Method for manufacturing the mold

Abstract

Provided is a method for manufacturing molds with which it is possible to accommodate small lots and a wide variety of products.　In a cutting step, a mold matching surface is cut and formed on each of upper and lower molds, and a cavity C1, C2, is cut and formed on each of the upper and lower molds respectively using the mold matching surfaces as reference. In a mold matching step, at least three points PU1-3 that are not located on the same straight line on the mold matching surface of the lower mold placed on a placement surface are measured, and the z-coordinates of the respective points are recognized. At least three points PL1-3 that are not located on the same straight line on the mold matching surface of the upper mold gripped by a gripping arm are measured, and the z-coordinates of the respective points are recognized. Mold matching is then carried out in an attitude in which the mold matching surfaces SmU, SmL of the upper and lower molds are kept parallel.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a casting mold, more specifically, to a method for manufacturing a casting mold, in which foundry sand and a binder are mixed and kneaded, filled into a formwork, pressurized, and hardened in the formwork, and then removed from the formwork to prepare a sand block, which is then subjected to a cutting step and a mold joining step to manufacture a sand mold. [Background technology]

[0002] Regarding the above-mentioned method for manufacturing a casting mold, Patent Document 1 is known for the cutting process, and Patent Document 2 is known for the mold-matching process. In the former, the molding of a sand block is combined with cutting to shorten the cutting process. In the latter, reference pattern blocks 24-27 are used as the molding mold, reference patterns 28-31 are formed in the sand mold, and the sand mold is matched based on the reference patterns.

[0003] However, neither of the prior art technologies was sufficient to meet the needs of small-lot production of a wide variety of castings. In the former, the sand block molding molds could not accommodate a wide variety of castings, and in the latter, the finishing dimensions of the sand block molding were adjusted, and in small lots, the dimensional errors associated with the hardening conditions meant that the accuracy of the reference pattern could not be guaranteed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-131901 A [Patent Document 2] Special Publication No. 2019-536636 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned conventional circumstances, an object of the present invention is to provide a method for manufacturing a casting mold that can handle small-lot production of a wide variety of products. [Means for solving the problem]

[0006] In order to achieve the above object, a characteristic configuration of a method for manufacturing a casting mold according to the present invention is a method for manufacturing a sand mold by kneading foundry sand and a binder, filling and pressurizing a formwork and hardening within the formwork, removing the formwork to prepare a sand block, and carrying out a cutting step and a molding step, the method comprising the steps of: a processing head operated by a robot for cutting the sand block and molding an upper and lower molds; a gripping arm operated by a robot for gripping the upper mold and matching the mating surfaces where the cavities of the upper and lower molds are formed; and a coordinate measuring sensor for detecting the coordinates by bringing at least the upper mold gripped by the gripping arm into contact with a detection piece, wherein the side surfaces of the sand mold have a gradient such that they approach each other closer to the opposing surfaces as they approach the molding surfaces, and the gripping arm the gripping surface of the sand mold has a slope similar to that of the side surface of the sand mold, the Z axis defining the Z coordinate is oriented in the vertical direction, and in the cutting process, the processing head cuts and forms the mating surfaces of the upper and lower molds respectively, and cuts and forms the cavities on the upper and lower molds respectively based on the same mating surfaces, and in the mating process, measures at least three points that are not located on the same line on the mating surface of the lower mold placed on the mounting surface to recognize the Z coordinate of each point, and measures at least three points that are not located on the same line on the mating surface of the upper mold held by abutting the gripping surface of the gripping arm against the side surface to recognize the Z coordinate of each point, and then performs mold alignment using the gripping arm in a position where the mating surfaces of the upper and lower molds are kept parallel.

[0007] According to this configuration, the machining head cuts and forms the mold mating surfaces of the upper and lower molds in the cutting step, and cuts and forms the cavities on the upper and lower molds based on the same mold mating surfaces, so that the cavities are accurately formed even if the finished dimensions of the sand block after hardening are different. In addition, in the mold mating step, at least three points not located on the same line are measured on the mold mating surface of the lower mold placed on the placement surface to recognize the Z coordinates of each point, and at least three points not located on the same line on the mold mating surface of the upper mold held by the gripping arm in contact with the side surface are measured to recognize the Z coordinates of each point, and then the mold mating is performed by the gripping arm in a position where the mold mating surfaces of the upper and lower molds are kept parallel, so that the upper and lower molds can be accurately mated regardless of the position of the lower mold. The molding mold of the sand block can be used in common with different casting molds, and different sand molds can be manufactured by cutting only, so it is possible to handle a wide variety of small lots.

