A profiled drill jig and positioning method for composite vehicle body drilling

Abstract

The application discloses a profiling drill jig and positioning method for composite vehicle body drilling, and the profiling drill jig comprises an L-shaped profiling fixing base and a strip-shaped drill jig. When the profiling drill jig is installed, the L-shaped profiling fixing base is arranged on a side beam so that a transverse installation part is attached to the bottom of the side beam, and a vertical supporting part and an outer side surface of a side wall are attached, then a first fastener is arranged on the transverse installation part and the bottom of the side beam to fix the L-shaped profiling fixing base, then the strip-shaped drill jig is arranged on a drill jig fixing groove, and finally the drill jig is pressed on the side wall. After the strip-shaped drill jig is fixed, drilling work can be performed. The L-shaped profiling fixing base can effectively improve the fixing stability of the strip-shaped drill jig, thereby improving the drilling precision.

Description

Technical Field

[0001] The present invention relates to the technical field of rail vehicles, and in particular to a profile drilling jig and a positioning method for making holes in composite vehicle bodies. Background Art

[0002] During assembly of a rail vehicle's composite body, for example, when connecting the side walls and chassis, rivets are required. After the side walls and chassis are assembled, manual drilling is required. The two layers of panels are drilled to a specific depth through the base hole, and then countersunk holes are prepared using a countersink drill bit and a depth setting device. This manual drilling process presents at least the following issues:

[0003] 1. Manual drilling is done on the vertical surface, which is not easy to meet the verticality requirements.

[0004] 2. The speed and feed rate of manual drilling are manually controlled. Under the condition of large-scale continuous operation, the consistency of hole making accuracy is difficult to ensure.

[0005] 3. After the through hole preparation is completed, the countersink drill bit needs to be replaced for secondary drilling. During manual operation, it is not easy to ensure the consistency of the two drillings.

[0006] 4. Since the inner cavity of the aluminum alloy side beam is a closed cavity, the cutting chips generated during the drilling process are not easy to be cleaned.

[0007] Therefore, how to improve the hole-making accuracy of composite vehicle bodies is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0008] One object of the present invention is to provide a profiled drilling jig for composite lathe hole making, and another object is to provide a positioning method for composite lathe hole making, which can effectively improve the hole making accuracy.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A profiled drilling jig for drilling holes in a composite vehicle body, wherein the composite vehicle body comprises side beams and side walls, wherein the lower ends of the side walls are located above the outer sides of the side beams, and the profiled drilling jig comprises:

[0011] An L-shaped fixing seat, the L-shaped fixing seat comprising a transverse mounting portion and a vertical support fixing portion, the transverse mounting portion being used to be connected to the bottom of the side beam via a first fastener, the vertical support fixing portion being provided with a profiled support portion on a side facing the outer side of the side beam, the profiled support portion being used to fit together with the outer side of the side beam, and a jig fixing groove being provided on the upper end of the vertical support fixing portion and on a side facing the side wall;

[0012] A strip drill jig, wherein the strip drill jig is provided with a plurality of drill tool fixing holes distributed along its length, the drill jig fixing groove is used to accommodate the strip drill jig, and the strip drill jig is used for an automatic feed drill to drill holes one by one on the side beam and the side wall;

[0013] A second connecting hole extending in the horizontal direction is provided on the upper portion of the vertical support fixing portion, and the second connecting hole is used for a second fastener to pass through, and the second fastener is used to press the strip drill template onto the side wall.

[0014] In some embodiments, a surface of the contoured support portion facing the outer side surface of the side beam is an arc-shaped convex surface.

[0015] In some embodiments, a groove is provided between the transverse mounting portion and the contoured support portion, and the groove is used to accommodate the outer eaves of the side beam extending obliquely downward.

[0016] In some embodiments, the imitation drill jig further includes a drill jig positioning pin, a base hole is provided on the side wall, and the drill jig positioning pin is used to position the strip drill jig on the side wall through the base hole.

[0017] In some embodiments, the drill tool fixing hole is a countersunk hole, and the outer periphery of the drill jig positioning pin is provided with a step surface that cooperates with the countersunk hole.

