. The raised portion is formed along the oblique blade. According to the broaching tool configured in this way, while the tip of the cutting edge is in contact with the workpiece on one end side of the blade width, the back portion is also separated by the raised portion on the other end side of the blade width. Can support force. In this way, the resistance associated with cutting is such that the cutting edge is formed obliquely with respect to the feed direction, so that the resistance gradually increases and smooth cutting can be performed, and the back component of the cutting resistance of the raised portion is reduced. Support can be performed smoothly, and vibrations and movements associated with the processing of the workpiece can be reduced.

  In the machining method using the broaching tool according to the present invention, a plurality of cutting edges are arranged along the tool feed direction, and a bulge that supports a back force of cutting resistance applied to the cutting edge on the flank of the cutting edge A workpiece processing method using a broaching tool in which a portion is formed, wherein the workpiece is cut so as to support a back force of a cutting resistance while cutting the workpiece. It is characterized by contacting the cutting surface.

  Further, in the processing method using the broaching tool according to the present invention, when contacting the cutting surface of the workpiece, at least the raised portion on the rear side in the tool feeding direction among the plurality of raised portions, It is more preferable to press the cutting surface of the workpiece to plastically process the cutting surface.

  In the processing method using the broaching tool configured in this way, the workpiece is cut with the cutting edge, and when the cutting edge passes through the workpiece, the raised portion comes into contact with the workpiece and the cutting resistance Therefore, the workpiece can be stably cut by suppressing vibration and movement of the workpiece. Furthermore, since the cutting surface cut by the cutting edge can be plastically processed by the raised portion formed behind the cutting edge, plastic processing such as burnishing processing can be performed simultaneously with the cutting processing, and the processing surface can be made smooth. it can.

  The broaching tool of the present invention can suppress vibration and movement of a workpiece during cutting, can perform cutting in a stable state, and can improve processing accuracy. In addition, plastic processing can be performed simultaneously with the cutting processing, and the surface accuracy of the processed surface can be improved.

The perspective view in the state where a part of one embodiment of the broaching tool concerning this embodiment was omitted. The enlarged view which shows the cutting-blade part of FIG. 1 in detail. Sectional drawing which shows the cutting state by one cutting edge shown in FIG. The schematic diagram which shows the cutting state by one cutting blade. The schematic diagram which shows the state which one cutting blade passed the workpiece. The front view which shows the positional relationship of the broaching tool which has a some cutting edge, and a workpiece. Explanatory drawing of the positional relationship of the broaching tool of FIG. 6, and a workpiece. (A) is explanatory drawing which shows the change of the load (back component force) added to one cutting edge, (b) is explanatory drawing which shows the change of the load (back component force) added to a broaching tool. Explanatory drawing which shows the relationship between the force and position when cutting a workpiece with the broaching tool which has the oblique blade which concerns on this embodiment as a cutting blade. (A) is explanatory drawing of the synthetic | combination force by several cutting blades based on the relationship between the force and position of one slanting blade of FIG. 9, (b) is explanatory drawing of the effect based on (a), (c) is Explanatory drawing of the synthetic force by the some cutting blade based on the relationship between the force and position of one straight blade, (d) is explanatory drawing of the effect based on (c). The correlation diagram of the load which shows the relationship between the load before overlap of the broaching tool which concerns on this invention, and overlap load. The schematic diagram which shows the cutting state of other embodiment of the broaching tool which concerns on this invention. Explanatory drawing of the positional relationship of the broaching tool of FIG. 12, and a workpiece. The top view and front view of the workpiece which were cut with the broaching tool which concerns on this invention. The diagram which shows the relationship between the number of blades for performing the distribution of the cutting amount according to each cutting blade of several cutting blades, and a scheduled load. The diagram which shows the relationship between the time designed based on FIG. 15, and the sum of cutting resistance. The perspective view which shows the conventional broaching tool. Explanatory drawing when cutting a workpiece with the broaching tool of FIG. The diagram which shows the relationship between the time of the broaching tool of FIG. 17, and the number of biting blades. The diagram which shows the cutting resistance sum during the cutting of the broaching tool of FIG. Explanatory drawing of the positional relationship of the broaching tool of FIG. 17, and a workpiece.