[0008] In the above feature, it is preferable that the machining head has XY coordinates that define the lateral direction with XY axes perpendicular to the Z axis, and in the cutting step, cuts and forms at least two lateral alignment surfaces oriented at an intersection angle of the XY axes near the mating surfaces of the upper and lower dies, respectively, and in the mating step, the XY coordinates of each of the lateral alignment surfaces of the upper and lower dies are recognized, and the lateral positions of the upper and lower dies are matched to perform mold alignment by the gripping arm. According to this feature, it is not necessary to cut the lateral alignment surfaces only and other lateral surfaces, and lateral alignment can be performed accurately while minimizing the amount of sand cut.

[0009] At least one of the at least two lateral mating surfaces is preferably provided at two or more separated positions (one of the lateral mating surfaces is cut at two or more positions so that the lateral mating surfaces are separated). By providing at least one of the lateral mating surfaces at two or more separated positions, the inclination of the side on the lateral mating surface side can be detected, and lateral alignment becomes more accurate.

[0010] The sand blocks constituting the upper and lower molds each have a convex polygonal shape in a plan view, and the lateral mating surfaces are preferably formed at the corners of the convex polygon.

[0011] The convex polygon is a rectangle, and the horizontal alignment surfaces have different cutting lengths at adjacent corners and opposing corners of the rectangle, and the upper and lower molds are preferably formed to have the same cutting length. With this configuration, if the upper and lower molds are in different rotational positions when mating, it can be immediately detected by visual inspection, image recognition, etc., and detection is particularly easy when horizontal alignment surfaces are formed at all corners of the sand mold.

[0012] In addition to the two lateral alignment surfaces, the upper and lower dies each have at least two other lateral alignment surfaces machined by the robot near the lateral alignment surfaces, which are not all parallel to each other, and the alignment can be confirmed by recognizing the XY coordinates of two points on the other lateral alignment surfaces of the upper and lower dies, respectively. This makes it possible to check the accuracy of the alignment and cutting errors, etc.

[0013] During cutting by the robot, the upper side of the sand block is the surface that constitutes the cavity, and the side of the sand block near the lower side has a vertical wall, and a positioning piece is brought into contact with this vertical wall to serve as the reference for the horizontal coordinate of the cutting by the robot. With this configuration, it is possible to reduce the inclination of the sand block more accurately, align it with the coordinate, and reduce the amount of cutting. In other words, assuming a case in which the sand block is inclined with respect to the coordinate, it is necessary to increase the amount of cutting to ensure accuracy, but this invention reduces the need for this.

[0014] The gripping arm is provided with a coordinate measurement sensor that measures coordinates by contacting the detection piece, and after the lower mold is placed on a support surface on which the lower mold is placed, the coordinate measurement sensor is used to recognize the coordinates of the lower mold placed on the support surface, and another coordinate measurement sensor is provided at a portion connected to the support surface on which the lower mold is placed, and the other coordinate measurement sensor is used for the upper mold gripped by the gripping arm to recognize the coordinates of the upper mold in the gripped state. According to this configuration, the coordinates of the lower mold are measured while placed on the support surface, and the coordinates of the upper mold are measured while gripped by the gripping arm, and the mold can be matched while minimizing variable factors with the positional relationship between the two being understood, so that the mold can be matched accurately. Effect of the Invention

[0015] According to the above-mentioned characteristic configuration of the mold manufacturing method of the present invention, it is possible to provide a mold manufacturing method that can handle small lot production of a wide variety of products by rational cutting and matching. In addition, according to another characteristic configuration of the present invention, it is possible to minimize the amount of cutting of the sand mold and streamline the processing, thereby further promoting the handling of small lot production of a wide variety of products.