[0018] In some embodiments, the head of the jig locating pin is provided with a locating protrusion, and the locating protrusion is used to be placed in the base hole. The tail of the jig locating pin is provided with a pull rod, and the pull rod is located outside the drill tool fixing hole.

[0019] In some embodiments, a keyhole is provided at the bottom of the side beam, and a convex pressing block is provided at the upper end of the first fastener, and the convex pressing block is used to be inserted into the keyhole to fix the L-shaped fixing seat.

[0020] In some embodiments, the upper surface of the transverse mounting portion is provided with a receiving groove for accommodating the convex pressure block, and the transverse mounting portion is also provided with a first connecting hole for the first fastener to pass through, and the first connecting hole and the receiving groove are connected to each other.

[0021] In some embodiments, a second connection hole extending in the horizontal direction is provided on the upper portion of the vertical support fixing portion, and the second connection hole is used for a second fastener to pass through, and the second fastener is used to press the strip drill template onto the side wall.

[0022] A positioning method for making holes in composite turning systems, using any of the above-described profiled drilling jigs for making holes in composite turning systems, the positioning method comprising the following steps:

[0023] Fix the L-shaped fixing seat to the side beam so that the horizontal mounting portion of the L-shaped fixing seat is in contact with the bottom of the side beam, and the vertical support fixing portion of the L-shaped fixing seat is in contact with the outer side of the side beam, and fix the horizontal mounting portion to the bottom of the side beam using a first fastener;

[0024] Placing the strip drill template on the drill template fixing groove of the vertical support fixing portion, and pressing the strip drill template against the side wall;

[0025] The drill bits of the automatic feed drill are inserted into the drill tool fixing holes of the strip drill jig one by one to drill holes in the side beam and the side wall one by one.

[0026] Compared with the existing technology, the above technical solution has the following advantages:

[0027] The present invention provides a profiled drilling jig and positioning method for drilling holes in composite materials. The profiled drilling jig comprises an L-shaped fixing base and a strip drilling jig. During installation, the L-shaped fixing base is placed on the side beam so that the transverse mounting portion is aligned with the bottom of the side beam and the vertical support portion is aligned with the outer side of the side wall. A first fastener is then inserted through the transverse mounting portion and the bottom of the side beam to secure the L-shaped fixing base. The strip drilling jig is then placed in the jig fixing groove and finally pressed against the side wall. After the strip drilling jig is secured, drilling can be performed. The L-shaped fixing base can effectively improve the fixing stability of the strip drilling jig, thereby improving drilling accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 A schematic diagram of a partial structure of a composite vehicle body provided by a specific embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a profiled drilling jig for making holes in composite materials provided by a specific embodiment of the present invention;

[0031] Figure 3 It is a structural diagram of the L-shaped fixing seat;

[0032] Figure 4 Schematic diagram of the structure of the strip drill template;

[0033] Figure 5This is a schematic diagram of the structure when the L-shaped fixing seat is placed on the side beam;

[0034] Figure 6 This is a schematic diagram of the structure when the L-shaped fixing seat is fixed on the side beam;

[0035] Figure 7 This is a schematic diagram of the three-dimensional structure when the L-shaped fixing seat is fixed on the side beam;

[0036] Figure 8 This is a schematic diagram of the structure after the L-shaped fixing seat and the strip drilling template are assembled;

[0037] Figure 9 It is a cross-sectional view of the strip drilling jig when it is positioned on the side wall by the positioning pins;

[0038] Figure 10 This is a structural diagram of an automatic feed drill when drilling with a countersink drill bit;

[0039] Figure 11 This is a flow chart of the drill and countersink drill bit during drilling;

[0040] Figure 12 It is a structural diagram of a drill bit with integrated drilling and countersinking function.