  Hereinafter, an embodiment of a broaching tool according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a state in which a part of the broaching tool according to the present embodiment is omitted, FIG. 2 is an enlarged view showing the cutting edge portion of FIG. 1 in detail, and FIG. 3 is shown in FIGS. FIG. 4 is an explanatory view showing the main component force and the back component force in the cutting state of FIG. 3, and FIG. 5 is an explanation of the state in which the cutting blade has passed through the workpiece. FIG. The back component force is a value having a substantially linear relationship with the cutting force, and in this specification, this back component force is described as the cutting force.

  1-3, as an example of a broaching tool, a broach 1 has a plurality of cutting edges 4 along a tool feed direction 3 on one surface of a tool body 2 made of metal such as tool steel, high speed steel, or super steel. 4 ... are arranged. In this embodiment, the plurality of cutting edges are straight edges formed in a direction orthogonal to the tool feed direction 3. The cutting edges 4, 4,... Are basically formed in a sawtooth shape, and the rear side is formed gradually higher along the tool feed direction 3. In FIG. 2, when the height of the cutting edge 4 a is H 1, the tool feed direction 3, the height of the cutting edge 4b of the rear cutting edge is set to H2, which is higher than H1, and the height of the cutting edge 4c of the rear cutting edge is formed to be higher in order of H3 higher than H2. The heights H1, H2, and H3 of the cutting edges are set with the surface of the tool body 2 as the reference plane 2a.

  The cutting edges 4, 4... Are formed so that rough cutting is performed with the first blade, intermediate cutting is performed with the intermediate blade, and finishing cutting is performed with the last blade. The height of each cutting edge is set to a height difference of about 0.01 mm to 0.1 mm. That is, the amount of increase in the height of each cutting edge is gradually reduced toward the rear side in the tool feed direction 3, and specifically, the cutting edges of the first cutting edge and the second cutting edge are reduced. The difference is set to be large and rough cutting is possible. The cutting edge for medium cutting is set to have a small difference in cutting edge, and the cutting edge for finishing cutting is set to have a smaller difference in cutting edge.

  In this embodiment, as shown in FIGS. 3 and 4, the cutting edges 4, 4... Are formed on the flank 5 with raised portions 6, 6. The raised portion is formed so as to be proximate to the cutting surface cut by the cutting edge 4. That is, when the workpiece W, which is a workpiece, is cut by the broach 1, the cutting surface Wb of the workpiece W is cut lower than the surface Wa of the workpiece, chips Wc are formed, and the flank 5 of the cutting edge 4 is formed. The raised portion 6 that is raised is configured to face the cutting surface Wb with a gap d1.

  The gap d1 can be set as appropriate, but in the present embodiment, it is set between 0 mm and 0.1 mm. The distance between the lowermost surface of the raised portion 6 and the cutting edge of the cutting edge is set to d2 (see FIG. 4). The raised portions 6, 6... Are formed along the cutting edge 4 of the broach 1 in parallel with the cutting edge. In addition, the cross-sectional shape of the raised portion is not limited to the mountain shape as illustrated, and may be formed with, for example, a narrow protrusion. In addition, the cross-sectional shape of the raised portion is preferably a curved surface having no corners or protrusions, and is difficult to damage the cutting surface.

  Further, among the plurality of ridges 6, 6..., At least the ridge 6 on the front side in the tool feed direction 3 is formed so as to have a gap in the cutting surface cut by the cutting edge, and the plurality of ridges 6, 6. ..., at least the ridge 6 on the rear side in the tool feed direction 3 is formed so as to be in contact with the cutting surface cut by the cutting edge 4.

  The raised portions 6, 6... Have a function of supporting the back force of cutting resistance applied from the workpiece to the cutting edge 4 when cutting the workpiece W with the broach 1. That is, in the cutting state shown in FIG. 4, when the cutting resistance P is applied to the tip of the cutting edge 4 of the broach 1, the main component force Fc is applied in the extending direction of the cutting surface Wb and the cutting resistance is perpendicular to the cutting surface Wb. A back force Ft substantially equal to is applied. As a result, chips Wc are formed along the shearing surface Wd, and the raised portion 6 facing the cutting surface Wb with the gap d1 passes through the workpiece W as shown in FIG. When it comes off from the workpiece, it comes into contact with the cutting surface Wb and supports this back force.

  In other words, the raised portions 6, 6... On the front side in the tool feed direction 3 (before the rough cutting process) are cut by the cutting edge while the workpiece is being cut by one cutting edge 4 with the broach 1. When the cutting edge passes through the workpiece and leaves the workpiece W, the cutting surface Wb of the workpiece W and the raised portion 6 of the cutting blade 4 come into contact with each other to support the back force. Has been. As a result, the raised portion 6 presses the cutting surface Wb, and the pressing force can be adjusted by setting the gap d1 between the raised portion 6 and the cutting surface Wb of the workpiece.