[0016] Other objects, configurations and effects of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is an explanatory diagram showing an overview of the entire process. [Diagram 2] 1A is a vertical cross-sectional view of the mold separated from the mold, FIG. 1B is a vertical cross-sectional view during molding, and FIG. 1C is a plan view of the mold removed. [Diagram 3] 1 shows a cutting equipment for performing a cutting process, where (a) is a side view and (b) is a plan view of a base. [Figure 4] The figures show the mold joining equipment used in the mold joining process, with (a) being a plan view and (b) being a front view. [Diagram 5] 5 shows the vicinity of the gripping arm in FIG. 4, with (a) being a front view and (b) being a plan view. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] This is an expanded plan view of the sand mold with the Y axis as the axis of symmetry. [Figure 9] 1A and 1B are diagrams showing the procedure for matching the coordinates of an upper mold and a lower mold, in which (a) shows the state before matching the coordinates, and (b) shows the state after matching the coordinates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Next, the present invention will be described in more detail with reference to the accompanying drawings as appropriate. As shown in Fig. 1, the manufacturing method of the sand mold according to the present invention (all manufacturing steps ST001) includes a molding step ST100 in which foundry sand and a binder are mixed, filled and pressurized into a mold, and hardened in the mold to produce a sand block, a cutting step ST200 in which a sand mold is cut from the sand block, and a mold joining step ST300 in which the cut upper and lower molds are joined together. As the processing equipment 100, a molding equipment 110 shown in Fig. 2, a cutting equipment 120 shown in Fig. 3, and a mold joining equipment 130 shown in Figs. 4 and 5 are used. As the robot 101 of the equipment 100, a cutting robot 121 is used in the cutting equipment 120, and a mold joining robot 131 is used in the mold joining equipment 130, but a common robot may be used and only the processing head and the gripping arm are replaced as attachments.

[0019] The lower mold molding step ST110, the lower mold cutting step ST210, and the lower mold cleaning step ST310 are performed consecutively. Similarly, the upper mold molding step ST130, the upper mold cutting step ST230, and the upper mold cleaning step ST330 are performed sequentially, followed by the upper and lower mold combining step ST350. Figures 6 to 9 show a sand mold, and the sand mold that is cut and formed and combined will be described first, followed by the manufacturing steps. In the case of batch processing, the upper and lower molds may be molded and cut in large quantities and stored in a primary location, and the upper and lower sand molds may be cleaned and combined as needed.

[0020] The sand mold M shown in Figures 6 to 9 includes an upper mold MU and a lower mold ML. The upper and lower molds are joined at a mold mating surface Sm, which is the upper mold mating surface SmU and the lower mold mating surface SmL, respectively. In the figure, XYZ axes intersecting at 90 degrees with each other and their origin O are shown, but the directions of the axes are basically the same in Figures 2 to 5. The Z axis indicates the up-down direction and is basically vertical, but is not limited to this. The XY axes indicate the lateral direction and is basically horizontal, but is not limited to this. The upper and lower molds are formed with a cavity C, and the upper cavity C1 and the lower cavity C2 are joined to form the cavity C. The upper mold is formed with a gate W1 and a runner (drop) W3, and molten metal is supplied to the cavity C through the runner W2 and further on.

[0021] Each sand mold has a vertical wall Sv rising from the bottom surface Sb, which is continued by a gently sloping side surface Ss toward the mold mating surface Sm. The vertical wall Sv is used for lateral alignment during cutting, which will be described later. The gently sloping surface Ss is provided to provide a draft angle to make it easier to remove the sand mold from the molding die, and also to facilitate gripping by the gripping arms, which will be described later, and to prevent the lateral alignment surface from protruding sideways and becoming damaged. This basic structure is the same for sand blocks.

[0022] The upper and lower mold mating surfaces are provided on the upper and lower molds, respectively. By using the upper and lower mold mating surfaces SmU and SmL to grasp the Z-axis positions at at least three points PU1-3 and PL1-3 that are not on the same line, the upper and lower mold mating surfaces SmU and SmL can be kept parallel to each other and mold mating can be performed. By providing these three points PU1-3 and PL1-3 near the corners of the upper and lower molds, respectively, interference with the cavity C can be prevented, and the distance between each point is increased, so that the inclination of the upper and lower mold mating surfaces SmU and SmL can be obtained more accurately.