[0041] The reference numerals are as follows:

[0042] 100-side beam;

[0043] 200-side wall, 201-base hole;

[0044] 10-L-shaped fixing seat, 11-horizontal mounting portion, 111-first connecting hole, 112-accommodating groove, 12-vertical support fixing portion, 121-shaped support portion, 122-drilling template fixing groove, 13-groove;

[0045] 20-bar drilling template, 21-drilling tool fixing hole;

[0046] 30-first fastener, 31-convex pressing block;

[0047] 40- second fastener;

[0048] 50-drilling jig locating pin, 51-locating protrusion, 52-pull rod. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] Please refer to Figures 1 to 12 .

[0051] The embodiment of the present invention provides a profiled drilling jig for making holes in a composite car body, comprising: an L-shaped fixing seat 10 and a strip drilling jig 20. The composite car body can be a car body used on a train, which includes a side beam 100 and a side wall 200. Figure 1 As shown, the lower end of the side wall 200 is located at the upper part of the outer side of the side beam 100, and a base hole 201 is provided on the side wall 200. The side beam 100 can be made of aluminum alloy. The interior of the side beam 100 is a closed cavity. The side wall 200 can be made of carbon fiber composite material. The side wall 200 has a plurality of base holes 201 arranged in a straight line. For example, 478 6.6mm countersunk holes need to be prepared at the connection between the side wall 200 and the side beam 100. The countersunk hole spacing at the door frame is 57.15mm, and the countersunk hole spacing in other areas is 50mm. Figure 2 and Figure 3 As shown, the L-shaped fixing seat 10 is L-shaped, specifically including a horizontal mounting portion 11 and a vertical support fixing portion 12. The horizontal mounting portion 11 is used to be connected to the bottom of the side beam 100 through a first fastener 30. The vertical support fixing portion 12 is provided with a profiled support portion 121 on the side facing the outer side of the side beam 100. The profiled support portion 121 is used to fit the outer side of the side beam 100. The upper end of the vertical support fixing portion 12 and the side facing the side wall 200 are provided with a drilling template fixing groove 122. Figure 4 As shown, the strip drill jig 20 is provided with a plurality of drill tool fixing holes 21 distributed along its length. The size and spacing of the drill tool fixing holes 21 can be selected based on the base holes 201 on the side wall 200. For example, a strip drill jig 20 with one spacing can be prepared for the base holes 201 spacing at the door frame location, and a strip drill jig 20 with another spacing can be prepared for the base holes 201 spacing at other locations. The drill jig fixing groove 122 on the L-shaped fixing base 10 is used to accommodate the strip drill jig 20, and the L-shaped fixing base 10 is used to press the strip drill jig 20 against the side wall 200. During installation, the L-shaped fixing base 10 is placed on the side beam 100 so that the horizontal mounting portion 11 is aligned with the bottom of the side beam 100 and the vertical support portion is aligned with the outer surface of the side wall 200. Then, the first fastener 30 is inserted through the horizontal mounting portion 11 and the bottom of the side beam 100 to achieve the fixation of the L-shaped fixing base 10. Then, the strip drill jig 20 is placed on the drill jig fixing groove 122, and finally, the drill jig is pressed against the side wall 200. After the imitation drill jig is fixed, the drilling operation can be carried out. The imitation drill jig can effectively improve the fixing stability of the strip drill jig 20, thereby improving the drilling accuracy.

[0052] In some embodiments, as Figure 3 、 Figure 5 and Figure 6As shown, the side of the profiled support portion 121 facing the outer side of the side beam 100 is an arc-shaped convex surface, and the structure of the arc-shaped convex surface matches the outer side of the side beam 100. Therefore, the arc-shaped convex surface can improve the fit tightness with the outer side of the side beam 100, thereby ensuring the connection stability between the profiled support portion 121 and the side beam 100.

[0053] In some embodiments, as Figure 3 、 Figure 5 and Figure 6 As shown, a groove 13 is provided between the transverse mounting portion 11 and the contoured support portion 121. This groove 13 is designed to accommodate the obliquely downwardly extending outer edge of the side beam 100. Specifically, the inner surface of the L-shaped fixture 10 mates with the bottom and side surfaces of the side beam 100, further enhancing the stability of the L-shaped fixture 10. During installation, the fixture 10 can be pushed upward along the outer edge, causing the groove 13 of the L-shaped fixture 10 to engage with the outer edge.