  Specifically, by reducing the gap d1, the step of the back component force when the raised portion 6 presses the cutting surface Wb after the cutting edge of one cutting edge 4 passes the workpiece W is reduced. Thus, the pressing force can be reduced, and the workpiece W can be prevented from vibrating or rotating during the cutting process.

  Further, when the gap d1 of the raised portion 6 on the rear side in the tool feed direction 3 (the latter stage where finishing is performed) is set to “0 mm” or less (specifically, the height of the raised portion is higher than the cutting edge). When the cutting blade passes through the cutting surface Wb, no step is generated, so that the state in which the raised portion 6 presses the workpiece W can be maintained. Thereby, the raised portion 6 can support the back component force and press the cutting surface Wb, and can perform plastic working (burnishing) on the cutting surface.

  The cutting operation of the broaching tool of this embodiment configured as described above will be described below. As shown in FIG. 6, for example, when the pitch P of the cutting edges 4, 4... Is 5 mm and the cutting length L of the workpiece W is 7 mm, the two cutting edges 4 and 4 are Cutting in contact with W. In this state, as shown in FIG. 7A, the two cutting edges 4 and 4 press the workpiece W with F1 and F2, and the height of the workpiece W is set to h2.

  At the position of the two-dot chain line in FIG. 6 where the broach 1 moves along the tool feed direction 3 and one cutting edge 4 is in contact with the workpiece W, there is no raised portion in the prior art. As shown, since only one cutting edge 4 presses the workpiece W with only F2, the position of the work surface of the workpiece W becomes h1 which is larger than the height h2 at which the two cutting edges 4 and 4 are in contact with each other. Is increased by (h1-h2).

  However, in this embodiment, since the raised portions 6, 6... Are formed on the cutting edges 4, 4..., As shown in detail in FIG. As shown in FIG. 7C, the raised portion 6 of one cutting edge presses the workpiece W with F1a, the next cutting edge presses with F2, and the raised portion of the next cutting edge presses with F2a. Therefore, the position of the workpiece W in FIG. 7B becomes ha smaller than h1, and the cut is suppressed to (h1-ha). Moreover, since the workpiece | work W is pressed by the one cutting edge 4 and the two raised parts 6 and 6, the vibration and rotation during cutting are prevented.

  As described above, when cutting is performed using the broach 1 of the present embodiment, when the cutting of one cutting edge 4 is finished and separated from the workpiece W, the raised portion 6 of the cutting edge 4 comes into contact with the cutting surface Wb. Thus, the vibration and rotation of the workpiece W can be suppressed. Moreover, the surface of this cutting surface can be finished smoothly because the protruding part 6 presses the cutting surface Wb. Since the pressing force for pressing the cutting surface can be adjusted by adjusting the gap d1 between the raised portion 6 and the cutting surface Wb, the surface roughness of the finished surface can be improved.

  That is, in the broach 1 of this embodiment, the gap d1 shown in FIGS. 3 and 4 is reduced, the force (F1a + F2a) for pressing the cutting surface Wb is minimized, and the sum of the four forces (F1 + F2 + F1a + F2a) The fluctuation is reduced. If F1a = 0 in FIG. 7C, the ratio of F1: F1a becomes 1: 0, and the load of α1 shown in FIG. 8A changes. This load change of α1 corresponds to the load change of FIG. 20 showing the cutting resistance sum of the prior art. Assuming that F1≈F1a, the load remains large as indicated by α2 in FIG. 8B, and when the raised portion 6 is abruptly separated from the workpiece, the load also changes abruptly. When the change is adjusted to F1 / 2≈F1a, an intermediate change is made as indicated by α3 in FIG. That is, the change of the load applied to the broach 1 becomes a step shape by the step-like separation, and a gentle change with a step-like corner can be set. The horizontal distance d2 that is the stepped portion of α3 corresponds to the distance between the raised portion 6 shown in FIG. 4 and the cutting edge of the cutting edge. The feature point of this embodiment is that the load applied to the cutting edge during cutting (a back force substantially equal to the cutting resistance) is stepped, and the load is gently changed as shown in FIG. 8B. It is.