[0023] The lateral posture and position of the upper and lower dies in die alignment are grasped and corrected by the lateral alignment surfaces. The X-axis lateral alignment surfaces SUWX1, SLNX2 for grasping the displacement in the X-axis direction are surfaces along the Y-axis. Similarly, the Y-axis lateral alignment surfaces SUWY1, SLNY2 for grasping the displacement in the X-axis direction are surfaces along the X-axis. Also, the lateral alignment surfaces on the left side of the paper in Figures 6 to 9 are wider than the lateral alignment surfaces on the right side. As an example, the left side is 55 mm and the right side is 35 mm, but this is not limited to this. Therefore, the former are represented as wide lateral alignment surfaces SUW, SLW with the third letter W, and the latter are represented as narrow lateral alignment surfaces SUN, SLN with the third letter N.

[0024] The wide and narrow lateral alignment surfaces are formed to match the upper and lower dies so that the orientation of the upper and lower dies is not mistaken. In Fig. 8, the wide alignment surface is on the left and the narrow alignment surface is on the right, and both are arranged so that the wide and narrow surfaces face each other diagonally. With this arrangement, if the overlapping direction of the upper and lower dies is incorrect, the error will be immediately detected on the alignment surface. The judgment can be made visually or automatically by image recognition.

[0025] According to the above notation, the X-axis lateral positioning surfaces are SUWX1, SLNX2, and the Y-axis lateral positioning surfaces are SUWY1, SLNY2. As an example, the notation would be an upper wide first X-axis lateral positioning surface SUWX1, and a lower narrow second Y-axis lateral positioning surface SLNY2.

[0026] Next, the contents of each process and the manufacturing equipment used therein will be explained in order. First, as shown in Fig. 2, the molding equipment 110 used in the molding process ST100 includes a molding die 111, a compression plate 112, a lower plate 113, and a molding sand injection device and a compression device capable of vibration (not shown). The molding die 111 is used for the upper block BU and the lower block BL, but the lower plate 113 is provided with only the alignment pin 113b in common, and the gate die 113a is provided only for the upper block BU. By sharing the die between the upper block BU and the lower block BL as much as possible, molding errors are reduced. Furthermore, by providing the gate die 113a, the amount of cutting of the sand mold is reduced, and it is not necessary to perform reverse cutting to cut the gate from the back side, so the number of steps in manufacturing the sand mold is reduced.

[0027] 3, the cutting equipment 120 used in the cutting process ST200 includes a cutting robot 121, a base floor 124, a mounting surface 125, and a positioning piece 126. The cutting robot 121 has an articulated arm 121b on a base stand 121a connected to the base floor 124 and the mounting surface 125, and can freely move a processing head 122 that rotates a tool 123 such as a cutting bit in the XYZ directions.

[0028] The origin O of the coordinate axis is set in accordance with the positioning piece 126 of the mounting surface 125. In the figure, for ease of understanding, the origin O is set on the mounting surface 125 at the intersection of the extension of the X-axis positioning piece 126X, which performs positioning in the X-axis direction along the Y-axis, and the extension of the Y-axis positioning piece 126Y, which performs positioning in the Y-axis direction along the X-axis. Each sand mold has a vertical wall portion Sv rising from the bottom surface Sb, and by abutting both the positioning piece 126 and the pressing piece 127, the lateral position of the sand block is aligned with the origin O, and the amount of cutting is minimized. Specifically, the vertical wall portion Sv is fixed and supported by both one X-axis positioning piece 126X and two Y-axis positioning pieces 126Y, and the X-axis pressing piece 127X and the Y-axis pressing piece 127Y are brought close to and into contact with the vertical wall portion Sv on the opposite side of each side to regulate the inclination in the XY direction.

[0029] Regarding the cutting order, if the lower mold ML is cut first, and then the upper mold MU is cut, it is advantageous in terms of reducing the number of steps, since in the later mold mating process, the upper mold MU can be directly inserted into the mold after being cleaned, but the cutting order is not limited to this. Regarding the cutting of each part, it is preferable to first cut the mold mating surfaces SmU, SmL for each sand block BU, BL, and then cut the lateral positioning surfaces SU, SL, cavity C, runner W2, etc. This is because cutting based on the mold mating surfaces SmU, SmL allows the entire cavity C, runners W2, W3, etc. to be accurately formed, and also ensures reliable lateral alignment.