[0054] In some embodiments, as Figure 8 As shown, the imitation drill jig further includes a drill jig locating pin 50. A base hole 201 is provided on the side wall 200. A plurality of base holes 201 can be provided on the side wall 200 distributed along a straight line. The drill tool fixing holes 21 on the strip drill jig 20 correspond one-to-one with the base holes 201 on the side wall 200. When positioning the strip drill jig 20, two of the base holes 201 can be selected for positioning. A drill jig locating pin 50 can be inserted into one of the drill tool fixing holes 21 on the strip drill jig 20. At the same time, the head of the drill jig locating pin 50 is inserted into the base hole 201 on the side wall 200. This allows the strip drill jig 20 to be positioned on the side wall 200. The drill jig locating pin 50 can effectively improve the positioning accuracy of the strip drill jig 20.

[0055] In some embodiments, the drill fixing hole 21 is a countersunk hole, and the outer periphery of the jig positioning pin 50 is provided with a stepped surface that cooperates with the countersunk hole, such as Figure 9 As shown, the outer diameter of the left section on the outer periphery of the drill jig locating pin 50 is smaller than the outer diameter of the right section. The step surface can play an axial limiting role on the strip drill jig 20 to ensure the positioning stability of the strip drill jig 20.

[0056] In some embodiments, as Figure 9 As shown, the left end of the drill jig locating pin 50 is the head, and the right end is the tail. The head of the drill jig locating pin 50 is provided with a positioning protrusion 51. The outer diameter of the positioning protrusion 51 is adapted to the inner diameter of the base hole 201 on the side wall 200. The positioning protrusion 51 is used to be placed in the base hole 201 to position the strip drill jig 20. The tail of the drill jig locating pin 50 is provided with a pull rod 52. The pull rod 52 is located outside the drill tool fixing hole 21. The pull rod 52 facilitates pulling out the drill jig locating pin 50.

[0057] In some embodiments, a keyhole is provided at the bottom of the side beam 100, and the keyhole is used to install a hanging part. In this embodiment, the keyhole can be used to fix the L-shaped fixing seat 10, wherein the upper end of the first fastener 30 is provided with a convex pressing block 31, which is used to be inserted into the keyhole to fix the L-shaped fixing seat 10. Figure 5 As shown, first place the L-shaped fixing seat 10 on the side beam 100 so that the convex pressing block 31 corresponds to the keyhole; Figure 6 As shown, the L-shaped fixing base 10 and the side beam 100 can be fixed by inserting the convex pressing block 31 into the keyhole through the first fastener 30. After drilling is completed, the first fastener 30 can be moved downward to remove the convex pressing block 31 from the keyhole, thereby releasing the fixed relationship between the L-shaped fixing base 10 and the side beam 100.

[0058] In some embodiments, as Figure 3 and Figure 5 As shown, the upper surface of the transverse mounting portion 11 is provided with a receiving groove 112 for accommodating the convex pressure block 31. When the L-shaped fixing base 10 is placed on the side rail 100, the upper surface of the convex pressure block 31 is not higher than the upper surface of the transverse mounting portion 11, ensuring a tight fit between the upper surface of the transverse mounting portion 11 and the lower surface of the side rail 100. The transverse mounting portion 11 is also provided with a first connecting hole 111 for the first fastener 30 to pass through. The first connecting hole 111 and the receiving groove 112 are interconnected, and the first fastener 30 can be a bolt. To improve the stability of the connection, the transverse mounting portion 11 can be fixed to the bottom of the side rail 100 using two first fasteners 30.

[0059] In some embodiments, as Figure 5 and Figure 6 As shown, the upper part of the vertical support fixing portion 12 is provided with a second connecting hole extending in the horizontal direction. When the strip drill jig 20 is positioned on the side wall 200 by the drill jig positioning pin 50, the second fastener 40 is passed through the second connecting hole. The second fastener 40 can press the strip drill jig 20 onto the side wall 200 through its axial force to improve the stability of the strip drill jig 20 when it is attached to the side wall 200.