  The resultant force inherent to broaching when cutting is performed with the broach 1 of the present embodiment will be described with reference to FIGS. FIG. 9 is an explanatory diagram showing the relationship between force and position when a workpiece is cut with a broaching tool having the oblique blade according to the present embodiment as a cutting edge. 10A is an explanatory diagram of the combined force by a plurality of cutting edges based on the relationship between the force and position of one slant blade of FIG. 9, and FIG. 10B is an explanation of the effects based on (a). (C) is explanatory drawing of the synthetic | combination force by several cutting blades based on the relationship between the force and position of one straight blade, (d) is explanatory drawing of the effect based on (c).

  As shown in FIG. 9, the workpiece W is cut by a broach 1 </ b> A that has one oblique cutting edge (oblique blade) 4 </ b> A that obliquely intersects the tool feed direction 3 and has a raised portion 6 </ b> A behind the cutting edge. In this case, when the workpiece reaches the position w1, cutting is started, the cutting resistance increases with the feed of the tool, and the cutting resistance force (F) increases with an inclination. Since the workpiece is cut with the entire width of the oblique cutting edge 4 between w2 and w3, the cutting resistance force (F) is constant. When the position of the workpiece exceeds w3, a part of the cutting edge is separated from the workpiece, so that the cutting resistance gradually decreases and the cutting resistance becomes zero at the position of w4, so that the cutting resistance force force (F) is inclined. It decreases to the state and becomes zero at w4.

  FIG. 10 shows a case where there are a plurality of cutting edges. FIG. 10A shows the case of four slanting blades with a pitch p, the cutting amount gradually decreases at N, N + 1, N + 2, and N + 3, and rough machining is performed with the first cutting blade (N). An example is shown in which intermediate machining is performed with an intermediate cutting edge (N + 1) and finish cutting is performed with the third and fourth cutting edges (N + 2) and (N + 3). In this example, as shown in FIG. 10B, while the cutting force is decreasing, the raised portion 6A formed at the escape portion of the cutting edge 4A is lowered by the gap d1 at a position between the positions w3 and w4. Thus, the distance in which the contact resistance is maintained by contacting the cutting surface can be extended from L1 to L2 in the tool feed direction, the rate of decrease of the cutting resistance can be suppressed, and stable cutting can be performed.

  FIG. 10C shows a case where cutting is performed with four cutting edges (straight edges) perpendicular to the tool feed direction at a pitch p. In this example, since the cutting edge is a straight blade, the contact resistance does not increase in an inclined manner, and is constant at the position where the cutting edge and the workpiece contact, and is constant until the cutting edge passes through the workpiece. Also in the case of this straight blade, the height of the blade edge is set so that the cutting amount of the four cutting blades gradually decreases. In this example, when the linear cutting edge is separated from the workpiece, the raised portion formed in the relief part of the cutting edge descends by a gap d1 at a position between the positions w3 and w4 and comes into contact with the cutting surface of the cutting edge. Since the distance that the contact resistance lasts can be extended from L1 to L2 in the tool feed direction, the reduction rate of the cutting resistance can be suppressed, and stable cutting can be performed.

  Next, the relationship between the load before overlapping applied to the plurality of cutting edges of the broach 1 and the overlapping load will be described with reference to FIG. For example, with the broach 1 having a plurality of straight blades shown in FIG. 10C, the actual test piece was cut with the cutting resistance f1 of the Nth cutting edge and the cutting resistance f2 of the (N + 1) th cutting edge. FIG. 11 shows a case where the number of blades is 25 when the number of blades is read, with f1 being an overlap preload and f1 + f2 being an overlap load.

  When the cutting amounts of the adjacent cutting blades are substantially the same and the cutting edges have the same sharpness, theoretically, Fy = 2 · Fx in FIG. 11 should be obtained, but the measurement data follows Fy = 2 · Fx. It turned out to be a gently curved curve. From these results, the raised portions 6, 6... Are set in the escape portions of the cutting edges 4, 4,..., And stable cutting can be performed without causing vibration or movement during processing of the test piece. Here, if the height of the raised portion and the distance from the cutting edge to the raised portion are designed so that the line connecting such distributions becomes smooth, stable broaching can be performed.