[0030] The mold joining equipment 130 used in the lower mold cleaning process ST310, the upper mold cleaning process ST330, and the upper and lower mold joining process ST350 is equipped with a mold joining robot 131, an air cleaning booth 133, a foundation floor 134, a mounting surface 135, a first coordinate measuring sensor 136, and a second coordinate measuring sensor 137, as shown in Figures 4 and 5.

[0031] The mold mating robot 131 has a gripping arm 132 attached to the tip of an arm 131b, the tip of which can be freely moved in three dimensions on a base 131a. The gripping arm 132 can grip the sand mold M between a pair of opposing gripping surfaces 132a by moving a pair of gripping pieces close to and away from each other. Unlike the vertical wall portion Sv, the side surface Ss of the sand mold M has a taper that approaches the opposing surface as it approaches the mold mating surface Sm. The gripping surface 132a also has a similar taper, and in particular, by bringing the gripping surface 132a into contact with the side surface Ss as shown in Figure 5 with the mold mating surface Sm of the upper mold MU facing downward, it is possible to prevent the upper mold MU from being displaced downward.

[0032] The air cleaning booth 133 is used to clean cutting debris such as sand grains that adhere to the sand mold M, and the cutting debris is blown away and cleaned using airflow from an air nozzle 133b having multiple air holes provided below the air cleaning chamber 133a.

[0033] The mold matching robot 131 and the placement surface 135 are provided on a foundation floor 134, and further, a first coordinate measuring sensor 136 is provided on the gripping arm 132, and a second coordinate measuring sensor (another coordinate measuring sensor) 137 is provided on the foundation floor 134. The first and second coordinate measuring sensors 136, 137 grasp the spatial coordinates of the object they contact on the XYZ coordinate axes by their detection pieces 136a, 137a, respectively. The coordinate positions of each surface Sm, SU, SL of the sand mold M on the placement surface 135 are grasped by the first coordinate measuring sensor 136 of the gripping arm 132, and the coordinate positions of the sand mold M grasped by the gripping arm 132 are grasped by the second coordinate measuring sensor 137 on the foundation floor 134.

[0034] In this facility, after the lower mold cleaning step ST310 and the upper mold cleaning step ST330, the above-mentioned coordinate determination is performed in each of these steps, and the upper and lower mold combining step ST350 is performed based on the results. The upper mold cleaning step ST330 is similar to the lower mold cleaning step ST310, so only the differences will be described below.

[0035] In the lower mold cleaning step ST310, first, the lower mold ML after the cutting step is placed with the mold mating surface Sm facing up on any one of the first to third mounting surfaces 135a-c among the mounting surfaces 135. Then, the detection piece 136a of the first coordinate measuring sensor 136 measures the positions of the multiple lateral positioning surfaces SL, and the lower mold ML is gripped by the gripping arm 132 and rotated in an inversion axis parallel to the X-axis to enter the air cleaning chamber 133a of the air cleaning booth 133, where the air nozzle 133b blows an air flow from below against the cavity C side to perform cleaning.

[0036] Thereafter, the mold mating surface Sm is turned up again around the inversion axis and placed on any one of the first to third placement surfaces 135a to 135c among the placement surfaces 135. Then, the positions of the mold mating surface Sm and the lateral position mating surface SL are measured by the detection piece 136a of the first coordinate measuring sensor 136 of the gripping arm 132 as described later, and the mold mating is performed.

[0037] In the upper mold cleaning step ST330, the process up to the cleaning is similar, but the following points are different: With the mold mating surface Sm facing downward, the upper mold MU held by the holding arm 132 is brought close to the detection piece 137a of the second coordinate measuring sensor 137 on the base floor 134, and the positions of the mold mating surface Sm and the lateral position mating surface SL are measured as described below, and mold matching begins.