[0060] An embodiment of the present invention further provides a positioning method for a hole in a composite lathe. Using the profiled drilling jig for a hole in a composite lathe provided in any of the above embodiments, the positioning method includes the following steps:

[0061] Installation of the L-shaped fixing base 10: Secure the L-shaped fixing base 10 to the side rail 100 so that its transverse mounting portion 11 aligns with the bottom of the side rail 100 and its vertical support mounting portion 12 aligns with the outer side of the side rail 100. Secure the transverse mounting portion 11 to the bottom of the side rail 100 using the first fastener 30. Two L-shaped fixing bases 10 can be secured to the side rail 100.

[0062] Installation of the strip jig 20: Place the strip jig 20 in the jig fixing slot 122 of the vertical support fixing portion 12 and press the strip jig 20 against the side wall 200. One end of the strip jig 20 can be secured by one of the L-shaped fixing seats 10, and the other end can be secured by the other L-shaped fixing seat 10. Before securing, the strip jig 20 can be positioned using two jig locating pins 50, and then the second fastener 40 can be used to press the strip jig 20 against the side wall 200.

[0063] Hole making and countersinking: The drill bits of the automatic feed drill are inserted into the drill fixing holes 21 of the bar drill jig 20 one by one to drill holes on the side beam 100 and the side wall 200 one by one. The expansion clamping function of the automatic feed drill can be used to fix it in the drill fixing hole 21, and its automatic feeding function can be used to complete the through hole processing and countersinking processing at one time, which can effectively ensure the drilling quality. Figure 10 and Figure 11 As shown, since the drill and countersink integrated drill bit of the automatic feed drill is used for drilling, the automatic cleaning drilling function can be utilized to clean the drill chips while making the hole, preventing the drill chips from entering the closed cavity in the side beam 100.

[0064] Parameter design and description of drilling and countersinking drill bit: Figure 11As shown, the drill and countersink bit is a solid carbide drill and countersink, with specifications of D6.6×15×100°×D14×75×D10. The structure to be drilled is a carbon fiber composite sidewall on the upper layer and an aluminum alloy side beam on the lower layer. The carbon fiber composite sidewall has a 5.5mm diameter base hole. During the hole making process, the rivet hole is prepared mainly by drilling and cutting slightly and then expanding the hole to 6.6mm. The lower plate has no base hole, so it is drilled to 6.6mm. After drilling is completed, a 100° countersink (also known as a countersink) is drilled in the upper plate. When preparing through holes, the drilling of aluminum alloy materials is the main method, and the drilling of carbon fiber materials is auxiliary. Therefore, when setting the top angle, priority is given to the fact that when drilling aluminum alloy metal materials, the surface hardening degree is high, the cutting temperature is high, and the tool is surrounded by the hole walls on all sides of the metal material. Selecting a larger top angle can improve the heat dissipation conditions and reduce thermal damage to the composite material. At the same time, a larger top angle can also increase the strength of the drill bit and the cutting edge. Taking into account the small amount of drilling distribution requirements for composite materials, the top angle is set to 125°. The helix angle setting takes into account that during the hole making process, the cut material is pushed toward the spiral surface of the drill bit and pulled up along the spiral surface. This behavior generates an upward peeling force, and the larger the helix angle, the greater the peeling force, which can offset part of the axial force generated during drilling. Excessive helix angles will cause entry peeling and delamination, so the helix angle is set to 30°.