  Another embodiment of the present invention will be described in detail with reference to FIG. FIG. 12 is a schematic view showing a cutting state of another embodiment of the broaching tool according to the present invention. Note that this embodiment is characterized in that the height of the raised portion that rises rearward in the feed direction of the cutting edge is different from the above-described embodiment. Specifically, the gap between the raised portion and the cutting surface is negative, and the raised portion of the raised portion is higher than the height of the cutting edge. Other substantially equivalent configurations are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the broach 1B of this embodiment, a plurality of cutting edges 4B, 4B,... Are arranged along the tool feed direction 3 in the same manner as the broach 1 of the above-described embodiment. A raised portion 6B that rises toward the cutting surface Wb cut by the cutting edge is formed. The height of the raised portion 6B is higher than the cutting surface Wb, that is, is formed so as to protrude from the cutting edge of the cutting edge 4A, and the gap d1 between the raised portion 6 and the cutting surface Wb in the above embodiment is negative. Yes. The raised portion 6B is formed in a state parallel to the cutting edge, and the protruding surface is formed as a curved surface having no corners.

  In the cutting edge 4B of this embodiment, since the ridges 6B on the rear side in the feed direction of the plurality of cutting edges are higher than the cutting edge of the cutting edges, the ridges 6B press the cutting surface Wb by the cutting edges and perform plastic working. Thus, burnishing can be performed. As a result, the cutting surface Wb is crushed by plastic processing, a plastic processing surface We lower than the cutting surface Wb is formed, the processing surface is smoothly finished, and a smooth processing surface can be obtained. Then, further cutting can be performed with the next cutting edge, and further plastic working can be performed.

  Thus, in the broach 1B of the present embodiment, as shown in FIG. 13C, when the pressing force F1 of the first cutting edge is released, the pressing force of the raised portion 6B of the first cutting edge F1b acts to perform plastic working, and the position of the workpiece W is set to a height of hb lower than h2. Along with the movement of the broach 1B, the pressing force F2 of the second cutting edge acts, and the pressing force F2b of the raised portion 6B of the second cutting edge acts to perform plastic working, thereby reducing the back component force of the broach 1B. Since it supports, the vibration and rotation of the workpiece | work W accompanying a tool feed are suppressed. Moreover, the change of the notch of the broach 1B can be reduced, and the surface accuracy of the finished surface can be increased. FIGS. 13A and 13B are conventional ones, correspond to FIGS. 7A and 7B, and are shown for comparison with the conventional ones.

  When the broach 1, 1A, 1B configured as described above is used, for example, the connection terminal T of the module incorporating the electric circuit can be processed with high accuracy. Specifically, when terminal processing of a copper wire terminal as shown in FIG. 14 is performed, one end of the terminal end becomes an inclined surface Ta which is a cutting surface without plumping both ends of the terminal material. The corners Tb and Tb of about 30 ° are applied to both corners of the inclined surface, and the inclined surface Ta can accurately process the connection terminal having the upper surface and a step Tc of about 0.2 mm. .

  For example, when the connection terminal T shown in FIG. 14 is processed by conventional plastic processing, the shape is not optimal, elongation and cracking occur, the surface treatment of the copper wire surface remains, and the back coating peels off. . In addition, when cutting is performed with a milling machine, deburring is required and man-hours are increased, surface roughness needs to be improved, and dimensional accuracy also needs to be improved. On the other hand, when the terminal processing of the connection terminal T is performed using the broaching tool 1, 1A or 1B of the present invention, the cutting surface cut by the cutting edges 4, 4A, 4B is pressed by the raised portions 6, 6A, 6B. Therefore, vibration and rotation are suppressed without clamping the connection terminal T which is a workpiece (even without a clamp), moderate plastic processing is performed, and dimensional accuracy, surface roughness of the inclined surface, etc. are required. Can be kept within the range.

  Further, the shape that can be cut with the broach according to the present embodiment is not limited to the shape shown in FIG. 14, and an optimum shape can be cut even with an appropriate shape. When the workpiece W such as a terminal is cut by the broach 1, if one of the cutting edges 4, 4 A, 4 B of the broach 1, 1 A, 1 B passes the workpiece W, the cutting edge in the tool feed direction Raised portions 6, 6A, 6B are formed on the flank on the rear side, and these raised portions press and clamp the workpiece W. Therefore, the broaching tool of this embodiment is a clampless or workpiece such as a terminal. It has the feature that can be cut.

  The broaching tool according to the present embodiment preferably distributes the cutting amounts of a plurality of cutting edges arranged along the tool feed direction based on a predetermined mathematical formula. For example, in FIG. When the vertical axis is the cutting resistance of each cutting edge, the planned load of cutting resistance based on the following formula is shown.