[0038] For the mold mating surface Sm, as shown in Figures 7 and 8, the Z coordinates of at least three points PU1 to 3 that are not located on the same line are recognized at the upper mold mating surface SmU. Similarly, the Z coordinates of at least three points PL1 to 3 that are not located on the same line are recognized at the lower mold mating surface SmL. Even if a different lateral position is selected, the posture of the upper side MU is adjusted by the mold mating robot 131 as shown in Figure 9 described later so that the inclination of the lower mold mating surface SmL and the inclination of the upper mold mating surface SmU are parallel to each other, and the two mold mating surfaces SmU and SmL are brought into close proximity and joined.

[0039] 7 and 8, two Y-axis lateral positioning surfaces SUWY1, SUWY2, SLWY1, SLWY2 and one X-axis lateral positioning surface SUNX1, SLNX1 are measured for each of the upper and lower molds MU, ML. Then, the posture of the upper mold MU is adjusted by the mold mating robot 131 so that the positions of the respective positioning surfaces coincide with the lower mold ML, and the mold mating surfaces SmU, SmL are brought into close proximity and joined.

[0040] If it is only necessary to align the lateral positions, one X-axis and one Y-axis lateral positioning surface each will suffice for the upper and lower molds MU and ML. However, by measuring two Y-axis lateral positioning surfaces SUWY1, SUWY2, SLWY1, and SLWY2 at positions spaced apart from each other, it is possible to correct the inclination around an axis parallel to the Z-axis.

[0041] Regarding the sign of the coordinates of the mold fitting, the position and posture of the Xl, Yl, Zl coordinate axes defined by the side surface of the lower mold ML and the mold fitting surface SmL shown in Fig. 9(a) are measured with respect to the XYZ coordinate axes shown by the dashed line of the mold fitting equipment 130 by measuring the horizontal position fitting surfaces SLWX1, SLWY1, SLWY2 of the lower mold ML and three points PL1-3 on the lower mold fitting surface SmL in Fig. 7 and 8. Similarly, the position and posture of the Xu, Yu, Zu coordinate axes defined by the side surface of the upper mold MU and the mold fitting surface SmU shown in Fig. 9(a) are measured with respect to the XYZ coordinate axes shown by the dashed line (-Z is a vector indicating the negative direction of Z, and -Zl is a vector indicating the negative direction of Zl, and are substantially the same).

[0042] Thereafter, the position and posture of the gripping arm 132 of the mold matching robot 131 is adjusted, and the posture is adjusted and brought close so that the Xl, Yl, Zl coordinate axes coincide with the Xu, Yu, Zu coordinate axes, thereby matching the coordinates and enabling accurate mold matching.

[0043] In addition, as a horizontal coordinate check, after the mold alignment, one Y-axis horizontal alignment surface SUNY2, SLNY2 and one X-axis horizontal alignment surface SUNX2, SLNX2 are measured for each of the upper and lower molds MU, ML as shown in Figures 7 and 8. By matching these coordinates for the top and bottom, the accuracy of the mold alignment can be checked.

[0044] After the above-mentioned matching process, the mold M is sent to the well-known pouring process. Molten metal is poured from the gate W1 side, and the casting is completed.

[0045] Finally, another embodiment of the present invention will be described. The present invention is not limited to the above and following embodiments, and can be modified without departing from the spirit of the present invention. In the following description, the same reference numerals will be used to designate the same components as those in the above embodiment.

[0046] The X, Y and Z axes do not necessarily have to be arranged at 90 degrees to each other, but if they are arranged at 90 degrees, it is convenient to grasp the coordinates. If the crossing angle of the lateral alignment surface and the crossing angle of the X and Y axes are the same, alignment can be achieved by grasping the coordinates in only the single axial direction of the X or Y axis.

[0047] The XYZ coordinate axes can be appropriately converted by a known method to grasp the position, which makes it easy to control the mold alignment. For example, in the mold mating step ST300, if the lower mold mating surface SmL is not parallel to the XY plane, the XY plane can be coordinate-converted from the origin O using the lower mold mating surface SmL as a reference plane, and the vertical axis can be perpendicularly aligned to it to grasp it, so that the upper mold mating surface SmU can be kept parallel to the lower mold mating surface SmL by measuring the above three points in the vertical direction. Similarly, if the plane defined by the lower wide first and second Y-axis horizontal positioning surfaces SLNY1,Y2 is not parallel to the XZ plane, the X-axis and Y-axis coordinates can be converted from the origin O using the plane defined by the lower wide first and second Y-axis horizontal positioning surfaces SLNY1,Y2 as a reference plane to grasp each horizontal positioning surface.