[0065] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0066] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0067] The above describes in detail the profiled drilling jig and positioning method for composite lathe holes provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above examples is intended only to facilitate understanding of the core concepts of the present invention. It should be noted that those skilled in the art may make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A profiled drilling jig for drilling holes in a composite vehicle body, the composite vehicle body comprising a side beam (100) and a side wall (200), wherein the lower end of the side wall (200) is located above the outer side surface of the side beam (100), characterized in that: include: An L-shaped fixing seat (10), the L-shaped fixing seat (10) comprising a transverse mounting portion (11) and a vertical support fixing portion (12), the transverse mounting portion (11) being used to be connected to the bottom of the side beam (100) via a first fastener (30), the vertical support fixing portion (12) being provided with a profiled support portion (121) on a side facing the outer side of the side beam (100), the profiled support portion (121) being used to fit together with the outer side of the side beam (100), and a jig fixing groove (122) being provided on an upper end of the vertical support fixing portion (12) facing the side wall (200); A strip drill jig (20), wherein the strip drill jig (20) is provided with a plurality of drill tool fixing holes (21) distributed along its length direction, the drill jig fixing groove (122) is used to accommodate the strip drill jig (20), and the strip drill jig (20) is used for an automatic feed drill to drill holes one by one on the side beam (100) and the side wall (200); A second connection hole extending in the horizontal direction is provided on the upper portion of the vertical support fixing portion (12), the second connection hole being used for a second fastener (40) to pass through, and the second fastener (40) being used to press the strip drill template (20) onto the side wall (200).

2. The profiled drilling jig for making holes in composite materials according to claim 1, characterized in that: A surface of the contoured support portion (121) facing the outer side surface of the side beam (100) is an arc-shaped convex surface.

3. The profiled drilling jig for making holes in composite materials according to claim 2, characterized in that: A groove (13) is provided between the transverse mounting portion (11) and the contoured support portion (121), and the groove (13) is used to accommodate the outer edge of the side beam (100) that extends obliquely downward.

4. The profiled drilling jig for making holes in composite materials according to claim 1, characterized in that: The imitation drilling jig further comprises a drilling jig positioning pin (50), a plurality of base holes (201) are provided on the side wall (200), and the drilling jig positioning pin (50) is used to position the strip drilling jig (20) on the side wall (200) through the base holes (201).

5. The profiled drilling jig for making holes in composite materials according to claim 4, characterized in that: The drilling tool fixing hole (21) is a countersunk hole, and the outer periphery of the drilling jig positioning pin (50) is provided with a stepped surface that cooperates with the countersunk hole.

6. The profiled drilling jig for making holes in composite materials according to claim 5, characterized in that: The head of the jig locating pin (50) is provided with a locating protrusion (51), and the locating protrusion (51) is used to be placed in the base hole (201). The tail of the jig locating pin (50) is provided with a pull rod (52), and the pull rod (52) is located outside the drilling tool fixing hole (21).

7. The profiled drilling jig for making holes in composite materials according to claim 1, characterized in that: A keyhole is provided at the bottom of the side beam (100), and a convex pressing block (31) is provided at the upper end of the first fastener (30). The convex pressing block (31) is used to be inserted into the keyhole to fix the L-shaped fixing seat (10).

8. The profiled drilling jig for making holes in composite materials according to claim 7, characterized in that: The upper surface of the transverse mounting portion (11) is provided with a receiving groove (112) for receiving the convex pressing block (31), and the transverse mounting portion (11) is further provided with a first connecting hole (111) for the first fastener (30) to pass through, and the first connecting hole (111) and the receiving groove (112) are in communication with each other.

9. A method for positioning holes in composite turning, using the profiled drilling jig for composite turning according to any one of claims 1 to 8, characterized in that: The positioning method comprises the following steps: The L-shaped fixing seat (10) is fixed to the side beam (100) so that the transverse mounting portion (11) of the L-shaped fixing seat (10) is in contact with the bottom of the side beam (100), and the vertical support fixing portion (12) of the L-shaped fixing seat (10) is in contact with the outer side surface of the side beam (100), and the transverse mounting portion (11) is fixed to the bottom of the side beam (100) by a first fastener (30); Placing a strip drill template (20) on the drill template fixing groove (122) of the vertical support fixing portion (12), and pressing the strip drill template (20) onto the side wall (200); The drill bits of the automatic feed drill are inserted into the drill tool fixing holes (21) of the strip drill jig (20) one by one to drill holes on the side beam (100) and the side wall (200) one by one.

Images