  That is, in order to distribute the amount of cutting according to each cutting edge of a plurality of cutting edges, the specific cutting resistance KK of the following equation (1) is examined, and the tool types are examined for the first time from analysis of jig and tool damage. The accuracy of KK according to the original is increased with FKK (t, ta, α), formula (2) is completed, and the height of the raised part of the first cutting edge is set to the minimum necessary to fix the workpiece. The final cutting edge is set so that the gap d1 of the raised portion is sufficiently large and the processing surface is crushed (burnishing). Here, FKK is an arithmetic expression according to the two-dimensional cutting theory, and corresponds to KKa × Fan1 (t, ta, α).

F1≈KK × A≈770 × b × t (1)
F1 = KKa × Fan1 (t, ta, α) × A
≒ KKa × Fan2 (α) × b ¹ × t ^{0.6 to 0.9} (2)

In the above formula, specific cutting resistance: KK (N / mm ² ), depth of cut: t (mm), chip thickness: ta (mm), cutting width: b (mm), cutting cross-sectional area: A (mm ² ), Constant: KKa (N / mm ² ), tool rake angle: α (deg), and a practical expression including the function Fan1 is created. Then, the function Fan2 is experimentally summarized by a regression equation.

  The distribution of the cutting amounts of the plurality of cutting edges according to the equation (2) is based on the condition that Fan1 and Fan2 are completed. An example of the result of regression of the function Fan2 with a quintic equation is shown below.

^{y = 0.0029x 5 -0.02074x 4 + 5.4657x} 3 -67x 2 + 361.02x-273.13 (R 2 = 0.9987) ... (3)

  FIG. 16 is a design aiming at the result of FIG. 15 obtained by the quintic equation shown in the equation (3), and the machining width of the workpiece in which the number of simultaneous machining blades is changed to one and two is, for example, The sum of the four forces shown in FIG. 7 (c) is 6.3 mm and the number of teeth is 5 mm. In FIG. 16, the design in which the action point of the force F1 and F1a in FIG. 7C is changed from 1.4 mm to 2.9 mm is adjusted by the blade edge and the raised portion. In this way, when the cutting amounts of a plurality of cutting edges are distributed, cutting can be performed with a plurality of cutting edges, and the workpiece can be clamped with a raised portion behind the plurality of cutting edges, and cutting can be performed in a stable state. The accuracy of the processed surface can be improved. As shown in FIG. 16, the sum of the cutting forces decreases with time, and the amplitude of the sum of the cutting forces becomes smaller and converges, so that it is understood that the machining state is suppressed in vibration.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, as an example of a cutting edge of a broaching tool, an example of a straight straight blade perpendicular to the feed direction of the tool has been shown, but it goes without saying that a slant blade intersecting at a predetermined angle may be used.

  Further, the cutting edge of the broach may be a cutting edge having a predetermined shape for forming a final shape on the workpiece.

  As an application example of the present invention, cutting can be performed with a cutting edge having a special shape using a broaching tool, and the cutting surface is not limited to a flat surface, but also applied to applications such as cutting curved surfaces such as the inner surface of holes. it can.

  1, 1A, 1B: Broach (broaching tool), 2: Tool body, 3: Tool feed direction, 4, 4A, 4B: Cutting edge, 4a, 4b, 4c: Cutting edge, 5: Flank, 6, 6A, 6B: Raised portion, F: Cutting resistance, Fc: Main component force, Ft: Back component force, d1: Gap between the raised portion and the workpiece, W: Workpiece (workpiece), Wa: Workpiece surface, Wb: Cutting surface, Wc: Chip, Wd: Shear surface, We: Plastic working surface (burnishing surface)

Claims (4)

A broaching tool in which a plurality of cutting edges are arranged along the tool feed direction,
On the flank of the cutting edge, a ridge is formed that supports the back force of the cutting force applied to the cutting edge ,
The height of the cutting edge sequentially increases toward the rear side in the tool feed direction,
The broaching tool, wherein each raised portion of the cutting edge is gradually higher toward the rear side in the tool feeding direction than the cutting edge of each cutting edge .   The broaching tool according to claim 1, wherein the cutting edge is an oblique blade that obliquely intersects the tool feeding direction. A method for processing a workpiece using the broaching tool according to claim 1 ,
A machining method using a broaching tool, wherein the raised portion is brought into contact with a cutting surface of the workpiece so as to support a back component force of a cutting resistance while cutting the workpiece. When brought into contact with the cutting surface of the workpiece, at least a ridge on the rear side in the tool feed direction among the plurality of ridges is pressed against the cutting surface of the workpiece, and the cutting surface is made plastic. The processing method using the broaching tool according to claim 3 , wherein the processing is performed.

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