[0048] The above-mentioned selection of the horizontal mating surfaces is merely an example, and the horizontal mating surfaces at any corner may be selected.

[0049] In the above embodiment, sand blocks that are approximately square in plan view are used, but the shape of the sand blocks can be changed as appropriate, such as to a rectangle, a triangle or a polygon with more sides.

[0050] The upper and lower molds each have one continuous surface, but they may be divided into two or more. In the latter case, three points may be measured at one point among the multiple mold mating surfaces, or three points may be measured separately on each of the separate mold mating surfaces. It is sufficient that the parts of the mating surfaces that match are parallel to each other on the upper and lower molds. According to the matching method of FIG. 9, the Z coordinates of at least three points PU1-3, PL1-3 that are not located on the same line do not necessarily have to be selected at the same horizontal coordinates in the upper and lower sand molds. However, if the ratio between the measurement points on the Z coordinates at each part is determined by selecting the parts at the same horizontal coordinates in the upper and lower sand molds, it becomes easy to derive the inclination of the mold mating surfaces SmU and SmL, and the control parameters during mold matching are also simplified.

[0051] Of the three points PU1-3 and PL1-3 that are not located on the same line, four or more points may be measured for each. The upper and lower mating surfaces may be estimated by a mathematical or geometrical method, such as measuring four or more points to estimate the surface and eliminating points that may be in error, and the upper and lower mating surfaces may be approximated while maintaining parallelism, and the method is not limited to the method of matching coordinates shown in FIG. 9. [Industrial Applicability]

[0052] The present invention can be used as a method for manufacturing a casting mold. It is particularly suitable for small-lot production of a wide variety of products, and can provide a casting mold with small dimensional error. [Explanation of symbols]

[0053] 100: processing equipment, 101: robot, 110: molding equipment, 111: molding mold, 112: compression plate, 113: lower plate, 113a: sprue mold, 113b: alignment pin, 120: cutting equipment, 121: cutting robot, 121a: base, 121b: arm, 122: processing head, 123: tool, 124: base floor, 125: mounting surface, 126: alignment piece, 126X: X-axis alignment piece, 126Y: Y-axis alignment piece, 127: pressing piece, 127X: X-axis pressing piece, 127Y: Y-axis pressing piece, 130: mold fitting equipment, 131: mold fitting robot, 131a: base, 131b: arm, 132: gripping arm, 132a: gripping surface, 133: air cleaning booth, 133a: air cleaning room, 133b: air nozzle, 134: base floor, 135: placement surface, 135a to c: first to third placement surfaces, 136: first coordinate measuring sensor, 136a: detection piece, 137: second coordinate measuring sensor (another coordinate measuring sensor), 137a: detection piece B: sand block, BU: upper block, BL: lower block, M: sand mold, MU: upper mold, ML: lower mold, SmU: upper mold mating surface, SmL: lower mold mating surface, O: XYZ origin (reference of spatial coordinates), Z axis (vertical axis), XY axis (horizontal axis) perpendicular to the Z axis, C: cavity, C1: upper cavity, C2: lower cavity, W1: sprue, W2: runner, W3: runner (drop), SU, SL: lateral position mating surface, SU: upper lateral position mating surface, SL: lower lateral position mating surface, Ss: side surface, Sv: vertical wall, Sb: bottom surface, SUW, SLW: Wide lateral positioning surface, SUN, SLN: Narrow lateral positioning surface, SUWX1, SLNX2: X-axis lateral positioning surface, SUWY1, SLNY2: Y-axis lateral positioning surface, SUWX1: (Example) Upper wide first X-axis lateral positioning surface, SLNY2: (Example) Lower narrow second Y-axis lateral positioning surface, PU1~3, PL1~3: at least three points that are not on the same line, ST001: All manufacturing processes, ST100: Molding process, ST110: Lower molding process, ST130: Upper molding process, ST200: Cutting process, ST210: Lower mold cutting process, ST230: Upper mold cutting process, ST300: Mold assembly process, ST310: Lower mold cleaning process, ST330: Upper mold cleaning process, ST350: Upper and lower mold assembly process

Claims

1. A method for manufacturing a casting mold, comprising the steps of kneading molding sand and a binder, filling and pressurizing the mixture into a formwork, hardening the mixture in the formwork, removing the mixture from the formwork to prepare a sand block, and then manufacturing a sand mold by a cutting step and a mold joining step, A processing head is operated by a robot to cut the sand block and cut the upper and lower molds; a gripping arm operated by a robot to grip the upper mold and align the mold mating surfaces where the cavities are formed in the upper and lower molds; a coordinate measuring sensor that detects coordinates by bringing at least the upper mold held by the holding arm into contact with a detection piece, The side surfaces of the sand mold have a slope such that they approach each other toward the opposing surfaces as they approach the mold mating surface, The gripping surface of the gripping arm also has a slope similar to that of the side surface of the sand mold, The Z axis defining the Z coordinate is oriented in the up-down direction; In the cutting step, the processing head cuts and forms a mold mating surface on each of the upper and lower molds, and cuts and forms the cavity on each of the upper and lower molds based on the same mold mating surface, In the mold mating process, at least three points that are not located on the same straight line on the mold mating surface of the lower mold placed on the mounting surface are measured to determine the Z coordinates of each point, and at least three points that are not located on the same straight line on the mold mating surface of the upper mold held by the gripping arm with the gripping surface in contact with the side surface are measured to determine the Z coordinates of each point, and then the mold is mated using the gripping arm in a position where the mold mating surfaces of the upper and lower molds are kept parallel.

2. 2. A method for manufacturing a mold as described in claim 1, wherein the cutting step has an XY coordinate system that defines a lateral direction with an XY axis perpendicular to the Z axis, and the machining head cuts and forms at least two lateral alignment surfaces oriented at an intersection angle of the XY axes near the mating surfaces of the upper and lower molds in the cutting step, and in the mating step, the XY coordinates of each of the lateral alignment surfaces of the upper and lower molds are recognized, and the lateral positions of the upper and lower molds are matched to perform mold alignment using the gripping arm.

3. 3. The method of claim 2, wherein at least one of said at least two lateral mating surfaces is provided at two or more locations spaced apart from each other.

4. 4. The method for manufacturing a mold according to claim 3, wherein the sand blocks constituting the upper and lower molds each have a convex polygonal shape in a plan view, and the lateral mating surfaces are formed at corners of the convex polygon.

5. 5. A method for manufacturing a casting mold as described in claim 4, wherein the convex polygon is a rectangle, and the lateral positioning surfaces have different cutting lengths at adjacent corners and opposing corners of the rectangle, and are formed to have the same cutting length in the upper and lower molds.

6. 3. A method for manufacturing a mold as described in claim 2, wherein in addition to the two lateral alignment surfaces, at least two other lateral alignment surfaces that are machined by the robot near the mating surfaces of the upper and lower molds and are not all parallel to each other are provided, and the mold alignment is confirmed by recognizing the XY coordinates of two points on the other lateral alignment surfaces of the upper and lower molds, respectively.

7. 3. A method for manufacturing a mold as described in claim 2, wherein, during cutting by the robot, the upper side of the sand block is the constituent surface of the cavity, and the side surface of the sand block near the lower surface has a vertical wall portion, and a positioning piece is abutted against this vertical wall portion to serve as a reference for the horizontal coordinate of the cutting by the robot.

8. A method for manufacturing a mold as described in any one of claims 1 to 7, wherein the gripping arm is provided with a coordinate measuring sensor which measures coordinates by contacting the detection piece, and after the lower mold is placed on a support surface on which the lower mold is placed, the coordinate measuring sensor is used to recognize each of the coordinates of the lower mold placed on the support surface, and another coordinate measuring sensor is provided at a location connected to the support surface on which the lower mold is placed, and this other coordinate measuring sensor is used for the upper mold gripped by the gripping arm to recognize each of the coordinates of the upper mold in the gripped state.

Images